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#define JEMALLOC_CHUNK_DSS_C_
#include "jemalloc/internal/jemalloc_internal.h"
/******************************************************************************/
/* Data. */
const char *dss_prec_names[] = {
"disabled",
"primary",
"secondary",
"N/A"
};
/* Current dss precedence default, used when creating new arenas. */
static dss_prec_t dss_prec_default = DSS_PREC_DEFAULT;
/*
* Protects sbrk() calls. This avoids malloc races among threads, though it
* does not protect against races with threads that call sbrk() directly.
*/
static malloc_mutex_t dss_mtx;
/* Base address of the DSS. */
static void *dss_base;
/* Current end of the DSS, or ((void *)-1) if the DSS is exhausted. */
static void *dss_prev;
/* Current upper limit on DSS addresses. */
static void *dss_max;
/******************************************************************************/
static void *
chunk_dss_sbrk(intptr_t increment)
{
#ifdef JEMALLOC_DSS
return (sbrk(increment));
#else
not_implemented();
return (NULL);
#endif
}
dss_prec_t
chunk_dss_prec_get(void)
{
dss_prec_t ret;
if (!have_dss)
return (dss_prec_disabled);
malloc_mutex_lock(&dss_mtx);
ret = dss_prec_default;
malloc_mutex_unlock(&dss_mtx);
return (ret);
}
bool
chunk_dss_prec_set(dss_prec_t dss_prec)
{
if (!have_dss)
return (dss_prec != dss_prec_disabled);
malloc_mutex_lock(&dss_mtx);
dss_prec_default = dss_prec;
malloc_mutex_unlock(&dss_mtx);
return (false);
}
void *
chunk_alloc_dss(arena_t *arena, void *new_addr, size_t size, size_t alignment,
bool *zero, bool *commit)
{
cassert(have_dss);
assert(size > 0 && (size & chunksize_mask) == 0);
assert(alignment > 0 && (alignment & chunksize_mask) == 0);
/*
* sbrk() uses a signed increment argument, so take care not to
* interpret a huge allocation request as a negative increment.
*/
if ((intptr_t)size < 0)
return (NULL);
malloc_mutex_lock(&dss_mtx);
if (dss_prev != (void *)-1) {
/*
* The loop is necessary to recover from races with other
* threads that are using the DSS for something other than
* malloc.
*/
do {
void *ret, *cpad, *dss_next;
size_t gap_size, cpad_size;
intptr_t incr;
/* Avoid an unnecessary system call. */
if (new_addr != NULL && dss_max != new_addr)
break;
/* Get the current end of the DSS. */
dss_max = chunk_dss_sbrk(0);
/* Make sure the earlier condition still holds. */
if (new_addr != NULL && dss_max != new_addr)
break;
/*
* Calculate how much padding is necessary to
* chunk-align the end of the DSS.
*/
gap_size = (chunksize - CHUNK_ADDR2OFFSET(dss_max)) &
chunksize_mask;
/*
* Compute how much chunk-aligned pad space (if any) is
* necessary to satisfy alignment. This space can be
* recycled for later use.
*/
cpad = (void *)((uintptr_t)dss_max + gap_size);
ret = (void *)ALIGNMENT_CEILING((uintptr_t)dss_max,
alignment);
cpad_size = (uintptr_t)ret - (uintptr_t)cpad;
dss_next = (void *)((uintptr_t)ret + size);
if ((uintptr_t)ret < (uintptr_t)dss_max ||
(uintptr_t)dss_next < (uintptr_t)dss_max) {
/* Wrap-around. */
malloc_mutex_unlock(&dss_mtx);
return (NULL);
}
incr = gap_size + cpad_size + size;
dss_prev = chunk_dss_sbrk(incr);
if (dss_prev == dss_max) {
/* Success. */
dss_max = dss_next;
malloc_mutex_unlock(&dss_mtx);
if (cpad_size != 0) {
chunk_hooks_t chunk_hooks =
CHUNK_HOOKS_INITIALIZER;
chunk_dalloc_wrapper(arena,
&chunk_hooks, cpad, cpad_size,
true);
}
if (*zero) {
JEMALLOC_VALGRIND_MAKE_MEM_UNDEFINED(
ret, size);
memset(ret, 0, size);
}
if (!*commit)
*commit = pages_decommit(ret, size);
return (ret);
}
} while (dss_prev != (void *)-1);
}
malloc_mutex_unlock(&dss_mtx);
return (NULL);
}
bool
chunk_in_dss(void *chunk)
{
bool ret;
cassert(have_dss);
malloc_mutex_lock(&dss_mtx);
if ((uintptr_t)chunk >= (uintptr_t)dss_base
&& (uintptr_t)chunk < (uintptr_t)dss_max)
ret = true;
else
ret = false;
malloc_mutex_unlock(&dss_mtx);
return (ret);
}
bool
chunk_dss_boot(void)
{
cassert(have_dss);
if (malloc_mutex_init(&dss_mtx))
return (true);
dss_base = chunk_dss_sbrk(0);
dss_prev = dss_base;
dss_max = dss_base;
return (false);
}
void
chunk_dss_prefork(void)
{
if (have_dss)
malloc_mutex_prefork(&dss_mtx);
}
void
chunk_dss_postfork_parent(void)
{
if (have_dss)
malloc_mutex_postfork_parent(&dss_mtx);
}
void
chunk_dss_postfork_child(void)
{
if (have_dss)
malloc_mutex_postfork_child(&dss_mtx);
}
/******************************************************************************/
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