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#include "thread_pool.h"
#include <cassert>
#include <utility>
#include "check.h"
#include "logging.h"
namespace gitstatus {
ThreadPool::ThreadPool(size_t num_threads) : num_inflight_(num_threads) {
for (size_t i = 0; i != num_threads; ++i) {
threads_.emplace_back([=]() { Loop(i + 1); });
}
}
ThreadPool::~ThreadPool() {
{
std::lock_guard<std::mutex> lock(mutex_);
exit_ = true;
}
cv_.notify_all();
sleeper_cv_.notify_one();
for (std::thread& t : threads_) t.join();
}
void ThreadPool::Schedule(Time t, std::function<void()> f) {
std::condition_variable* wake = nullptr;
{
std::unique_lock<std::mutex> lock(mutex_);
work_.push(Work{std::move(t), ++last_idx_, std::move(f)});
if (work_.top().idx == last_idx_) wake = have_sleeper_ ? &sleeper_cv_ : &cv_;
}
if (wake) wake->notify_one();
}
void ThreadPool::Loop(size_t tid) {
auto Next = [&]() -> std::function<void()> {
std::unique_lock<std::mutex> lock(mutex_);
--num_inflight_;
if (work_.empty() && num_inflight_ == 0) idle_cv_.notify_all();
while (true) {
if (exit_) return nullptr;
if (work_.empty()) {
cv_.wait(lock);
continue;
}
Time now = Clock::now();
const Work& top = work_.top();
if (top.t <= now) {
std::function<void()> res = std::move(top.f);
work_.pop();
++num_inflight_;
bool notify = !work_.empty() && !have_sleeper_;
lock.unlock();
if (notify) cv_.notify_one();
return res;
}
if (have_sleeper_) {
cv_.wait(lock);
continue;
}
have_sleeper_ = true;
sleeper_cv_.wait_until(lock, top.t);
assert(have_sleeper_);
have_sleeper_ = false;
}
};
while (std::function<void()> f = Next()) f();
}
void ThreadPool::Wait() {
std::unique_lock<std::mutex> lock(mutex_);
idle_cv_.wait(lock, [&] { return work_.empty() && num_inflight_ == 0; });
}
static ThreadPool* g_thread_pool = nullptr;
void InitGlobalThreadPool(size_t num_threads) {
CHECK(!g_thread_pool);
LOG(INFO) << "Spawning " << num_threads << " thread(s)";
g_thread_pool = new ThreadPool(num_threads);
}
ThreadPool* GlobalThreadPool() { return g_thread_pool; }
} // namespace gitstatus
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