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-rw-r--r-- | src/Page.hxx | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/src/Page.hxx b/src/Page.hxx new file mode 100644 index 000000000..2bc9a6ac5 --- /dev/null +++ b/src/Page.hxx @@ -0,0 +1,104 @@ +/* + * Copyright (C) 2003-2011 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. + */ + +/** \file + * + * This is a library which manages reference counted buffers. + */ + +#ifndef MPD_PAGE_HXX +#define MPD_PAGE_HXX + +#include "util/RefCount.hxx" + +#include <algorithm> + +#include <stddef.h> + +/** + * A dynamically allocated buffer which keeps track of its reference + * count. This is useful for passing buffers around, when several + * instances hold references to one buffer. + */ +class Page { + /** + * The number of references to this buffer. This library uses + * atomic functions to access it, i.e. no locks are required. + * As soon as this attribute reaches zero, the buffer is + * freed. + */ + RefCount ref; + +public: + /** + * The size of this buffer in bytes. + */ + const size_t size; + + /** + * Dynamic array containing the buffer data. + */ + unsigned char data[sizeof(long)]; + +protected: + Page(size_t _size):size(_size) {} + ~Page() = default; + + /** + * Allocates a new #Page object, without filling the data + * element. + */ + static Page *Create(size_t size); + +public: + /** + * Creates a new #page object, and copies data from the + * specified buffer. It is initialized with a reference count + * of 1. + * + * @param data the source buffer + * @param size the size of the source buffer + */ + static Page *Copy(const void *data, size_t size); + + /** + * Concatenates two pages to a new page. + * + * @param a the first page + * @param b the second page, which is appended + */ + static Page *Concat(const Page &a, const Page &b); + + /** + * Increases the reference counter. + */ + void Ref() { + ref.Increment(); + } + + /** + * Decreases the reference counter. If it reaches zero, the #page is + * freed. + * + * @return true if the #page has been freed + */ + bool Unref(); +}; + +#endif |