fifo_buffer: move to util/

src/util/fifo_buffer.c

@@ -0,0 +1,210 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "fifo_buffer.h"
+
+#include <glib.h>
+
+#include <assert.h>
+#include <string.h>
+
+struct fifo_buffer {
+	size_t size, start, end;
+	unsigned char buffer[sizeof(size_t)];
+};
+
+struct fifo_buffer *
+fifo_buffer_new(size_t size)
+{
+	struct fifo_buffer *buffer;
+
+	assert(size > 0);
+
+	buffer = (struct fifo_buffer *)g_malloc(sizeof(*buffer) -
+						sizeof(buffer->buffer) + size);
+
+	buffer->size = size;
+	buffer->start = 0;
+	buffer->end = 0;
+
+	return buffer;
+}
+
+static void
+fifo_buffer_move(struct fifo_buffer *buffer);
+
+struct fifo_buffer *
+fifo_buffer_realloc(struct fifo_buffer *buffer, size_t new_size)
+{
+	if (buffer == NULL)
+		return new_size > 0
+			? fifo_buffer_new(new_size)
+			: NULL;
+
+	/* existing data must fit in new size */
+	assert(new_size >= buffer->end - buffer->start);
+
+	if (new_size == 0) {
+		fifo_buffer_free(buffer);
+		return NULL;
+	}
+
+	/* compress the buffer when we're shrinking and the tail of
+	   the buffer would exceed the new size */
+	if (buffer->end > new_size)
+		fifo_buffer_move(buffer);
+
+	/* existing data must fit in new size: second check */
+	assert(buffer->end <= new_size);
+
+	buffer = g_realloc(buffer, sizeof(*buffer) - sizeof(buffer->buffer) +
+			   new_size);
+	buffer->size = new_size;
+	return buffer;
+}
+
+void
+fifo_buffer_free(struct fifo_buffer *buffer)
+{
+	assert(buffer != NULL);
+
+	g_free(buffer);
+}
+
+size_t
+fifo_buffer_capacity(const struct fifo_buffer *buffer)
+{
+	assert(buffer != NULL);
+
+	return buffer->size;
+}
+
+size_t
+fifo_buffer_available(const struct fifo_buffer *buffer)
+{
+	assert(buffer != NULL);
+
+	return buffer->end - buffer->start;
+}
+
+void
+fifo_buffer_clear(struct fifo_buffer *buffer)
+{
+	assert(buffer != NULL);
+
+	buffer->start = 0;
+	buffer->end = 0;
+}
+
+const void *
+fifo_buffer_read(const struct fifo_buffer *buffer, size_t *length_r)
+{
+	assert(buffer != NULL);
+	assert(buffer->end >= buffer->start);
+	assert(length_r != NULL);
+
+	if (buffer->start == buffer->end)
+		/* the buffer is empty */
+		return NULL;
+
+	*length_r = buffer->end - buffer->start;
+	return buffer->buffer + buffer->start;
+}
+
+void
+fifo_buffer_consume(struct fifo_buffer *buffer, size_t length)
+{
+	assert(buffer != NULL);
+	assert(buffer->end >= buffer->start);
+	assert(buffer->start + length <= buffer->end);
+
+	buffer->start += length;
+}
+
+/**
+ * Move data to the beginning of the buffer, to make room at the end.
+ */
+static void
+fifo_buffer_move(struct fifo_buffer *buffer)
+{
+	if (buffer->start == 0)
+		return;
+
+	if (buffer->end > buffer->start)
+		memmove(buffer->buffer,
+			buffer->buffer + buffer->start,
+			buffer->end - buffer->start);
+
+	buffer->end -= buffer->start;
+	buffer->start = 0;
+}
+
+void *
+fifo_buffer_write(struct fifo_buffer *buffer, size_t *max_length_r)
+{
+	assert(buffer != NULL);
+	assert(buffer->end <= buffer->size);
+	assert(max_length_r != NULL);
+
+	if (buffer->end == buffer->size) {
+		fifo_buffer_move(buffer);
+		if (buffer->end == buffer->size)
+			return NULL;
+	} else if (buffer->start > 0 && buffer->start == buffer->end) {
+		buffer->start = 0;
+		buffer->end = 0;
+	}
+
+	*max_length_r = buffer->size - buffer->end;
+	return buffer->buffer + buffer->end;
+}
+
+void
+fifo_buffer_append(struct fifo_buffer *buffer, size_t length)
+{
+	assert(buffer != NULL);
+	assert(buffer->end >= buffer->start);
+	assert(buffer->end + length <= buffer->size);
+
+	buffer->end += length;
+}
+
+bool
+fifo_buffer_is_empty(struct fifo_buffer *buffer)
+{
+	return buffer->start == buffer->end;
+}
+
+bool
+fifo_buffer_is_full(struct fifo_buffer *buffer)
+{
+	return buffer->start == 0 && buffer->end == buffer->size;
+}

src/util/fifo_buffer.h

@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** \file
+ *
+ * This is a general purpose FIFO buffer library.  You may append data
+ * at the end, while another instance reads data from the beginning.
+ * It is optimized for zero-copy usage: you get pointers to the real
+ * buffer, where you may operate on.
+ *
+ * This library is not thread safe.
+ */
+
+#ifndef MPD_FIFO_BUFFER_H
+#define MPD_FIFO_BUFFER_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct fifo_buffer;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Creates a new #fifo_buffer object.  Free this object with
+ * fifo_buffer_free().
+ *
+ * @param size the size of the buffer in bytes
+ * @return the new #fifo_buffer object
+ */
+struct fifo_buffer *
+fifo_buffer_new(size_t size);
+
+/**
+ * Change the capacity of the #fifo_buffer, while preserving existing
+ * data.
+ *
+ * @param buffer the old buffer, may be NULL
+ * @param new_size the requested new size of the #fifo_buffer; must
+ * not be smaller than the data which is stored in the old buffer
+ * @return the new buffer, may be NULL if the requested new size is 0
+ */
+struct fifo_buffer *
+fifo_buffer_realloc(struct fifo_buffer *buffer, size_t new_size);
+
+/**
+ * Frees the resources consumed by this #fifo_buffer object.
+ */
+void
+fifo_buffer_free(struct fifo_buffer *buffer);
+
+/**
+ * Return the capacity of the buffer, i.e. the size that was passed to
+ * fifo_buffer_new().
+ */
+size_t
+fifo_buffer_capacity(const struct fifo_buffer *buffer);
+
+/**
+ * Return the number of bytes currently stored in the buffer.
+ */
+size_t
+fifo_buffer_available(const struct fifo_buffer *buffer);
+
+/**
+ * Clears all data currently in this #fifo_buffer object.  This does
+ * not overwrite the actuall buffer; it just resets the internal
+ * pointers.
+ */
+void
+fifo_buffer_clear(struct fifo_buffer *buffer);
+
+/**
+ * Reads from the beginning of the buffer.  To remove consumed data
+ * from the buffer, call fifo_buffer_consume().
+ *
+ * @param buffer the #fifo_buffer object
+ * @param length_r the maximum amount to read is returned here
+ * @return a pointer to the beginning of the buffer, or NULL if the
+ * buffer is empty
+ */
+const void *
+fifo_buffer_read(const struct fifo_buffer *buffer, size_t *length_r);
+
+/**
+ * Marks data at the beginning of the buffer as "consumed".
+ *
+ * @param buffer the #fifo_buffer object
+ * @param length the number of bytes which were consumed
+ */
+void
+fifo_buffer_consume(struct fifo_buffer *buffer, size_t length);
+
+/**
+ * Prepares writing to the buffer.  This returns a buffer which you
+ * can write to.  To commit the write operation, call
+ * fifo_buffer_append().
+ *
+ * @param buffer the #fifo_buffer object
+ * @param max_length_r the maximum amount to write is returned here
+ * @return a pointer to the end of the buffer, or NULL if the buffer
+ * is already full
+ */
+void *
+fifo_buffer_write(struct fifo_buffer *buffer, size_t *max_length_r);
+
+/**
+ * Commits the write operation initiated by fifo_buffer_write().
+ *
+ * @param buffer the #fifo_buffer object
+ * @param length the number of bytes which were written
+ */
+void
+fifo_buffer_append(struct fifo_buffer *buffer, size_t length);
+
+/**
+ * Checks if the buffer is empty.
+ */
+bool
+fifo_buffer_is_empty(struct fifo_buffer *buffer);
+
+/**
+ * Checks if the buffer is full.
+ */
+bool
+fifo_buffer_is_full(struct fifo_buffer *buffer);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/util/growing_fifo.c

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "growing_fifo.h"
+#include "fifo_buffer.h"
+
+#include <assert.h>
+#include <string.h>
+
+/**
+ * Align buffer sizes at 8 kB boundaries.  Must be a power of two.
+ */
+static const size_t GROWING_FIFO_ALIGN = 8192;
+
+/**
+ * Align the specified size to the next #GROWING_FIFO_ALIGN boundary.
+ */
+static size_t
+align(size_t size)
+{
+	return ((size - 1) | (GROWING_FIFO_ALIGN - 1)) + 1;
+}
+
+struct fifo_buffer *
+growing_fifo_new(void)
+{
+	return fifo_buffer_new(GROWING_FIFO_ALIGN);
+}
+
+void *
+growing_fifo_write(struct fifo_buffer **buffer_p, size_t length)
+{
+	assert(buffer_p != NULL);
+
+	struct fifo_buffer *buffer = *buffer_p;
+	assert(buffer != NULL);
+
+	size_t max_length;
+	void *p = fifo_buffer_write(buffer, &max_length);
+	if (p != NULL && max_length >= length)
+		return p;
+
+	/* grow */
+	size_t new_size = fifo_buffer_available(buffer) + length;
+	assert(new_size > fifo_buffer_capacity(buffer));
+	*buffer_p = buffer = fifo_buffer_realloc(buffer, align(new_size));
+
+	/* try again */
+	p = fifo_buffer_write(buffer, &max_length);
+	assert(p != NULL);
+	assert(max_length >= length);
+
+	return p;
+}
+
+void
+growing_fifo_append(struct fifo_buffer **buffer_p,
+		    const void *data, size_t length)
+{
+	void *p = growing_fifo_write(buffer_p, length);
+	memcpy(p, data, length);
+	fifo_buffer_append(*buffer_p, length);
+}

src/util/growing_fifo.h

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2003-2011 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** \file
+ *
+ * Helper functions for our FIFO buffer library (fifo_buffer.h) that
+ * allows growing the buffer on demand.
+ *
+ * This library is not thread safe.
+ */
+
+#ifndef MPD_GROWING_FIFO_H
+#define MPD_GROWING_FIFO_H
+
+#include <stddef.h>
+
+struct fifo_buffer;
+
+/**
+ * Allocate a new #fifo_buffer with the default size.
+ */
+struct fifo_buffer *
+growing_fifo_new(void);
+
+/**
+ * Prepares writing to the buffer, see fifo_buffer_write() for
+ * details.  The difference is that this function will automatically
+ * grow the buffer if it is too small.
+ *
+ * The caller is responsible for limiting the capacity of the buffer.
+ *
+ * @param length the number of bytes that will be written
+ * @return a pointer to the end of the buffer (will not be NULL)
+ */
+void *
+growing_fifo_write(struct fifo_buffer **buffer_p, size_t length);
+
+/**
+ * A helper function that combines growing_fifo_write(), memcpy(),
+ * fifo_buffer_append().
+ */
+void
+growing_fifo_append(struct fifo_buffer **buffer_p,
+		    const void *data, size_t length);
+
+#endif