// Copyright 2014 The Chromium Authors. All rights reserved.
|
// Use of this source code is governed by a BSD-style license that can be
|
// found in the LICENSE file.
|
|
#include "base/debug/task_annotator.h"
|
|
#include <array>
|
|
#include "base/debug/activity_tracker.h"
|
#include "base/debug/alias.h"
|
#include "base/no_destructor.h"
|
#include "base/pending_task.h"
|
#include "base/threading/thread_local.h"
|
#include "base/trace_event/trace_event.h"
|
|
namespace base {
|
namespace debug {
|
|
namespace {
|
|
TaskAnnotator::ObserverForTesting* g_task_annotator_observer = nullptr;
|
|
// Returns the TLS slot that stores the PendingTask currently in progress on
|
// each thread. Used to allow creating a breadcrumb of program counters on the
|
// stack to help identify a task's origin in crashes.
|
ThreadLocalPointer<const PendingTask>* GetTLSForCurrentPendingTask() {
|
static NoDestructor<ThreadLocalPointer<const PendingTask>>
|
tls_for_current_pending_task;
|
return tls_for_current_pending_task.get();
|
}
|
|
} // namespace
|
|
TaskAnnotator::TaskAnnotator() = default;
|
|
TaskAnnotator::~TaskAnnotator() = default;
|
|
void TaskAnnotator::WillQueueTask(const char* queue_function,
|
PendingTask* pending_task) {
|
if (queue_function) {
|
TRACE_EVENT_WITH_FLOW0(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
|
queue_function,
|
TRACE_ID_MANGLE(GetTaskTraceID(*pending_task)),
|
TRACE_EVENT_FLAG_FLOW_OUT);
|
}
|
|
// TODO(https://crbug.com/826902): Fix callers that invoke WillQueueTask()
|
// twice for the same PendingTask.
|
// DCHECK(!pending_task.task_backtrace[0])
|
// << "Task backtrace was already set, task posted twice??";
|
if (!pending_task->task_backtrace[0]) {
|
const PendingTask* parent_task = GetTLSForCurrentPendingTask()->Get();
|
if (parent_task) {
|
pending_task->task_backtrace[0] =
|
parent_task->posted_from.program_counter();
|
std::copy(parent_task->task_backtrace.begin(),
|
parent_task->task_backtrace.end() - 1,
|
pending_task->task_backtrace.begin() + 1);
|
}
|
}
|
}
|
|
void TaskAnnotator::RunTask(const char* queue_function,
|
PendingTask* pending_task) {
|
ScopedTaskRunActivity task_activity(*pending_task);
|
|
if (queue_function) {
|
TRACE_EVENT_WITH_FLOW0(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
|
queue_function,
|
TRACE_ID_MANGLE(GetTaskTraceID(*pending_task)),
|
TRACE_EVENT_FLAG_FLOW_IN);
|
}
|
|
// Before running the task, store the task backtrace with the chain of
|
// PostTasks that resulted in this call and deliberately alias it to ensure
|
// it is on the stack if the task crashes. Be careful not to assume that the
|
// variable itself will have the expected value when displayed by the
|
// optimizer in an optimized build. Look at a memory dump of the stack.
|
static constexpr int kStackTaskTraceSnapshotSize =
|
std::tuple_size<decltype(pending_task->task_backtrace)>::value + 3;
|
std::array<const void*, kStackTaskTraceSnapshotSize> task_backtrace;
|
|
// Store a marker to locate |task_backtrace| content easily on a memory
|
// dump.
|
task_backtrace.front() = reinterpret_cast<void*>(0xefefefefefefefef);
|
task_backtrace.back() = reinterpret_cast<void*>(0xfefefefefefefefe);
|
|
task_backtrace[1] = pending_task->posted_from.program_counter();
|
std::copy(pending_task->task_backtrace.begin(),
|
pending_task->task_backtrace.end(), task_backtrace.begin() + 2);
|
debug::Alias(&task_backtrace);
|
|
ThreadLocalPointer<const PendingTask>* tls_for_current_pending_task =
|
GetTLSForCurrentPendingTask();
|
const PendingTask* previous_pending_task =
|
tls_for_current_pending_task->Get();
|
tls_for_current_pending_task->Set(pending_task);
|
|
if (g_task_annotator_observer)
|
g_task_annotator_observer->BeforeRunTask(pending_task);
|
std::move(pending_task->task).Run();
|
|
tls_for_current_pending_task->Set(previous_pending_task);
|
}
|
|
uint64_t TaskAnnotator::GetTaskTraceID(const PendingTask& task) const {
|
return (static_cast<uint64_t>(task.sequence_num) << 32) |
|
((static_cast<uint64_t>(reinterpret_cast<intptr_t>(this)) << 32) >>
|
32);
|
}
|
|
// static
|
void TaskAnnotator::RegisterObserverForTesting(ObserverForTesting* observer) {
|
DCHECK(!g_task_annotator_observer);
|
g_task_annotator_observer = observer;
|
}
|
|
// static
|
void TaskAnnotator::ClearObserverForTesting() {
|
g_task_annotator_observer = nullptr;
|
}
|
|
} // namespace debug
|
} // namespace base
|
