Client: move output buffer code to new class PeakBuffer

2 files changed, 209 insertions, 0 deletions

diff --git a/src/util/PeakBuffer.cxx b/src/util/PeakBuffer.cxx
new file mode 100644
index 000000000..a3659b8f4
--- /dev/null
+++ b/src/util/PeakBuffer.cxx
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2003-2013 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.
+ */
+
+#include "PeakBuffer.hxx"
+#include "HugeAllocator.hxx"
+#include "fifo_buffer.h"
+
+#include <algorithm>
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+
+PeakBuffer::~PeakBuffer()
+{
+	if (normal_buffer != nullptr)
+		fifo_buffer_free(normal_buffer);
+
+	if (peak_buffer != nullptr)
+		HugeFree(peak_buffer, peak_size);
+}
+
+bool
+PeakBuffer::IsEmpty() const
+{
+	return (normal_buffer == nullptr ||
+		fifo_buffer_is_empty(normal_buffer)) &&
+		(peak_buffer == nullptr ||
+		 fifo_buffer_is_empty(peak_buffer));
+}
+
+const void *
+PeakBuffer::Read(size_t *length_r) const
+{
+	if (normal_buffer != nullptr) {
+		const void *p = fifo_buffer_read(normal_buffer, length_r);
+		if (p != nullptr)
+			return p;
+	}
+
+	if (peak_buffer != nullptr) {
+		const void *p = fifo_buffer_read(peak_buffer, length_r);
+		if (p != nullptr)
+			return p;
+	}
+
+	return nullptr;
+}
+
+void
+PeakBuffer::Consume(size_t length)
+{
+	if (normal_buffer != nullptr && !fifo_buffer_is_empty(normal_buffer)) {
+		fifo_buffer_consume(normal_buffer, length);
+		return;
+	}
+
+	if (peak_buffer != nullptr && !fifo_buffer_is_empty(peak_buffer)) {
+		fifo_buffer_consume(peak_buffer, length);
+		if (fifo_buffer_is_empty(peak_buffer)) {
+			HugeFree(peak_buffer, peak_size);
+			peak_buffer = nullptr;
+		}
+
+		return;
+	}
+}
+
+static size_t
+AppendTo(fifo_buffer *buffer, const void *data, size_t length)
+{
+	assert(data != nullptr);
+	assert(length > 0);
+
+	size_t total = 0;
+
+	do {
+		size_t max_length;
+		void *p = fifo_buffer_write(buffer, &max_length);
+		if (p == nullptr)
+			break;
+
+		const size_t nbytes = std::min(length, max_length);
+		memcpy(p, data, nbytes);
+		fifo_buffer_append(buffer, nbytes);
+
+		data = (const uint8_t *)data + nbytes;
+		length -= nbytes;
+		total += nbytes;
+	} while (length > 0);
+
+	return total;
+}
+
+bool
+PeakBuffer::Append(const void *data, size_t length)
+{
+	if (length == 0)
+		return true;
+
+	if (peak_buffer != nullptr && !fifo_buffer_is_empty(peak_buffer)) {
+		size_t nbytes = AppendTo(peak_buffer, data, length);
+		return nbytes == length;
+	}
+
+	if (normal_buffer == nullptr)
+		normal_buffer = fifo_buffer_new(normal_size);
+
+	size_t nbytes = AppendTo(normal_buffer, data, length);
+	if (nbytes > 0) {
+		data = (const uint8_t *)data + nbytes;
+		length -= nbytes;
+		if (length == 0)
+			return true;
+	}
+
+	if (peak_buffer == nullptr && peak_size > 0) {
+		peak_buffer = (fifo_buffer *)HugeAllocate(peak_size);
+		if (peak_buffer == nullptr)
+			return false;
+
+		fifo_buffer_init(peak_buffer, peak_size);
+	}
+
+	nbytes = AppendTo(peak_buffer, data, length);
+	return nbytes == length;
+}
diff --git a/src/util/PeakBuffer.hxx b/src/util/PeakBuffer.hxx
new file mode 100644
index 000000000..0fbba8d77
--- /dev/null
+++ b/src/util/PeakBuffer.hxx
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2003-2013 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_PEAK_BUFFER_HXX
+#define MPD_PEAK_BUFFER_HXX
+
+#include "gcc.h"
+
+#include <stddef.h>
+
+struct fifo_buffer;
+
+/**
+ * A FIFO-like buffer that will allocate more memory on demand to
+ * allow large peaks.  This second buffer will be given back to the
+ * kernel when it has been consumed.
+ */
+class PeakBuffer {
+	size_t normal_size, peak_size;
+
+	fifo_buffer *normal_buffer, *peak_buffer;
+
+public:
+	PeakBuffer(size_t _normal_size, size_t _peak_size)
+		:normal_size(_normal_size), peak_size(_peak_size),
+		 normal_buffer(nullptr), peak_buffer(nullptr) {}
+
+	PeakBuffer(PeakBuffer &&other)
+		:normal_size(other.normal_size), peak_size(other.peak_size),
+		 normal_buffer(other.normal_buffer),
+		 peak_buffer(other.peak_buffer) {
+		other.normal_buffer = nullptr;
+		other.peak_buffer = nullptr;
+	}
+
+	~PeakBuffer();
+
+	PeakBuffer(const PeakBuffer &) = delete;
+	PeakBuffer &operator=(const PeakBuffer &) = delete;
+
+	gcc_pure
+	bool IsEmpty() const;
+
+	const void *Read(size_t *length_r) const;
+	void Consume(size_t length);
+
+	bool Append(const void *data, size_t length);
+};
+
+#endif