ce0b7ab6c8
The previous approach managed the thread name in a separate buffer, which causes races because the thread name update (triggered by new samples) can happen at the same time as prof dumping (which reads the thread names) -- these two operations are under separate locks to avoid blocking each other. Implemented the thread name storage as part of the tdata struct, which resolves the lifetime issue and also avoids internal alloc / dalloc during prof_sample.
293 lines
7.6 KiB
C
293 lines
7.6 KiB
C
#ifndef JEMALLOC_INTERNAL_PROF_INLINES_H
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#define JEMALLOC_INTERNAL_PROF_INLINES_H
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#include "jemalloc/internal/safety_check.h"
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#include "jemalloc/internal/sz.h"
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#include "jemalloc/internal/thread_event.h"
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#include "jemalloc/internal/jemalloc_internal_inlines_c.h"
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JEMALLOC_ALWAYS_INLINE void
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prof_active_assert() {
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cassert(config_prof);
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/*
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* If opt_prof is off, then prof_active must always be off, regardless
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* of whether prof_active_mtx is in effect or not.
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*/
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assert(opt_prof || !prof_active_state);
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}
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JEMALLOC_ALWAYS_INLINE bool
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prof_active_get_unlocked(void) {
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prof_active_assert();
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/*
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* Even if opt_prof is true, sampling can be temporarily disabled by
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* setting prof_active to false. No locking is used when reading
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* prof_active in the fast path, so there are no guarantees regarding
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* how long it will take for all threads to notice state changes.
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*/
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return prof_active_state;
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}
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JEMALLOC_ALWAYS_INLINE bool
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prof_gdump_get_unlocked(void) {
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/*
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* No locking is used when reading prof_gdump_val in the fast path, so
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* there are no guarantees regarding how long it will take for all
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* threads to notice state changes.
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*/
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return prof_gdump_val;
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_thread_name_assert(prof_tdata_t *tdata) {
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if (!config_debug) {
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return;
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}
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prof_active_assert();
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bool terminated = false;
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for (unsigned i = 0; i < PROF_THREAD_NAME_MAX_LEN; i++) {
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if (tdata->thread_name[i] == '\0') {
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terminated = true;
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}
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}
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assert(terminated);
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}
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JEMALLOC_ALWAYS_INLINE prof_tdata_t *
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prof_tdata_get(tsd_t *tsd, bool create) {
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prof_tdata_t *tdata;
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cassert(config_prof);
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tdata = tsd_prof_tdata_get(tsd);
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if (create) {
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assert(tsd_reentrancy_level_get(tsd) == 0);
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if (unlikely(tdata == NULL)) {
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if (tsd_nominal(tsd)) {
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tdata = prof_tdata_init(tsd);
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tsd_prof_tdata_set(tsd, tdata);
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}
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} else if (unlikely(tdata->expired)) {
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tdata = prof_tdata_reinit(tsd, tdata);
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tsd_prof_tdata_set(tsd, tdata);
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}
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assert(tdata == NULL || tdata->attached);
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}
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if (tdata != NULL) {
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prof_thread_name_assert(tdata);
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}
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return tdata;
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_info_get(tsd_t *tsd, const void *ptr, emap_alloc_ctx_t *alloc_ctx,
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prof_info_t *prof_info) {
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cassert(config_prof);
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assert(ptr != NULL);
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assert(prof_info != NULL);
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arena_prof_info_get(tsd, ptr, alloc_ctx, prof_info, false);
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_info_get_and_reset_recent(tsd_t *tsd, const void *ptr,
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emap_alloc_ctx_t *alloc_ctx, prof_info_t *prof_info) {
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cassert(config_prof);
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assert(ptr != NULL);
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assert(prof_info != NULL);
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arena_prof_info_get(tsd, ptr, alloc_ctx, prof_info, true);
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_tctx_reset(tsd_t *tsd, const void *ptr, emap_alloc_ctx_t *alloc_ctx) {
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cassert(config_prof);
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assert(ptr != NULL);
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arena_prof_tctx_reset(tsd, ptr, alloc_ctx);
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_tctx_reset_sampled(tsd_t *tsd, const void *ptr) {
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cassert(config_prof);
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assert(ptr != NULL);
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arena_prof_tctx_reset_sampled(tsd, ptr);
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_info_set(tsd_t *tsd, edata_t *edata, prof_tctx_t *tctx, size_t size) {
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cassert(config_prof);
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assert(edata != NULL);
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assert((uintptr_t)tctx > (uintptr_t)1U);
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arena_prof_info_set(tsd, edata, tctx, size);
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}
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JEMALLOC_ALWAYS_INLINE bool
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prof_sample_should_skip(tsd_t *tsd, bool sample_event) {
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cassert(config_prof);
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/* Fastpath: no need to load tdata */
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if (likely(!sample_event)) {
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return true;
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}
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/*
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* sample_event is always obtained from the thread event module, and
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* whenever it's true, it means that the thread event module has
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* already checked the reentrancy level.
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*/
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assert(tsd_reentrancy_level_get(tsd) == 0);
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prof_tdata_t *tdata = prof_tdata_get(tsd, true);
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if (unlikely(tdata == NULL)) {
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return true;
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}
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return !tdata->active;
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}
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JEMALLOC_ALWAYS_INLINE prof_tctx_t *
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prof_alloc_prep(tsd_t *tsd, bool prof_active, bool sample_event) {
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prof_tctx_t *ret;
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if (!prof_active ||
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likely(prof_sample_should_skip(tsd, sample_event))) {
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ret = (prof_tctx_t *)(uintptr_t)1U;
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} else {
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ret = prof_tctx_create(tsd);
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}
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return ret;
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_malloc(tsd_t *tsd, const void *ptr, size_t size, size_t usize,
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emap_alloc_ctx_t *alloc_ctx, prof_tctx_t *tctx) {
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cassert(config_prof);
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assert(ptr != NULL);
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assert(usize == isalloc(tsd_tsdn(tsd), ptr));
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if (unlikely((uintptr_t)tctx > (uintptr_t)1U)) {
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prof_malloc_sample_object(tsd, ptr, size, usize, tctx);
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} else {
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prof_tctx_reset(tsd, ptr, alloc_ctx);
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}
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_realloc(tsd_t *tsd, const void *ptr, size_t size, size_t usize,
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prof_tctx_t *tctx, bool prof_active, const void *old_ptr, size_t old_usize,
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prof_info_t *old_prof_info, bool sample_event) {
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bool sampled, old_sampled, moved;
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cassert(config_prof);
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assert(ptr != NULL || (uintptr_t)tctx <= (uintptr_t)1U);
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if (prof_active && ptr != NULL) {
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assert(usize == isalloc(tsd_tsdn(tsd), ptr));
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if (prof_sample_should_skip(tsd, sample_event)) {
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/*
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* Don't sample. The usize passed to prof_alloc_prep()
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* was larger than what actually got allocated, so a
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* backtrace was captured for this allocation, even
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* though its actual usize was insufficient to cross the
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* sample threshold.
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*/
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prof_alloc_rollback(tsd, tctx);
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tctx = (prof_tctx_t *)(uintptr_t)1U;
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}
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}
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sampled = ((uintptr_t)tctx > (uintptr_t)1U);
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old_sampled = ((uintptr_t)old_prof_info->alloc_tctx > (uintptr_t)1U);
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moved = (ptr != old_ptr);
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if (unlikely(sampled)) {
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prof_malloc_sample_object(tsd, ptr, size, usize, tctx);
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} else if (moved) {
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prof_tctx_reset(tsd, ptr, NULL);
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} else if (unlikely(old_sampled)) {
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/*
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* prof_tctx_reset() would work for the !moved case as well,
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* but prof_tctx_reset_sampled() is slightly cheaper, and the
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* proper thing to do here in the presence of explicit
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* knowledge re: moved state.
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*/
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prof_tctx_reset_sampled(tsd, ptr);
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} else {
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prof_info_t prof_info;
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prof_info_get(tsd, ptr, NULL, &prof_info);
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assert((uintptr_t)prof_info.alloc_tctx == (uintptr_t)1U);
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}
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/*
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* The prof_free_sampled_object() call must come after the
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* prof_malloc_sample_object() call, because tctx and old_tctx may be
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* the same, in which case reversing the call order could cause the tctx
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* to be prematurely destroyed as a side effect of momentarily zeroed
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* counters.
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*/
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if (unlikely(old_sampled)) {
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prof_free_sampled_object(tsd, old_ptr, old_usize,
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old_prof_info);
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}
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}
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JEMALLOC_ALWAYS_INLINE size_t
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prof_sample_align(size_t orig_align) {
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/*
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* Enforce page alignment, so that sampled allocations can be identified
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* w/o metadata lookup.
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*/
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assert(opt_prof);
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return (opt_cache_oblivious && orig_align < PAGE) ? PAGE :
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orig_align;
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}
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JEMALLOC_ALWAYS_INLINE bool
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prof_sampled(tsd_t *tsd, const void *ptr) {
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prof_info_t prof_info;
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prof_info_get(tsd, ptr, NULL, &prof_info);
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bool sampled = (uintptr_t)prof_info.alloc_tctx > (uintptr_t)1U;
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if (sampled) {
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assert(prof_sample_aligned(ptr));
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}
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return sampled;
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_free(tsd_t *tsd, const void *ptr, size_t usize,
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emap_alloc_ctx_t *alloc_ctx) {
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prof_info_t prof_info;
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prof_info_get_and_reset_recent(tsd, ptr, alloc_ctx, &prof_info);
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cassert(config_prof);
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assert(usize == isalloc(tsd_tsdn(tsd), ptr));
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if (unlikely((uintptr_t)prof_info.alloc_tctx > (uintptr_t)1U)) {
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assert(prof_sample_aligned(ptr));
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prof_free_sampled_object(tsd, ptr, usize, &prof_info);
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}
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}
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JEMALLOC_ALWAYS_INLINE bool
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prof_thread_name_empty(prof_tdata_t *tdata) {
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prof_active_assert();
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return (tdata->thread_name[0] == '\0');
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}
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JEMALLOC_ALWAYS_INLINE void
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prof_thread_name_clear(prof_tdata_t *tdata) {
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prof_active_assert();
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tdata->thread_name[0] = '\0';
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}
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#endif /* JEMALLOC_INTERNAL_PROF_INLINES_H */
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