util/DynamicFifoBuffer: new class replacing growing_fifo

3 files changed, 199 insertions, 163 deletions

diff --git a/src/util/DynamicFifoBuffer.hxx b/src/util/DynamicFifoBuffer.hxx
new file mode 100644
index 000000000..ead7389e9
--- /dev/null
+++ b/src/util/DynamicFifoBuffer.hxx
@@ -0,0 +1,199 @@
+/*
+ * Copyright (C) 2003-2013 Max Kellermann <max@duempel.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.
+ */
+
+#ifndef FIFO_BUFFER_HPP
+#define FIFO_BUFFER_HPP
+
+#include "WritableBuffer.hxx"
+
+#include <utility>
+#include <algorithm>
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+
+/**
+ * A first-in-first-out buffer: you can append data at the end, and
+ * read data from the beginning.  This class automatically shifts the
+ * buffer as needed.  It is not thread safe.
+ */
+template<typename T>
+class DynamicFifoBuffer {
+public:
+	typedef size_t size_type;
+	typedef WritableBuffer<T> Range;
+	typedef typename Range::pointer_type pointer_type;
+	typedef typename Range::const_pointer_type const_pointer_type;
+
+protected:
+	size_type head, tail, capacity;
+	T *data;
+
+public:
+	DynamicFifoBuffer(size_type _capacity)
+		:head(0), tail(0), capacity(_capacity),
+		 data(new T[capacity]) {}
+	~DynamicFifoBuffer() {
+		delete[] data;
+	}
+
+	DynamicFifoBuffer(const DynamicFifoBuffer &) = delete;
+
+	size_type GetCapacity() {
+		return capacity;
+	}
+
+	void Grow(size_type new_capacity) {
+		assert(new_capacity > capacity);
+
+		T *new_data = new T[new_capacity];
+		std::move(data + head, data + tail, new_data);
+		delete[] data;
+		data = new_data;
+		capacity = new_capacity;
+		tail -= head;
+		head = 0;
+	}
+
+	void Clear() {
+		head = tail = 0;
+	}
+
+	bool IsEmpty() const {
+		return head == tail;
+	}
+
+	bool IsFull() const {
+		return head == 0 && tail == capacity;
+	}
+
+	/**
+	 * Prepares writing.  Returns a buffer range which may be written.
+	 * When you are finished, call append().
+	 */
+	Range Write() {
+		Shift();
+		return Range(data + tail, capacity - tail);
+	}
+
+	/**
+	 * Expands the tail of the buffer, after data has been written to
+	 * the buffer returned by write().
+	 */
+	void Append(size_type n) {
+		assert(tail <= capacity);
+		assert(n <= capacity);
+		assert(tail + n <= capacity);
+
+		tail += n;
+	}
+
+	void WantWrite(size_type n) {
+		if (tail + n <= capacity)
+			/* enough space after the tail */
+			return;
+
+		const size_type in_use = tail - head;
+		const size_type required_capacity = in_use + n;
+		if (capacity >= required_capacity) {
+			Shift();
+		} else {
+			size_type new_capacity = capacity;
+			do {
+				new_capacity <<= 1;
+			} while (new_capacity < required_capacity);
+
+			Grow(new_capacity);
+		}
+	}
+
+	/**
+	 * Write data to the bfufer, growing it as needed.  Returns a
+	 * writable pointer.
+	 */
+	pointer_type Write(size_type n) {
+		WantWrite(n);
+		return data + tail;
+	}
+
+	/**
+	 * Append data to the buffer, growing it as needed.
+	 */
+	void Append(const_pointer_type p, size_type n) {
+		std::copy_n(p, n, Write(n));
+		Append(n);
+	}
+
+	/**
+	 * Return a buffer range which may be read.  The buffer pointer is
+	 * writable, to allow modifications while parsing.
+	 */
+	Range Read() {
+		return Range(data + head, tail - head);
+	}
+
+	/**
+	 * Marks a chunk as consumed.
+	 */
+	void Consume(size_type n) {
+		assert(tail <= capacity);
+		assert(head <= tail);
+		assert(n <= tail);
+		assert(head + n <= tail);
+
+		head += n;
+	}
+
+	size_type Read(pointer_type p, size_type n) {
+		auto range = Read();
+		if (n > range.size)
+			n = range.size;
+		std::copy_n(range.data, n, p);
+		Consume(n);
+		return n;
+	}
+
+protected:
+	void Shift() {
+		if (head == 0)
+			return;
+
+		assert(head <= capacity);
+		assert(tail <= capacity);
+		assert(tail >= head);
+
+		std::move(data + head, data + tail, data);
+
+		tail -= head;
+		head = 0;
+	}
+};
+
+#endif
diff --git a/src/util/growing_fifo.c b/src/util/growing_fifo.c
deleted file mode 100644
index 88431f60e..000000000
--- a/src/util/growing_fifo.c
+++ /dev/null
@@ -1,90 +0,0 @@
-/*
- * 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);
-}
diff --git a/src/util/growing_fifo.h b/src/util/growing_fifo.h
deleted file mode 100644
index 723c3b3ff..000000000
--- a/src/util/growing_fifo.h
+++ /dev/null
@@ -1,73 +0,0 @@
-/*
- * 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