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// Copyright (c) 2013, 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 <limits>
#include <list>
#include "util/mutexlock.h"
namespace ROCKSDB_NAMESPACE {
//
// Simple synchronized queue implementation with the option of
// bounding the queue
//
// On overflow, the elements will be discarded
//
template <class T>
class BoundedQueue {
public:
explicit BoundedQueue(
const size_t max_size = std::numeric_limits<size_t>::max())
: cond_empty_(&lock_), max_size_(max_size) {}
virtual ~BoundedQueue() {}
void Push(T&& t) {
MutexLock _(&lock_);
if (max_size_ != std::numeric_limits<size_t>::max() &&
size_ + t.Size() >= max_size_) {
// overflow
return;
}
size_ += t.Size();
q_.push_back(std::move(t));
cond_empty_.SignalAll();
}
T Pop() {
MutexLock _(&lock_);
while (q_.empty()) {
cond_empty_.Wait();
}
T t = std::move(q_.front());
size_ -= t.Size();
q_.pop_front();
return t;
}
size_t Size() const {
MutexLock _(&lock_);
return size_;
}
private:
mutable port::Mutex lock_;
port::CondVar cond_empty_;
std::list<T> q_;
size_t size_ = 0;
const size_t max_size_;
};
} // namespace ROCKSDB_NAMESPACE
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