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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_layers_RecentEventsBuffer_h
#define mozilla_layers_RecentEventsBuffer_h
#include <deque>
#include "mozilla/TimeStamp.h"
namespace mozilla {
namespace layers {
/**
* RecentEventsBuffer: maintains an age constrained buffer of events
*
* Intended for use with elements of type InputData, but the only requirement
* is a member "mTimeStamp" of type TimeStamp
*/
template <typename Event>
class RecentEventsBuffer {
public:
explicit RecentEventsBuffer(TimeDuration maxAge);
void push(Event event);
void clear();
typedef typename std::deque<Event>::size_type size_type;
size_type size() { return mBuffer.size(); }
// Delegate to container for iterators
typedef typename std::deque<Event>::iterator iterator;
typedef typename std::deque<Event>::const_iterator const_iterator;
iterator begin() { return mBuffer.begin(); }
iterator end() { return mBuffer.end(); }
const_iterator cbegin() const { return mBuffer.cbegin(); }
const_iterator cend() const { return mBuffer.cend(); }
// Also delegate for front/back
typedef typename std::deque<Event>::reference reference;
typedef typename std::deque<Event>::const_reference const_reference;
reference front() { return mBuffer.front(); }
reference back() { return mBuffer.back(); }
const_reference front() const { return mBuffer.front(); }
const_reference back() const { return mBuffer.back(); }
private:
TimeDuration mMaxAge;
std::deque<Event> mBuffer;
};
template <typename Event>
RecentEventsBuffer<Event>::RecentEventsBuffer(TimeDuration maxAge)
: mMaxAge(maxAge), mBuffer() {}
template <typename Event>
void RecentEventsBuffer<Event>::push(Event event) {
// Events must be pushed in chronological order
MOZ_ASSERT(mBuffer.empty() || mBuffer.back().mTimeStamp <= event.mTimeStamp);
mBuffer.push_back(event);
// Flush all events older than the given lifetime
TimeStamp bound = event.mTimeStamp - mMaxAge;
while (!mBuffer.empty()) {
if (mBuffer.front().mTimeStamp >= bound) {
break;
}
mBuffer.pop_front();
}
}
template <typename Event>
void RecentEventsBuffer<Event>::clear() {
mBuffer.clear();
}
} // namespace layers
} // namespace mozilla
#endif // mozilla_layers_RecentEventsBuffer_h