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// Copyright 2015 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 "chrome/common/stack_sampling_configuration.h"
#include "base/command_line.h"
#include "base/lazy_instance.h"
#include "base/rand_util.h"
#include "build/branding_buildflags.h"
#include "build/build_config.h"
#include "chrome/common/channel_info.h"
#include "chrome/common/chrome_switches.h"
#include "components/version_info/version_info.h"
#include "content/public/common/content_switches.h"
#include "extensions/buildflags/buildflags.h"
#if defined(OS_WIN)
#include "base/win/static_constants.h"
#endif
#if defined(OS_MACOSX)
#include "base/mac/mac_util.h"
#endif
#if BUILDFLAG(ENABLE_EXTENSIONS)
#include "extensions/common/switches.h"
#endif
namespace {
base::LazyInstance<StackSamplingConfiguration>::Leaky g_configuration =
LAZY_INSTANCE_INITIALIZER;
// The profiler is currently only implemented for Windows x64 and Mac x64.
bool IsProfilerSupported() {
#if (defined(OS_WIN) && defined(ARCH_CPU_X86_64)) || defined(OS_MACOSX)
#if BUILDFLAG(GOOGLE_CHROME_BRANDING)
// Only run on canary and dev.
const version_info::Channel channel = chrome::GetChannel();
return channel == version_info::Channel::CANARY ||
channel == version_info::Channel::DEV;
#else
return true;
#endif
#else
return false;
#endif
}
// Returns true if the current execution is taking place in the browser process.
bool IsBrowserProcess() {
const base::CommandLine* command_line =
base::CommandLine::ForCurrentProcess();
std::string process_type =
command_line->GetSwitchValueASCII(switches::kProcessType);
return process_type.empty();
}
// True if the command line corresponds to an extension renderer process.
bool IsExtensionRenderer(const base::CommandLine& command_line) {
#if BUILDFLAG(ENABLE_EXTENSIONS)
return command_line.HasSwitch(extensions::switches::kExtensionProcess);
#else
return false;
#endif
}
bool ShouldEnableProfilerForNextRendererProcess() {
// Enable for every N-th renderer process, where N = 5.
return base::RandInt(0, 4) == 0;
}
} // namespace
StackSamplingConfiguration::StackSamplingConfiguration()
: configuration_(GenerateConfiguration()) {
}
base::StackSamplingProfiler::SamplingParams
StackSamplingConfiguration::GetSamplingParamsForCurrentProcess() const {
base::StackSamplingProfiler::SamplingParams params;
params.initial_delay = base::TimeDelta::FromMilliseconds(0);
params.sampling_interval = base::TimeDelta::FromMilliseconds(0);
params.samples_per_profile = 0;
if (IsProfilerEnabledForCurrentProcess()) {
const base::TimeDelta duration = base::TimeDelta::FromSeconds(30);
params.sampling_interval = base::TimeDelta::FromMilliseconds(100);
params.samples_per_profile = duration / params.sampling_interval;
}
return params;
}
bool StackSamplingConfiguration::IsProfilerEnabledForCurrentProcess() const {
if (IsBrowserProcess()) {
return configuration_ == PROFILE_ENABLED ||
configuration_ == PROFILE_CONTROL;
}
DCHECK_EQ(PROFILE_FROM_COMMAND_LINE, configuration_);
// This is a child process. The |kStartStackProfiler| switch passed by the
// browser process determines whether the profiler is enabled for the process.
const base::CommandLine* command_line =
base::CommandLine::ForCurrentProcess();
return command_line->HasSwitch(switches::kStartStackProfiler);
}
bool StackSamplingConfiguration::GetSyntheticFieldTrial(
std::string* trial_name,
std::string* group_name) const {
DCHECK(IsBrowserProcess());
if (!IsProfilerSupported())
return false;
*trial_name = "SyntheticStackProfilingConfiguration";
*group_name = std::string();
switch (configuration_) {
case PROFILE_DISABLED:
*group_name = "Disabled";
break;
case PROFILE_CONTROL:
*group_name = "Control";
break;
case PROFILE_ENABLED:
*group_name = "Enabled";
break;
case PROFILE_FROM_COMMAND_LINE:
NOTREACHED();
break;
}
return !group_name->empty();
}
void StackSamplingConfiguration::AppendCommandLineSwitchForChildProcess(
const std::string& process_type,
base::CommandLine* command_line) const {
DCHECK(IsBrowserProcess());
bool enable =
configuration_ == PROFILE_ENABLED || configuration_ == PROFILE_CONTROL;
if (!enable)
return;
if (process_type == switches::kGpuProcess ||
(process_type == switches::kRendererProcess &&
// Do not start the profiler for extension processes since profiling the
// compositor thread in them is not useful.
!IsExtensionRenderer(*command_line) &&
ShouldEnableProfilerForNextRendererProcess())) {
command_line->AppendSwitch(switches::kStartStackProfiler);
}
}
// static
StackSamplingConfiguration* StackSamplingConfiguration::Get() {
return g_configuration.Pointer();
}
// static
StackSamplingConfiguration::ProfileConfiguration
StackSamplingConfiguration::ChooseConfiguration(
const std::vector<Variation>& variations) {
int total_weight = 0;
for (const Variation& variation : variations)
total_weight += variation.weight;
DCHECK_EQ(100, total_weight);
int chosen = base::RandInt(0, total_weight - 1); // Max is inclusive.
int cumulative_weight = 0;
for (const auto& variation : variations) {
if (chosen >= cumulative_weight &&
chosen < cumulative_weight + variation.weight) {
return variation.config;
}
cumulative_weight += variation.weight;
}
NOTREACHED();
return PROFILE_DISABLED;
}
// static
StackSamplingConfiguration::ProfileConfiguration
StackSamplingConfiguration::GenerateConfiguration() {
if (!IsBrowserProcess())
return PROFILE_FROM_COMMAND_LINE;
if (!IsProfilerSupported())
return PROFILE_DISABLED;
#if defined(OS_WIN)
// Do not start the profiler when Application Verifier is in use; running them
// simultaneously can cause crashes and has no known use case.
if (GetModuleHandleA(base::win::kApplicationVerifierDllName))
return PROFILE_DISABLED;
#endif
switch (chrome::GetChannel()) {
// Enable the profiler unconditionally for development/waterfall builds.
case version_info::Channel::UNKNOWN:
return PROFILE_ENABLED;
#if (defined(OS_WIN) && defined(ARCH_CPU_X86_64)) || defined(OS_MACOSX)
case version_info::Channel::CANARY:
case version_info::Channel::DEV:
return ChooseConfiguration({{PROFILE_ENABLED, 80},
{PROFILE_CONTROL, 10},
{PROFILE_DISABLED, 10}});
#endif
default:
return PROFILE_DISABLED;
}
}
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