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// Copyright 2015 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/trace_event/heap_profiler_allocation_context_tracker.h"
#include <ostream>
#include "base/check_op.h"
#include "base/no_destructor.h"
#include "base/notreached.h"
#include "base/threading/thread_local_storage.h"
namespace base::trace_event {
std::atomic<AllocationContextTracker::CaptureMode>
AllocationContextTracker::capture_mode_{
AllocationContextTracker::CaptureMode::kDisabled};
namespace {
const size_t kMaxTaskDepth = 16u;
AllocationContextTracker* const kInitializingSentinel =
reinterpret_cast<AllocationContextTracker*>(-1);
// This function is added to the TLS slot to clean up the instance when the
// thread exits.
void DestructAllocationContextTracker(void* alloc_ctx_tracker) {
delete static_cast<AllocationContextTracker*>(alloc_ctx_tracker);
}
ThreadLocalStorage::Slot& AllocationContextTrackerTLS() {
static NoDestructor<ThreadLocalStorage::Slot> tls_alloc_ctx_tracker(
&DestructAllocationContextTracker);
return *tls_alloc_ctx_tracker;
}
} // namespace
// static
AllocationContextTracker*
AllocationContextTracker::GetInstanceForCurrentThread() {
AllocationContextTracker* tracker = static_cast<AllocationContextTracker*>(
AllocationContextTrackerTLS().Get());
if (tracker == kInitializingSentinel) {
return nullptr; // Re-entrancy case.
}
if (!tracker) {
AllocationContextTrackerTLS().Set(kInitializingSentinel);
tracker = new AllocationContextTracker();
AllocationContextTrackerTLS().Set(tracker);
}
return tracker;
}
AllocationContextTracker::AllocationContextTracker() {
task_contexts_.reserve(kMaxTaskDepth);
task_contexts_.push_back("UntrackedTask");
}
AllocationContextTracker::~AllocationContextTracker() = default;
// static
void AllocationContextTracker::SetCurrentThreadName(const char* name) {
if (name && capture_mode() != CaptureMode::kDisabled) {
GetInstanceForCurrentThread()->thread_name_ = name;
}
}
// static
void AllocationContextTracker::SetCaptureMode(CaptureMode mode) {
// Release ordering ensures that when a thread observes |capture_mode_| to
// be true through an acquire load, the TLS slot has been initialized.
capture_mode_.store(mode, std::memory_order_release);
}
void AllocationContextTracker::PushCurrentTaskContext(const char* context) {
DCHECK(context);
if (task_contexts_.size() < kMaxTaskDepth) {
task_contexts_.push_back(context);
} else {
NOTREACHED();
}
}
void AllocationContextTracker::PopCurrentTaskContext(const char* context) {
// Guard for stack underflow. If tracing was started with a TRACE_EVENT in
// scope, the context was never pushed, so it is possible that pop is called
// on an empty stack. Note that the context always contains "UntrackedTask".
if (task_contexts_.size() == 1) {
return;
}
DCHECK_EQ(context, task_contexts_.back())
<< "Encountered an unmatched context end";
task_contexts_.pop_back();
}
} // namespace base::trace_event
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