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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_TRACING_STARTUP_TRACING_CONTROLLER_H_
#define CONTENT_BROWSER_TRACING_STARTUP_TRACING_CONTROLLER_H_
#include "base/files/file_path.h"
#include "base/threading/sequence_bound.h"
#include "content/common/content_export.h"
namespace content {
// Class responsible for starting and stopping startup tracing as configured by
// StartupTracingConfig. All interactions with it are limited to UI thread, but
// the actual logic lives on a background ThreadPool sequence.
class CONTENT_EXPORT StartupTracingController {
public:
StartupTracingController();
~StartupTracingController();
static StartupTracingController& GetInstance();
// Stop the trace recording, write the trace to disk and block until complete.
// Intended to be used in the situation when the browser process is going to
// crash (e.g. DCHECK failure) and we want to avoid losing the trace data. Can
// be called from any thread.
// May not succeed if called from a sequence that is required to be responsive
// during trace finalisation.
static void EmergencyStop();
void StartIfNeeded();
void WaitUntilStopped();
void ShutdownAndWaitForStopIfNeeded();
// By default, a trace is written into a temporary file which then is renamed,
// however this can lead to data loss when the browser process crashes.
// Embedders can disable this (especially if a name provided to
// SetDefaultBasename makes it clear that the trace is incomplete and final
// name will be provided via SetDefaultBasename call before calling Stop).
enum class TempFilePolicy {
kUseTemporaryFile,
kWriteDirectly,
};
void SetUsingTemporaryFile(TempFilePolicy temp_file_policy);
// Set default basename for the trace output file to allow //content embedders
// to customise it using some metadata (like test names).
//
// If --enable-trace-output is a directory (default value, empty, designated
// "current directory"), then the startup trace will be written in a file with
// the given basename in this directory. Depending on the |extension_type|,
// an appropriate extension (.json or .proto) will be added.
//
// Note that embedders can call it even after tracing has started and Perfetto
// started streaming the trace into it — in that case,
// StartupTracingController will rename the file after finishing. However,
// this is guaranteed to work only when tracing lasts until Stop() (not with
// duration-based tracing).
enum class ExtensionType {
kAppendAppropriate,
kNone,
};
void SetDefaultBasename(std::string basename, ExtensionType extension_type);
// As the test harness calls SetDefaultBasename, expose ForTest() version for
// the tests checking the StartupTracingController logic itself.
void SetDefaultBasenameForTest(std::string basename,
ExtensionType extension_type);
bool is_finished_for_testing() const { return state_ == State::kStopped; }
void set_continue_on_shutdown_for_testing() {
should_continue_on_shutdown_ = true;
}
private:
void Stop(base::OnceClosure on_finished_callback);
void OnStoppedOnUIThread();
base::FilePath GetOutputPath();
enum class State {
kNotEnabled,
kRunning,
kStopped,
};
State state_ = State::kNotEnabled;
// All actual interactions with the tracing service and the process of writing
// files happens on a background thread.
class BackgroundTracer;
base::SequenceBound<BackgroundTracer> background_tracer_;
base::OnceClosure on_tracing_finished_;
base::FilePath output_file_;
std::string default_basename_;
bool basename_for_test_set_ = false;
// Used for testing only
bool should_continue_on_shutdown_ = false;
TempFilePolicy temp_file_policy_ = TempFilePolicy::kUseTemporaryFile;
};
} // namespace content
#endif // CONTENT_BROWSER_TRACING_STARTUP_TRACING_CONTROLLER_H_
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