rocksdb/util/channel.h
Peter Dillinger bda8d93ba9 Fix and detect headers with missing dependencies (#8893)
Summary:
It's always annoying to find a header does not include its own
dependencies and only works when included after other includes. This
change adds `make check-headers` which validates that each header can
be included at the top of a file. Some headers are excluded e.g. because
of platform or external dependencies.

rocksdb_namespace.h had to be re-worked slightly to enable checking for
failure to include it. (ROCKSDB_NAMESPACE is a valid namespace name.)

Fixes mostly involve adding and cleaning up #includes, but for
FileTraceWriter, a constructor was out-of-lined to make a forward
declaration sufficient.

This check is not currently run with `make check` but is added to
CircleCI build-linux-unity since that one is already relatively fast.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8893

Test Plan: existing tests and resolving issues detected by new check

Reviewed By: mrambacher

Differential Revision: D30823300

Pulled By: pdillinger

fbshipit-source-id: 9fff223944994c83c105e2e6496d24845dc8e572
2021-09-10 10:00:26 -07:00

70 lines
1.6 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include <condition_variable>
#include <mutex>
#include <queue>
#include <utility>
#include "rocksdb/rocksdb_namespace.h"
namespace ROCKSDB_NAMESPACE {
template <class T>
class channel {
public:
explicit channel() : eof_(false) {}
channel(const channel&) = delete;
void operator=(const channel&) = delete;
void sendEof() {
std::lock_guard<std::mutex> lk(lock_);
eof_ = true;
cv_.notify_all();
}
bool eof() {
std::lock_guard<std::mutex> lk(lock_);
return buffer_.empty() && eof_;
}
size_t size() const {
std::lock_guard<std::mutex> lk(lock_);
return buffer_.size();
}
// writes elem to the queue
void write(T&& elem) {
std::unique_lock<std::mutex> lk(lock_);
buffer_.emplace(std::forward<T>(elem));
cv_.notify_one();
}
/// Moves a dequeued element onto elem, blocking until an element
/// is available.
// returns false if EOF
bool read(T& elem) {
std::unique_lock<std::mutex> lk(lock_);
cv_.wait(lk, [&] { return eof_ || !buffer_.empty(); });
if (eof_ && buffer_.empty()) {
return false;
}
elem = std::move(buffer_.front());
buffer_.pop();
cv_.notify_one();
return true;
}
private:
std::condition_variable cv_;
mutable std::mutex lock_;
std::queue<T> buffer_;
bool eof_;
};
} // namespace ROCKSDB_NAMESPACE