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// Copyright (c) 2013 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 "tools/gn/scheduler.h"
#include <algorithm>
#include "base/bind.h"
#include "base/command_line.h"
#include "base/strings/string_number_conversions.h"
#include "build/build_config.h"
#include "tools/gn/standard_out.h"
#include "tools/gn/switches.h"
#if defined(OS_WIN)
#include <windows.h>
#else
#include <unistd.h>
#endif
Scheduler* g_scheduler = nullptr;
namespace {
#if defined(OS_WIN)
int GetCPUCount() {
SYSTEM_INFO sysinfo;
::GetSystemInfo(&sysinfo);
return sysinfo.dwNumberOfProcessors;
}
#else
int GetCPUCount() {
return static_cast<int>(sysconf(_SC_NPROCESSORS_ONLN));
}
#endif
int GetThreadCount() {
std::string thread_count =
base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
switches::kThreads);
// See if an override was specified on the command line.
int result;
if (!thread_count.empty() && base::StringToInt(thread_count, &result))
return result;
// Base the default number of worker threads on number of cores in the
// system. When building large projects, the speed can be limited by how fast
// the main thread can dispatch work and connect the dependency graph. If
// there are too many worker threads, the main thread can be starved and it
// will run slower overall.
//
// One less worker thread than the number of physical CPUs seems to be a
// good value, both theoretically and experimentally. But always use at
// least three workers to prevent us from being too sensitive to I/O latency
// on low-end systems.
int num_cores = GetCPUCount() / 2; // Almost all CPUs now are hyperthreaded.
return std::max(num_cores - 1, 3);
}
} // namespace
Scheduler::Scheduler()
: pool_(new base::SequencedWorkerPool(GetThreadCount(), "worker_")),
input_file_manager_(new InputFileManager),
verbose_logging_(false),
work_count_(0),
is_failed_(false),
has_been_shutdown_(false) {
g_scheduler = this;
}
Scheduler::~Scheduler() {
if (!has_been_shutdown_)
pool_->Shutdown();
g_scheduler = nullptr;
}
bool Scheduler::Run() {
runner_.Run();
bool local_is_failed;
{
base::AutoLock lock(lock_);
local_is_failed = is_failed();
has_been_shutdown_ = true;
}
// Don't do this inside the lock since it will block on the workers, which
// may be in turn waiting on the lock.
pool_->Shutdown();
return !local_is_failed;
}
void Scheduler::Log(const std::string& verb, const std::string& msg) {
if (base::MessageLoop::current() == &main_loop_) {
LogOnMainThread(verb, msg);
} else {
// The run loop always joins on the sub threads, so the lifetime of this
// object outlives the invocations of this function, hence "unretained".
main_loop_.PostTask(FROM_HERE,
base::Bind(&Scheduler::LogOnMainThread,
base::Unretained(this), verb, msg));
}
}
void Scheduler::FailWithError(const Err& err) {
DCHECK(err.has_error());
{
base::AutoLock lock(lock_);
if (is_failed_ || has_been_shutdown_)
return; // Ignore errors once we see one.
is_failed_ = true;
}
if (base::MessageLoop::current() == &main_loop_) {
FailWithErrorOnMainThread(err);
} else {
// The run loop always joins on the sub threads, so the lifetime of this
// object outlives the invocations of this function, hence "unretained".
main_loop_.PostTask(FROM_HERE,
base::Bind(&Scheduler::FailWithErrorOnMainThread,
base::Unretained(this), err));
}
}
void Scheduler::ScheduleWork(const base::Closure& work) {
IncrementWorkCount();
pool_->PostWorkerTaskWithShutdownBehavior(
FROM_HERE, base::Bind(&Scheduler::DoWork,
base::Unretained(this), work),
base::SequencedWorkerPool::BLOCK_SHUTDOWN);
}
void Scheduler::AddGenDependency(const base::FilePath& file) {
base::AutoLock lock(lock_);
gen_dependencies_.push_back(file);
}
std::vector<base::FilePath> Scheduler::GetGenDependencies() const {
base::AutoLock lock(lock_);
return gen_dependencies_;
}
void Scheduler::AddWrittenFile(const SourceFile& file) {
base::AutoLock lock(lock_);
written_files_.push_back(file);
}
void Scheduler::AddUnknownGeneratedInput(const Target* target,
const SourceFile& file) {
base::AutoLock lock(lock_);
unknown_generated_inputs_.insert(std::make_pair(file, target));
}
std::multimap<SourceFile, const Target*>
Scheduler::GetUnknownGeneratedInputs() const {
base::AutoLock lock(lock_);
// Remove all unknown inputs that were written files. These are OK as inputs
// to build steps since they were written as a side-effect of running GN.
//
// It's assumed that this function is called once during cleanup to check for
// errors, so performing this work in the lock doesn't matter.
std::multimap<SourceFile, const Target*> filtered = unknown_generated_inputs_;
for (const SourceFile& file : written_files_)
filtered.erase(file);
return filtered;
}
void Scheduler::ClearUnknownGeneratedInputsAndWrittenFiles() {
base::AutoLock lock(lock_);
unknown_generated_inputs_.clear();
written_files_.clear();
}
void Scheduler::IncrementWorkCount() {
base::AtomicRefCountInc(&work_count_);
}
void Scheduler::DecrementWorkCount() {
if (!base::AtomicRefCountDec(&work_count_)) {
if (base::MessageLoop::current() == &main_loop_) {
OnComplete();
} else {
main_loop_.PostTask(FROM_HERE,
base::Bind(&Scheduler::OnComplete,
base::Unretained(this)));
}
}
}
void Scheduler::LogOnMainThread(const std::string& verb,
const std::string& msg) {
OutputString(verb, DECORATION_YELLOW);
OutputString(" " + msg + "\n");
}
void Scheduler::FailWithErrorOnMainThread(const Err& err) {
err.PrintToStdout();
runner_.Quit();
}
void Scheduler::DoWork(const base::Closure& closure) {
closure.Run();
DecrementWorkCount();
}
void Scheduler::OnComplete() {
// Should be called on the main thread.
DCHECK(base::MessageLoop::current() == main_loop());
runner_.Quit();
}
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