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pjs/gc/boehm/reclaim.c

729 строки
19 KiB
C
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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
/* Boehm, February 15, 1996 2:41 pm PST */
#include <stdio.h>
#include "gc_priv.h"
signed_word GC_mem_found = 0;
/* Number of words of memory reclaimed */
# ifdef FIND_LEAK
static void report_leak(p, sz)
ptr_t p;
word sz;
{
if (HDR(p) -> hb_obj_kind == PTRFREE) {
GC_err_printf0("Leaked atomic object at:\n");
} else {
GC_err_printf0("Leaked composite object at:\n");
}
if (GC_debugging_started && GC_has_debug_info(p)) {
GC_print_obj(p);
} else {
GC_err_printf2("0x%lx (appr. size = %ld)\n",
(unsigned long)p,
(unsigned long)WORDS_TO_BYTES(sz));
}
}
# define FOUND_FREE(hblk, word_no) \
if (abort_if_found) { \
report_leak((ptr_t)hblk + WORDS_TO_BYTES(word_no), \
HDR(hblk) -> hb_sz); \
}
# else
# define FOUND_FREE(hblk, word_no)
# endif
/*
* reclaim phase
*
*/
/*
* Test whether a block is completely empty, i.e. contains no marked
* objects. This does not require the block to be in physical
* memory.
*/
GC_bool GC_block_empty(hhdr)
register hdr * hhdr;
{
register word *p = (word *)(&(hhdr -> hb_marks[0]));
register word * plim =
(word *)(&(hhdr -> hb_marks[MARK_BITS_SZ]));
while (p < plim) {
if (*p++) return(FALSE);
}
return(TRUE);
}
# ifdef GATHERSTATS
# define INCR_WORDS(sz) n_words_found += (sz)
# else
# define INCR_WORDS(sz)
# endif
/*
* Restore unmarked small objects in h of size sz to the object
* free list. Returns the new list.
* Clears unmarked objects.
*/
/*ARGSUSED*/
ptr_t GC_reclaim_clear(hbp, hhdr, sz, list, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
register hdr * hhdr;
GC_bool abort_if_found; /* Abort if a reclaimable object is found */
register ptr_t list;
register word sz;
{
register int word_no;
register word *p, *q, *plim;
# ifdef GATHERSTATS
register int n_words_found = 0;
# endif
p = (word *)(hbp->hb_body);
word_no = HDR_WORDS;
plim = (word *)((((word)hbp) + HBLKSIZE)
- WORDS_TO_BYTES(sz));
/* go through all words in block */
while( p <= plim ) {
if( mark_bit_from_hdr(hhdr, word_no) ) {
p += sz;
} else {
FOUND_FREE(hbp, word_no);
INCR_WORDS(sz);
#if defined(FIND_LEAK) || 1
/* object is available - put on list */
obj_link(p) = list;
list = ((ptr_t)p);
/* Clear object, advance p to next object in the process */
q = p + sz;
p++; /* Skip link field */
while (p < q) {
*p++ = 0;
}
#else
/* let leaks accumulate. */
p += sz;
#endif
}
word_no += sz;
}
# ifdef GATHERSTATS
GC_mem_found += n_words_found;
# endif
return(list);
}
#ifndef SMALL_CONFIG
/*
* A special case for 2 word composite objects (e.g. cons cells):
*/
/*ARGSUSED*/
ptr_t GC_reclaim_clear2(hbp, hhdr, list, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
hdr * hhdr;
GC_bool abort_if_found; /* Abort if a reclaimable object is found */
register ptr_t list;
{
register word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p, *plim;
# ifdef GATHERSTATS
register int n_words_found = 0;
# endif
register word mark_word;
register int i;
# define DO_OBJ(start_displ) \
if (!(mark_word & ((word)1 << start_displ))) { \
FOUND_FREE(hbp, p - (word *)hbp + start_displ); \
p[start_displ] = (word)list; \
list = (ptr_t)(p+start_displ); \
p[start_displ+1] = 0; \
INCR_WORDS(2); \
}
p = (word *)(hbp->hb_body);
plim = (word *)(((word)hbp) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
for (i = 0; i < WORDSZ; i += 8) {
DO_OBJ(0);
DO_OBJ(2);
DO_OBJ(4);
DO_OBJ(6);
p += 8;
mark_word >>= 8;
}
}
# ifdef GATHERSTATS
GC_mem_found += n_words_found;
# endif
return(list);
# undef DO_OBJ
}
/*
* Another special case for 4 word composite objects:
*/
/*ARGSUSED*/
ptr_t GC_reclaim_clear4(hbp, hhdr, list, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
hdr * hhdr;
GC_bool abort_if_found; /* Abort if a reclaimable object is found */
register ptr_t list;
{
register word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p, *plim;
# ifdef GATHERSTATS
register int n_words_found = 0;
# endif
register word mark_word;
# define DO_OBJ(start_displ) \
if (!(mark_word & ((word)1 << start_displ))) { \
FOUND_FREE(hbp, p - (word *)hbp + start_displ); \
p[start_displ] = (word)list; \
list = (ptr_t)(p+start_displ); \
p[start_displ+1] = 0; \
p[start_displ+2] = 0; \
p[start_displ+3] = 0; \
INCR_WORDS(4); \
}
p = (word *)(hbp->hb_body);
plim = (word *)(((word)hbp) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
DO_OBJ(0);
DO_OBJ(4);
DO_OBJ(8);
DO_OBJ(12);
DO_OBJ(16);
DO_OBJ(20);
DO_OBJ(24);
DO_OBJ(28);
# if CPP_WORDSZ == 64
DO_OBJ(32);
DO_OBJ(36);
DO_OBJ(40);
DO_OBJ(44);
DO_OBJ(48);
DO_OBJ(52);
DO_OBJ(56);
DO_OBJ(60);
# endif
p += WORDSZ;
}
# ifdef GATHERSTATS
GC_mem_found += n_words_found;
# endif
return(list);
# undef DO_OBJ
}
#endif /* !SMALL_CONFIG */
/* The same thing, but don't clear objects: */
/*ARGSUSED*/
ptr_t GC_reclaim_uninit(hbp, hhdr, sz, list, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
register hdr * hhdr;
GC_bool abort_if_found; /* Abort if a reclaimable object is found */
register ptr_t list;
register word sz;
{
register int word_no;
register word *p, *plim;
# ifdef GATHERSTATS
register int n_words_found = 0;
# endif
p = (word *)(hbp->hb_body);
word_no = HDR_WORDS;
plim = (word *)((((word)hbp) + HBLKSIZE)
- WORDS_TO_BYTES(sz));
/* go through all words in block */
while( p <= plim ) {
if( !mark_bit_from_hdr(hhdr, word_no) ) {
FOUND_FREE(hbp, word_no);
INCR_WORDS(sz);
/* object is available - put on list */
obj_link(p) = list;
list = ((ptr_t)p);
}
p += sz;
word_no += sz;
}
# ifdef GATHERSTATS
GC_mem_found += n_words_found;
# endif
return(list);
}
#ifndef SMALL_CONFIG
/*
* Another special case for 2 word atomic objects:
*/
/*ARGSUSED*/
ptr_t GC_reclaim_uninit2(hbp, hhdr, list, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
hdr * hhdr;
GC_bool abort_if_found; /* Abort if a reclaimable object is found */
register ptr_t list;
{
register word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p, *plim;
# ifdef GATHERSTATS
register int n_words_found = 0;
# endif
register word mark_word;
register int i;
# define DO_OBJ(start_displ) \
if (!(mark_word & ((word)1 << start_displ))) { \
FOUND_FREE(hbp, p - (word *)hbp + start_displ); \
p[start_displ] = (word)list; \
list = (ptr_t)(p+start_displ); \
INCR_WORDS(2); \
}
p = (word *)(hbp->hb_body);
plim = (word *)(((word)hbp) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
for (i = 0; i < WORDSZ; i += 8) {
DO_OBJ(0);
DO_OBJ(2);
DO_OBJ(4);
DO_OBJ(6);
p += 8;
mark_word >>= 8;
}
}
# ifdef GATHERSTATS
GC_mem_found += n_words_found;
# endif
return(list);
# undef DO_OBJ
}
/*
* Another special case for 4 word atomic objects:
*/
/*ARGSUSED*/
ptr_t GC_reclaim_uninit4(hbp, hhdr, list, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
hdr * hhdr;
GC_bool abort_if_found; /* Abort if a reclaimable object is found */
register ptr_t list;
{
register word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p, *plim;
# ifdef GATHERSTATS
register int n_words_found = 0;
# endif
register word mark_word;
# define DO_OBJ(start_displ) \
if (!(mark_word & ((word)1 << start_displ))) { \
FOUND_FREE(hbp, p - (word *)hbp + start_displ); \
p[start_displ] = (word)list; \
list = (ptr_t)(p+start_displ); \
INCR_WORDS(4); \
}
p = (word *)(hbp->hb_body);
plim = (word *)(((word)hbp) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
DO_OBJ(0);
DO_OBJ(4);
DO_OBJ(8);
DO_OBJ(12);
DO_OBJ(16);
DO_OBJ(20);
DO_OBJ(24);
DO_OBJ(28);
# if CPP_WORDSZ == 64
DO_OBJ(32);
DO_OBJ(36);
DO_OBJ(40);
DO_OBJ(44);
DO_OBJ(48);
DO_OBJ(52);
DO_OBJ(56);
DO_OBJ(60);
# endif
p += WORDSZ;
}
# ifdef GATHERSTATS
GC_mem_found += n_words_found;
# endif
return(list);
# undef DO_OBJ
}
/* Finally the one word case, which never requires any clearing: */
/*ARGSUSED*/
ptr_t GC_reclaim1(hbp, hhdr, list, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
hdr * hhdr;
GC_bool abort_if_found; /* Abort if a reclaimable object is found */
register ptr_t list;
{
register word * mark_word_addr = &(hhdr->hb_marks[divWORDSZ(HDR_WORDS)]);
register word *p, *plim;
# ifdef GATHERSTATS
register int n_words_found = 0;
# endif
register word mark_word;
register int i;
# define DO_OBJ(start_displ) \
if (!(mark_word & ((word)1 << start_displ))) { \
FOUND_FREE(hbp, p - (word *)hbp + start_displ); \
p[start_displ] = (word)list; \
list = (ptr_t)(p+start_displ); \
INCR_WORDS(1); \
}
p = (word *)(hbp->hb_body);
plim = (word *)(((word)hbp) + HBLKSIZE);
/* go through all words in block */
while( p < plim ) {
mark_word = *mark_word_addr++;
for (i = 0; i < WORDSZ; i += 4) {
DO_OBJ(0);
DO_OBJ(1);
DO_OBJ(2);
DO_OBJ(3);
p += 4;
mark_word >>= 4;
}
}
# ifdef GATHERSTATS
GC_mem_found += n_words_found;
# endif
return(list);
# undef DO_OBJ
}
#endif /* !SMALL_CONFIG */
/*
* Restore unmarked small objects in the block pointed to by hbp
* to the appropriate object free list.
* If entirely empty blocks are to be completely deallocated, then
* caller should perform that check.
*/
void GC_reclaim_small_nonempty_block(hbp, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
int abort_if_found; /* Abort if a reclaimable object is found */
{
hdr * hhdr;
register word sz; /* size of objects in current block */
register struct obj_kind * ok;
register ptr_t * flh;
register int kind;
hhdr = HDR(hbp);
sz = hhdr -> hb_sz;
hhdr -> hb_last_reclaimed = (unsigned short) GC_gc_no;
kind = hhdr -> hb_obj_kind;
ok = &GC_obj_kinds[kind];
flh = &(ok -> ok_freelist[sz]);
GC_write_hint(hbp);
if (ok -> ok_init) {
switch(sz) {
# ifndef SMALL_CONFIG
case 1:
*flh = GC_reclaim1(hbp, hhdr, *flh, abort_if_found);
break;
case 2:
*flh = GC_reclaim_clear2(hbp, hhdr, *flh, abort_if_found);
break;
case 4:
*flh = GC_reclaim_clear4(hbp, hhdr, *flh, abort_if_found);
break;
# endif
default:
*flh = GC_reclaim_clear(hbp, hhdr, sz, *flh, abort_if_found);
break;
}
} else {
switch(sz) {
# ifndef SMALL_CONFIG
case 1:
*flh = GC_reclaim1(hbp, hhdr, *flh, abort_if_found);
break;
case 2:
*flh = GC_reclaim_uninit2(hbp, hhdr, *flh, abort_if_found);
break;
case 4:
*flh = GC_reclaim_uninit4(hbp, hhdr, *flh, abort_if_found);
break;
# endif
default:
*flh = GC_reclaim_uninit(hbp, hhdr, sz, *flh, abort_if_found);
break;
}
}
if (IS_UNCOLLECTABLE(kind)) GC_set_hdr_marks(hhdr);
}
/*
* Restore an unmarked large object or an entirely empty blocks of small objects
* to the heap block free list.
* Otherwise enqueue the block for later processing
* by GC_reclaim_small_nonempty_block.
* If abort_if_found is TRUE, then process any block immediately.
*/
void GC_reclaim_block(hbp, abort_if_found)
register struct hblk *hbp; /* ptr to current heap block */
word abort_if_found; /* Abort if a reclaimable object is found */
{
register hdr * hhdr;
register word sz; /* size of objects in current block */
register struct obj_kind * ok;
struct hblk ** rlh;
hhdr = HDR(hbp);
sz = hhdr -> hb_sz;
ok = &GC_obj_kinds[hhdr -> hb_obj_kind];
if( sz > MAXOBJSZ ) { /* 1 big object */
if( !mark_bit_from_hdr(hhdr, HDR_WORDS) ) {
FOUND_FREE(hbp, HDR_WORDS);
# ifdef GATHERSTATS
GC_mem_found += sz;
# endif
GC_freehblk(hbp);
}
} else {
GC_bool empty = GC_block_empty(hhdr);
if (abort_if_found) {
GC_reclaim_small_nonempty_block(hbp, (int)abort_if_found);
} else if (empty) {
# ifdef GATHERSTATS
GC_mem_found += BYTES_TO_WORDS(HBLKSIZE);
# endif
GC_freehblk(hbp);
} else {
/* group of smaller objects, enqueue the real work */
rlh = &(ok -> ok_reclaim_list[sz]);
hhdr -> hb_next = *rlh;
*rlh = hbp;
}
}
}
#if !defined(NO_DEBUGGING)
/* Routines to gather and print heap block info */
/* intended for debugging. Otherwise should be called */
/* with lock. */
static size_t number_of_blocks;
static size_t total_bytes;
/* Number of set bits in a word. Not performance critical. */
static int set_bits(n)
word n;
{
register word m = n;
register int result = 0;
while (m > 0) {
if (m & 1) result++;
m >>= 1;
}
return(result);
}
/* Return the number of set mark bits in the given header */
int GC_n_set_marks(hhdr)
hdr * hhdr;
{
register int result = 0;
register int i;
for (i = 0; i < MARK_BITS_SZ; i++) {
result += set_bits(hhdr -> hb_marks[i]);
}
return(result);
}
/*ARGSUSED*/
void GC_print_block_descr(h, dummy)
struct hblk *h;
word dummy;
{
register hdr * hhdr = HDR(h);
register size_t bytes = WORDS_TO_BYTES(hhdr -> hb_sz);
GC_printf3("(%lu:%lu,%lu)", (unsigned long)(hhdr -> hb_obj_kind),
(unsigned long)bytes,
(unsigned long)(GC_n_set_marks(hhdr)));
bytes += HDR_BYTES + HBLKSIZE-1;
bytes &= ~(HBLKSIZE-1);
total_bytes += bytes;
number_of_blocks++;
}
void GC_print_block_list()
{
GC_printf0("(kind(0=ptrfree,1=normal,2=unc.,3=stubborn):size_in_bytes, #_marks_set)\n");
number_of_blocks = 0;
total_bytes = 0;
GC_apply_to_all_blocks(GC_print_block_descr, (word)0);
GC_printf2("\nblocks = %lu, bytes = %lu\n",
(unsigned long)number_of_blocks,
(unsigned long)total_bytes);
}
#endif /* NO_DEBUGGING */
/*
* Do the same thing on the entire heap, after first clearing small object
* free lists (if we are not just looking for leaks).
*/
void GC_start_reclaim(abort_if_found)
int abort_if_found; /* Abort if a GC_reclaimable object is found */
{
int kind;
/* Clear reclaim- and free-lists */
for (kind = 0; kind < GC_n_kinds; kind++) {
register ptr_t *fop;
register ptr_t *lim;
register struct hblk ** rlp;
register struct hblk ** rlim;
register struct hblk ** rlist = GC_obj_kinds[kind].ok_reclaim_list;
if (rlist == 0) continue; /* This kind not used. */
if (!abort_if_found) {
lim = &(GC_obj_kinds[kind].ok_freelist[MAXOBJSZ+1]);
for( fop = GC_obj_kinds[kind].ok_freelist; fop < lim; fop++ ) {
*fop = 0;
}
} /* otherwise free list objects are marked, */
/* and its safe to leave them */
rlim = rlist + MAXOBJSZ+1;
for( rlp = rlist; rlp < rlim; rlp++ ) {
*rlp = 0;
}
}
# ifdef PRINTBLOCKS
GC_printf0("GC_reclaim: current block sizes:\n");
GC_print_block_list();
# endif
/* Go through all heap blocks (in hblklist) and reclaim unmarked objects */
/* or enqueue the block for later processing. */
GC_apply_to_all_blocks(GC_reclaim_block, (word)abort_if_found);
}
/*
* Sweep blocks of the indicated object size and kind until either the
* appropriate free list is nonempty, or there are no more blocks to
* sweep.
*/
void GC_continue_reclaim(sz, kind)
word sz; /* words */
int kind;
{
register hdr * hhdr;
register struct hblk * hbp;
register struct obj_kind * ok = &(GC_obj_kinds[kind]);
struct hblk ** rlh = ok -> ok_reclaim_list;
ptr_t *flh = &(ok -> ok_freelist[sz]);
if (rlh == 0) return; /* No blocks of this kind. */
rlh += sz;
while ((hbp = *rlh) != 0) {
hhdr = HDR(hbp);
*rlh = hhdr -> hb_next;
GC_reclaim_small_nonempty_block(hbp, FALSE);
if (*flh != 0) break;
}
}
/*
* Reclaim all small blocks waiting to be reclaimed.
* Abort and return FALSE when/if (*stop_func)() returns TRUE.
* If this returns TRUE, then it's safe to restart the world
* with incorrectly cleared mark bits.
* If ignore_old is TRUE, then reclain only blocks that have been
* recently reclaimed, and discard the rest.
* Stop_func may be 0.
*/
GC_bool GC_reclaim_all(stop_func, ignore_old)
GC_stop_func stop_func;
GC_bool ignore_old;
{
register word sz;
register int kind;
register hdr * hhdr;
register struct hblk * hbp;
register struct obj_kind * ok;
struct hblk ** rlp;
struct hblk ** rlh;
# ifdef PRINTTIMES
CLOCK_TYPE start_time;
CLOCK_TYPE done_time;
GET_TIME(start_time);
# endif
for (kind = 0; kind < GC_n_kinds; kind++) {
ok = &(GC_obj_kinds[kind]);
rlp = ok -> ok_reclaim_list;
if (rlp == 0) continue;
for (sz = 1; sz <= MAXOBJSZ; sz++) {
rlh = rlp + sz;
while ((hbp = *rlh) != 0) {
if (stop_func != (GC_stop_func)0 && (*stop_func)()) {
return(FALSE);
}
hhdr = HDR(hbp);
*rlh = hhdr -> hb_next;
if (!ignore_old || hhdr -> hb_last_reclaimed == GC_gc_no - 1) {
/* It's likely we'll need it this time, too */
/* It's been touched recently, so this */
/* shouldn't trigger paging. */
GC_reclaim_small_nonempty_block(hbp, FALSE);
}
}
}
}
# ifdef PRINTTIMES
GET_TIME(done_time);
GC_printf1("Disposing of reclaim lists took %lu msecs\n",
MS_TIME_DIFF(done_time,start_time));
# endif
return(TRUE);
}
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