music_pipe: added music_pipe_push()

Added music_pipe_allocate(), music_pipe_push() and
music_pipe_cancel().  Those functions allow the caller (decoder thread
in this case) to do its own chunk management.  The functions
music_pipe_flush() and music_pipe_tag() can now be removed.

src/decoder_internal.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2003-2009 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "decoder_internal.h"
+#include "decoder_control.h"
+#include "player_control.h"
+#include "pipe.h"
+#include "input_stream.h"
+
+#include <assert.h>
+
+/**
+ * All chunks are full of decoded data; wait for the player to free
+ * one.
+ */
+static enum decoder_command
+need_chunks(struct input_stream *is, bool do_wait)
+{
+	if (dc.command == DECODE_COMMAND_STOP ||
+	    dc.command == DECODE_COMMAND_SEEK)
+		return dc.command;
+
+	if ((is == NULL || input_stream_buffer(is) <= 0) && do_wait) {
+		notify_wait(&dc.notify);
+		notify_signal(&pc.notify);
+
+		return dc.command;
+	}
+
+	return DECODE_COMMAND_NONE;
+}
+
+struct music_chunk *
+decoder_get_chunk(struct decoder *decoder)
+{
+	assert(decoder != NULL);
+
+	if (decoder->chunk != NULL)
+		return decoder->chunk;
+
+	decoder->chunk = music_pipe_allocate();
+	return decoder->chunk;
+}
+
+enum decoder_command
+decoder_flush_chunk(struct decoder *decoder, struct input_stream *is)
+{
+	bool success;
+	enum decoder_command cmd;
+
+	assert(decoder != NULL);
+	assert(decoder->chunk != NULL);
+
+	while (true) {
+		success = music_pipe_push(decoder->chunk);
+		if (success) {
+			decoder->chunk = NULL;
+			return DECODE_COMMAND_NONE;
+		}
+
+		cmd = need_chunks(is, true);
+		if (cmd != DECODE_COMMAND_NONE)
+			return cmd;
+	}
+}