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Diffstat (limited to '')
| -rw-r--r-- | src/metadata_pipe.c | 151 |
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); +} |