libreoffice-online/common/MessageQueue.hpp

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
* This file is part of the LibreOffice project.
*
* 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 INCLUDED_MESSAGEQUEUE_HPP
#define INCLUDED_MESSAGEQUEUE_HPP
#include <algorithm>
#include <condition_variable>
#include <functional>
#include <map>
#include <mutex>
#include <vector>
/** Thread-safe message queue (FIFO).
*/
class MessageQueue
{
public:
typedef std::vector<char> Payload;
MessageQueue()
{
}
virtual ~MessageQueue();
MessageQueue(const MessageQueue&) = delete;
MessageQueue& operator=(const MessageQueue&) = delete;
/// Thread safe insert the message.
void put(const Payload& value);
void put(const std::string& value)
{
put(Payload(value.data(), value.data() + value.size()));
}
/// Thread safe obtaining of the message.
/// timeoutMs can be 0 to signify infinity.
Payload get(const unsigned timeoutMs = 0);
/// Thread safe removal of all the pending messages.
void clear();
/// Thread safe remove_if.
void remove_if(const std::function<bool(const Payload&)>& pred);
private:
std::mutex _mutex;
std::condition_variable _cv;
protected:
virtual void put_impl(const Payload& value);
bool wait_impl() const;
virtual Payload get_impl();
void clear_impl();
std::vector<Payload> _queue;
};
/** MessageQueue specialized for priority handling of tiles.
*/
class TileQueue : public MessageQueue
{
friend class TileQueueTests;
private:
class CursorPosition
{
public:
int Part;
int X;
int Y;
int Width;
int Height;
};
public:
TileQueue() :
_lastTileGetTime(std::chrono::steady_clock::now()),
_lastGetTime(_lastTileGetTime),
_lastGetTile(true)
{
}
void updateCursorPosition(int viewId, int part, int x, int y, int width, int height)
{
auto cursorPosition = CursorPosition({ part, x, y, width, height });
auto it = _cursorPositions.find(viewId);
if (it != _cursorPositions.end())
{
it->second = cursorPosition;
}
else
{
_cursorPositions[viewId] = cursorPosition;
}
// Move to front, so the current front view
// becomes the second.
const auto view = std::find(_viewOrder.begin(), _viewOrder.end(), viewId);
if (view != _viewOrder.end())
{
_viewOrder.erase(view);
}
_viewOrder.push_back(viewId);
}
void removeCursorPosition(int viewId)
{
const auto view = std::find(_viewOrder.begin(), _viewOrder.end(), viewId);
if (view != _viewOrder.end())
{
_viewOrder.erase(view);
}
_cursorPositions.erase(viewId);
}
protected:
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virtual void put_impl(const Payload& value) override;
virtual Payload get_impl() override;
private:
/// Search the queue for a duplicate tile and remove it (if present).
void removeDuplicate(const std::string& tileMsg);
/// Find the index of the first non-preview entry.
/// When preferTiles is false, it'll return index of
/// the first non-tile, otherwise, the index of the
/// first tile is returned.
/// Returns -1 if only previews are left.
int findFirstNonPreview(bool preferTiles) const;
/// Returns true if we should try to return
/// a tile, otherwise a non-tile.
bool shouldPreferTiles() const;
/// Update the tile/non-tile timestamps to
/// track how much time we spend for each.
/// isTile marks if the current message
/// is a tile or not.
void updateTimestamps(const bool isTile);
/// Given a positive index, move it to the top.
void bumpToTop(const size_t index);
/// Priority of the given tile message.
/// -1 means the lowest prio (the tile does not intersect any of the cursors),
/// the higher the number, the bigger is priority [up to _viewOrder.size()-1].
int priority(const std::string& tileMsg);
private:
std::map<int, CursorPosition> _cursorPositions;
/// Check the views in the order of how the editing (cursor movement) has
/// been happening (0 == oldest, size() - 1 == newest).
std::vector<int> _viewOrder;
std::chrono::steady_clock::time_point _lastTileGetTime;
std::chrono::steady_clock::time_point _lastGetTime;
bool _lastGetTile;
/// For responsiveness, we shouldn't have higher latency.
static const int MaxTileSkipDurationMs = 100;
};
#endif
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */