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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/allocator/dispatcher/reentry_guard.h"
#include "base/check.h"
#include "base/compiler_specific.h"
#include "base/debug/crash_logging.h"
#include "base/strings/string_number_conversions.h"
#include "build/build_config.h"
#if BUILDFLAG(IS_APPLE) || BUILDFLAG(IS_ANDROID)
#include <pthread.h>
#endif
namespace base::allocator::dispatcher {
#if BUILDFLAG(IS_APPLE) || BUILDFLAG(IS_ANDROID)
// pthread_key_t has different signedness on Mac and Android. Store the null
// value in a strongly-typed constant to avoid "comparison of integers of
// different signs" warnings when comparing with 0.
constexpr pthread_key_t kNullKey = 0;
pthread_key_t ReentryGuard::entered_key_ = kNullKey;
void ReentryGuard::InitTLSSlot() {
if (entered_key_ == kNullKey) {
int error = pthread_key_create(&entered_key_, nullptr);
CHECK(!error);
// Touch the TLS slot immediately to force any allocations.
// TODO(crbug.com/40062835): Use this technique to avoid allocations
// in PoissonAllocationSampler::ScopedMuteThreadSamples, which will make
// ReentryGuard redundant.
pthread_setspecific(entered_key_, nullptr);
}
DCHECK_NE(entered_key_, kNullKey);
}
#else
void ReentryGuard::InitTLSSlot() {}
#endif
void ReentryGuard::RecordTLSSlotToCrashKey() {
// Record the key in crash dumps to detect when it's higher than 32
// (PTHREAD_KEY_2NDLEVEL_SIZE).
// TODO(crbug.com/40062835): Remove this after diagnosing reentry crashes.
static auto* const crash_key = base::debug::AllocateCrashKeyString(
"reentry_guard_tls_slot", base::debug::CrashKeySize::Size32);
#if BUILDFLAG(IS_APPLE) || BUILDFLAG(IS_ANDROID)
base::debug::SetCrashKeyString(crash_key, base::NumberToString(entered_key_));
#else
base::debug::SetCrashKeyString(crash_key, "unused");
#endif
}
} // namespace base::allocator::dispatcher
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