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/*
* Copyright 2003-2020 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_BUFFERING_INPUT_STREAM_BUFFER_HXX
#define MPD_BUFFERING_INPUT_STREAM_BUFFER_HXX
#include "Ptr.hxx"
#include "Handler.hxx"
#include "thread/Thread.hxx"
#include "thread/Mutex.hxx"
#include "thread/Cond.hxx"
#include "util/SparseBuffer.hxx"
#include <exception>
/**
* A "huge" buffer which remembers the (partial) contents of an
* #InputStream. This works only if the #InputStream is a "file", not
* a "stream".
*/
class BufferingInputStream : InputStreamHandler {
InputStreamPtr input;
public:
Mutex &mutex;
private:
Thread thread;
/**
* This #Cond wakes up the #Thread. It is used by both the
* "client" thread (to submit commands) and #input's handler
* (to notify new data being available).
*/
Cond wake_cond;
/**
* This #Cond wakes up the client upon command completion.
*/
Cond client_cond;
SparseBuffer<uint8_t> buffer;
bool stop = false;
/* must be mutable because IsAvailable() acts as a hint to
modify this attribute */
mutable size_t want_offset = INVALID_OFFSET;
std::exception_ptr error, seek_error;
static constexpr size_t INVALID_OFFSET = ~size_t(0);
public:
/**
* Allocate a buffer which fits the given #InputStream and
* start a thread reading into the buffer.
*
* Throws on error.
*
* @param _input a seekable #InputStream with a known size
*/
explicit BufferingInputStream(InputStreamPtr _input);
~BufferingInputStream() noexcept;
/**
* Caller must lock the mutex.
*/
const auto &GetInput() const noexcept {
return *input;
}
auto size() const noexcept {
return buffer.size();
}
/**
* Wrapper for InputStream::Check().
*
* Throws on error.
*
* Caller must lock the mutex.
*/
void Check();
/**
* Check whether data is available in the buffer at the given
* offset..
*/
bool IsAvailable(size_t offset) const noexcept;
/**
* Copy data from the buffer into the given pointer.
*
* @return the number of bytes copied into the given pointer.
*/
size_t Read(std::unique_lock<Mutex> &lock, size_t offset,
void *ptr, size_t size);
protected:
/**
* This virtual method gets called each time data has been
* added to the buffer. During this method call, the mutex is
* locked.
*/
virtual void OnBufferAvailable() noexcept {}
private:
size_t FindFirstHole() const noexcept;
void RunThreadLocked(std::unique_lock<Mutex> &lock);
void RunThread() noexcept;
/* virtual methods from class InputStreamHandler */
void OnInputStreamReady() noexcept final {
/* this should never be called, because our input must
be "ready" already */
}
void OnInputStreamAvailable() noexcept final {
wake_cond.notify_one();
}
};
#endif