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-rw-r--r--src/metadata_pipe.c151
1 files changed, 151 insertions, 0 deletions
diff --git a/src/metadata_pipe.c b/src/metadata_pipe.c
new file mode 100644
index 000000000..83c36ce1b
--- /dev/null
+++ b/src/metadata_pipe.c
@@ -0,0 +1,151 @@
+/* the Music Player Daemon (MPD)
+ * Copyright (C) 2003-2007 by Warren Dukes (warren.dukes@gmail.com)
+ * This project's homepage is: 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 "metadata_pipe.h"
+#include "ringbuf.h"
+#include "decode.h"
+#include "os_compat.h"
+#include "log.h"
+#include "outputBuffer.h"
+#include "gcc.h"
+
+static struct ringbuf *mp;
+
+/* Each one of these is a packet inside the metadata pipe */
+struct tag_container {
+ float metadata_time;
+ uint8_t seq; /* ob.seq_decoder at time of metadata_pipe_send() */
+ struct mpd_tag *tag; /* our payload */
+};
+
+/*
+ * We have two readers even though ringbuf was designed for one (locklessly),
+ * so we will use a lock to allow readers to safely read. Writing is only
+ * done from one thread, so it will never block or clobber.
+ */
+static pthread_mutex_t read_lock = PTHREAD_MUTEX_INITIALIZER;
+static struct mpd_tag *current_tag; /* requires read_lock for both r/w access */
+
+static void metadata_pipe_finish(void)
+{
+ ringbuf_free(mp);
+ if (current_tag)
+ tag_free(current_tag);
+}
+
+void init_metadata_pipe(void)
+{
+ mp = ringbuf_create(sizeof(struct tag_container) * 16);
+ atexit(metadata_pipe_finish);
+}
+
+void metadata_pipe_send(struct mpd_tag *tag, float metadata_time)
+{
+ struct tag_container tc;
+ size_t written;
+
+ assert(pthread_equal(pthread_self(), dc.thread));
+
+ if (mpd_unlikely(ringbuf_write_space(mp)
+ < sizeof(struct tag_container))) {
+ DEBUG("metadata_pipe: insufficient buffer space, dropping\n");
+ tag_free(tag);
+ return;
+ }
+
+ tc.tag = tag;
+ tc.metadata_time = metadata_time;
+ tc.seq = ob_get_decoder_sequence();
+ written = ringbuf_write(mp, &tc, sizeof(struct tag_container));
+ assert(written == sizeof(struct tag_container));
+}
+
+struct mpd_tag * metadata_pipe_recv(void)
+{
+ struct tag_container tc;
+ size_t r;
+ static const size_t uint8_t_max = 255; /* XXX CLEANUP */
+ uint8_t expect_seq = ob_get_player_sequence();
+ unsigned long current_time = ob_get_elapsed_time();
+ struct mpd_tag *tag = NULL;
+
+ if (pthread_mutex_trylock(&read_lock) == EBUSY)
+ return NULL;
+retry:
+ if (!(r = ringbuf_peek(mp, &tc, sizeof(struct tag_container))))
+ goto out;
+
+ assert(r == sizeof(struct tag_container));
+ assert(tc.tag);
+ if (expect_seq == tc.seq) {
+ if (current_time < tc.metadata_time)
+ goto out; /* not ready for tag yet */
+ if (tag_equal(tc.tag, current_tag)) {
+ tag_free(tc.tag);
+ ringbuf_read_advance(mp, sizeof(struct tag_container));
+ goto out; /* nothing changed, don't bother */
+ }
+ tag = tag_dup(tc.tag);
+ if (current_tag)
+ tag_free(current_tag);
+ current_tag = tc.tag;
+ ringbuf_read_advance(mp, sizeof(struct tag_container));
+ } else if (expect_seq > tc.seq ||
+ (!expect_seq && tc.seq == uint8_t_max)) {
+ DEBUG("metadata_pipe: reader is ahead of writer\n");
+ tag_free(tc.tag);
+ ringbuf_read_advance(mp, sizeof(struct tag_container));
+ goto retry; /* read and skip packets */
+ } /* else not ready for tag yet */
+out:
+ pthread_mutex_unlock(&read_lock);
+ return tag;
+}
+
+struct mpd_tag *metadata_pipe_current(void)
+{
+ struct mpd_tag *tag;
+
+ assert(! pthread_equal(pthread_self(), dc.thread));
+ if (pthread_mutex_trylock(&read_lock) == EBUSY)
+ return NULL;
+ tag = current_tag ? tag_dup(current_tag) : NULL;
+ pthread_mutex_unlock(&read_lock);
+
+ return tag;
+}
+
+void metadata_pipe_clear(void)
+{
+ struct tag_container tc;
+ size_t r;
+
+ pthread_mutex_lock(&read_lock);
+
+ while ((r = ringbuf_read(mp, &tc, sizeof(struct tag_container)))) {
+ assert(r == sizeof(struct tag_container));
+ tag_free(tc.tag);
+ }
+
+ if (current_tag) {
+ tag_free(current_tag);
+ current_tag = NULL;
+ }
+
+ pthread_mutex_unlock(&read_lock);
+}