util/FifoBuffer: C++ version of the fifo_buffer library

Makefile.am

@@ -256,6 +256,8 @@ libutil_a_SOURCES = \
 	src/util/Manual.hxx \
 	src/util/RefCount.hxx \
 	src/util/fifo_buffer.c src/util/fifo_buffer.h \
+	src/util/FifoBuffer.hxx \
+	src/util/WritableBuffer.hxx \
 	src/util/growing_fifo.c src/util/growing_fifo.h \
 	src/util/LazyRandomEngine.cxx src/util/LazyRandomEngine.hxx \
 	src/util/SliceBuffer.hxx \

src/InotifySource.cxx

@@ -20,7 +20,6 @@
 #include "config.h"
 #include "InotifySource.hxx"
 #include "InotifyDomain.hxx"
-#include "util/fifo_buffer.h"
 #include "util/Error.hxx"
 #include "system/fd_util.h"
 #include "system/FatalError.hxx"
@@ -34,30 +33,27 @@
 bool
 InotifySource::OnSocketReady(gcc_unused unsigned flags)
 {
-	void *dest;
-	size_t length;
-	ssize_t nbytes;
-
-	dest = fifo_buffer_write(buffer, &length);
-	if (dest == NULL)
+	const auto dest = buffer.Write();
+	if (dest.IsEmpty())
 		FatalError("buffer full");
 
-	nbytes = read(Get(), dest, length);
+	ssize_t nbytes = read(Get(), dest.data, dest.size);
 	if (nbytes < 0)
 		FatalSystemError("Failed to read from inotify");
 	if (nbytes == 0)
 		FatalError("end of file from inotify");
 
-	fifo_buffer_append(buffer, nbytes);
+	buffer.Append(nbytes);
 
 	while (true) {
 		const char *name;
 
+		auto range = buffer.Read();
 		const struct inotify_event *event =
 			(const struct inotify_event *)
-			fifo_buffer_read(buffer, &length);
-		if (event == NULL || length < sizeof(*event) ||
-		    length < sizeof(*event) + event->len)
+			range.data;
+		if (range.size < sizeof(*event) ||
+		    range.size < sizeof(*event) + event->len)
 			break;
 
 		if (event->len > 0 && event->name[event->len - 1] == 0)
@@ -66,7 +62,7 @@ InotifySource::OnSocketReady(gcc_unused unsigned flags)
 			name = NULL;
 
 		callback(event->wd, event->mask, name, callback_ctx);
-		fifo_buffer_consume(buffer, sizeof(*event) + event->len);
+		buffer.Consume(sizeof(*event) + event->len);
 	}
 
 	return true;
@@ -77,8 +73,7 @@ InotifySource::InotifySource(EventLoop &_loop,
 			     mpd_inotify_callback_t _callback, void *_ctx,
 			     int _fd)
 	:SocketMonitor(_fd, _loop),
-	 callback(_callback), callback_ctx(_ctx),
-	 buffer(fifo_buffer_new(4096))
+	 callback(_callback), callback_ctx(_ctx)
 {
 	ScheduleRead();
 
@@ -98,11 +93,6 @@ InotifySource::Create(EventLoop &loop,
 	return new InotifySource(loop, callback, callback_ctx, fd);
 }
 
-InotifySource::~InotifySource()
-{
-	fifo_buffer_free(buffer);
-}
-
 int
 InotifySource::Add(const char *path_fs, unsigned mask, Error &error)
 {

src/InotifySource.hxx

@@ -21,6 +21,7 @@
 #define MPD_INOTIFY_SOURCE_HXX
 
 #include "event/SocketMonitor.hxx"
+#include "util/FifoBuffer.hxx"
 #include "Compiler.h"
 
 class Error;
@@ -32,7 +33,7 @@ class InotifySource final : private SocketMonitor {
 	mpd_inotify_callback_t callback;
 	void *callback_ctx;
 
-	struct fifo_buffer *buffer;
+	FifoBuffer<uint8_t, 4096> buffer;
 
 	InotifySource(EventLoop &_loop,
 		      mpd_inotify_callback_t callback, void *ctx, int fd);
@@ -49,9 +50,6 @@ public:
 				     void *ctx,
 				     Error &error);
 
-	~InotifySource();
-
-
 	/**
 	 * Adds a path to the notify list.
 	 *

src/TextInputStream.cxx

@@ -29,35 +29,23 @@
 #include <assert.h>
 #include <string.h>
 
-TextInputStream::TextInputStream(struct input_stream *_is)
-	: is(_is),
-	  buffer(fifo_buffer_new(4096))
-{
-}
-
-TextInputStream::~TextInputStream()
-{
-	fifo_buffer_free(buffer);
-}
-
 bool TextInputStream::ReadLine(std::string &line)
 {
-	void *dest;
 	const char *src, *p;
-	size_t length, nbytes;
 
 	do {
-		dest = fifo_buffer_write(buffer, &length);
-		if (dest != nullptr && length >= 2) {
+		size_t nbytes;
+		auto dest = buffer.Write();
+		if (dest.size >= 2) {
 			/* reserve one byte for the null terminator if
 			   the last line is not terminated by a
 			   newline character */
-			--length;
+			--dest.size;
 
 			Error error;
-			nbytes = is->LockRead(dest, length, error);
+			nbytes = is->LockRead(dest.data, dest.size, error);
 			if (nbytes > 0)
-				fifo_buffer_append(buffer, nbytes);
+				buffer.Append(nbytes);
 			else if (error.IsDefined()) {
 				LogError(error);
 				return false;
@@ -65,28 +53,28 @@ bool TextInputStream::ReadLine(std::string &line)
 		} else
 			nbytes = 0;
 
-		auto src_p = fifo_buffer_read(buffer, &length);
-		src = reinterpret_cast<const char *>(src_p);
-
-		if (src == nullptr)
+		auto src_p = buffer.Read();
+		if (src_p.IsEmpty())
 			return false;
 
-		p = reinterpret_cast<const char*>(memchr(src, '\n', length));
+		src = src_p.data;
+
+		p = reinterpret_cast<const char*>(memchr(src, '\n', src_p.size));
 		if (p == nullptr && nbytes == 0) {
 			/* end of file (or line too long): terminate
 			   the current line */
-			dest = fifo_buffer_write(buffer, &nbytes);
-			assert(dest != nullptr);
-			*(char *)dest = '\n';
-			fifo_buffer_append(buffer, 1);
+			dest = buffer.Write();
+			assert(!dest.IsEmpty());
+			dest.data[0] = '\n';
+			buffer.Append(1);
 		}
 	} while (p == nullptr);
 
-	length = p - src + 1;
+	size_t length = p - src + 1;
 	while (p > src && g_ascii_isspace(p[-1]))
 		--p;
 
 	line = std::string(src, p - src);
-	fifo_buffer_consume(buffer, length);
+	buffer.Consume(length);
 	return true;
 }

src/TextInputStream.hxx

@@ -20,6 +20,8 @@
 #ifndef MPD_TEXT_INPUT_STREAM_HXX
 #define MPD_TEXT_INPUT_STREAM_HXX
 
+#include "util/FifoBuffer.hxx"
+
 #include <string>
 
 struct input_stream;
@@ -27,7 +29,8 @@ struct fifo_buffer;
 
 class TextInputStream {
 	struct input_stream *is;
-	struct fifo_buffer *buffer;
+	FifoBuffer<char, 4096> buffer;
+
 public:
 	/**
 	 * Wraps an existing #input_stream object into a #TextInputStream,
@@ -35,13 +38,8 @@ public:
 	 *
 	 * @param _is an open #input_stream object
 	 */
-	explicit TextInputStream(struct input_stream *_is);
-
-	/**
-	 * Frees the #TextInputStream object.  Does not close or free the
-	 * underlying #input_stream.
-	 */
-	~TextInputStream();
+	explicit TextInputStream(struct input_stream *_is)
+		:is(_is) {}
 
 	TextInputStream(const TextInputStream &) = delete;
 	TextInputStream& operator=(const TextInputStream &) = delete;

src/event/BufferedSocket.cxx

@@ -20,20 +20,9 @@
 #include "config.h"
 #include "BufferedSocket.hxx"
 #include "system/SocketError.hxx"
-#include "util/fifo_buffer.h"
 #include "util/Error.hxx"
 #include "util/Domain.hxx"
 
-#include <assert.h>
-#include <stdint.h>
-#include <string.h>
-
-BufferedSocket::~BufferedSocket()
-{
-	if (input != nullptr)
-		fifo_buffer_free(input);
-}
-
 BufferedSocket::ssize_t
 BufferedSocket::DirectRead(void *data, size_t length)
 {
@@ -62,16 +51,12 @@ BufferedSocket::ReadToBuffer()
 {
 	assert(IsDefined());
 
-	if (input == nullptr)
-		input = fifo_buffer_new(8192);
-
-	size_t length;
-	void *buffer = fifo_buffer_write(input, &length);
-	assert(buffer != nullptr);
+	const auto buffer = input.Write();
+	assert(!buffer.IsEmpty());
 
-	const auto nbytes = DirectRead(buffer, length);
+	const auto nbytes = DirectRead(buffer.data, buffer.size);
 	if (nbytes > 0)
-		fifo_buffer_append(input, nbytes);
+		input.Append(nbytes);
 
 	return nbytes >= 0;
 }
@@ -81,23 +66,17 @@ BufferedSocket::ResumeInput()
 {
 	assert(IsDefined());
 
-	if (input == nullptr) {
-		ScheduleRead();
-		return true;
-	}
-
 	while (true) {
-		size_t length;
-		const void *data = fifo_buffer_read(input, &length);
-		if (data == nullptr) {
+		const auto buffer = input.Read();
+		if (buffer.IsEmpty()) {
 			ScheduleRead();
 			return true;
 		}
 
-		const auto result = OnSocketInput(data, length);
+		const auto result = OnSocketInput(buffer.data, buffer.size);
 		switch (result) {
 		case InputResult::MORE:
-			if (fifo_buffer_is_full(input)) {
+			if (input.IsFull()) {
 				// TODO
 				static constexpr Domain buffered_socket_domain("buffered_socket");
 				Error error;
@@ -123,14 +102,6 @@ BufferedSocket::ResumeInput()
 	}
 }
 
-void
-BufferedSocket::ConsumeInput(size_t nbytes)
-{
-	assert(IsDefined());
-
-	fifo_buffer_consume(input, nbytes);
-}
-
 bool
 BufferedSocket::OnSocketReady(unsigned flags)
 {
@@ -142,12 +113,12 @@ BufferedSocket::OnSocketReady(unsigned flags)
 	}
 
 	if (flags & READ) {
-		assert(input == nullptr || !fifo_buffer_is_full(input));
+		assert(!input.IsFull());
 
 		if (!ReadToBuffer() || !ResumeInput())
 			return false;
 
-		if (input == nullptr || !fifo_buffer_is_full(input))
+		if (input.IsFull())
 			ScheduleRead();
 	}
 

src/event/BufferedSocket.hxx

@@ -22,8 +22,12 @@
 
 #include "check.h"
 #include "SocketMonitor.hxx"
+#include "util/FifoBuffer.hxx"
 #include "Compiler.h"
 
+#include <assert.h>
+#include <stdint.h>
+
 struct fifo_buffer;
 class Error;
 
@@ -31,16 +35,14 @@ class Error;
  * A #SocketMonitor specialization that adds an input buffer.
  */
 class BufferedSocket : protected SocketMonitor {
-	fifo_buffer *input;
+	FifoBuffer<uint8_t, 8192> input;
 
 public:
 	BufferedSocket(int _fd, EventLoop &_loop)
-		:SocketMonitor(_fd, _loop), input(nullptr) {
+		:SocketMonitor(_fd, _loop) {
 		ScheduleRead();
 	}
 
-	~BufferedSocket();
-
 	using SocketMonitor::IsDefined;
 	using SocketMonitor::Close;
 	using SocketMonitor::Write;
@@ -67,7 +69,11 @@ protected:
 	 * does not invalidate the pointer passed to OnSocketInput()
 	 * yet.
 	 */
-	void ConsumeInput(size_t nbytes);
+	void ConsumeInput(size_t nbytes) {
+		assert(IsDefined());
+
+		input.Consume(nbytes);
+	}
 
 	enum class InputResult {
 		/**

src/util/FifoBuffer.hxx

+/*
+ * Copyright (C) 2003-2010 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>
+
+/**
+ * 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<class T, size_t size>
+class FifoBuffer {
+public:
+  typedef size_t size_type;
+
+public:
+  typedef WritableBuffer<T> Range;
+
+protected:
+  size_type head, tail;
+  T data[size];
+
+public:
+  constexpr
+  FifoBuffer():head(0), tail(0) {}
+
+protected:
+  void Shift() {
+    if (head == 0)
+      return;
+
+    assert(head <= size);
+    assert(tail <= size);
+    assert(tail >= head);
+
+    std::move(data + head, data + tail, data);
+
+    tail -= head;
+    head = 0;
+  }
+
+public:
+  void Clear() {
+    head = tail = 0;
+  }
+
+  bool IsEmpty() const {
+    return head == tail;
+  }
+
+  bool IsFull() const {
+    return head == 0 && tail == size;
+  }
+
+  /**
+   * Prepares writing.  Returns a buffer range which may be written.
+   * When you are finished, call append().
+   */
+  Range Write() {
+    Shift();
+    return Range(data + tail, size - 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 <= size);
+    assert(n <= size);
+    assert(tail + n <= size);
+
+    tail += 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 <= size);
+    assert(head <= tail);
+    assert(n <= tail);
+    assert(head + n <= tail);
+
+    head += n;
+  }
+};
+
+#endif

src/util/WritableBuffer.hxx

+/*
+ * Copyright (C) 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 WRITABLE_BUFFER_HPP
+#define WRITABLE_BUFFER_HPP
+
+#include "Compiler.h"
+
+#include <stddef.h>
+
+/**
+ * A reference to a memory area that is writable.
+ *
+ * @see ConstBuffer
+ */
+template<typename T>
+struct WritableBuffer {
+  typedef size_t size_type;
+  typedef T *pointer_type;
+  typedef const T *const_pointer_type;
+  typedef pointer_type iterator;
+  typedef const_pointer_type const_iterator;
+
+  pointer_type data;
+  size_type size;
+
+  WritableBuffer() = default;
+
+  constexpr WritableBuffer(pointer_type _data, size_type _size)
+    :data(_data), size(_size) {}
+
+  constexpr static WritableBuffer Null() {
+    return { nullptr, 0 };
+  }
+
+  constexpr bool IsNull() const {
+    return data == nullptr;
+  }
+
+  constexpr bool IsEmpty() const {
+    return size == 0;
+  }
+
+  constexpr iterator begin() const {
+    return data;
+  }
+
+  constexpr iterator end() const {
+    return data + size;
+  }
+
+  constexpr const_iterator cbegin() const {
+    return data;
+  }
+
+  constexpr const_iterator cend() const {
+    return data + size;
+  }
+};
+
+#endif

test/run_convert.cxx

@@ -28,7 +28,7 @@
 #include "AudioFormat.hxx"
 #include "pcm/PcmConvert.hxx"
 #include "ConfigGlobal.hxx"
-#include "util/fifo_buffer.h"
+#include "util/FifoBuffer.hxx"
 #include "util/Error.hxx"
 #include "stdbin.h"
 
@@ -59,8 +59,6 @@ int main(int argc, char **argv)
 {
 	AudioFormat in_audio_format, out_audio_format;
 	const void *output;
-	ssize_t nbytes;
-	size_t length;
 
 	if (argc != 3) {
 		g_printerr("Usage: run_convert IN_FORMAT OUT_FORMAT <IN >OUT\n");
@@ -92,28 +90,31 @@ int main(int argc, char **argv)
 
 	PcmConvert state;
 
-	struct fifo_buffer *buffer = fifo_buffer_new(4096);
+	FifoBuffer<uint8_t, 4096> buffer;
 
 	while (true) {
-		void *p = fifo_buffer_write(buffer, &length);
-		assert(p != NULL);
+		{
+			const auto dest = buffer.Write();
+			assert(!dest.IsEmpty());
 
-		nbytes = read(0, p, length);
-		if (nbytes <= 0)
-			break;
+			ssize_t nbytes = read(0, dest.data, dest.size);
+			if (nbytes <= 0)
+				break;
 
-		fifo_buffer_append(buffer, nbytes);
+			buffer.Append(nbytes);
+		}
 
-		const void *src = fifo_buffer_read(buffer, &length);
-		assert(src != NULL);
+		auto src = buffer.Read();
+		assert(!src.IsEmpty());
 
-		length -= length % in_frame_size;
-		if (length == 0)
+		src.size -= src.size % in_frame_size;
+		if (src.IsEmpty())
 			continue;
 
-		fifo_buffer_consume(buffer, length);
+		buffer.Consume(src.size);
 
-		output = state.Convert(in_audio_format, src, length,
+		size_t length;
+		output = state.Convert(in_audio_format, src.data, src.size,
 				       out_audio_format, &length, error);
 		if (output == NULL) {
 			g_printerr("Failed to convert: %s\n", error.GetMessage());