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Diffstat (limited to '')
-rw-r--r-- | src/input/InputStream.hxx | 365 |
1 files changed, 365 insertions, 0 deletions
diff --git a/src/input/InputStream.hxx b/src/input/InputStream.hxx new file mode 100644 index 000000000..15c350103 --- /dev/null +++ b/src/input/InputStream.hxx @@ -0,0 +1,365 @@ +/* + * Copyright (C) 2003-2014 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_INPUT_STREAM_HXX +#define MPD_INPUT_STREAM_HXX + +#include "check.h" +#include "Offset.hxx" +#include "thread/Mutex.hxx" +#include "Compiler.h" + +#include <string> + +#include <assert.h> +#include <stdint.h> + +class Cond; +class Error; +struct Tag; + +class InputStream { +public: + typedef ::offset_type offset_type; + +private: + /** + * The absolute URI which was used to open this stream. + */ + std::string uri; + +public: + /** + * A mutex that protects the mutable attributes of this object + * and its implementation. It must be locked before calling + * any of the public methods. + * + * This object is allocated by the client, and the client is + * responsible for freeing it. + */ + Mutex &mutex; + + /** + * A cond that gets signalled when the state of this object + * changes from the I/O thread. The client of this object may + * wait on it. Optional, may be nullptr. + * + * This object is allocated by the client, and the client is + * responsible for freeing it. + */ + Cond &cond; + +protected: + /** + * indicates whether the stream is ready for reading and + * whether the other attributes in this struct are valid + */ + bool ready; + + /** + * if true, then the stream is fully seekable + */ + bool seekable; + + static constexpr offset_type UNKNOWN_SIZE = -1; + + /** + * the size of the resource, or #UNKNOWN_SIZE if unknown + */ + offset_type size; + + /** + * the current offset within the stream + */ + offset_type offset; + +private: + /** + * the MIME content type of the resource, or empty if unknown. + */ + std::string mime; + +public: + InputStream(const char *_uri, Mutex &_mutex, Cond &_cond) + :uri(_uri), + mutex(_mutex), cond(_cond), + ready(false), seekable(false), + size(UNKNOWN_SIZE), offset(0) { + assert(_uri != nullptr); + } + + /** + * Close the input stream and free resources. + * + * The caller must not lock the mutex. + */ + virtual ~InputStream(); + + /** + * Opens a new input stream. You may not access it until the "ready" + * flag is set. + * + * @param mutex a mutex that is used to protect this object; must be + * locked before calling any of the public methods + * @param cond a cond that gets signalled when the state of + * this object changes; may be nullptr if the caller doesn't want to get + * notifications + * @return an #InputStream object on success, nullptr on error + */ + gcc_nonnull_all + gcc_malloc + static InputStream *Open(const char *uri, Mutex &mutex, Cond &cond, + Error &error); + + /** + * Just like Open(), but waits for the stream to become ready. + * It is a wrapper for Open(), WaitReady() and Check(). + */ + gcc_malloc gcc_nonnull_all + static InputStream *OpenReady(const char *uri, + Mutex &mutex, Cond &cond, + Error &error); + + /** + * The absolute URI which was used to open this stream. + * + * No lock necessary for this method. + */ + const char *GetURI() const { + return uri.c_str(); + } + + void Lock() { + mutex.lock(); + } + + void Unlock() { + mutex.unlock(); + } + + /** + * Check for errors that may have occurred in the I/O thread. + * + * @return false on error + */ + virtual bool Check(Error &error); + + /** + * Update the public attributes. Call before accessing attributes + * such as "ready" or "offset". + */ + virtual void Update(); + + void SetReady(); + + /** + * Return whether the stream is ready for reading and whether + * the other attributes in this struct are valid. + * + * The caller must lock the mutex. + */ + bool IsReady() const { + return ready; + } + + void WaitReady(); + + /** + * Wrapper for WaitReady() which locks and unlocks the mutex; + * the caller must not be holding it already. + */ + void LockWaitReady(); + + gcc_pure + bool HasMimeType() const { + assert(ready); + + return !mime.empty(); + } + + gcc_pure + const char *GetMimeType() const { + assert(ready); + + return mime.empty() ? nullptr : mime.c_str(); + } + + gcc_nonnull_all + void SetMimeType(const char *_mime) { + assert(!ready); + + mime = _mime; + } + + void SetMimeType(std::string &&_mime) { + assert(!ready); + + mime = std::move(_mime); + } + + gcc_nonnull_all + void OverrideMimeType(const char *_mime) { + assert(ready); + + mime = _mime; + } + + gcc_pure + bool KnownSize() const { + assert(ready); + + return size != UNKNOWN_SIZE; + } + + gcc_pure + offset_type GetSize() const { + assert(ready); + assert(KnownSize()); + + return size; + } + + void AddOffset(offset_type delta) { + assert(ready); + + offset += delta; + } + + gcc_pure + offset_type GetOffset() const { + assert(ready); + + return offset; + } + + gcc_pure + offset_type GetRest() const { + assert(ready); + assert(KnownSize()); + + return size - offset; + } + + gcc_pure + bool IsSeekable() const { + assert(ready); + + return seekable; + } + + /** + * Determines whether seeking is cheap. This is true for local files. + */ + gcc_pure + bool CheapSeeking() const; + + /** + * Seeks to the specified position in the stream. This will most + * likely fail if the "seekable" flag is false. + * + * The caller must lock the mutex. + * + * @param offset the relative offset + */ + virtual bool Seek(offset_type offset, Error &error); + + /** + * Wrapper for Seek() which locks and unlocks the mutex; the + * caller must not be holding it already. + */ + bool LockSeek(offset_type offset, Error &error); + + /** + * Rewind to the beginning of the stream. This is a wrapper + * for Seek(0, error). + */ + bool Rewind(Error &error) { + return Seek(0, error); + } + + bool LockRewind(Error &error) { + return LockSeek(0, error); + } + + /** + * Returns true if the stream has reached end-of-file. + * + * The caller must lock the mutex. + */ + gcc_pure + virtual bool IsEOF() = 0; + + /** + * Wrapper for IsEOF() which locks and unlocks the mutex; the + * caller must not be holding it already. + */ + gcc_pure + bool LockIsEOF(); + + /** + * Reads the tag from the stream. + * + * The caller must lock the mutex. + * + * @return a tag object which must be freed by the caller, or + * nullptr if the tag has not changed since the last call + */ + gcc_malloc + virtual Tag *ReadTag(); + + /** + * Wrapper for ReadTag() which locks and unlocks the mutex; + * the caller must not be holding it already. + */ + gcc_malloc + Tag *LockReadTag(); + + /** + * Returns true if the next read operation will not block: either data + * is available, or end-of-stream has been reached, or an error has + * occurred. + * + * The caller must lock the mutex. + */ + gcc_pure + virtual bool IsAvailable(); + + /** + * Reads data from the stream into the caller-supplied buffer. + * Returns 0 on error or eof (check with IsEOF()). + * + * The caller must lock the mutex. + * + * @param is the InputStream object + * @param ptr the buffer to read into + * @param size the maximum number of bytes to read + * @return the number of bytes read + */ + gcc_nonnull_all + virtual size_t Read(void *ptr, size_t size, Error &error) = 0; + + /** + * Wrapper for Read() which locks and unlocks the mutex; + * the caller must not be holding it already. + */ + gcc_nonnull_all + size_t LockRead(void *ptr, size_t size, Error &error); +}; + +#endif |