2014-05-02 22:31:02 +02:00
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/*
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2016-02-26 17:54:05 +01:00
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* Copyright 2003-2016 The Music Player Daemon Project
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2014-05-02 22:31:02 +02:00
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_ASYNC_INPUT_STREAM_HXX
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#define MPD_ASYNC_INPUT_STREAM_HXX
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#include "InputStream.hxx"
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#include "event/DeferredMonitor.hxx"
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2016-06-17 18:06:02 +02:00
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#include "util/HugeAllocator.hxx"
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2014-05-02 22:31:02 +02:00
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#include "util/CircularBuffer.hxx"
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#include "util/Error.hxx"
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/**
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* Helper class for moving asynchronous (non-blocking) InputStream
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* implementations to the I/O thread. Data is being read into a ring
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* buffer, and that buffer is then consumed by another thread using
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* the regular #InputStream API.
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*/
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class AsyncInputStream : public InputStream, private DeferredMonitor {
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enum class SeekState : uint8_t {
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NONE, SCHEDULED, PENDING
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};
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2016-06-17 18:06:02 +02:00
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HugeAllocation allocation;
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2014-05-02 22:31:02 +02:00
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CircularBuffer<uint8_t> buffer;
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const size_t resume_at;
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bool open;
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/**
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* Is the connection currently paused? That happens when the
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* buffer was getting too large. It will be unpaused when the
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* buffer is below the threshold again.
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*/
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bool paused;
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SeekState seek_state;
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/**
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* The #Tag object ready to be requested via
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* InputStream::ReadTag().
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*/
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Tag *tag;
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offset_type seek_offset;
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protected:
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Error postponed_error;
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public:
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2014-12-14 14:21:08 +01:00
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/**
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* @param _buffer a buffer allocated with HugeAllocate(); the
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* destructor will free it using HugeFree()
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*/
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2014-05-02 22:31:02 +02:00
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AsyncInputStream(const char *_url,
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Mutex &_mutex, Cond &_cond,
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2016-06-17 18:06:02 +02:00
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size_t _buffer_size,
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2014-05-02 22:31:02 +02:00
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size_t _resume_at);
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virtual ~AsyncInputStream();
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/* virtual methods from InputStream */
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bool Check(Error &error) final;
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bool IsEOF() final;
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bool Seek(offset_type new_offset, Error &error) final;
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Tag *ReadTag() final;
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bool IsAvailable() final;
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size_t Read(void *ptr, size_t read_size, Error &error) final;
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protected:
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2014-07-10 10:33:43 +02:00
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/**
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* Pass an tag from the I/O thread to the client thread.
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*/
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2014-05-02 22:31:02 +02:00
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void SetTag(Tag *_tag);
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2014-11-02 13:00:25 +01:00
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void ClearTag() {
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SetTag(nullptr);
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}
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2014-05-02 22:31:02 +02:00
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void Pause();
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2014-09-02 20:02:56 +02:00
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bool IsPaused() const {
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return paused;
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}
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2014-07-10 10:33:43 +02:00
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/**
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* Declare that the underlying stream was closed. We will
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* continue feeding Read() calls from the buffer until it runs
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* empty.
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*/
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2014-05-02 22:31:02 +02:00
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void SetClosed() {
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open = false;
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}
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2014-07-10 10:33:43 +02:00
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/**
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* Pass an error from the I/O thread to the client thread.
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*/
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2014-06-17 00:52:12 +02:00
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void PostponeError(Error &&error);
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2014-05-02 22:31:02 +02:00
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bool IsBufferEmpty() const {
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return buffer.IsEmpty();
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}
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2014-06-17 02:32:10 +02:00
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bool IsBufferFull() const {
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return buffer.IsFull();
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}
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2014-07-10 10:33:43 +02:00
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/**
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* Determine how many bytes can be added to the buffer.
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*/
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2014-05-02 22:31:02 +02:00
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gcc_pure
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size_t GetBufferSpace() const {
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return buffer.GetSpace();
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}
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2014-07-10 10:33:43 +02:00
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/**
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* Append data to the buffer. The size must fit into the
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* buffer; see GetBufferSpace().
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*/
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2014-05-02 22:31:02 +02:00
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void AppendToBuffer(const void *data, size_t append_size);
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2014-07-10 10:33:43 +02:00
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/**
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* Implement code here that will resume the stream after it
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* has been paused due to full input buffer.
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*/
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2014-05-02 22:31:02 +02:00
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virtual void DoResume() = 0;
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/**
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* The actual Seek() implementation. This virtual method will
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* be called from within the I/O thread. When the operation
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* is finished, call SeekDone() to notify the caller.
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*/
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virtual void DoSeek(offset_type new_offset) = 0;
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bool IsSeekPending() const {
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return seek_state == SeekState::PENDING;
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}
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2014-07-10 10:33:43 +02:00
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/**
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* Call this after seeking has finished. It will notify the
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* client thread.
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*/
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2014-05-02 22:31:02 +02:00
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void SeekDone();
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private:
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void Resume();
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/* virtual methods from DeferredMonitor */
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void RunDeferred() final;
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};
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#endif
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