pipe: added music_buffer, rewrite music_pipe

Turn the music_pipe into a simple music_chunk queue.  The music_chunk
allocation code is moved to music_buffer, and is now managed with a
linked list instead of a ring buffer.  Two separate music_pipe objects
are used by the decoder for the "current" and the "next" song, which
greatly simplifies the cross-fading code.

5 files changed, 52 insertions, 45 deletions

diff --git a/src/decoder_api.c b/src/decoder_api.c
index 88864befa..0992eac9a 100644
--- a/src/decoder_api.c
+++ b/src/decoder_api.c
@@ -23,6 +23,7 @@
 #include "player_control.h"
 #include "audio.h"
 #include "song.h"
+#include "buffer.h"
 
 #include "normalize.h"
 #include "pipe.h"
@@ -90,11 +91,11 @@ void decoder_command_finished(G_GNUC_UNUSED struct decoder * decoder)
 		/* delete frames from the old song position */
 
 		if (decoder->chunk != NULL) {
-			music_pipe_cancel(decoder->chunk);
+			music_buffer_return(dc.buffer, decoder->chunk);
 			decoder->chunk = NULL;
 		}
 
-		music_pipe_clear();
+		music_pipe_clear(dc.pipe, dc.buffer);
 	}
 
 	dc.command = DECODE_COMMAND_NONE;
@@ -167,15 +168,18 @@ do_send_tag(struct decoder *decoder, struct input_stream *is,
 	if (decoder->chunk != NULL) {
 		/* there is a partial chunk - flush it, we want the
 		   tag in a new chunk */
-		enum decoder_command cmd =
-			decoder_flush_chunk(decoder, is);
-		if (cmd != DECODE_COMMAND_NONE)
-			return cmd;
+		decoder_flush_chunk(decoder);
+		notify_signal(&pc.notify);
 	}
 
 	assert(decoder->chunk == NULL);
 
-	chunk = decoder_get_chunk(decoder);
+	chunk = decoder_get_chunk(decoder, is);
+	if (chunk == NULL) {
+		assert(dc.command != DECODE_COMMAND_NONE);
+		return dc.command;
+	}
+
 	chunk->tag = tag_dup(tag);
 	return DECODE_COMMAND_NONE;
 }
@@ -256,15 +260,18 @@ decoder_data(struct decoder *decoder,
 		size_t nbytes;
 		bool full;
 
-		chunk = decoder_get_chunk(decoder);
+		chunk = decoder_get_chunk(decoder, is);
+		if (chunk == NULL) {
+			assert(dc.command != DECODE_COMMAND_NONE);
+			return dc.command;
+		}
+
 		dest = music_chunk_write(chunk, &dc.out_audio_format,
 					 data_time, bitRate, &nbytes);
 		if (dest == NULL) {
 			/* the chunk is full, flush it */
-			enum decoder_command cmd =
-				decoder_flush_chunk(decoder, is);
-			if (cmd != DECODE_COMMAND_NONE)
-				return cmd;
+			decoder_flush_chunk(decoder);
+			notify_signal(&pc.notify);
 			continue;
 		}
 
@@ -291,10 +298,8 @@ decoder_data(struct decoder *decoder,
 		full = music_chunk_expand(chunk, &dc.out_audio_format, nbytes);
 		if (full) {
 			/* the chunk is full, flush it */
-			enum decoder_command cmd =
-				decoder_flush_chunk(decoder, is);
-			if (cmd != DECODE_COMMAND_NONE)
-				return cmd;
+			decoder_flush_chunk(decoder);
+			notify_signal(&pc.notify);
 		}
 
 		data += nbytes;
diff --git a/src/decoder_control.h b/src/decoder_control.h
index d1d0625e1..f981074d4 100644
--- a/src/decoder_control.h
+++ b/src/decoder_control.h
@@ -66,6 +66,12 @@ struct decoder_control {
 	struct song *current_song;
 	struct song *next_song;
 	float total_time;
+
+	/** the #music_chunk allocator */
+	struct music_buffer *buffer;
+
+	/** the destination pipe for decoded chunks */
+	struct music_pipe *pipe;
 };
 
 extern struct decoder_control dc;
diff --git a/src/decoder_internal.c b/src/decoder_internal.c
index 93ad80e5e..120115ed2 100644
--- a/src/decoder_internal.c
+++ b/src/decoder_internal.c
@@ -21,6 +21,7 @@
 #include "player_control.h"
 #include "pipe.h"
 #include "input_stream.h"
+#include "buffer.h"
 
 #include <assert.h>
 
@@ -46,35 +47,32 @@ need_chunks(struct input_stream *is, bool do_wait)
 }
 
 struct music_chunk *
-decoder_get_chunk(struct decoder *decoder)
+decoder_get_chunk(struct decoder *decoder, struct input_stream *is)
 {
+	enum decoder_command cmd;
+
 	assert(decoder != NULL);
 
 	if (decoder->chunk != NULL)
 		return decoder->chunk;
 
-	decoder->chunk = music_pipe_allocate();
-	return decoder->chunk;
+	do {
+		decoder->chunk = music_buffer_allocate(dc.buffer);
+		if (decoder->chunk != NULL)
+			return decoder->chunk;
+
+		cmd = need_chunks(is, true);
+	} while (cmd == DECODE_COMMAND_NONE);
+
+	return NULL;
 }
 
-enum decoder_command
-decoder_flush_chunk(struct decoder *decoder, struct input_stream *is)
+void
+decoder_flush_chunk(struct decoder *decoder)
 {
-	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;
-	}
+	music_pipe_push(dc.pipe, decoder->chunk);
+	decoder->chunk = NULL;
 }
diff --git a/src/decoder_internal.h b/src/decoder_internal.h
index ab52ab037..cf46eb2c9 100644
--- a/src/decoder_internal.h
+++ b/src/decoder_internal.h
@@ -42,17 +42,16 @@ struct decoder {
 /**
  * Returns the current chunk the decoder writes to, or allocates a new
  * chunk if there is none.
+ *
+ * @return the chunk, or NULL if we have received a decoder command
  */
 struct music_chunk *
-decoder_get_chunk(struct decoder *decoder);
+decoder_get_chunk(struct decoder *decoder, struct input_stream *is);
 
 /**
- * Flushes a chunk.  Waits for room in the music pipe if required.
- *
- * @return DECODE_COMMAND_NONE on success, any other command if we
- * have received a decoder command while waiting
+ * Flushes the current chunk.
  */
-enum decoder_command
-decoder_flush_chunk(struct decoder *decoder, struct input_stream *is);
+void
+decoder_flush_chunk(struct decoder *decoder);
 
 #endif
diff --git a/src/decoder_thread.c b/src/decoder_thread.c
index 97e92d295..a48f4160b 100644
--- a/src/decoder_thread.c
+++ b/src/decoder_thread.c
@@ -196,9 +196,8 @@ static void decoder_run_song(const struct song *song, const char *uri)
 	pcm_convert_deinit(&decoder.conv_state);
 
 	/* flush the last chunk */
-	if (decoder.chunk != NULL &&
-	    decoder_flush_chunk(&decoder, NULL) != DECODE_COMMAND_NONE)
-		music_pipe_cancel(decoder.chunk);
+	if (decoder.chunk != NULL)
+		decoder_flush_chunk(&decoder);
 
 	if (close_instream)
 		input_stream_close(&input_stream);