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status-go/vendor/gopkg.in/olebedev/go-duktape.v3/duk_alloc_pool.c

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/*
* Pool allocator for low memory targets.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdarg.h>
#include "duktape.h"
#include "duk_alloc_pool.h"
/* Define to enable some debug printfs. */
/* #define DUK_ALLOC_POOL_DEBUG */
/* Define to enable approximate waste tracking. */
/* #define DUK_ALLOC_POOL_TRACK_WASTE */
/* Define to track global highwater for used and waste bytes. VERY SLOW, only
* useful for manual testing.
*/
/* #define DUK_ALLOC_POOL_TRACK_HIGHWATER */
#if defined(DUK_ALLOC_POOL_ROMPTR_COMPRESSION)
#if 0 /* This extern declaration is provided by duktape.h, array provided by duktape.c. */
extern const void * const duk_rom_compressed_pointers[];
#endif
const void *duk_alloc_pool_romptr_low = NULL;
const void *duk_alloc_pool_romptr_high = NULL;
static void duk__alloc_pool_romptr_init(void);
#endif
#if defined(DUK_USE_HEAPPTR16)
void *duk_alloc_pool_ptrcomp_base = NULL;
#endif
#if defined(DUK_ALLOC_POOL_DEBUG)
static void duk__alloc_pool_dprintf(const char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
}
#endif
/*
* Pool initialization
*/
void *duk_alloc_pool_init(char *buffer,
size_t size,
const duk_pool_config *configs,
duk_pool_state *states,
int num_pools,
duk_pool_global *global) {
double t_min, t_max, t_curr, x;
int step, i, j, n;
size_t total;
char *p;
/* XXX: check that 'size' is not too large when using pointer
* compression.
*/
/* To optimize pool counts first come up with a 't' which still allows
* total pool size to fit within user provided region. After that
* sprinkle any remaining bytes to the counts. Binary search with a
* fixed step count; last round uses 't_min' as 't_curr' to ensure it
* succeeds.
*/
t_min = 0.0; /* Unless config is insane, this should always be "good". */
t_max = 1e6;
for (step = 0; ; step++) {
if (step >= 100) {
/* Force "known good", rerun config, and break out.
* Deals with rounding corner cases where t_curr is
* persistently "bad" even though t_min is a valid
* solution.
*/
t_curr = t_min;
} else {
t_curr = (t_min + t_max) / 2.0;
}
for (i = 0, total = 0; i < num_pools; i++) {
states[i].size = configs[i].size;
/* Target bytes = A*t + B ==> target count = (A*t + B) / block_size.
* Rely on A and B being small enough so that 'x' won't wrap.
*/
x = ((double) configs[i].a * t_curr + (double) configs[i].b) / (double) configs[i].size;
states[i].count = (unsigned int) x;
total += (size_t) states[i].size * (size_t) states[i].count;
if (total > size) {
goto bad;
}
}
/* t_curr is good. */
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_alloc_pool_init: step=%d, t=[%lf %lf %lf] -> total %ld/%ld (good)\n",
step, t_min, t_curr, t_max, (long) total, (long) size);
#endif
if (step >= 100) {
/* Keep state[] initialization state. The state was
* created using the highest 't_min'.
*/
break;
}
t_min = t_curr;
continue;
bad:
/* t_curr is bad. */
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_alloc_pool_init: step=%d, t=[%lf %lf %lf] -> total %ld/%ld (bad)\n",
step, t_min, t_curr, t_max, (long) total, (long) size);
#endif
if (step >= 1000) {
/* Cannot find any good solution; shouldn't happen
* unless config is bad or 'size' is so small that
* even a baseline allocation won't fit.
*/
return NULL;
}
t_max = t_curr;
/* continue */
}
/* The base configuration is now good; sprinkle any leftovers to
* pools in descending order. Note that for good t_curr, 'total'
* indicates allocated bytes so far and 'size - total' indicates
* leftovers.
*/
for (i = num_pools - 1; i >= 0; i--) {
while (size - total >= states[i].size) {
/* Ignore potential wrapping of states[i].count as the count
* is 32 bits and shouldn't wrap in practice.
*/
states[i].count++;
total += states[i].size;
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_alloc_pool_init: sprinkle %ld bytes (%ld left after) to pool index %ld, new count %ld\n",
(long) states[i].size, (long) (size - total), (long) i, (long) states[i].count);
#endif
}
}
/* Pool counts are final. Allocate the user supplied region based
* on the final counts, initialize free lists for each block size,
* and otherwise finalize 'state' for use.
*/
p = buffer;
global->num_pools = num_pools;
global->states = states;
#if defined(DUK_ALLOC_POOL_TRACK_HIGHWATER)
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_alloc_pool_init: global highwater mark tracking enabled, THIS IS VERY SLOW!\n");
#endif
global->hwm_used_bytes = 0U;
global->hwm_waste_bytes = 0U;
#endif
#if defined(DUK_ALLOC_POOL_TRACK_WASTE)
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_alloc_pool_init: approximate waste tracking enabled\n");
#endif
#endif
#if defined(DUK_USE_HEAPPTR16)
/* Register global base value for pointer compression, assumes
* a single active pool -4 allows a single subtract to be used and
* still ensures no non-NULL pointer encodes to zero.
*/
duk_alloc_pool_ptrcomp_base = (void *) (p - 4);
#endif
for (i = 0; i < num_pools; i++) {
n = (int) states[i].count;
if (n > 0) {
states[i].first = (duk_pool_free *) p;
for (j = 0; j < n; j++) {
char *p_next = p + states[i].size;
((duk_pool_free *) p)->next =
(j == n - 1) ? (duk_pool_free *) NULL : (duk_pool_free *) p_next;
p = p_next;
}
} else {
states[i].first = (duk_pool_free *) NULL;
}
states[i].alloc_end = p;
#if defined(DUK_ALLOC_POOL_TRACK_HIGHWATER)
states[i].hwm_used_count = 0;
#endif
/* All members of 'state' now initialized. */
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_alloc_pool_init: block size %5ld, count %5ld, %8ld total bytes, "
"end %p\n",
(long) states[i].size, (long) states[i].count,
(long) states[i].size * (long) states[i].count,
(void *) states[i].alloc_end);
#endif
}
#if defined(DUK_ALLOC_POOL_ROMPTR_COMPRESSION)
/* ROM pointer compression precomputation. Assumes a single active
* pool.
*/
duk__alloc_pool_romptr_init();
#endif
/* Use 'global' as udata. */
return (void *) global;
}
/*
* Misc helpers
*/
#if defined(DUK_ALLOC_POOL_TRACK_WASTE)
static void duk__alloc_pool_set_waste_marker(void *ptr, size_t used, size_t size) {
/* Rely on the base pointer and size being divisible by 4 and thus
* aligned. Use 32-bit markers: a 4-byte resolution is good enough,
* and comparing 32 bits at a time makes false waste estimates less
* likely than when comparing as bytes.
*/
duk_uint32_t *p, *p_start, *p_end;
size_t used_round;
used_round = (used + 3U) & ~0x03U; /* round up to 4 */
p_end = (duk_uint32_t *) ((duk_uint8_t *) ptr + size);
p_start = (duk_uint32_t *) ((duk_uint8_t *) ptr + used_round);
p = (duk_uint32_t *) p_start;
while (p != p_end) {
*p++ = DUK_ALLOC_POOL_WASTE_MARKER;
}
}
#else /* DUK_ALLOC_POOL_TRACK_WASTE */
static void duk__alloc_pool_set_waste_marker(void *ptr, size_t used, size_t size) {
(void) ptr; (void) used; (void) size;
}
#endif /* DUK_ALLOC_POOL_TRACK_WASTE */
#if defined(DUK_ALLOC_POOL_TRACK_WASTE)
static size_t duk__alloc_pool_get_waste_estimate(void *ptr, size_t size) {
duk_uint32_t *p, *p_end, *p_start;
/* Assumes size is >= 4. */
p_start = (duk_uint32_t *) ptr;
p_end = (duk_uint32_t *) ((duk_uint8_t *) ptr + size);
p = p_end;
/* This scan may cause harmless valgrind complaints: there may be
* uninitialized bytes within the legitimate allocation or between
* the start of the waste marker and the end of the allocation.
*/
do {
p--;
if (*p == DUK_ALLOC_POOL_WASTE_MARKER) {
;
} else {
return (size_t) (p_end - p - 1) * 4U;
}
} while (p != p_start);
return size;
}
#else /* DUK_ALLOC_POOL_TRACK_WASTE */
static size_t duk__alloc_pool_get_waste_estimate(void *ptr, size_t size) {
(void) ptr; (void) size;
return 0;
}
#endif /* DUK_ALLOC_POOL_TRACK_WASTE */
static int duk__alloc_pool_ptr_in_freelist(duk_pool_state *s, void *ptr) {
duk_pool_free *curr;
for (curr = s->first; curr != NULL; curr = curr->next) {
if ((void *) curr == ptr) {
return 1;
}
}
return 0;
}
void duk_alloc_pool_get_pool_stats(duk_pool_state *s, duk_pool_stats *res) {
void *curr;
size_t free_count;
size_t used_count;
size_t waste_bytes;
curr = s->alloc_end - (s->size * s->count);
free_count = 0U;
waste_bytes = 0U;
while (curr != s->alloc_end) {
if (duk__alloc_pool_ptr_in_freelist(s, curr)) {
free_count++;
} else {
waste_bytes += duk__alloc_pool_get_waste_estimate(curr, s->size);
}
curr = curr + s->size;
}
used_count = (size_t) (s->count - free_count);
res->used_count = used_count;
res->used_bytes = (size_t) (used_count * s->size);
res->free_count = free_count;
res->free_bytes = (size_t) (free_count * s->size);
res->waste_bytes = waste_bytes;
#if defined(DUK_ALLOC_POOL_TRACK_HIGHWATER)
res->hwm_used_count = s->hwm_used_count;
#else
res->hwm_used_count = 0U;
#endif
}
void duk_alloc_pool_get_global_stats(duk_pool_global *g, duk_pool_global_stats *res) {
int i;
size_t total_used = 0U;
size_t total_free = 0U;
size_t total_waste = 0U;
for (i = 0; i < g->num_pools; i++) {
duk_pool_state *s = &g->states[i];
duk_pool_stats stats;
duk_alloc_pool_get_pool_stats(s, &stats);
total_used += stats.used_bytes;
total_free += stats.free_bytes;
total_waste += stats.waste_bytes;
}
res->used_bytes = total_used;
res->free_bytes = total_free;
res->waste_bytes = total_waste;
#if defined(DUK_ALLOC_POOL_TRACK_HIGHWATER)
res->hwm_used_bytes = g->hwm_used_bytes;
res->hwm_waste_bytes = g->hwm_waste_bytes;
#else
res->hwm_used_bytes = 0U;
res->hwm_waste_bytes = 0U;
#endif
}
#if defined(DUK_ALLOC_POOL_TRACK_HIGHWATER)
static void duk__alloc_pool_update_highwater(duk_pool_global *g) {
int i;
size_t total_used = 0U;
size_t total_free = 0U;
size_t total_waste = 0U;
/* Per pool highwater used count, useful to checking if a pool is
* too small.
*/
for (i = 0; i < g->num_pools; i++) {
duk_pool_state *s = &g->states[i];
duk_pool_stats stats;
duk_alloc_pool_get_pool_stats(s, &stats);
if (stats.used_count > s->hwm_used_count) {
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk__alloc_pool_update_highwater: pool %ld (%ld bytes) highwater updated: count %ld -> %ld\n",
(long) i, (long) s->size,
(long) s->hwm_used_count, (long) stats.used_count);
#endif
s->hwm_used_count = stats.used_count;
}
total_used += stats.used_bytes;
total_free += stats.free_bytes;
total_waste += stats.waste_bytes;
}
/* Global highwater mark for used and waste bytes. Both fields are
* updated from the same snapshot based on highest used count.
* This is VERY, VERY slow and only useful for development.
* (Note that updating HWM states for pools individually and then
* summing them won't create a consistent global snapshot. There
* are still easy ways to make this much, much faster.)
*/
if (total_used > g->hwm_used_bytes) {
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk__alloc_pool_update_highwater: global highwater updated: used=%ld, bytes=%ld -> "
"used=%ld, bytes=%ld\n",
(long) g->hwm_used_bytes, (long) g->hwm_waste_bytes,
(long) total_used, (long) total_waste);
#endif
g->hwm_used_bytes = total_used;
g->hwm_waste_bytes = total_waste;
}
}
#else /* DUK_ALLOC_POOL_TRACK_HIGHWATER */
static void duk__alloc_pool_update_highwater(duk_pool_global *g) {
(void) g;
}
#endif /* DUK_ALLOC_POOL_TRACK_HIGHWATER */
/*
* Allocation providers
*/
void *duk_alloc_pool(void *udata, duk_size_t size) {
duk_pool_global *g = (duk_pool_global *) udata;
int i, n;
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_alloc_pool: %p %ld\n", udata, (long) size);
#endif
if (size == 0) {
return NULL;
}
for (i = 0, n = g->num_pools; i < n; i++) {
duk_pool_state *st = g->states + i;
if (size <= st->size) {
duk_pool_free *res = st->first;
if (res != NULL) {
st->first = res->next;
duk__alloc_pool_set_waste_marker((void *) res, size, st->size);
duk__alloc_pool_update_highwater(g);
return (void *) res;
}
}
/* Allocation doesn't fit or no free entries, try to borrow
* from the next block size. There's no support for preventing
* a borrow at present.
*/
}
return NULL;
}
void *duk_realloc_pool(void *udata, void *ptr, duk_size_t size) {
duk_pool_global *g = (duk_pool_global *) udata;
int i, j, n;
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_realloc_pool: %p %p %ld\n", udata, ptr, (long) size);
#endif
if (ptr == NULL) {
return duk_alloc_pool(udata, size);
}
if (size == 0) {
duk_free_pool(udata, ptr);
return NULL;
}
/* Non-NULL pointers are necessarily from the pool so we should
* always be able to find the allocation.
*/
for (i = 0, n = g->num_pools; i < n; i++) {
duk_pool_state *st = g->states + i;
char *new_ptr;
/* Because 'ptr' is assumed to be in the pool and pools are
* allocated in sequence, it suffices to check for end pointer
* only.
*/
if ((char *) ptr >= st->alloc_end) {
continue;
}
if (size <= st->size) {
/* Allocation still fits existing allocation. Check if
* we can shrink the allocation to a smaller block size
* (smallest possible).
*/
for (j = 0; j < i; j++) {
duk_pool_state *st2 = g->states + j;
if (size <= st2->size) {
new_ptr = (char *) st2->first;
if (new_ptr != NULL) {
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_realloc_pool: shrink, block size %ld -> %ld\n",
(long) st->size, (long) st2->size);
#endif
st2->first = ((duk_pool_free *) new_ptr)->next;
memcpy((void *) new_ptr, (const void *) ptr, (size_t) size);
((duk_pool_free *) ptr)->next = st->first;
st->first = (duk_pool_free *) ptr;
duk__alloc_pool_set_waste_marker((void *) new_ptr, size, st2->size);
duk__alloc_pool_update_highwater(g);
return (void *) new_ptr;
}
}
}
/* Failed to shrink; return existing pointer. */
duk__alloc_pool_set_waste_marker((void *) ptr, size, st->size);
return ptr;
}
/* Find first free larger block. */
for (j = i + 1; j < n; j++) {
duk_pool_state *st2 = g->states + j;
if (size <= st2->size) {
new_ptr = (char *) st2->first;
if (new_ptr != NULL) {
st2->first = ((duk_pool_free *) new_ptr)->next;
memcpy((void *) new_ptr, (const void *) ptr, (size_t) st->size);
((duk_pool_free *) ptr)->next = st->first;
st->first = (duk_pool_free *) ptr;
duk__alloc_pool_set_waste_marker((void *) new_ptr, size, st2->size);
duk__alloc_pool_update_highwater(g);
return (void *) new_ptr;
}
}
}
/* Failed to resize. */
return NULL;
}
/* We should never be here because 'ptr' should be a valid pool
* entry and thus always found above.
*/
return NULL;
}
void duk_free_pool(void *udata, void *ptr) {
duk_pool_global *g = (duk_pool_global *) udata;
int i, n;
#if defined(DUK_ALLOC_POOL_DEBUG)
duk__alloc_pool_dprintf("duk_free_pool: %p %p\n", udata, ptr);
#endif
if (ptr == NULL) {
return;
}
for (i = 0, n = g->num_pools; i < n; i++) {
duk_pool_state *st = g->states + i;
/* Enough to check end address only. */
if ((char *) ptr >= st->alloc_end) {
continue;
}
((duk_pool_free *) ptr)->next = st->first;
st->first = (duk_pool_free *) ptr;
#if 0 /* never necessary when freeing */
duk__alloc_pool_update_highwater(g);
#endif
return;
}
/* We should never be here because 'ptr' should be a valid pool
* entry and thus always found above.
*/
}
/*
* Pointer compression
*/
#if defined(DUK_ALLOC_POOL_ROMPTR_COMPRESSION)
static void duk__alloc_pool_romptr_init(void) {
/* Scan ROM pointer range for faster detection of "is 'p' a ROM pointer"
* later on.
*/
const void * const * ptrs = (const void * const *) duk_rom_compressed_pointers;
duk_alloc_pool_romptr_low = duk_alloc_pool_romptr_high = (const void *) *ptrs;
while (*ptrs) {
if (*ptrs > duk_alloc_pool_romptr_high) {
duk_alloc_pool_romptr_high = (const void *) *ptrs;
}
if (*ptrs < duk_alloc_pool_romptr_low) {
duk_alloc_pool_romptr_low = (const void *) *ptrs;
}
ptrs++;
}
}
#endif
/* Encode/decode functions are defined in the header to allow inlining. */
#if defined(DUK_ALLOC_POOL_ROMPTR_COMPRESSION)
duk_uint16_t duk_alloc_pool_enc16_rom(void *ptr) {
/* The if-condition should be the fastest possible check
* for "is 'ptr' in ROM?". If pointer is in ROM, we'd like
* to compress it quickly. Here we just scan a ~1K array
* which is very bad for performance.
*/
const void * const * ptrs = duk_rom_compressed_pointers;
while (*ptrs) {
if (*ptrs == ptr) {
return DUK_ALLOC_POOL_ROMPTR_FIRST + (duk_uint16_t) (ptrs - duk_rom_compressed_pointers);
}
ptrs++;
}
/* We should really never be here: Duktape should only be
* compressing pointers which are in the ROM compressed
* pointers list, which are known at 'make dist' time.
* We go on, causing a pointer compression error.
*/
return 0;
}
#endif
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