// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Adapted from chrome/common/profiler/thread_profiler.cc
#include "ios/chrome/browser/web/model/ios_thread_profiler.h"
#include <string>
#include <utility>
#include <vector>
#include "base/functional/bind.h"
#include "base/memory/ptr_util.h"
#include "base/memory/raw_ptr.h"
#include "base/message_loop/work_id_provider.h"
#include "base/process/process.h"
#include "base/profiler/call_stack_profile_params.h"
#include "base/profiler/process_type.h"
#include "base/profiler/profiler_buildflags.h"
#include "base/profiler/sample_metadata.h"
#include "base/profiler/sampling_profiler_thread_token.h"
#include "base/rand_util.h"
#include "base/task/single_thread_task_runner.h"
#include "base/threading/platform_thread.h"
#include "base/threading/sequence_local_storage_slot.h"
#include "build/blink_buildflags.h"
#include "build/build_config.h"
#include "components/metrics/call_stacks/call_stack_profile_builder.h"
#include "components/metrics/call_stacks/call_stack_profile_metrics_provider.h"
#if BUILDFLAG(USE_BLINK)
#include "base/process/port_provider_mac.h"
#endif
using CallStackProfileBuilder = metrics::CallStackProfileBuilder;
using CallStackProfileParams = base::CallStackProfileParams;
using StackSamplingProfiler = base::StackSamplingProfiler;
namespace {
// Pointer to the main thread instance, if any. Stored as a global because it's
// created very early in chrome/app - and is thus otherwise inaccessible from
// chrome_dll, by the time we need to register the main thread task runner.
IOSThreadProfiler* g_main_thread_instance = nullptr;
// Run continuous profiling 2% of the time.
constexpr double kFractionOfExecutionTimeToSample = 0.02;
bool IsCurrentProcessBackgrounded() {
#if BUILDFLAG(USE_BLINK)
base::SelfPortProvider self_provider;
return base::Process::Current().GetPriority(&self_provider) ==
base::Process::Priority::kBestEffort;
#else
return base::Process::Current().GetPriority() ==
base::Process::Priority::kBestEffort;
#endif
}
base::StackSamplingProfiler::UnwindersFactory CreateCoreUnwindersFactory() {
return base::StackSamplingProfiler::UnwindersFactory();
}
const base::RepeatingClosure GetApplyPerSampleMetadataCallback(
base::ProfilerProcessType process) {
if (process != base::ProfilerProcessType::kRenderer) {
return base::RepeatingClosure();
}
static const base::SampleMetadata process_backgrounded(
"ProcessBackgrounded", base::SampleMetadataScope::kProcess);
return base::BindRepeating(
[](base::SampleMetadata process_backgrounded) {
process_backgrounded.Set(IsCurrentProcessBackgrounded());
},
process_backgrounded);
}
} // namespace
// The scheduler works by splitting execution time into repeated periods such
// that the time to take one collection represents
// `fraction_of_execution_time_to_sample` of the period, and the time not spent
// sampling represents 1 - `fraction_of_execution_time_to_sample` of the period.
// The collection start time is chosen randomly within each period such that the
// entire collection is contained within the period.
//
// The kFractionOfExecutionTimeToSample and SamplingParams settings at the top
// of the file specify fraction = 0.02 and sampling period = 1 sample / .1s
// sampling interval * 300 samples = 30s. The period length works out to
// 30s/0.02 = 1500s = 25m. So every 25 minutes a random 30 second continuous
// interval will be picked to sample.
PeriodicSamplingScheduler::PeriodicSamplingScheduler(
base::TimeDelta sampling_duration,
double fraction_of_execution_time_to_sample,
base::TimeTicks start_time)
: period_duration_(sampling_duration /
fraction_of_execution_time_to_sample),
sampling_duration_(sampling_duration),
period_start_time_(start_time) {
DCHECK(sampling_duration_ <= period_duration_);
}
PeriodicSamplingScheduler::~PeriodicSamplingScheduler() = default;
base::TimeDelta PeriodicSamplingScheduler::GetTimeToNextCollection() {
const base::TimeTicks now = Now();
// Avoid scheduling in the past in the presence of discontinuous jumps in
// the current TimeTicks.
period_start_time_ = std::max(period_start_time_, now);
const base::TimeDelta sampling_offset =
(period_duration_ - sampling_duration_) * RandDouble();
const base::TimeTicks next_collection_time =
period_start_time_ + sampling_offset;
period_start_time_ += period_duration_;
return next_collection_time - now;
}
double PeriodicSamplingScheduler::RandDouble() const {
return base::RandDouble();
}
base::TimeTicks PeriodicSamplingScheduler::Now() const {
return base::TimeTicks::Now();
}
// Records the current unique id for the work item being executed in the target
// thread's message loop.
class IOSThreadProfiler::WorkIdRecorder : public metrics::WorkIdRecorder {
public:
explicit WorkIdRecorder(base::WorkIdProvider* work_id_provider)
: work_id_provider_(work_id_provider) {}
// Invoked on the profiler thread while the target thread is suspended.
unsigned int RecordWorkId() const override {
return work_id_provider_->GetWorkId();
}
WorkIdRecorder(const WorkIdRecorder&) = delete;
WorkIdRecorder& operator=(const WorkIdRecorder&) = delete;
private:
const raw_ptr<base::WorkIdProvider> work_id_provider_;
};
IOSThreadProfiler::~IOSThreadProfiler() {
if (g_main_thread_instance == this)
g_main_thread_instance = nullptr;
}
// static
std::unique_ptr<IOSThreadProfiler>
IOSThreadProfiler::CreateAndStartOnMainThread() {
DCHECK(!g_main_thread_instance);
auto instance =
base::WrapUnique(new IOSThreadProfiler(base::ProfilerThreadType::kMain));
if (!g_main_thread_instance)
g_main_thread_instance = instance.get();
return instance;
}
// static
void IOSThreadProfiler::SetMainThreadTaskRunner(
scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
DCHECK(g_main_thread_instance);
g_main_thread_instance->SetMainThreadTaskRunnerImpl(task_runner);
}
// static
void IOSThreadProfiler::StartOnChildThread(base::ProfilerThreadType thread) {
// The profiler object is stored in a SequenceLocalStorageSlot on child
// threads to give it the same lifetime as the threads.
static base::SequenceLocalStorageSlot<std::unique_ptr<IOSThreadProfiler>>
child_thread_profiler_sequence_local_storage;
child_thread_profiler_sequence_local_storage.emplace(new IOSThreadProfiler(
thread, base::SingleThreadTaskRunner::GetCurrentDefault()));
}
// static
void IOSThreadProfiler::SetBrowserProcessReceiverCallback(
const base::RepeatingCallback<void(base::TimeTicks,
metrics::SampledProfile)>& callback) {
CallStackProfileBuilder::SetBrowserProcessReceiverCallback(callback);
}
// static
void IOSThreadProfiler::SetCollectorForChildProcess(
mojo::PendingRemote<metrics::mojom::CallStackProfileCollector> collector) {
CallStackProfileBuilder::SetParentProfileCollectorForChildProcess(
std::move(collector));
}
// static
base::StackSamplingProfiler::SamplingParams
IOSThreadProfiler::GetSamplingParams() {
base::StackSamplingProfiler::SamplingParams params;
params.initial_delay = base::Milliseconds(0);
const base::TimeDelta duration = base::Seconds(30);
params.sampling_interval = base::Milliseconds(100);
params.samples_per_profile = duration / params.sampling_interval;
return params;
}
// IOSThreadProfiler implementation synopsis:
//
// On creation, the profiler creates and starts the startup
// StackSamplingProfiler, and configures the PeriodicSamplingScheduler such that
// it starts scheduling from the time the startup profiling will be complete.
// When a message loop is available (either in the constructor, or via
// SetMainThreadTaskRunner) a task is posted to start the first periodic
// collection at the initial scheduled collection time.
//
// When the periodic collection task executes, it creates and starts a new
// periodic profiler and configures it to call OnPeriodicCollectionCompleted as
// its completion callback. OnPeriodicCollectionCompleted is called on the
// profiler thread and schedules a task on the original thread to schedule
// another periodic collection. When the task runs, it posts a new task to start
// another periodic collection at the next scheduled collection time.
//
// The process in previous paragraph continues until the IOSThreadProfiler is
// destroyed prior to thread exit.
IOSThreadProfiler::IOSThreadProfiler(
base::ProfilerThreadType thread,
scoped_refptr<base::SingleThreadTaskRunner> owning_thread_task_runner)
: process_(base::ProfilerProcessType::kBrowser),
thread_(thread),
owning_thread_task_runner_(owning_thread_task_runner),
work_id_recorder_(std::make_unique<WorkIdRecorder>(
base::WorkIdProvider::GetForCurrentThread())) {
const base::StackSamplingProfiler::SamplingParams sampling_params =
IOSThreadProfiler::GetSamplingParams();
startup_profiler_ = std::make_unique<StackSamplingProfiler>(
base::GetSamplingProfilerCurrentThreadToken(), sampling_params,
std::make_unique<CallStackProfileBuilder>(
CallStackProfileParams(
process_, thread,
CallStackProfileParams::Trigger::kProcessStartup),
work_id_recorder_.get()),
CreateCoreUnwindersFactory(),
GetApplyPerSampleMetadataCallback(process_));
startup_profiler_->Start();
// Estimated time at which the startup profiling will be completed. It's OK if
// this doesn't exactly coincide with the end of the startup profiling, since
// there's no harm in having a brief overlap of startup and periodic
// profiling.
base::TimeTicks startup_profiling_completion_time =
base::TimeTicks::Now() +
sampling_params.samples_per_profile * sampling_params.sampling_interval;
periodic_sampling_scheduler_ = std::make_unique<PeriodicSamplingScheduler>(
sampling_params.samples_per_profile * sampling_params.sampling_interval,
kFractionOfExecutionTimeToSample, startup_profiling_completion_time);
if (owning_thread_task_runner_)
ScheduleNextPeriodicCollection();
}
// static
void IOSThreadProfiler::OnPeriodicCollectionCompleted(
scoped_refptr<base::SingleThreadTaskRunner> owning_thread_task_runner,
base::WeakPtr<IOSThreadProfiler> thread_profiler) {
owning_thread_task_runner->PostTask(
FROM_HERE,
base::BindOnce(&IOSThreadProfiler::ScheduleNextPeriodicCollection,
thread_profiler));
}
void IOSThreadProfiler::SetMainThreadTaskRunnerImpl(
scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
// This should only be called if the task runner wasn't provided in the
// constructor.
DCHECK(!owning_thread_task_runner_);
owning_thread_task_runner_ = task_runner;
ScheduleNextPeriodicCollection();
}
void IOSThreadProfiler::ScheduleNextPeriodicCollection() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
owning_thread_task_runner_->PostDelayedTask(
FROM_HERE,
base::BindOnce(&IOSThreadProfiler::StartPeriodicSamplingCollection,
weak_factory_.GetWeakPtr()),
periodic_sampling_scheduler_->GetTimeToNextCollection());
}
void IOSThreadProfiler::StartPeriodicSamplingCollection() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
// NB: Destroys the previous profiler as side effect.
periodic_profiler_ = std::make_unique<StackSamplingProfiler>(
base::GetSamplingProfilerCurrentThreadToken(),
IOSThreadProfiler::GetSamplingParams(),
std::make_unique<CallStackProfileBuilder>(
CallStackProfileParams(
process_, thread_,
CallStackProfileParams::Trigger::kPeriodicCollection),
work_id_recorder_.get(),
base::BindOnce(&IOSThreadProfiler::OnPeriodicCollectionCompleted,
owning_thread_task_runner_,
weak_factory_.GetWeakPtr())),
CreateCoreUnwindersFactory(),
GetApplyPerSampleMetadataCallback(process_));
periodic_profiler_->Start();
}
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