/**
* Cyclone Scheme
* https://github.com/justinethier/cyclone
*
* Copyright (c) 2015-2016, Justin Ethier
* All rights reserved.
*
* Heap garbage collector used by the Cyclone runtime for major collections.
*
* Concurrent Mark-Sweep GC algorithm is based on the one from
* "Implementing an on-the-fly * garbage collector for Java", by Domani et al.
*
* Data structures for the heap implementation are based on code from Chibi Scheme.
*
* Note there is also a minor GC (in runtime.c) that collects objects allocated
* on the stack, based on "Cheney on the MTA".
*/
#include <ck_array.h>
#include <ck_pr.h>
#include "cyclone/types.h"
#include <stdint.h>
#include <time.h>
//#define DEBUG_THREADS // Debugging!!!
#ifdef DEBUG_THREADS
#include <sys/syscall.h> /* Linux-only? */
#endif
// 64-bit is 3, 32-bit is 2
#define GC_BLOCK_BITS 5
#define GC_BLOCK_SIZE (1 << GC_BLOCK_BITS)
/* HEAP definitions, based off heap from Chibi scheme */
#define gc_heap_first_block(h) ((object)(h->data + gc_heap_align(gc_free_chunk_size)))
#define gc_heap_last_block(h) ((object)((char*)h->data + h->size - gc_heap_align(gc_free_chunk_size)))
#define gc_heap_end(h) ((object)((char*)h->data + h->size))
#define gc_heap_pad_size(s) (sizeof(struct gc_heap_t) + (s) + gc_heap_align(1))
#define gc_free_chunk_size (sizeof(gc_free_list))
#define gc_align(n, bits) (((n)+(1<<(bits))-1)&(((uintptr_t)-1)-((1<<(bits))-1)))
//#define gc_word_align(n) gc_align((n), 2)
#define gc_heap_align(n) gc_align(n, GC_BLOCK_BITS)
////////////////////
// Global variables
// Note: will need to use atomics and/or locking to access any
// variables shared between threads
static unsigned char gc_color_mark = 5; // Black, is swapped during GC
static unsigned char gc_color_clear = 3; // White, is swapped during GC
static unsigned char gc_color_purple = 1; // There are many "shades" of purple, this is the most recent one
// unfortunately this had to be split up; const colors are located in types.h
static int gc_status_col = STATUS_SYNC1;
static int gc_stage = STAGE_RESTING;
// Does not need sync, only used by collector thread
static void **mark_stack = NULL;
static int mark_stack_len = 0;
static int mark_stack_i = 0;
// Data for the "main" thread which is guaranteed to always be there.
// Per SRFI 18:
// All threads are terminated when the primordial
// thread terminates (normally or not).
static gc_thread_data *primordial_thread = NULL;
/** Data for each individual mutator thread */
ck_array_t Cyc_mutators, old_mutators;
static pthread_mutex_t mutators_lock;
static void my_free(void *p, size_t m, bool d)
{
free(p);
return;
}
static void *my_malloc(size_t b)
{
return malloc(b);
}
static void *my_realloc(void *r, size_t a, size_t b, bool d)
{
return realloc(r, b);
}
static struct ck_malloc my_allocator = {
.malloc = my_malloc,
.free = my_free,
.realloc = my_realloc
};
/** Mark buffers
*
* For these, we need a buffer than can grow as needed but that can also be
* used concurrently by both a mutator thread and a collector thread.
*/
static mark_buffer *mark_buffer_init(unsigned initial_size)
{
mark_buffer *mb = malloc(sizeof(mark_buffer));
mb->buf = malloc(sizeof(void *) * initial_size);
mb->buf_len = initial_size;
mb->next = NULL;
return mb;
}
static void *mark_buffer_get(mark_buffer *mb, unsigned i) // TODO: macro?
{
while (i >= mb->buf_len) {
// Not on this page, try the next one
i -= mb->buf_len;
mb = mb->next;
if (mb == NULL) { // Safety check
// For now this is a fatal error, could return NULL instead
fprintf(stderr, "mark_buffer_get ran out of mark buffers, exiting\n");
exit(1);
}
}
return mb->buf[i];
}
static void mark_buffer_set(mark_buffer *mb, unsigned i, void *obj)
{
// Find index i
while (i >= mb->buf_len) {
// Not on this page, try the next one
i -= mb->buf_len;
if (mb->next == NULL) {
// If it does not exist, allocate a new buffer
mb->next = mark_buffer_init(mb->buf_len * 2);
}
mb = mb->next;
}
mb->buf[i] = obj;
}
static void mark_buffer_free(mark_buffer *mb)
{
mark_buffer *next;
while (mb) {
next = mb->next;
free(mb->buf);
free(mb);
mb = next;
}
}
// END mark buffer
#if GC_DEBUG_TRACE
const int NUM_ALLOC_SIZES = 10;
static double allocated_size_counts[10] = {
0,0,0,0,0,
0,0,0,0,0};
static double allocated_obj_counts[25] = {
0,0,0,0,0,
0,0,0,0,0,
0,0,0,0,0,
0,0,0,0,0,
0,0,0,0,0};
// TODO: allocated object sizes (EG: 32, 64, etc).
static double allocated_heap_counts[4] = {0, 0, 0, 0};
void print_allocated_obj_counts()
{
int i;
fprintf(stderr, "Allocated sizes:\n");
fprintf(stderr, "Size, Allocations\n");
for (i = 0; i < NUM_ALLOC_SIZES; i++){
fprintf(stderr, "%d, %lf\n", 32 + (i*32), allocated_size_counts[i]);
}
fprintf(stderr, "Allocated objects:\n");
fprintf(stderr, "Tag, Allocations\n");
for (i = 0; i < 25; i++){
fprintf(stderr, "%d, %lf\n", i, allocated_obj_counts[i]);
}
fprintf(stderr, "Allocated heaps:\n");
fprintf(stderr, "Heap, Allocations\n");
for (i = 0; i < 4; i++){
fprintf(stderr, "%d, %lf\n", i, allocated_heap_counts[i]);
}
}
void gc_log(FILE *stream, const char *format, ...)
{
va_list vargs;
time_t rawtime;
struct tm * timeinfo;
time ( &rawtime );
timeinfo = localtime ( &rawtime );
fprintf(stream, "%.2d:%.2d:%.2d - ",
timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec);
va_start(vargs, format);
vfprintf(stream, format, vargs);
fprintf(stream, "\n");
va_end(vargs);
}
#endif
/////////////
// Functions
/**
* @brief Perform one-time initialization before mutators can be executed
*/
void gc_initialize(void)
{
if (ck_array_init(&Cyc_mutators, CK_ARRAY_MODE_SPMC, &my_allocator, 10) == 0) {
fprintf(stderr, "Unable to initialize mutator array\n");
exit(1);
}
if (ck_array_init(&old_mutators, CK_ARRAY_MODE_SPMC, &my_allocator, 10) == 0) {
fprintf(stderr, "Unable to initialize mutator array\n");
exit(1);
}
// Initialize collector's mark stack
mark_stack_len = 128;
mark_stack = vpbuffer_realloc(mark_stack, &(mark_stack_len));
// Here is as good a place as any to do this...
if (pthread_mutex_init(&(mutators_lock), NULL) != 0) {
fprintf(stderr, "Unable to initialize mutators_lock mutex\n");
exit(1);
}
}
/**
* @brief Add data for a new mutator
* @param thd Thread data for the mutator
*/
void gc_add_mutator(gc_thread_data * thd)
{
pthread_mutex_lock(&mutators_lock);
if (ck_array_put_unique(&Cyc_mutators, (void *)thd) < 0) {
fprintf(stderr, "Unable to allocate memory for a new thread, exiting\n");
exit(1);
}
ck_array_commit(&Cyc_mutators);
pthread_mutex_unlock(&mutators_lock);
// Main thread is always the first one added
if (primordial_thread == NULL) {
primordial_thread = thd;
}
}
/**
* @brief Remove selected mutator from the mutator list.
* This is done for terminated threads. Note data is queued to be
* freed, to prevent accidentally freeing it while the collector
* thread is potentially accessing it.
* @param thd Thread data for the mutator
*/
void gc_remove_mutator(gc_thread_data * thd)
{
pthread_mutex_lock(&mutators_lock);
if (!ck_array_remove(&Cyc_mutators, (void *)thd)) {
fprintf(stderr, "Unable to remove thread data, exiting\n");
exit(1);
}
ck_array_commit(&Cyc_mutators);
// Place on list of old mutators to cleanup
if (ck_array_put_unique(&old_mutators, (void *)thd) < 0) {
fprintf(stderr, "Unable to add thread data to GC list, existing\n");
exit(1);
}
ck_array_commit(&old_mutators);
pthread_mutex_unlock(&mutators_lock);
}
int gc_is_mutator_active(gc_thread_data *thd)
{
ck_array_iterator_t iterator;
gc_thread_data *m;
CK_ARRAY_FOREACH(&Cyc_mutators, &iterator, &m) {
if (m == thd) {
return 1;
}
}
return 0;
}
/**
* @brief Free thread data for all terminated mutators
*/
void gc_free_old_thread_data()
{
ck_array_iterator_t iterator;
gc_thread_data *m;
int freed = 0;
pthread_mutex_lock(&mutators_lock);
CK_ARRAY_FOREACH(&old_mutators, &iterator, &m) {
//printf("JAE DEBUG - freeing old thread data...");
gc_thread_data_free(m);
if (!ck_array_remove(&old_mutators, (void *)m)) {
fprintf(stderr, "Error removing old mutator data\n");
exit(1);
}
freed = 1;
//printf(" done\n");
}
if (freed) {
ck_array_commit(&old_mutators);
//printf("commited old mutator data deletions\n");
}
pthread_mutex_unlock(&mutators_lock);
}
/**
* @brief Return the amount of free space on the heap
* @param gc_heap Root of the heap
* @return Free space in bytes
*/
uint64_t gc_heap_free_size(gc_heap *h) {
uint64_t free_size = 0;
for (; h; h = h->next){
if (h->is_unswept == 1) { // Assume all free prior to sweep
free_size += h->size;
} else {
free_size += (h->free_size);
}
}
return free_size;
}
/**
* @brief Create a new heap page.
* The caller must hold the necessary locks.
* @param heap_type Define the size of objects that will be allocated on this heap
* @param size Requested size (unpadded) of the heap
* @param max_size Define the heap page max size parameter
* @param chunk_size Define the heap chunk size parameter
* @param thd Calling mutator's thread data object
* @return Pointer to the newly allocated heap page, or NULL
* if the allocation failed.
*/
gc_heap *gc_heap_create(int heap_type, size_t size, size_t max_size,
size_t chunk_size, gc_thread_data *thd)
{
gc_free_list *free, *next;
gc_heap *h;
size_t padded_size;
size = gc_heap_align(size);
padded_size = gc_heap_pad_size(size);
h = malloc(padded_size); // TODO: mmap?
if (!h)
return NULL;
h->type = heap_type;
h->size = size;
h->ttl = 10;
h->next_free = h;
h->next_frees = NULL;
h->last_alloc_size = 0;
thd->cached_heap_total_sizes[heap_type] += size;
thd->cached_heap_free_sizes[heap_type] += size;
h->chunk_size = chunk_size;
h->max_size = max_size;
h->data = (char *)gc_heap_align(sizeof(h->data) + (uintptr_t) & (h->data));
h->next = NULL;
//h->num_children = 1;
h->num_unswept_children = 0;
free = h->free_list = (gc_free_list *) h->data;
next = (gc_free_list *) (((char *)free) + gc_heap_align(gc_free_chunk_size));
free->size = 0; // First one is just a dummy record
free->next = next;
next->size = size - gc_heap_align(gc_free_chunk_size);
next->next = NULL;
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG h->data addr: %p\n", &(h->data));
fprintf(stderr, "DEBUG h->data addr: %p\n", h->data);
fprintf(stderr, ("heap: %p-%p data: %p-%p size: %zu\n"),
h, ((char *)h) + gc_heap_pad_size(size), h->data, h->data + size,
size);
fprintf(stderr, ("first: %p end: %p\n"), (object) gc_heap_first_block(h),
(object) gc_heap_end(h));
fprintf(stderr, ("free1: %p-%p free2: %p-%p\n"), free,
((char *)free) + free->size, next, ((char *)next) + next->size);
#endif
if (heap_type <= LAST_FIXED_SIZE_HEAP_TYPE) {
h->block_size = (heap_type + 1) * 32;
//
h->remaining = size - (size % h->block_size);
h->data_end = h->data + h->remaining;
h->free_list = NULL; // No free lists with bump&pop
// This is for starting with a free list, but we want bump&pop instead
// h->remaining = 0;
// h->data_end = NULL;
// gc_init_fixed_size_free_list(h);
} else {
h->block_size = 0;
h->remaining = 0;
h->data_end = NULL;
}
// Lazy sweeping
h->free_size = size;
h->is_full = 0;
h->is_unswept = 0;
return h;
}
/**
* @brief Initialize free lists within a single heap page.
* Assumes that there is no data currently on the heap page!
* @param h Heap page to initialize
*/
void gc_init_fixed_size_free_list(gc_heap *h)
{
// for this flavor, just layer a free list on top of unitialized memory
gc_free_list *next;
//int i = 0;
size_t remaining = h->size - (h->size % h->block_size) - h->block_size; // Starting at first one so skip it
next = h->free_list = (gc_free_list *)h->data;
//printf("data start = %p\n", h->data);
//printf("data end = %p\n", h->data + h->size);
while (remaining >= h->block_size) {
//printf("%d init remaining=%d next = %p\n", i++, remaining, next);
next->next = (gc_free_list *)(((char *) next) + h->block_size);
next = next->next;
remaining -= h->block_size;
}
next->next = NULL;
h->data_end = NULL; // Indicate we are using free lists
}
/**
* @brief Diagnostic function to print all free lists on a fixed-size heap page
* @param h Heap page to output
*/
void gc_print_fixed_size_free_list(gc_heap *h)
{
gc_free_list *f = h->free_list;
fprintf(stderr, "printing free list:\n");
while(f) {
fprintf(stderr, "%p\n", f);
f = f->next;
}
fprintf(stderr, "done\n");
}
/**
* @brief Essentially this is half of the sweep code, for sweeping bump&pop
* @param h Heap page to convert
*/
size_t gc_convert_heap_page_to_free_list(gc_heap *h, gc_thread_data *thd)
{
size_t freed = 0;
object p;
gc_free_list *next;
int remaining = h->size - (h->size % h->block_size);
if (h->data_end == NULL) return 0; // Already converted
next = h->free_list = NULL;
while (remaining > h->remaining) {
p = h->data_end - remaining;
//int tag = type_of(p);
int color = mark(p);
// printf("found object %d color %d at %p with remaining=%lu\n", tag, color, p, remaining);
// free space, add it to the free list
if (color != thd->gc_alloc_color &&
color != thd->gc_trace_color) { //gc_color_clear)
// Run any finalizers
if (type_of(p) == mutex_tag) {
#if GC_DEBUG_VERBOSE
fprintf(stderr, "pthread_mutex_destroy from sweep\n");
#endif
if (pthread_mutex_destroy(&(((mutex) p)->lock)) != 0) {
fprintf(stderr, "Error destroying mutex\n");
exit(1);
}
} else if (type_of(p) == cond_var_tag) {
#if GC_DEBUG_VERBOSE
fprintf(stderr, "pthread_cond_destroy from sweep\n");
#endif
if (pthread_cond_destroy(&(((cond_var) p)->cond)) != 0) {
fprintf(stderr, "Error destroying condition variable\n");
exit(1);
}
} else if (type_of(p) == bignum_tag) {
// TODO: this is no good if we abandon bignum's on the stack
// in that case the finalizer is never called
#if GC_DEBUG_VERBOSE
fprintf(stderr, "mp_clear from sweep\n");
#endif
mp_clear(&(((bignum_type *)p)->bn));
}
// Free block
freed += h->block_size;
if (next == NULL) {
next = h->free_list = p;
}
else {
next->next = p;
next = next->next;
}
h->free_size += h->block_size;
}
remaining -= h->block_size;
}
// Convert any empty space at the end
while (remaining) {
p = h->data_end - remaining;
// printf("no object at %p fill with free list\n", p);
if (next == NULL) {
next = h->free_list = p;
}
else {
next->next = p; //(gc_free_list *)(((char *) next) + h->block_size);
next = next->next;
}
remaining -= h->block_size;
}
if (next) {
next->next = NULL;
}
// Let GC know this heap is not bump&pop
h->remaining = 0;
h->data_end = NULL;
return freed;
}
/**
* @brief Sweep portion of the GC algorithm
* @param h Heap to sweep
* @param heap_type Type of heap, based on object sizes allocated on it
* @param thd Thread data object for the mutator using this heap
* @return Return the size of the largest object freed, in bytes
*
* This portion of the major GC algorithm is responsible for returning unused
* memory slots to the heap. It is only called by the collector thread after
* the heap has been traced to identify live objects.
*/
gc_heap *gc_sweep_fixed_size(gc_heap * h, int heap_type, gc_thread_data *thd)
{
short heap_is_empty;
object p, end;
gc_free_list *q, *r, *s;
#if GC_DEBUG_SHOW_SWEEP_DIAG
gc_heap *orig_heap_ptr = h;
#endif
//gc_heap *prev_h = NULL;
gc_heap *rv = h;
h->next_free = h;
h->is_unswept = 0;
#if GC_DEBUG_SHOW_SWEEP_DIAG
fprintf(stderr, "\nBefore sweep -------------------------\n");
fprintf(stderr, "Heap %d diagnostics:\n", heap_type);
gc_print_stats(orig_heap_ptr);
#endif
if (h->data_end != NULL) {
// Special case, bump&pop heap
gc_convert_heap_page_to_free_list(h, thd);
heap_is_empty = 0; // For now, don't try to free bump&pop
} else {
//gc_free_list *next;
size_t remaining = h->size - (h->size % h->block_size); // - h->block_size; // Remove first one??
char *data_end = h->data + remaining;
heap_is_empty = 1; // Base case is an empty heap
end = (object)data_end;
p = h->data;
q = h->free_list;
while (p < end) {
// find preceding/succeeding free list pointers for p
for (r = (q?q->next:NULL); r && ((char *)r < (char *)p); q = r, r = r->next) ;
if ((char *)q == (char *)p || (char *)r == (char *)p) { // this is a free block, skip it
//printf("Sweep skip free block %p remaining=%lu\n", p, remaining);
p = (object) (((char *)p) + h->block_size);
continue;
}
#if GC_SAFETY_CHECKS
if (!is_object_type(p)) {
fprintf(stderr, "sweep: invalid object at %p", p);
exit(1);
}
if (type_of(p) > 21) {
fprintf(stderr, "sweep: invalid object tag %d at %p", type_of(p), p);
exit(1);
}
#endif
if (mark(p) != thd->gc_alloc_color &&
mark(p) != thd->gc_trace_color) { //gc_color_clear)
#if GC_DEBUG_VERBOSE
fprintf(stderr, "sweep is freeing unmarked obj: %p with tag %d\n", p,
type_of(p));
#endif
// Run finalizers
if (type_of(p) == mutex_tag) {
#if GC_DEBUG_VERBOSE
fprintf(stderr, "pthread_mutex_destroy from sweep\n");
#endif
if (pthread_mutex_destroy(&(((mutex) p)->lock)) != 0) {
fprintf(stderr, "Error destroying mutex\n");
exit(1);
}
} else if (type_of(p) == cond_var_tag) {
#if GC_DEBUG_VERBOSE
fprintf(stderr, "pthread_cond_destroy from sweep\n");
#endif
if (pthread_cond_destroy(&(((cond_var) p)->cond)) != 0) {
fprintf(stderr, "Error destroying condition variable\n");
exit(1);
}
} else if (type_of(p) == bignum_tag) {
// TODO: this is no good if we abandon bignum's on the stack
// in that case the finalizer is never called
#if GC_DEBUG_VERBOSE
fprintf(stderr, "mp_clear from sweep\n");
#endif
mp_clear(&(((bignum_type *)p)->bn));
}
// free p
//heap_freed += h->block_size;
if (h->free_list == NULL) {
// No free list, start one at p
q = h->free_list = p;
h->free_list->next = NULL;
//printf("sweep reclaimed remaining=%d, %p, assign h->free_list\n", remaining, p);
} else if ((char *)p < (char *)h->free_list) {
// p is before the free list, prepend it as the start
// note if this is the case, either there is no free_list (see above case) or
// the free list is after p, which is handled now. these are the only situations
// where there is no q
s = (gc_free_list *)p;
s->next = h->free_list;
q = h->free_list = p;
//printf("sweep reclaimed remaining=%d, %p, assign h->free_list which was %p\n", remaining, p, h->free_list);
} else {
s = (gc_free_list *)p;
s->next = r;
q->next = s;
//printf("sweep reclaimed remaining=%d, %p, q=%p, r=%p\n", remaining, p, q, r);
}
h->free_size += h->block_size;
} else {
//printf("sweep block is still used remaining=%d p = %p\n", remaining, p);
heap_is_empty = 0;
}
//next->next = (gc_free_list *)(((char *) next) + h->block_size);
//next = next->next;
p = (object) (((char *)p) + h->block_size);
}
}
// Free the heap page if possible.
if (heap_is_empty) {
if (h->type == HEAP_HUGE || (h->ttl--) <= 0) {
rv = NULL; // Let caller know heap needs to be freed
} else {
// Convert back to bump&pop
h->remaining = h->size - (h->size % h->block_size);
h->data_end = h->data + h->remaining;
h->free_list = NULL; // No free lists with bump&pop
}
} else {
//(thd->heap->heap[heap_type])->num_unswept_children--;
}
#if GC_DEBUG_SHOW_SWEEP_DIAG
fprintf(stderr, "\nAfter sweep -------------------------\n");
fprintf(stderr, "Heap %d diagnostics:\n", heap_type);
gc_print_stats(orig_heap_ptr);
#endif
return rv;
}
gc_heap *gc_find_heap_with_chunk_size(gc_heap *h, size_t chunk_size)
{
while (h) {
if (h->chunk_size == chunk_size) return h;
h = h->next;
}
return NULL;
}
/**
* @brief Free a page of the heap
* @param page Page to free
* @param prev_page Previous page in the heap
* @return Previous page if successful, NULL otherwise
*/
gc_heap *gc_heap_free(gc_heap *page, gc_heap *prev_page)
{
// At least for now, do not free first page
if (prev_page == NULL || page == NULL) {
return NULL;
}
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG freeing heap type %d page at addr: %p\n", page->type, page);
#endif
prev_page->next = page->next;
free(page);
return prev_page;
}
/**
* @brief Determine if a heap page is empty.
* @param h Heap to inspect. The caller should acquire any necessary locks.
* @return A truthy value if the heap is empty, 0 otherwise.
*/
int gc_is_heap_empty(gc_heap *h)
{
gc_free_list *f;
if (!h) return 0;
if (h->data_end) { // Fixed-size bump&pop
return (h->remaining == (h->size - (h->size % h->block_size)));
}
if (!h->free_list) return 0;
f = h->free_list;
if (f->size != 0 || !f->next) return 0;
f = f->next;
return (f->size + gc_heap_align(gc_free_chunk_size)) == h->size;
}
/**
* @brief Print heap usage information. Before calling this function the
* current thread must have the heap lock
* @param h Heap to analyze.
*/
void gc_print_stats(gc_heap * h)
{
gc_free_list *f;
unsigned int free, free_chunks, free_min, free_max;
int heap_is_empty;
for (; h; h = h->next) {
free = 0;
free_chunks = 0;
free_min = h->size;
free_max = 0;
for (f = h->free_list; f; f = f->next) {
free += f->size;
free_chunks++;
if (f->size < free_min && f->size > 0)
free_min = f->size;
if (f->size > free_max)
free_max = f->size;
}
if (free == 0){ // No free chunks
free_min = 0;
}
heap_is_empty = gc_is_heap_empty(h);
fprintf(stderr,
"Heap type=%d, page size=%u, is empty=%d, used=%u, free=%u, free chunks=%u, min=%u, max=%u\n",
h->type, h->size, heap_is_empty, h->size - free, free, free_chunks, free_min, free_max);
}
}
/**
* @brief Copy given object into given heap object
* @param dest Pointer to destination heap memory slot
* @param obj Object to copy
* @param thd Thread data object for the applicable mutator
* @return The appropriate pointer to use for `obj`
*
* NOTE: There is no additional type checking because this function is
* called from `gc_move` which already does that.
*/
char *gc_copy_obj(object dest, char *obj, gc_thread_data * thd)
{
#if GC_DEBUG_TRACE
allocated_obj_counts[type_of(obj)]++;
#endif
switch (type_of(obj)) {
case closureN_tag:{
closureN_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = closureN_tag;
hp->fn = ((closureN) obj)->fn;
hp->num_args = ((closureN) obj)->num_args;
hp->num_elements = ((closureN) obj)->num_elements;
hp->elements = (object *) (((char *)hp) + sizeof(closureN_type));
memcpy(hp->elements, ((closureN)obj)->elements, sizeof(object *) * hp->num_elements);
return (char *)hp;
}
case pair_tag:{
list hp = dest;
hp->hdr.mark = thd->gc_alloc_color;
type_of(hp) = pair_tag;
car(hp) = car(obj);
cdr(hp) = cdr(obj);
return (char *)hp;
}
case string_tag:{
char *s;
string_type *hp = dest;
s = ((char *)hp) + sizeof(string_type);
memcpy(s, string_str(obj), string_len(obj) + 1);
mark(hp) = thd->gc_alloc_color;
type_of(hp) = string_tag;
string_num_cp(hp) = string_num_cp(obj);
string_len(hp) = string_len(obj);
string_str(hp) = s;
return (char *)hp;
}
case double_tag:{
double_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = double_tag;
hp->value = ((double_type *) obj)->value;
return (char *)hp;
}
case vector_tag:{
vector_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = vector_tag;
hp->num_elements = ((vector) obj)->num_elements;
hp->elements = (object *) (((char *)hp) + sizeof(vector_type));
memcpy(hp->elements, ((vector)obj)->elements, sizeof(object *) * hp->num_elements);
return (char *)hp;
}
case bytevector_tag:{
bytevector_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = bytevector_tag;
hp->len = ((bytevector) obj)->len;
hp->data = (((char *)hp) + sizeof(bytevector_type));
memcpy(hp->data, ((bytevector) obj)->data, hp->len);
return (char *)hp;
}
case port_tag:{
port_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = port_tag;
hp->fp = ((port_type *) obj)->fp;
hp->mode = ((port_type *) obj)->mode;
hp->flags = ((port_type *) obj)->flags;
hp->line_num = ((port_type *) obj)->line_num;
hp->col_num = ((port_type *) obj)->col_num;
hp->buf_idx = ((port_type *) obj)->buf_idx;
hp->tok_start = ((port_type *) obj)->tok_start;
hp->tok_end = ((port_type *) obj)->tok_end;
hp->tok_buf = ((port_type *) obj)->tok_buf;
hp->tok_buf_len = ((port_type *) obj)->tok_buf_len;
hp->mem_buf = ((port_type *)obj)->mem_buf;
hp->mem_buf_len = ((port_type *)obj)->mem_buf_len;
hp->str_bv_in_mem_buf = ((port_type *)obj)->str_bv_in_mem_buf;
hp->str_bv_in_mem_buf_len = ((port_type *)obj)->str_bv_in_mem_buf_len;
hp->read_len = ((port_type *)obj)->read_len;
return (char *)hp;
}
case bignum_tag:{
bignum_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = bignum_tag;
((bignum_type *)hp)->bn.used = ((bignum_type *)obj)->bn.used;
((bignum_type *)hp)->bn.alloc = ((bignum_type *)obj)->bn.alloc;
((bignum_type *)hp)->bn.sign = ((bignum_type *)obj)->bn.sign;
((bignum_type *)hp)->bn.dp = ((bignum_type *)obj)->bn.dp;
return (char *)hp;
}
case cvar_tag:{
cvar_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = cvar_tag;
hp->pvar = ((cvar_type *) obj)->pvar;
return (char *)hp;
}
case mutex_tag:{
mutex_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = mutex_tag;
// NOTE: don't copy mutex itself, caller will do that (this is a special case)
return (char *)hp;
}
case cond_var_tag:{
cond_var_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = cond_var_tag;
// NOTE: don't copy cond_var itself, caller will do that (this is a special case)
return (char *)hp;
}
case macro_tag:{
macro_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = macro_tag;
hp->fn = ((macro) obj)->fn;
hp->num_args = ((macro) obj)->num_args;
return (char *)hp;
}
case closure1_tag:{
closure1_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = closure1_tag;
hp->fn = ((closure1) obj)->fn;
hp->num_args = ((closure1) obj)->num_args;
hp->element = ((closure1) obj)->element;
return (char *)hp;
}
case c_opaque_tag:{
c_opaque_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = c_opaque_tag;
hp->ptr = ((c_opaque_type *) obj)->ptr;
return (char *)hp;
}
case forward_tag:
return (char *)forward(obj);
case eof_tag:
case primitive_tag:
case boolean_tag:
case symbol_tag:
case closure0_tag:
break;
case integer_tag:{
integer_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = integer_tag;
hp->value = ((integer_type *) obj)->value;
return (char *)hp;
}
case complex_num_tag:{
complex_num_type *hp = dest;
mark(hp) = thd->gc_alloc_color;
type_of(hp) = complex_num_tag;
hp->value = ((complex_num_type *) obj)->value;
return (char *)hp;
}
default:
fprintf(stderr, "gc_copy_obj: bad tag obj=%p obj.tag=%d\n", (object) obj,
type_of(obj));
exit(1);
}
return (char *)obj;
}
/**
* @brief Grow a heap by allocating a new page.
* @param h Heap to be expanded
* @param heap_type Define the size of objects that will be allocated on this heap
* @param size Not applicable, can set to 0
* @param chunk_size Heap chunk size, or 0 if not applicable
* @param thd Thread data for the mutator using this heap
* @return A true value if the heap was grown, or 0 otherwise
*
* Heaps are increased in size by adding a newly-allocated page at the
* end of the heap's linked list.
*
* Page size is determined by starting at the minimum page size and
* increasing size using the Fibonnaci Sequence until reaching the
* max size.
*/
int gc_grow_heap(gc_heap * h, int heap_type, size_t size, size_t chunk_size, gc_thread_data *thd)
{
size_t /*cur_size,*/ new_size;
gc_heap *h_last = h, *h_new;
//pthread_mutex_lock(&(thd->heap_lock));
// Compute size of new heap page
if (heap_type == HEAP_HUGE) {
new_size = gc_heap_align(size) + 128;
while (h_last->next) {
h_last = h_last->next;
}
// } else if (heap_type == HEAP_SM || heap_type == HEAP_64) {
// new_size = gc_heap_align(64 * 4096); // Completely insane(?), match linux page size
} else {
// Grow heap gradually using fibonnaci sequence.
size_t prev_size = GROW_HEAP_BY_SIZE;
new_size = 0;
while (h_last->next) {
if (new_size < HEAP_SIZE) {
new_size = prev_size + h_last->size;
prev_size = h_last->size;
if (new_size > HEAP_SIZE) {
new_size = HEAP_SIZE;
break;
}
} else {
new_size = HEAP_SIZE;
break;
}
h_last = h_last->next;
}
if (new_size == 0) {
new_size = prev_size + h_last->size;
if (new_size > HEAP_SIZE) {
new_size = HEAP_SIZE;
}
}
// Fast-track heap page size if allocating a large block
if (new_size < size && size < HEAP_SIZE) {
new_size = HEAP_SIZE;
}
#if GC_DEBUG_TRACE
fprintf(stderr, "Growing heap %d new page size = %zu\n", heap_type,
new_size);
#endif
}
h_last = gc_heap_last(h_last); // Ensure we don't unlink any heaps
// cur_size = h_last->size;
// new_size = cur_size; //gc_heap_align(((cur_size > size) ? cur_size : size) * 2);
// allocate larger pages if size will not fit on the page
//new_size = gc_heap_align(((cur_size > size) ? cur_size : size));
// Done with computing new page size
h_new = gc_heap_create(heap_type, new_size, h_last->max_size, chunk_size, thd);
h_last->next = h_new;
//pthread_mutex_unlock(&(thd->heap_lock));
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - grew heap\n");
#endif
return (h_new != NULL);
}
/**
* @brief Attempt to allocate a new heap slot for the given object
* @param h Heap to allocate from
* @param heap_type Define the size of objects that will be allocated on this heap
* @param size Size of the requested object, in bytes
* @param obj Object containing data that will be copied to the heap
* @param thd Thread data for the mutator using this heap
* @return Pointer to the newly-allocated object, or `NULL` if allocation failed
*
* This function will fail if there is no space on the heap for the
* requested object.
*/
void *gc_try_alloc(gc_heap * h, int heap_type, size_t size, char *obj,
gc_thread_data * thd)
{
gc_free_list *f1, *f2, *f3;
for (f1 = h->free_list, f2 = f1->next; f2; f1 = f2, f2 = f2->next) { // all free in this heap
if (f2->size >= size) { // Big enough for request
// TODO: take whole chunk or divide up f2 (using f3)?
if (f2->size >= (size + gc_heap_align(1) /* min obj size */ )) {
f3 = (gc_free_list *) (((char *)f2) + size);
f3->size = f2->size - size;
f3->next = f2->next;
f1->next = f3;
} else { /* Take the whole chunk */
f1->next = f2->next;
}
if (heap_type != HEAP_HUGE) {
// Copy object into heap now to avoid any uninitialized memory issues
#if GC_DEBUG_TRACE
if (size < (32 * NUM_ALLOC_SIZES)) {
allocated_size_counts[(size / 32) - 1]++;
}
#endif
gc_copy_obj(f2, obj, thd);
// Done after sweep now instead of with each allocation
//ck_pr_sub_ptr(&(thd->cached_heap_free_sizes[heap_type]), size);
//thd->cached_heap_free_sizes[heap_type] -= size;
h->free_size -= size;
} else {
thd->heap_num_huge_allocations++;
}
return f2;
}
}
return NULL;
}
/**
* @brief Return number of unswept heaps
* @param h Heap we are starting from (assume first in the chain)
* @return Count of heaps that have not been swept yet.
*/
int gc_num_unswept_heaps(gc_heap *h)
{
int count = 0;
while (h) {
if (h->is_unswept == 1 /*||
gc_is_heap_empty(h)*/) {
count++;
}
h = h->next;
}
return count;
}
void gc_start_major_collection(gc_thread_data *thd){
if (ck_pr_load_int(&gc_stage) == STAGE_RESTING) {
#if GC_DEBUG_TRACE
gc_log(stderr, "gc_start_major_collection - initiating collector");
#endif
ck_pr_cas_int(&gc_stage, STAGE_RESTING, STAGE_CLEAR_OR_MARKING);
}
}
void *gc_try_alloc_slow(gc_heap *h_passed, gc_heap *h, int heap_type, size_t size, char *obj, gc_thread_data *thd)
{
gc_heap *h_start = h, *h_prev;
void *result = NULL;
// Find next heap
while (result == NULL) {
h_prev = h;
h = h->next;
if (h == NULL) {
// Wrap around to the first heap block
h_prev = NULL;
h = h_passed;
}
if (h == h_start) {
// Tried all and no heap exists with free space
break;
}
// check allocation status to make sure we can use it
if (h->is_full) {
continue; // Cannot sweep until next GC cycle
} else if (h->is_unswept == 1 && !gc_is_heap_empty(h)) { // TODO: empty function does not support fixed-size heaps yet
unsigned int h_size = h->size;
//unsigned int prev_free_size = h->free_size;
//if (h->is_unswept == 1) {
// prev_free_size = h_size; // Full size was cached
//}
gc_heap *keep = gc_sweep(h, heap_type, thd); // Clean up garbage objects
h_passed->num_unswept_children--;
if (!keep) {
// Heap marked for deletion, remove it and keep searching
gc_heap *freed = gc_heap_free(h, h_prev);
if (freed) {
if (h_prev) {
h = h_prev;
} else {
h = h_passed;
}
//thd->cached_heap_free_sizes[heap_type] -= prev_free_size;
thd->cached_heap_total_sizes[heap_type] -= h_size;
//h_passed->num_children--;
//h_passed->num_unswept_children--;
continue;
}
}
// Adjust free sizes accordingly (we skip this if page was freed above)
// For example:
// total free = 100
// this heap prev free = 50
// this heap curr free = 25
// this heap delta = 25 - 50 = -25
// new total free = 100 + (25 - 50) = 75
// thd->cached_heap_free_sizes[heap_type] -= prev_free_size; // Start at a baseline
// thd->cached_heap_free_sizes[heap_type] += h->free_size; // And incorporate what we just freed
// if (thd->cached_heap_free_sizes[heap_type] > thd->cached_heap_total_sizes[heap_type]) {
// fprintf(stderr, "gc_try_alloc_slow - Invalid cached heap sizes, free=%zu total=%zu, prev free=%u, new free=%u\n",
// thd->cached_heap_free_sizes[heap_type], thd->cached_heap_total_sizes[heap_type],
// prev_free_size,
// h->free_size);
// }
}
result = gc_try_alloc(h, heap_type, size, obj, thd);
if (result) {
h_passed->next_free = h;
h_passed->last_alloc_size = size;
} else {
// TODO: else, assign heap full? YES for fixed-size, for REST maybe not??
h->is_full = 1;
}
}
return result;
}
/**
* @brief Same as `gc_try_alloc` but optimized for heaps for fixed-sized objects.
* @param h Heap to allocate from
* @param heap_type Define the size of objects that will be allocated on this heap
* @param size Size of the requested object, in bytes
* @param obj Object containing data that will be copied to the heap
* @param thd Thread data for the mutator using this heap
* @return Pointer to the newly-allocated object, or `NULL` if allocation failed
*
* This function will fail if there is no space on the heap for the
* requested object.
*/
void *gc_try_alloc_fixed_size(gc_heap * h, int heap_type, size_t size, char *obj, gc_thread_data * thd)
{
void *result;
//gc_heap *h_passed = h;
//h = h->next_free;
//for (; h; h = h->next) { // All heaps
if (h->free_list) {
result = h->free_list;
h->free_list = h->free_list->next;
} else if (h->remaining) {
h->remaining -= h->block_size;
result = h->data_end - h->remaining - h->block_size;
} else {
// Cannot allocate on this page, skip it
result = NULL;
}
if (result) {
// Copy object into heap now to avoid any uninitialized memory issues
#if GC_DEBUG_TRACE
if (size < (32 * NUM_ALLOC_SIZES)) {
allocated_size_counts[(size / 32) - 1]++;
}
#endif
gc_copy_obj(result, obj, thd);
//ck_pr_sub_ptr(&(thd->cached_heap_free_sizes[heap_type]), size);
//h_passed->next_free = h;
h->free_size -= size;
return result;
}
//}
return NULL;
}
void *gc_try_alloc_slow_fixed_size(gc_heap *h_passed, gc_heap *h, int heap_type, size_t size, char *obj, gc_thread_data *thd)
{
gc_heap *h_start = h, *h_prev;
void *result = NULL;
// Find next heap
while (result == NULL) {
h_prev = h;
h = h->next;
if (h == NULL) {
// Wrap around to the first heap block
h_prev = NULL;
h = h_passed;
}
if (h == h_start) {
// Tried all and no heap exists with free space
break;
}
// check allocation status to make sure we can use it
if (h->is_full) {
continue; // Cannot sweep until next GC cycle
} else if (h->is_unswept == 1 && !gc_is_heap_empty(h)) {
unsigned int h_size = h->size;
gc_heap *keep = gc_sweep_fixed_size(h, heap_type, thd); // Clean up garbage objects
h_passed->num_unswept_children--;
if (!keep) {
// Heap marked for deletion, remove it and keep searching
gc_heap *freed = gc_heap_free(h, h_prev);
if (freed) {
if (h_prev) {
h = h_prev;
} else {
h = h_passed;
}
//thd->cached_heap_free_sizes[heap_type] -= prev_free_size;
thd->cached_heap_total_sizes[heap_type] -= h_size;
//h_passed->num_children--;
//h_passed->num_unswept_children--;
continue;
}
}
}
result = gc_try_alloc_fixed_size(h, heap_type, size, obj, thd);
if (result) {
h_passed->next_free = h;
h_passed->last_alloc_size = size;
} else {
// TODO: else, assign heap full? YES for fixed-size, for REST maybe not??
h->is_full = 1;
}
}
return result;
}
/**
* @brief A convenience function for allocating bignums
* @param data The mutator's thread data object
* @return Pointer to a heap object for the bignum
*/
void *gc_alloc_bignum(gc_thread_data *data)
{
int heap_grown, result;
bignum_type *bn;
bignum_type tmp;
tmp.hdr.mark = gc_color_red;
tmp.hdr.grayed = 0;
tmp.tag = bignum_tag;
bn = gc_alloc(((gc_thread_data *)data)->heap, sizeof(bignum_type), (char *)(&tmp), (gc_thread_data *)data, &heap_grown);
if ((result = mp_init(&bignum_value(bn))) != MP_OKAY) {
fprintf(stderr, "Error initializing number %s",
mp_error_to_string(result));
exit(1);
}
return bn;
}
/**
* @brief A helper function to create a heap-allocated copy of a bignum
* @param data The mutator's thread data object
* @param src The bignum instance to copy to the heap
* @return Pointer to the heap object
*/
void *gc_alloc_from_bignum(gc_thread_data *data, bignum_type *src)
{
int heap_grown;
return gc_alloc(((gc_thread_data *)data)->heap, sizeof(bignum_type), (char *)(src), (gc_thread_data *)data, &heap_grown);
}
/**
* @brief Allocate memory on the heap for an object
* @param hrt The root of the heap to allocate from
* @param size Size of the object to allocate
* @param obj Object containing data to copy to the heap
* @param thd The requesting mutator's thread data object
* @param heap_grown Pointer to an "out" parameter that will be set to
* `1` if the heap is grown in size.
* @return Pointer to the heap object
*
* This function will attempt to grow the heap if it is full, and will
* terminate the program if the OS is out of memory.
*/
void *gc_alloc(gc_heap_root * hrt, size_t size, char *obj, gc_thread_data * thd,
int *heap_grown)
{
void *result = NULL;
gc_heap *h_passed, *h = NULL;
int heap_type;
void *(*try_alloc)(gc_heap * h, int heap_type, size_t size, char *obj, gc_thread_data * thd);
void *(*try_alloc_slow)(gc_heap *h_passed, gc_heap *h, int heap_type, size_t size, char *obj, gc_thread_data *thd);
size = gc_heap_align(size);
if (size <= 32) {
heap_type = HEAP_SM;
//try_alloc = &gc_try_alloc;
//try_alloc_slow = &gc_try_alloc_slow;
// TODO:
try_alloc = &gc_try_alloc_fixed_size;
try_alloc_slow = &gc_try_alloc_slow_fixed_size;
} else if (size <= 64) {
heap_type = HEAP_64;
//try_alloc = &gc_try_alloc;
//try_alloc_slow = &gc_try_alloc_slow;
// TODO:
try_alloc = &gc_try_alloc_fixed_size;
try_alloc_slow = &gc_try_alloc_slow_fixed_size;
// Only use this heap on 64-bit platforms, where larger objs are used more often
// Code from http://stackoverflow.com/a/32717129/101258
#if INTPTR_MAX == INT64_MAX
} else if (size <= 96) {
heap_type = HEAP_96;
//try_alloc = &gc_try_alloc;
//try_alloc_slow = &gc_try_alloc_slow;
// TODO:
try_alloc = &gc_try_alloc_fixed_size;
try_alloc_slow = &gc_try_alloc_slow_fixed_size;
#endif
} else if (size >= MAX_STACK_OBJ) {
heap_type = HEAP_HUGE;
try_alloc = &gc_try_alloc;
try_alloc_slow = &gc_try_alloc_slow;
} else {
heap_type = HEAP_REST;
try_alloc = &gc_try_alloc;
try_alloc_slow = &gc_try_alloc_slow;
}
h = hrt->heap[heap_type];
h_passed = h;
// Start searching from the last heap page we had a successful
// allocation from, unless the current request is for a smaller
// block in which case there may be available memory closer to
// the start of the heap.
if (size >= h->last_alloc_size) {
h = h->next_free;
}
// Fast path
result = try_alloc(h, heap_type, size, obj, thd);
if (result) {
h_passed->next_free = h;
h_passed->last_alloc_size = size;
} else {
// Slow path, find another heap block
h->is_full = 1;
result = try_alloc_slow(h_passed, h, heap_type, size, obj, thd);
#if GC_DEBUG_VERBOSE
fprintf(stderr, "slow alloc of %p\n", result);
#endif
if (result) {
// Check if we need to start a major collection
if (heap_type != HEAP_HUGE &&
(//(try_alloc == &gc_try_alloc_fixed_size && // Fixed-size object heap
// h_passed->num_unswept_children < (GC_COLLECT_UNDER_UNSWEPT_HEAP_COUNT * 128)) ||
h_passed->num_unswept_children < GC_COLLECT_UNDER_UNSWEPT_HEAP_COUNT)) {
// gc_num_unswept_heaps(h_passed) < GC_COLLECT_UNDER_UNSWEPT_HEAP_COUNT)){
// printf("major collection heap_type = %d h->num_unswept = %d, computed = %d\n", heap_type, h_passed->num_unswept_children, gc_num_unswept_heaps(h_passed));
//if (h_passed->num_unswept_children != gc_num_unswept_heaps(h_passed)) {
// printf("ERROR, counts do not match!\n");
//}
gc_start_major_collection(thd);
}
} else {
// Slowest path, allocate a new heap block
/* A vanilla mark&sweep collector would collect now, but unfortunately */
/* we can't do that because we have to go through multiple stages, some */
/* of which are asynchronous. So... no choice but to grow the heap. */
gc_grow_heap(h, heap_type, size, 0, thd);
*heap_grown = 1;
//h_passed->num_children++;
//h_passed->num_unswept_children++;
// TODO: would be nice if gc_grow_heap returns new page (maybe it does) then we can start from there
// otherwise will be a bit of a bottleneck since with lazy sweeping there is no guarantee we are at
// the end of the heap anymore
result = try_alloc_slow(h_passed, h, heap_type, size, obj, thd);
#if GC_DEBUG_VERBOSE
fprintf(stderr, "slowest alloc of %p\n", result);
#endif
if (result) {
// We had to allocate memory, start a major collection ASAP!
if (heap_type != HEAP_HUGE) {
gc_start_major_collection(thd);
}
} else {
fprintf(stderr, "out of memory error allocating %zu bytes\n", size);
fprintf(stderr, "Heap type %d diagnostics:\n", heap_type);
gc_print_stats(h);
exit(1); /* could throw error, but OOM is a major issue, so... */
}
}
}
#if GC_DEBUG_TRACE
allocated_heap_counts[heap_type]++;
#endif
#if GC_DEBUG_VERBOSE
fprintf(stderr, "alloc %p size = %zu, obj=%p, tag=%d, mark=%d, thd->alloc=%d, thd->trace=%d\n", result,
size, obj, type_of(obj), mark(((object) result)),
thd->gc_alloc_color, thd->gc_trace_color);
// Debug check, should no longer be necessary
//if (is_value_type(result)) {
// printf("Invalid allocated address - is a value type %p\n", result);
//}
#endif
return result;
}
/**
* @brief Get the number of bytes that will be allocated for `obj`.
* @param obj Object to inspect
* @param q Previous free list pointer, set to `NULL` if not applicable
* @param r Next free list pointer, set to `NULL` if not applicable
* @return Number of bytes, including any needed for alignment
*/
size_t gc_allocated_bytes(object obj, gc_free_list * q, gc_free_list * r)
{
tag_type t;
#if GC_SAFETY_CHECKS
if (is_value_type(obj)) {
fprintf(stderr,
"gc_allocated_bytes - passed value type %p q=[%p, %d] r=[%p, %d]\n",
obj, q, q->size, r, r->size);
exit(1);
}
#endif
t = type_of(obj);
if (t == pair_tag)
return gc_heap_align(sizeof(pair_type));
if (t == closureN_tag) {
return gc_heap_align(sizeof(closureN_type) +
sizeof(object) *
((closureN_type *) obj)->num_elements);
}
if (t == double_tag)
return gc_heap_align(sizeof(double_type));
if (t == closure1_tag)
return gc_heap_align(sizeof(closure1_type));
if (t == string_tag) {
return gc_heap_align(sizeof(string_type) + string_len(obj) + 1);
}
if (t == vector_tag) {
return gc_heap_align(sizeof(vector_type) +
sizeof(object) * ((vector_type *) obj)->num_elements);
}
if (t == bytevector_tag) {
return gc_heap_align(sizeof(bytevector_type) +
sizeof(char) * ((bytevector) obj)->len);
}
if (t == macro_tag)
return gc_heap_align(sizeof(macro_type));
if (t == bignum_tag)
return gc_heap_align(sizeof(bignum_type));
if (t == port_tag)
return gc_heap_align(sizeof(port_type));
if (t == cvar_tag)
return gc_heap_align(sizeof(cvar_type));
if (t == c_opaque_tag)
return gc_heap_align(sizeof(c_opaque_type));
if (t == mutex_tag)
return gc_heap_align(sizeof(mutex_type));
if (t == cond_var_tag)
return gc_heap_align(sizeof(cond_var_type));
if (t == integer_tag)
return gc_heap_align(sizeof(integer_type));
if (t == complex_num_tag)
return gc_heap_align(sizeof(complex_num_type));
fprintf(stderr, "gc_allocated_bytes: unexpected object %p of type %d\n", obj,
t);
exit(1);
return 0;
}
/**
* @brief Get the heap's last page
* @param h Heap to inspect
* @return Pointer to the heap's last page
*
* This function does not do any locking, it is the responsibility of
* the caller to hold the appropriate locks prior to calling.
*/
gc_heap *gc_heap_last(gc_heap * h)
{
while (h->next)
h = h->next;
return h;
}
/**
* @brief A convenient front-end to the actual gc_sweep function.
*/
void gc_collector_sweep()
{
ck_array_iterator_t iterator;
gc_thread_data *m;
CK_ARRAY_FOREACH(&Cyc_mutators, &iterator, &m) {
// Tracing is done, remove the trace color
m->gc_trace_color = m->gc_alloc_color;
// Let mutator know we are done tracing
ck_pr_cas_8(&(m->gc_done_tracing), 0, 1);
}
#if GC_DEBUG_TRACE
fprintf(stderr, "all thread heap sweeps done\n");
#endif
}
/**
* @brief Sweep portion of the GC algorithm
* @param h Heap to sweep
* @param heap_type Type of heap, based on object sizes allocated on it
* @param thd Thread data object for the mutator using this heap
* @return Pointer to the heap, or NULL if heap is to be freed
*
* This portion of the major GC algorithm is responsible for returning unused
* memory slots to the heap. It is only called by the allocator to free up space
* after the heap has been traced to identify live objects.
*/
gc_heap *gc_sweep(gc_heap * h, int heap_type, gc_thread_data *thd)
{
size_t freed, size;
object p, end;
gc_free_list *q, *r, *s;
#if GC_DEBUG_SHOW_SWEEP_DIAG
gc_heap *orig_heap_ptr = h;
#endif
gc_heap *rv = h;
//int markColor = ck_pr_load_8(&gc_color_mark);
//h->next_free = h;
h->last_alloc_size = 0;
//h->free_size = 0;
h->is_unswept = 0;
#if GC_DEBUG_SHOW_SWEEP_DIAG
fprintf(stderr, "\nBefore sweep -------------------------\n");
fprintf(stderr, "Heap %d diagnostics:\n", heap_type);
gc_print_stats(orig_heap_ptr);
#endif
//for (; h; prev_h = h, h = h->next) // All heaps
#if GC_DEBUG_TRACE
fprintf(stderr, "sweep heap %p, size = %zu\n", h, (size_t) h->size);
#endif
#if GC_DEBUG_VERBOSE
{
gc_free_list *tmp = h->free_list;
while (tmp) {
fprintf(stderr, "free list %p\n", tmp);
tmp = tmp->next;
}
}
#endif
p = gc_heap_first_block(h);
q = h->free_list;
end = gc_heap_end(h);
while (p < end) {
// find preceding/succeeding free list pointers for p
for (r = q->next; r && ((char *)r < (char *)p); q = r, r = r->next) ;
if ((char *)r == (char *)p) { // this is a free block, skip it
p = (object) (((char *)p) + r->size);
//h->free_size += r->size;
#if GC_DEBUG_VERBOSE
fprintf(stderr, "skip free block %p size = %zu\n", p, r->size);
#endif
continue;
}
size = gc_allocated_bytes(p, q, r);
#if GC_SAFETY_CHECKS
if (!is_object_type(p)) {
fprintf(stderr, "sweep: invalid object at %p", p);
exit(1);
}
if ((char *)q + q->size > (char *)p) {
fprintf(stderr, "bad size at %p < %p + %u", p, q, q->size);
exit(1);
}
if (r && ((char *)p) + size > (char *)r) {
fprintf(stderr, "sweep: bad size at %p + %zu > %p", p, size, r);
exit(1);
}
#endif
// Use the object's mark to determine if we keep it.
// Need to check for both colors because:
// - Objects that are either newly-allocated or recently traced are given
// the alloc color, and we need to keep them.
// - If the collector is currently tracing, objects not traced yet will
// have the trace/clear color. We need to keep any of those to make sure
// the collector has a chance to trace the entire heap.
if (//mark(p) != markColor &&
mark(p) != thd->gc_alloc_color &&
mark(p) != thd->gc_trace_color) { //gc_color_clear)
#if GC_DEBUG_VERBOSE
fprintf(stderr, "sweep is freeing unmarked obj: %p with tag %d mark %d - alloc color %d trace color %d\n", p,
type_of(p),
mark(p),
thd->gc_alloc_color, thd->gc_trace_color);
#endif
//mark(p) = gc_color_blue; // Needed?
if (type_of(p) == mutex_tag) {
#if GC_DEBUG_VERBOSE
fprintf(stderr, "pthread_mutex_destroy from sweep\n");
#endif
if (pthread_mutex_destroy(&(((mutex) p)->lock)) != 0) {
fprintf(stderr, "Error destroying mutex\n");
exit(1);
}
} else if (type_of(p) == cond_var_tag) {
#if GC_DEBUG_VERBOSE
fprintf(stderr, "pthread_cond_destroy from sweep\n");
#endif
if (pthread_cond_destroy(&(((cond_var) p)->cond)) != 0) {
fprintf(stderr, "Error destroying condition variable\n");
exit(1);
}
} else if (type_of(p) == bignum_tag) {
// TODO: this is no good if we abandon bignum's on the stack
// in that case the finalizer is never called
#if GC_DEBUG_VERBOSE
fprintf(stderr, "mp_clear from sweep\n");
#endif
mp_clear(&(((bignum_type *)p)->bn));
}
// free p
if (((((char *)q) + q->size) == (char *)p) && (q != h->free_list)) {
/* merge q with p */
if (r && r->size && ((((char *)p) + size) == (char *)r)) {
// ... and with r
q->next = r->next;
freed = q->size + size + r->size;
p = (object) (((char *)p) + size + r->size);
} else {
freed = q->size + size;
p = (object) (((char *)p) + size);
}
q->size = freed;
} else {
s = (gc_free_list *) p;
if (r && r->size && ((((char *)p) + size) == (char *)r)) {
// merge p with r
s->size = size + r->size;
s->next = r->next;
q->next = s;
freed = size + r->size;
} else {
s->size = size;
s->next = r;
q->next = s;
freed = size;
}
p = (object) (((char *)p) + freed);
}
h->free_size += size;
} else {
//#if GC_DEBUG_VERBOSE
// fprintf(stderr, "sweep: object is marked %p\n", p);
//#endif
p = (object) (((char *)p) + size);
}
}
// Free the heap page if possible.
//
// With huge heaps, this becomes more important. one of the huge
// pages only has one object, so it is likely that the page
// will become free at some point and could be reclaimed.
//
// The newly created flag is used to attempt to avoid situtaions
// where a page is allocated because there is not enough free space,
// but then we do a sweep and see it is empty so we free it, and
// so forth. A better solution might be to keep empty heap pages
// off to the side and only free them if there is enough free space
// remaining without them.
//
// Experimenting with only freeing huge heaps
if (gc_is_heap_empty(h)) {
if (h->type == HEAP_HUGE || (h->ttl--) <= 0) {
rv = NULL; // Let caller know heap needs to be freed
}
} else {
//(thd->heap->heap[heap_type])->num_unswept_children--;
}
#if GC_DEBUG_SHOW_SWEEP_DIAG
fprintf(stderr, "\nAfter sweep -------------------------\n");
fprintf(stderr, "Heap %d diagnostics:\n", heap_type);
gc_print_stats(orig_heap_ptr);
#endif
return rv;
}
/**
* @brief Increase the size of the mutator's move buffer
* @param d Mutator's thread data object
*/
void gc_thr_grow_move_buffer(gc_thread_data * d)
{
if (!d)
return;
if (d->moveBufLen == 0) { // Special case
d->moveBufLen = 128;
d->moveBuf = NULL;
} else {
d->moveBufLen *= 2;
}
d->moveBuf = realloc(d->moveBuf, d->moveBufLen * sizeof(void *));
#if GC_DEBUG_TRACE
fprintf(stderr, "grew moveBuffer, len = %d\n", d->moveBufLen);
#endif
}
/**
* @brief Add an object to the move buffer
* @param d Mutator data object containing the buffer
* @param alloci Pointer to the next open slot in the buffer
* @param obj Object to add
*/
void gc_thr_add_to_move_buffer(gc_thread_data * d, int *alloci, object obj)
{
if (*alloci == d->moveBufLen) {
gc_thr_grow_move_buffer(d);
}
d->moveBuf[*alloci] = obj;
(*alloci)++;
}
// END heap definitions
// Tri-color GC section
/////////////////////////////////////////////
// GC functions called by the Mutator threads
/**
* @brief Clear thread data read/write fields
* @param thd Mutator's thread data object
*/
void gc_zero_read_write_counts(gc_thread_data * thd)
{
pthread_mutex_lock(&(thd->lock));
#if GC_SAFETY_CHECKS
if (thd->last_read < thd->last_write) {
fprintf(stderr,
"gc_zero_read_write_counts - last_read (%d) < last_write (%d)\n",
thd->last_read, thd->last_write);
} else if (thd->pending_writes) {
fprintf(stderr,
"gc_zero_read_write_counts - pending_writes (%d) is not zero\n",
thd->pending_writes);
}
#endif
thd->last_write = 0;
thd->last_read = 0;
thd->pending_writes = 0;
pthread_mutex_unlock(&(thd->lock));
}
/**
* @brief Move pending writes to 'last_write'
* @param thd Mutator's thread data object
* @param locked Does the caller hold the mutator lock?
*/
void gc_sum_pending_writes(gc_thread_data * thd, int locked)
{
if (!locked) {
pthread_mutex_lock(&(thd->lock));
}
thd->last_write += thd->pending_writes;
thd->pending_writes = 0;
if (!locked) {
pthread_mutex_unlock(&(thd->lock));
}
}
/**
* @brief Determine if object lives on the thread's stack
* @param thd Mutator's thread data
* @param obj Object to inspect
* @return True if `obj` is on the mutator's stack, false otherwise
*/
int gc_is_stack_obj(gc_thread_data * thd, object obj)
{
char tmp;
object low_limit = &tmp;
object high_limit = thd->stack_start;
return (stack_overflow(low_limit, obj) && stack_overflow(obj, high_limit));
}
/**
* @brief Helper function for `gc_mut_update`
*/
static void mark_stack_or_heap_obj(gc_thread_data * thd, object obj, int locked)
{
if (!is_object_type(obj) || type_of(obj) == boolean_tag) {
return;
} else if (gc_is_stack_obj(thd, obj)) {
// Set object to be marked after moved to heap by next GC.
// This avoids having to recursively examine the stack now,
// which we have to do anyway during minor GC.
grayed(obj) = 1;
} else {
// Value is on the heap, mark gray right now
if (!locked) { pthread_mutex_lock(&(thd->lock)); }
gc_mark_gray(thd, obj);
if (!locked) { pthread_mutex_unlock(&(thd->lock)); }
}
}
/**
* @brief Write barrier for updates to heap-allocated objects
* @param thd Mutator's thread data
* @param old_obj Old object value prior to the mutation
* @param value New object value
*
* The key for this barrier is to identify stack objects that contain
* heap references, so they can be marked to avoid collection.
*/
void gc_mut_update(gc_thread_data * thd, object old_obj, object value)
{
int //status = ck_pr_load_int(&gc_status_col),
stage = ck_pr_load_int(&gc_stage);
if (ck_pr_load_int(&(thd->gc_status)) != STATUS_ASYNC) {
pthread_mutex_lock(&(thd->lock));
mark_stack_or_heap_obj(thd, old_obj, 1);
mark_stack_or_heap_obj(thd, value, 1);
pthread_mutex_unlock(&(thd->lock));
} else if (stage == STAGE_TRACING) {
//fprintf(stderr, "DEBUG - GC async tracing marking heap obj %p ", old_obj);
//Cyc_display(thd, old_obj, stderr);
//fprintf(stderr, "\n");
mark_stack_or_heap_obj(thd, old_obj, 0);
#if GC_DEBUG_VERBOSE
if (is_object_type(old_obj) && (mark(old_obj) == gc_color_clear ||
mark(old_obj) == gc_color_purple)) {
fprintf(stderr,
"added to mark buffer (trace) from write barrier %p:mark %d:",
old_obj, mark(old_obj));
Cyc_display(thd, old_obj, stderr);
fprintf(stderr, "\n");
}
#endif
}
}
/**
* @brief Called by a mutator to cooperate with the collector thread
* @param thd Mutator's thread data
* @param buf_len Number of objects moved to the heap by the mutator during minor GC
*
* This function must be called periodically by each mutator to coordinate
* with the collector. In our implementation it is called after minor GC.
*/
void gc_mut_cooperate(gc_thread_data * thd, int buf_len)
{
int i, status_c, status_m;
#if GC_DEBUG_VERBOSE
int debug_print = 0;
#endif
// Handle any pending marks from write barrier
gc_sum_pending_writes(thd, 0);
// I think below is thread safe, but this code is tricky.
// Worst case should be that some work is done twice if there is
// a race condition
//
// TODO: should use an atomic comparison here
status_c = ck_pr_load_int(&gc_status_col);
status_m = ck_pr_load_int(&(thd->gc_status));
if (status_m != status_c) {
ck_pr_cas_int(&(thd->gc_status), status_m, status_c);
if (status_m == STATUS_ASYNC) {
// Async is done, so clean up old mark data from the last collection
gc_zero_read_write_counts(thd);
} else if (status_m == STATUS_SYNC2) {
#if GC_DEBUG_VERBOSE
debug_print = 1;
#endif
//printf("DEBUG - mutator is cooperating\n");
// Mark thread "roots":
// Begin by marking current continuation, which may have already
// been on the heap prior to latest minor GC
pthread_mutex_lock(&(thd->lock));
gc_mark_gray(thd, thd->gc_cont);
for (i = 0; i < thd->gc_num_args; i++) {
gc_mark_gray(thd, thd->gc_args[i]);
}
// Mark thread object, if applicable. Very likely this is its only ref
if (thd->scm_thread_obj) {
gc_mark_gray(thd, thd->scm_thread_obj);
}
if (thd->exception_handler_stack) {
gc_mark_gray(thd, thd->exception_handler_stack);
}
if (thd->param_objs) {
gc_mark_gray(thd, thd->param_objs);
}
// Also, mark everything the collector moved to the heap
for (i = 0; i < buf_len; i++) {
gc_mark_gray(thd, thd->moveBuf[i]);
}
pthread_mutex_unlock(&(thd->lock));
thd->gc_alloc_color = ck_pr_load_8(&gc_color_mark);
}
}
#if GC_DEBUG_VERBOSE
if (debug_print) {
fprintf(stderr, "coop mark gc_cont %p\n", thd->gc_cont);
for (i = 0; i < thd->gc_num_args; i++) {
fprintf(stderr, "coop mark gc_args[%d] %p\n", i, thd->gc_args[i]);
}
for (i = 0; i < buf_len; i++) {
fprintf(stderr, "coop mark from move buf %i %p\n", i, thd->moveBuf[i]);
}
}
#endif
// If we have finished tracing, clear any "full" bits on the heap
if(ck_pr_cas_8(&(thd->gc_done_tracing), 1, 0)) {
int heap_type, unswept;
gc_heap *h_tmp, *h_head;
#if GC_DEBUG_VERBOSE
fprintf(stdout, "done tracing, cooperator is clearing full bits\n");
#endif
for (heap_type = 0; heap_type < NUM_HEAP_TYPES; heap_type++) {
h_head = h_tmp = thd->heap->heap[heap_type];
unswept = 0;
for (; h_tmp; h_tmp = h_tmp->next) {
if (h_tmp && h_tmp->is_full == 1) {
h_tmp->is_full = 0;
h_tmp->is_unswept = 1;
unswept++;
//// Assume heap is completely free for purposes of GC free space tracking
//thd->cached_heap_free_sizes[heap_type] += h_tmp->size - h_tmp->free_size;
//if (thd->cached_heap_free_sizes[heap_type] > thd->cached_heap_total_sizes[heap_type]) {
// fprintf(stderr, "gc_mut_cooperate - Invalid cached heap sizes, free=%zu total=%zu\n",
// thd->cached_heap_free_sizes[heap_type], thd->cached_heap_total_sizes[heap_type]);
//}
//h_tmp->free_size = h_tmp->size;
} else if (h_tmp->is_unswept == 1) {
unswept++;
}
}
h_head->num_unswept_children = unswept;
//printf("set num_unswept_children = %d computed = %d\n", h_head->num_unswept_children, gc_num_unswept_heaps(h_head));
}
// At least for now, let the main thread help clean up any terminated threads
if (thd == primordial_thread) {
#if GC_DEBUG_TRACE
fprintf(stderr, "main thread is cleaning up any old thread data\n");
#endif
gc_free_old_thread_data();
}
// Clear allocation counts to delay next GC trigger
thd->heap_num_huge_allocations = 0;
thd->num_minor_gcs = 0;
// TODO: can't do this now because we don't know how much of the heap is free, as none if it has
// been swept and we are sweeping incrementally
//
// for (heap_type = 0; heap_type < 2; heap_type++) {
// uint64_t free_size = gc_heap_free_size(thd->heap->heap[heap_type]),
// threshold = (thd->cached_heap_total_sizes[heap_type]) * GC_FREE_THRESHOLD;
// if (free_size < threshold) {
// int i, new_heaps = (int)((threshold - free_size) / HEAP_SIZE);
// if (new_heaps < 1) {
// new_heaps = 1;
// }
////#if GC_DEBUG_TRACE
// fprintf(stderr, "Less than %f%% of the heap %d is free (%llu / %llu), growing it %d times\n",
// 100.0 * GC_FREE_THRESHOLD, heap_type, free_size, threshold, new_heaps);
////#endif
//if (new_heaps > 100){ exit(1);} // Something is wrong!
// for(i = 0; i < new_heaps; i++){
// gc_grow_heap(thd->heap->heap[heap_type], heap_type, 0, 0, thd);
// }
// // while ( gc_heap_free_size(thd->heap->heap[heap_type]) < //thd->cached_heap_free_sizes[heap_type] <
// // if (heap_type == HEAP_SM) {
// // gc_grow_heap(thd->heap->heap[heap_type], heap_type, 0, 0, thd);
// // } else if (heap_type == HEAP_64) {
// // gc_grow_heap(thd->heap->heap[heap_type], heap_type, 0, 0, thd);
// // } else if (heap_type == HEAP_REST) {
// // gc_grow_heap(thd->heap->heap[heap_type], heap_type, 0, 0, thd);
// // }
// }
// }
// DEBUG diagnostics
#if GC_DEBUG_SHOW_SWEEP_DIAG
for (heap_type = 0; heap_type < NUM_HEAP_TYPES; heap_type++) {
h_tmp = thd->heap->heap[heap_type];
if (h_tmp) {
fprintf(stderr, "From collector - Heap %d diagnostics:\n", heap_type);
gc_print_stats(h_tmp);
}
}
#endif
}
thd->num_minor_gcs++;
if (thd->num_minor_gcs % 10 == 9) { // Throttle a bit since usually we do not need major GC
thd->cached_heap_free_sizes[HEAP_SM] = gc_heap_free_size(thd->heap->heap[HEAP_SM]) ;
thd->cached_heap_free_sizes[HEAP_64] = gc_heap_free_size(thd->heap->heap[HEAP_64]) ;
thd->cached_heap_free_sizes[HEAP_96] = gc_heap_free_size(thd->heap->heap[HEAP_96]) ;
thd->cached_heap_free_sizes[HEAP_REST] = gc_heap_free_size(thd->heap->heap[HEAP_REST]);
#if GC_DEBUG_VERBOSE
fprintf(stderr, "heap %d free %zu total %zu\n", HEAP_SM, thd->cached_heap_free_sizes[HEAP_SM], thd->cached_heap_total_sizes[HEAP_SM]);
if (thd->cached_heap_free_sizes[HEAP_SM] > thd->cached_heap_total_sizes[HEAP_SM]) {
fprintf(stderr, "gc_mut_cooperate - Invalid cached heap sizes, free=%zu total=%zu\n",
thd->cached_heap_free_sizes[HEAP_SM], thd->cached_heap_total_sizes[HEAP_SM]);
exit(1);
}
fprintf(stderr, "heap %d free %zu total %zu\n", HEAP_64, thd->cached_heap_free_sizes[HEAP_64], thd->cached_heap_total_sizes[HEAP_64]);
if (thd->cached_heap_free_sizes[HEAP_64] > thd->cached_heap_total_sizes[HEAP_64]) {
fprintf(stderr, "gc_mut_cooperate - Invalid cached heap sizes, free=%zu total=%zu\n",
thd->cached_heap_free_sizes[HEAP_64], thd->cached_heap_total_sizes[HEAP_64]);
exit(1);
}
fprintf(stderr, "heap %d free %zu total %zu\n", HEAP_96, thd->cached_heap_free_sizes[HEAP_96], thd->cached_heap_total_sizes[HEAP_96]);
if (thd->cached_heap_free_sizes[HEAP_96] > thd->cached_heap_total_sizes[HEAP_96]) {
fprintf(stderr, "gc_mut_cooperate - Invalid cached heap sizes, free=%zu total=%zu\n",
thd->cached_heap_free_sizes[HEAP_96], thd->cached_heap_total_sizes[HEAP_96]);
exit(1);
}
fprintf(stderr, "heap %d free %zu total %zu\n", HEAP_REST, thd->cached_heap_free_sizes[HEAP_REST], thd->cached_heap_total_sizes[HEAP_REST]);
if (thd->cached_heap_free_sizes[HEAP_REST] > thd->cached_heap_total_sizes[HEAP_REST]) {
fprintf(stderr, "gc_mut_cooperate - Invalid cached heap sizes, free=%zu total=%zu\n",
thd->cached_heap_free_sizes[HEAP_REST], thd->cached_heap_total_sizes[HEAP_REST]);
exit(1);
}
#endif
// Initiate collection cycle if free space is too low.
// Threshold is intentially low because we have to go through an
// entire handshake/trace/sweep cycle, ideally without growing heap.
if (ck_pr_load_int(&gc_stage) == STAGE_RESTING &&
(
//(gc_heap_free_size(thd->heap->heap[HEAP_SM]) < //thd->cached_heap_free_sizes[HEAP_SM] <
(thd->cached_heap_free_sizes[HEAP_SM] <
thd->cached_heap_total_sizes[HEAP_SM] * GC_COLLECTION_THRESHOLD) ||
//(gc_heap_free_size(thd->heap->heap[HEAP_64]) < //thd->cached_heap_free_sizes[HEAP_64] <
(thd->cached_heap_free_sizes[HEAP_64] <
thd->cached_heap_total_sizes[HEAP_64] * GC_COLLECTION_THRESHOLD) ||
#if INTPTR_MAX == INT64_MAX
//(gc_heap_free_size(thd->heap->heap[HEAP_96]) < //thd->cached_heap_free_sizes[HEAP_96] <
(thd->cached_heap_free_sizes[HEAP_96] <
thd->cached_heap_total_sizes[HEAP_96] * GC_COLLECTION_THRESHOLD) ||
#endif
//(gc_heap_free_size(thd->heap->heap[HEAP_REST]) < //thd->cached_heap_free_sizes[HEAP_REST] <
(thd->cached_heap_free_sizes[HEAP_REST] <
thd->cached_heap_total_sizes[HEAP_REST] * GC_COLLECTION_THRESHOLD) ||
// Separate huge heap threshold since these are typically allocated as whole pages
(thd->heap_num_huge_allocations > 100)
)) {
#if GC_DEBUG_TRACE
fprintf(stderr,
"Less than %f%% of the heap is free, initiating collector\n",
100.0 * GC_COLLECTION_THRESHOLD);
#endif
ck_pr_cas_int(&gc_stage, STAGE_RESTING, STAGE_CLEAR_OR_MARKING);
}
}
}
/////////////////////////////////////////////
// Collector functions
/**
* @brief Mark the given object gray if it is on the heap.
* @param thd Mutator's thread data
* @param obj Object to gray
*
* Note marking is done implicitly by placing it in a buffer,
* to avoid repeated re-scanning.
*
* This function must be executed once the thread lock has been acquired.
*/
void gc_mark_gray(gc_thread_data * thd, object obj)
{
// From what I can tell, no other thread would be modifying
// either object type or mark. Both should be stable once the object is placed
// into the heap, with the collector being the only thread that changes marks.
//
// Note when marking we check for both clear and purple to prevent against
// timing issues when incrementing colors and since if we ever reach a
// purple object during tracing we would want to mark it.
// TODO: revisit if checking for gc_color_purple is truly necessary here and elsewhere.
if (is_object_type(obj) && (mark(obj) == gc_color_clear ||
mark(obj) == gc_color_purple)) { // TODO: sync??
// Place marked object in a buffer to avoid repeated scans of the heap.
// TODO:
// Note that ideally this should be a lock-free data structure to make the
// algorithm more efficient. So this code (and the corresponding collector
// trace code) should be converted at some point.
mark_buffer_set(thd->mark_buffer, thd->last_write, obj);
(thd->last_write)++; // Already locked, just do it...
}
}
/**
* @brief Add a pending write to the mark buffer.
* @param thd Mutator's thread data
* @param obj Object to gray
*
* These are pended because they are written in a batch during minor GC.
* To prevent race conditions we wait until all of the writes are made before
* updating last write.
*
* TODO: figure out a new name for this function.
*/
void gc_mark_gray2(gc_thread_data * thd, object obj)
{
if (is_object_type(obj) && (mark(obj) == gc_color_clear ||
mark(obj) == gc_color_purple)) {
mark_buffer_set(thd->mark_buffer, thd->last_write + thd->pending_writes, obj);
thd->pending_writes++;
}
}
/**
* @brief "Color" objects gray by adding them to the mark stack for further processing.
* @param parent Parent of object, used for debugging only
* @param obj Object to mark
*
* Note that stack objects are always colored red during creation, so
* they should never be added to the mark stack. Which would be bad because it
* could lead to stack corruption.
*/
#if GC_DEBUG_VERBOSE
static void gc_collector_mark_gray(object parent, object obj)
{
if (is_object_type(obj) && (mark(obj) == gc_color_clear ||
mark(obj) == gc_color_purple)) {
mark_stack = vpbuffer_add(mark_stack, &mark_stack_len, mark_stack_i++, obj);
fprintf(stderr, "mark gray parent = %p (%d) obj = %p\n", parent,
type_of(parent), obj);
} else if (is_object_type(obj)) {
fprintf(stderr, "not marking gray, parent = %p (%d) obj = %p mark(obj) = %d, gc_color_clear = %d\n", parent,
type_of(parent), obj, mark(obj), gc_color_clear);
}
}
#else
//
// Attempt to speed this up by forcing an inline
//
#define gc_collector_mark_gray(parent, gobj) \
if (is_object_type(gobj) && (mark(gobj) == gc_color_clear || mark(gobj) == gc_color_purple)) { \
mark_stack = vpbuffer_add(mark_stack, &mark_stack_len, mark_stack_i++, gobj); \
}
#endif
#if GC_DEBUG_VERBOSE
void gc_mark_black(object obj)
{
// TODO: is sync required to get colors? probably not on the collector
// thread (at least) since colors are only changed once during the clear
// phase and before the first handshake.
int markColor = ck_pr_load_8(&gc_color_mark);
if (is_object_type(obj) && mark(obj) != markColor) {
// Gray any child objects
// Note we probably should use some form of atomics/synchronization
// for cons and vector types, as these pointers could change.
switch (type_of(obj)) {
case pair_tag:{
gc_collector_mark_gray(obj, car(obj));
gc_collector_mark_gray(obj, cdr(obj));
break;
}
case closure1_tag:
gc_collector_mark_gray(obj, ((closure1) obj)->element);
break;
case closureN_tag:{
int i, n = ((closureN) obj)->num_elements;
for (i = 0; i < n; i++) {
gc_collector_mark_gray(obj, ((closureN) obj)->elements[i]);
}
break;
}
case vector_tag:{
int i, n = ((vector) obj)->num_elements;
for (i = 0; i < n; i++) {
gc_collector_mark_gray(obj, ((vector) obj)->elements[i]);
}
break;
}
case cvar_tag:{
cvar_type *c = (cvar_type *) obj;
object pvar = *(c->pvar);
if (pvar) {
gc_collector_mark_gray(obj, pvar);
}
break;
}
default:
break;
}
if (mark(obj) != gc_color_red) {
// Only blacken objects on the heap
mark(obj) = markColor;
}
if (mark(obj) != gc_color_red) {
fprintf(stderr, "marked %p %d\n", obj, markColor);
} else {
fprintf(stderr, "not marking stack obj %p %d\n", obj, markColor);
}
}
}
#else
// See full version above for debugging purposes.
// Also sync any changes to this macro with the function version
#define gc_mark_black(obj) \
{ \
int markColor = ck_pr_load_8(&gc_color_mark); \
if (is_object_type(obj) && mark(obj) != markColor) { \
switch (type_of(obj)) { \
case pair_tag:{ \
gc_collector_mark_gray(obj, car(obj)); \
gc_collector_mark_gray(obj, cdr(obj)); \
break; \
} \
case closure1_tag: \
gc_collector_mark_gray(obj, ((closure1) obj)->element); \
break; \
case closureN_tag:{ \
int i, n = ((closureN) obj)->num_elements; \
for (i = 0; i < n; i++) { \
gc_collector_mark_gray(obj, ((closureN) obj)->elements[i]); \
} \
break; \
} \
case vector_tag:{ \
int i, n = ((vector) obj)->num_elements; \
for (i = 0; i < n; i++) { \
gc_collector_mark_gray(obj, ((vector) obj)->elements[i]); \
} \
break; \
} \
case cvar_tag:{ \
cvar_type *c = (cvar_type *) obj; \
object pvar = *(c->pvar); \
if (pvar) { \
gc_collector_mark_gray(obj, pvar); \
} \
break; \
} \
default: \
break; \
} \
if (mark(obj) != gc_color_red) { \
mark(obj) = markColor; \
} \
} \
}
#endif
/**
* @brief The collector's tracing algorithm
*
* This function ensures all live objects are marked prior to transitioning
* to the collector's sweep phase.
*/
void gc_collector_trace()
{
ck_array_iterator_t iterator;
gc_thread_data *m;
int clean = 0, last_write;
while (!clean) {
clean = 1;
CK_ARRAY_FOREACH(&Cyc_mutators, &iterator, &m) {
pthread_mutex_lock(&(m->lock));
// Try doing this loop (majority of tracing) without the lock. We
// shouldn't need to be locked to do it anyway and we still lock
// below as a fail-safe. One potential issue here is this would be
// broken if the mark buffer needs to be grown. But this is not a
// problem because we will only go as far as the mutator already
// went with the version of last write we are holding here... so
// we avoid that race condition.
last_write = m->last_write;
pthread_mutex_unlock(&(m->lock));
while (m->last_read < last_write) {
clean = 0;
#if GC_DEBUG_VERBOSE
fprintf(stderr,
"gc_mark_black mark buffer %p, last_read = %d last_write = %d\n",
mark_buffer_get(m->mark_buffer, m->last_read), m->last_read, last_write);
#endif
gc_mark_black(mark_buffer_get(m->mark_buffer, m->last_read));
gc_empty_collector_stack();
(m->last_read)++; // Inc here to prevent off-by-one error
}
//pthread_mutex_unlock(&(m->lock));
// Try checking the condition once more after giving the
// mutator a chance to respond, to prevent exiting early.
// This is experimental, not sure if it is necessary
if (clean) {
pthread_mutex_lock(&(m->lock));
if (m->last_read < m->last_write) {
#if GC_SAFETY_CHECKS
fprintf(stderr,
"gc_collector_trace - might have exited trace early\n");
#endif
clean = 0;
} else if (m->pending_writes) {
clean = 0;
}
pthread_mutex_unlock(&(m->lock));
}
}
}
}
/**
* @brief Empty the collector's mark stack
*
* Objects on the stack are removed one at a time and marked
*/
void gc_empty_collector_stack()
{
object obj;
// Mark stack is only used by the collector thread, so no sync needed
while (mark_stack_i > 0) { // not empty
mark_stack_i--;
//#if GC_DEBUG_VERBOSE
// fprintf(stderr, "gc_mark_black mark stack %p \n",
// mark_stack[mark_stack_i]);
//#endif
obj = mark_stack[mark_stack_i];
gc_mark_black(obj);
}
}
/**
* @brief Called by the collector thread to perform a handshake with
* all of the mutators
* @param s Transition to this GC status
*/
void gc_handshake(gc_status_type s)
{
gc_post_handshake(s);
gc_wait_handshake();
}
/**
* @brief Change GC status to the given type
* @param s Transition to this GC status
*/
void gc_post_handshake(gc_status_type s)
{
int status = ck_pr_load_int(&gc_status_col);
while (!ck_pr_cas_int(&gc_status_col, status, s)) {
}
}
/**
* @brief Wait for all mutators to handshake
*
* This function is always called by the collector. If a mutator
* is blocked and cannot handshake, the collector will cooperate
* on its behalf, including invoking a minor GC of the mutator's
* stack, so major GC can proceed.
*/
void gc_wait_handshake()
{
ck_array_iterator_t iterator;
gc_thread_data *m;
int statusm, statusc, thread_status, i, buf_len;
struct timespec tim;
tim.tv_sec = 0;
tim.tv_nsec = 1000000; // 1 millisecond
CK_ARRAY_FOREACH(&Cyc_mutators, &iterator, &m) {
while (1) {
// TODO: use an atomic comparison
statusc = ck_pr_load_int(&gc_status_col);
statusm = ck_pr_load_int(&(m->gc_status));
if (statusc == statusm) {
// Handshake succeeded, check next mutator
break;
}
thread_status = ck_pr_load_int((int *)&(m->thread_state));
if (thread_status == CYC_THREAD_STATE_BLOCKED ||
thread_status == CYC_THREAD_STATE_BLOCKED_COOPERATING) {
if (statusm == STATUS_ASYNC) { // Prev state
ck_pr_cas_int(&(m->gc_status), statusm, statusc);
// Async is done, so clean up old mark data from the last collection
gc_zero_read_write_counts(m);
} else if (statusm == STATUS_SYNC1) {
ck_pr_cas_int(&(m->gc_status), statusm, statusc);
} else if (statusm == STATUS_SYNC2) {
//printf("DEBUG - is mutator still blocked?\n");
pthread_mutex_lock(&(m->lock));
// Check again, if thread is still blocked we need to cooperate
if (ck_pr_cas_int((int *)&(m->thread_state),
CYC_THREAD_STATE_BLOCKED,
CYC_THREAD_STATE_BLOCKED_COOPERATING)
||
ck_pr_cas_int((int *)&(m->thread_state),
CYC_THREAD_STATE_BLOCKED_COOPERATING,
CYC_THREAD_STATE_BLOCKED_COOPERATING)
) {
//printf("DEBUG - update mutator GC status\n");
ck_pr_cas_int(&(m->gc_status), statusm, statusc);
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - collector is cooperating for blocked mutator\n");
#endif
buf_len =
gc_minor(m, m->stack_limit, m->stack_start, m->gc_cont, NULL,
0);
// Handle any pending marks from write barrier
gc_sum_pending_writes(m, 1);
// Mark thread "roots", based on code from mutator's cooperator
gc_mark_gray(m, m->gc_cont);
//for (i = 0; i < m->gc_num_args; i++) {
// gc_mark_gray(m, m->gc_args[i]);
//}
if (m->scm_thread_obj) {
gc_mark_gray(m, m->scm_thread_obj);
}
if (m->exception_handler_stack) {
gc_mark_gray(m, m->exception_handler_stack);
}
if (m->param_objs) {
gc_mark_gray(m, m->param_objs);
}
// Also, mark everything the collector moved to the heap
for (i = 0; i < buf_len; i++) {
gc_mark_gray(m, m->moveBuf[i]);
}
m->gc_alloc_color = ck_pr_load_8(&gc_color_mark);
}
pthread_mutex_unlock(&(m->lock));
}
} else if (thread_status == CYC_THREAD_STATE_TERMINATED) {
// Thread is no longer running
break;
}
// At least for now, just give up quantum and come back to
// this quickly to test again. This probably could be more
// efficient.
nanosleep(&tim, NULL);
}
}
}
/////////////////////////////////////////////
// GC Collection cycle
void debug_dump_globals();
/**
* @brief Main collector function
*/
void gc_collector()
{
//int old_clear, old_mark;
#if GC_DEBUG_TRACE
print_allocated_obj_counts();
gc_log(stderr, "Starting gc_collector");
#endif
//fprintf(stderr, " - Starting gc_collector\n"); // TODO: DEBUGGING!!!
//clear :
ck_pr_cas_int(&gc_stage, STAGE_RESTING, STAGE_CLEAR_OR_MARKING);
// exchange values of markColor and clearColor
//
// We now increment both so that clear becomes the old mark color and a
// new value is used for the mark color. The old clear color becomes
// purple, indicating any of these objects are garbage
ck_pr_add_8(&gc_color_purple, 2);
ck_pr_add_8(&gc_color_clear, 2);
ck_pr_add_8(&gc_color_mark, 2);
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - swap clear %d / mark %d\n", gc_color_clear,
gc_color_mark);
#endif
gc_handshake(STATUS_SYNC1);
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - after handshake sync 1\n");
#endif
//mark :
gc_handshake(STATUS_SYNC2);
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - after handshake sync 2\n");
#endif
ck_pr_cas_int(&gc_stage, STAGE_CLEAR_OR_MARKING, STAGE_TRACING);
gc_post_handshake(STATUS_ASYNC);
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - after post_handshake async\n");
#endif
gc_wait_handshake();
gc_request_mark_globals(); // Wait until mutators have new mark color
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - after wait_handshake async\n");
#endif
//trace :
gc_collector_trace();
#if GC_DEBUG_TRACE
fprintf(stderr, "DEBUG - after trace\n");
//debug_dump_globals();
#endif
ck_pr_cas_int(&gc_stage, STAGE_TRACING, STAGE_SWEEPING);
//
//sweep :
gc_collector_sweep();
// Idle the GC thread
ck_pr_cas_int(&gc_stage, STAGE_SWEEPING, STAGE_RESTING);
}
void *collector_main(void *arg)
{
int stage;
struct timespec tim;
#ifdef DEBUG_THREADS
pthread_t tid = pthread_self();
int sid = syscall(SYS_gettid);
printf("GC thread LWP id is %d\n", sid);
//printf("GC thread POSIX thread id is %d\n", tid);
#endif
tim.tv_sec = 0;
tim.tv_nsec = 100 * NANOSECONDS_PER_MILLISECOND;
while (1) {
stage = ck_pr_load_int(&gc_stage);
if (stage != STAGE_RESTING) {
gc_collector();
}
nanosleep(&tim, NULL);
}
return NULL;
}
/**
* @brief A high-resolution sleep function.
*
* @param ms Sleep time in milliseconds
*/
void gc_sleep_ms(int ms)
{
struct timespec tim;
tim.tv_sec = 0;
tim.tv_nsec = ms * NANOSECONDS_PER_MILLISECOND;
nanosleep(&tim, NULL);
}
static pthread_t collector_thread;
/**
* @brief Spawn the collector thread
*/
void gc_start_collector()
{
if (pthread_create
(&collector_thread, NULL, collector_main, &collector_thread)) {
fprintf(stderr, "Error creating collector thread\n");
exit(1);
}
}
/**
* @brief Mark globals as part of the tracing collector
* @param globals
* @param global_table
*
* This is called by the collector thread
*/
void gc_mark_globals(object globals, object global_table)
{
#if GC_DEBUG_TRACE
//fprintf(stderr, "(gc_mark_globals heap: %p size: %d)\n", h, (unsigned int)gc_heap_total_size(h));
fprintf(stderr, "Cyc_global_variables %p\n", globals);
#endif
// Mark global variables
gc_mark_black(globals); // Internal global used by the runtime
// Marking it ensures all glos are marked
{
list l = global_table;
for (; l != NULL; l = cdr(l)) {
cvar_type *c = (cvar_type *) car(l);
object glo = *(c->pvar);
if (glo != NULL) {
#if GC_DEBUG_VERBOSE
fprintf(stderr, "global pvar %p\n", glo);
#endif
gc_mark_black(glo); // Mark actual object the global points to
}
}
}
}
/////////////////////////////////////////////
// END tri-color marking section
/////////////////////////////////////////////
/**
* @brief Initialize runtime data structures for a thread.
* @param thd Mutator's thread data
* @param mut_num Unused
* @param stack_base Bottom of the mutator's stack
* @param stack_size Max allowed size of mutator's stack before triggering minor GC
*
* Must be called on the target thread itself during startup,
* to verify stack limits are setup correctly.
*/
void gc_thread_data_init(gc_thread_data * thd, int mut_num, char *stack_base,
long stack_size)
{
char stack_ref;
thd->stack_start = stack_base;
#if STACK_GROWTH_IS_DOWNWARD
thd->stack_limit = stack_base - stack_size;
#else
thd->stack_limit = stack_base + stack_size;
#endif
if (stack_overflow(stack_base, &stack_ref)) {
fprintf(stderr,
"Error: Stack is growing in the wrong direction! Rebuild with STACK_GROWTH_IS_DOWNWARD changed to %d\n",
(1 - STACK_GROWTH_IS_DOWNWARD));
exit(1);
}
thd->stack_traces = calloc(MAX_STACK_TRACES, sizeof(char *));
thd->stack_trace_idx = 0;
thd->stack_prev_frame = NULL;
thd->mutations = NULL;
thd->mutation_buflen = 128;
thd->mutation_count = 0;
thd->mutations =
vpbuffer_realloc(thd->mutations, &(thd->mutation_buflen));
thd->globals_changed = 1;
thd->param_objs = NULL;
thd->exception_handler_stack = NULL;
thd->scm_thread_obj = NULL;
thd->thread_state = CYC_THREAD_STATE_NEW;
//thd->mutator_num = mut_num;
thd->jmp_start = malloc(sizeof(jmp_buf));
thd->gc_args = malloc(sizeof(object) * NUM_GC_ARGS);
thd->gc_num_args = 0;
thd->moveBufLen = 0;
gc_thr_grow_move_buffer(thd);
thd->gc_alloc_color = ck_pr_load_8(&gc_color_clear);
thd->gc_trace_color = thd->gc_alloc_color;
thd->gc_done_tracing = 0;
thd->gc_status = ck_pr_load_int(&gc_status_col);
thd->pending_writes = 0;
thd->last_write = 0;
thd->last_read = 0;
thd->mark_buffer = mark_buffer_init(128);
if (pthread_mutex_init(&(thd->lock), NULL) != 0) {
fprintf(stderr, "Unable to initialize thread mutex\n");
exit(1);
}
thd->heap_num_huge_allocations = 0;
thd->num_minor_gcs = 0;
thd->cached_heap_free_sizes = calloc(5, sizeof(uintptr_t));
thd->cached_heap_total_sizes = calloc(5, sizeof(uintptr_t));
thd->heap = calloc(1, sizeof(gc_heap_root));
thd->heap->heap = calloc(1, sizeof(gc_heap *) * NUM_HEAP_TYPES);
thd->heap->heap[HEAP_REST] = gc_heap_create(HEAP_REST, INITIAL_HEAP_SIZE, 0, 0, thd);
thd->heap->heap[HEAP_SM] = gc_heap_create(HEAP_SM, INITIAL_HEAP_SIZE, 0, 0, thd);
thd->heap->heap[HEAP_64] = gc_heap_create(HEAP_64, INITIAL_HEAP_SIZE, 0, 0, thd);
if (sizeof(void *) == 8) { // Only use this heap on 64-bit platforms
thd->heap->heap[HEAP_96] = gc_heap_create(HEAP_96, INITIAL_HEAP_SIZE, 0, 0, thd);
}
thd->heap->heap[HEAP_HUGE] = gc_heap_create(HEAP_HUGE, 1024, 0, 0, thd);
}
/**
* @brief Free all data for the given mutator
* @param thd Mutator's thread data object containing data to free
*/
void gc_thread_data_free(gc_thread_data * thd)
{
if (thd) {
if (pthread_mutex_destroy(&thd->lock) != 0) {
// TODO: can only destroy the lock if it is unlocked. need to make sure we
// can guarantee that is the case prior to making this call
// On the other hand, can we just use sleep and a loop to retry??
fprintf(stderr, "Thread mutex is locked, unable to free\n");
exit(1);
}
// Merge heaps for the terminating thread into the main thread's heap.
// Eventually any data that is unused will be freed, but we need to
// keep the heap pages for now because they could still contain live
// objects.
// Lock the primordial thread (hopefully will not cause any deadlocks)
// but don't bother locking thd since it is already done by now.
// TODO: need to figure out a new solution since we no longer have the heap lock!!!!
// pthread_mutex_lock(&(primordial_thread->heap_lock));
gc_merge_all_heaps(primordial_thread, thd);
// pthread_mutex_unlock(&(primordial_thread->heap_lock));
if (thd->cached_heap_free_sizes)
free(thd->cached_heap_free_sizes);
if (thd->cached_heap_total_sizes)
free(thd->cached_heap_total_sizes);
if (thd->jmp_start)
free(thd->jmp_start);
if (thd->gc_args)
free(thd->gc_args);
if (thd->moveBuf)
free(thd->moveBuf);
if (thd->mark_buffer)
mark_buffer_free(thd->mark_buffer);
if (thd->stack_traces)
free(thd->stack_traces);
if (thd->mutations) {
free(thd->mutations);
}
free(thd);
}
}
/**
* @brief Merge one heap into another.
* @param hdest Heap that will receive new pages
* @param hsrc Heap that is being merged to the end of `hdest`
*
* This function assumes appropriate locks are already held.
*/
void gc_heap_merge(gc_heap *hdest, gc_heap *hsrc)
{
gc_heap *last = gc_heap_last(hdest);
last->next = hsrc;
}
/**
* @brief Merge all thread heaps into another.
* @param dest Heap receiving new pages
* @param src Heap containing pages to be appended
*
* Assumes appropriate locks are already held.
*/
void gc_merge_all_heaps(gc_thread_data *dest, gc_thread_data *src)
{
gc_heap *hdest, *hsrc;
int heap_type;
for (heap_type = 0; heap_type < NUM_HEAP_TYPES; heap_type++) {
hdest = dest->heap->heap[heap_type];
hsrc = src->heap->heap[heap_type];
if (hdest && hsrc) {
gc_heap_merge(hdest, hsrc);
ck_pr_add_ptr(&(dest->cached_heap_total_sizes[heap_type]),
ck_pr_load_ptr(&(src->cached_heap_total_sizes[heap_type])));
ck_pr_add_ptr(&(dest->cached_heap_free_sizes[heap_type]),
ck_pr_load_ptr(&(src->cached_heap_free_sizes[heap_type])));
}
}
ck_pr_add_int(&(dest->heap_num_huge_allocations),
ck_pr_load_int(&(src->heap_num_huge_allocations)));
#if GC_DEBUG_TRACE
fprintf(stderr, "Finished merging old heap data\n");
#endif
}
/**
* @brief Called explicitly from a mutator thread to let the collector know
* it (may) block for an unknown period of time.
* @param thd Mutator's thread data
* @param cont The mutator's current continuation. This is required so that we can trace over this object in case the collector has to cooperate for the mutator.
*/
void gc_mutator_thread_blocked(gc_thread_data * thd, object cont)
{
thd->gc_cont = cont;
thd->gc_num_args = 0; // Will be set later, after collection
if (!ck_pr_cas_int((int *)&(thd->thread_state),
CYC_THREAD_STATE_RUNNABLE, CYC_THREAD_STATE_BLOCKED)) {
fprintf(stderr,
"Unable to change thread from runnable to blocked. status = %d\n",
thd->thread_state);
exit(1);
}
}
void Cyc_apply_from_buf(void *data, int argc, object prim, object * buf);
/**
* @brief While a mutator has declared itself blocked, it is possible
* that an object on its stack may be copied to the heap by
* the collector. The purpose of this function is to copy
* such an object again to ensure all fields are updated
* to their latest values.
* @param obj Object to copy
* @param thd Thread data object for the applicable mutator
*/
void gc_recopy_obj(object obj, gc_thread_data *thd)
{
// Temporarily change obj type so we can copy it
object fwd = forward(obj);
tag_type tag = type_of(fwd);
type_of(obj) = tag;
#if GC_DEBUG_TRACE
fprintf(stderr, "\n!!! Recopying object %p with tag %d !!!\n\n", obj, tag);
#endif
gc_copy_obj(fwd, obj, thd); // Copy it again
type_of(obj) = forward_tag; // Restore forwarding pointer tag on stack obj
}
/**
* @brief Called explicitly from a mutator thread to let the collector know
* that it has finished blocking.
* @param thd Mutator's thread data
* @param result Data returned by the blocking function
* @param maybe_copied An object used by the mutator while blocked that may
* have been copied to the heap by the collector.
*
* In addition, if the collector cooperated on behalf of the mutator while
* it was blocking, the mutator will move any remaining stack objects to
* the heap and longjmp.
*/
void gc_mutator_thread_runnable(gc_thread_data * thd, object result, object maybe_copied)
{
char stack_limit;
// Transition from blocked back to runnable using CAS.
// If we are unable to transition back, assume collector
// has cooperated on behalf of this mutator thread.
if (!ck_pr_cas_int((int *)&(thd->thread_state),
CYC_THREAD_STATE_BLOCKED, CYC_THREAD_STATE_RUNNABLE)) {
//printf("DEBUG - Collector cooperated, wait for it to finish. status is %d\n", thd->thread_state);
// wait for the collector to finish
pthread_mutex_lock(&(thd->lock));
pthread_mutex_unlock(&(thd->lock));
// update thread status
while (!ck_pr_cas_int((int *)&(thd->thread_state),
CYC_THREAD_STATE_BLOCKED_COOPERATING,
CYC_THREAD_STATE_RUNNABLE)) {
}
// Setup value to send to continuation
thd->gc_args[0] = result;
thd->gc_num_args = 1;
// Check if obj was copied while we slept
if (maybe_copied &&
is_object_type(maybe_copied) &&
gc_is_stack_obj(thd, maybe_copied) &&
type_of(maybe_copied) == forward_tag) {
gc_recopy_obj(maybe_copied, thd);
}
// Move any remaining stack objects (should only be the result?) to heap
gc_minor(thd, &stack_limit, thd->stack_start, thd->gc_cont, thd->gc_args,
thd->gc_num_args);
// Handle any pending marks from write barrier
gc_sum_pending_writes(thd, 0);
//printf("DEBUG - Call into gc_cont after collector coop\n");
// Whoa.
longjmp(*(thd->jmp_start), 1);
} else {
// Collector didn't do anything; make a normal continuation call
if (type_of(thd->gc_cont) == pair_tag || prim(thd->gc_cont)) {
thd->gc_args[0] = result;
Cyc_apply_from_buf(thd, 1, thd->gc_cont, thd->gc_args);
} else {
(((closure) (thd->gc_cont))->fn) (thd, 1, thd->gc_cont, result);
}
}
}
//// Unit testing:
//int main(int argc, char **argv) {
// int a = 1, b = 2, c = 3, i;
// void **buf = NULL;
// int size = 1;
//
// buf = vpbuffer_realloc(buf, &size);
// printf("buf = %p, size = %d\n", buf, size);
// buf = vpbuffer_add(buf, &size, 0, &a);
// printf("buf = %p, size = %d\n", buf, size);
// buf = vpbuffer_add(buf, &size, 1, &b);
// printf("buf = %p, size = %d\n", buf, size);
// buf = vpbuffer_add(buf, &size, 2, &c);
// printf("buf = %p, size = %d\n", buf, size);
// buf = vpbuffer_add(buf, &size, 3, &a);
// printf("buf = %p, size = %d\n", buf, size);
// buf = vpbuffer_add(buf, &size, 4, &b);
// printf("buf = %p, size = %d\n", buf, size);
// for (i = 5; i < 20; i++) {
// buf = vpbuffer_add(buf, &size, i, &c);
// }
//
// for (i = 0; i < 20; i++){
// printf("%d\n", *((int *) buf[i]));
// }
// vpbuffer_free(buf);
// printf("buf = %p, size = %d\n", buf, size);
// return 0;
//}
//