6 files changed, 125 insertions, 1 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index 82e46e6ee..91accd88b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -29,6 +29,7 @@ mpd_inputPlugins = \
 
 
 mpd_headers = \
+	notify.h \
 	ack.h \
 	audio.h \
 	audioOutput.h \
@@ -87,6 +88,7 @@ mpd_SOURCES = \
 	$(mpd_headers) \
 	$(mpd_audioOutputs) \
 	$(mpd_inputPlugins) \
+	notify.c \
 	audio.c \
 	audioOutput.c \
 	buffer2array.c \
diff --git a/src/decode.c b/src/decode.c
index 316cd34ba..3681e8025 100644
--- a/src/decode.c
+++ b/src/decode.c
@@ -623,6 +623,7 @@ static void decodeParent(PlayerControl * pc, DecoderControl * dc, OutputBuffer *
 				cb->begin = 0;
 			} else
 				cb->begin++;
+			signalNotify(&cb->notify);
 		} else if (cb->begin != end && cb->begin == next) {
 			if (doCrossFade == 1 && nextChunk >= 0) {
 				nextChunk = cb->begin + crossFadeChunks;
diff --git a/src/notify.c b/src/notify.c
new file mode 100644
index 000000000..85db46192
--- /dev/null
+++ b/src/notify.c
@@ -0,0 +1,70 @@
+/* the Music Player Daemon (MPD)
+ * Copyright (C) 2008 Max Kellermann <max@duempel.org>
+ * 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 "notify.h"
+
+#include <assert.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+int set_nonblock(int fd)
+{
+	int ret;
+
+	assert(fd >= 0);
+
+	ret = fcntl(fd, F_GETFL, 0);
+	if (ret < 0)
+		return ret;
+
+	return fcntl(fd, F_SETFL, ret|O_NONBLOCK);
+}
+
+int initNotify(Notify *notify)
+{
+	int ret;
+
+	ret = pipe(notify->fds);
+	if (ret < 0)
+		return -1;
+
+	ret = set_nonblock(notify->fds[1]);
+	if (ret < 0) {
+		close(notify->fds[0]);
+		close(notify->fds[1]);
+		return -1;
+	}
+
+	return 0;
+}
+
+int waitNotify(Notify *notify)
+{
+	char buffer[64];
+	ssize_t nbytes;
+
+	nbytes = read(notify->fds[0], buffer, sizeof(buffer));
+	return (int)nbytes;
+}
+
+int signalNotify(Notify *notify)
+{
+	char buffer[1] = { 0 };
+
+	return (int)write(notify->fds[1], &buffer, sizeof(buffer));
+}
diff --git a/src/notify.h b/src/notify.h
new file mode 100644
index 000000000..ce6396a96
--- /dev/null
+++ b/src/notify.h
@@ -0,0 +1,47 @@
+/* the Music Player Daemon (MPD)
+ * Copyright (C) 2008 Max Kellermann <max@duempel.org>
+ * 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
+ */
+
+#ifndef NOTIFY_H
+#define NOTIFY_H
+
+/*
+ * This library implements inter-process signalling using blocking
+ * read() on an anonymous pipe.  As a side effect, the read() system
+ * call has the same signal interruption behaviour as the old sleep
+ * function.
+ *
+ * As soon as mpd uses threading instead of fork()/shm, we can replace
+ * this library with a pthread_cond object.
+ *
+ * This code is experimental and carries a lot of overhead.  Still, it
+ * uses less resources than the old polling code with a fixed sleep
+ * time.
+ *
+ */
+
+typedef struct _Notify {
+	int fds[2];
+} Notify;
+
+int initNotify(Notify *notify);
+
+int waitNotify(Notify *notify);
+
+int signalNotify(Notify *notify);
+
+#endif
diff --git a/src/outputBuffer.c b/src/outputBuffer.c
index 25c9b3c12..cda56d4b1 100644
--- a/src/outputBuffer.c
+++ b/src/outputBuffer.c
@@ -45,6 +45,8 @@ void initOutputBuffer(OutputBuffer * cb, char *chunks)
 	    (float *)(((char *)cb->metaChunk) +
 		      buffered_chunks * sizeof(mpd_sint8));
 	cb->acceptMetadata = 0;
+
+	initNotify(&cb->notify);
 }
 
 void clearAllMetaChunkSets(OutputBuffer * cb)
@@ -131,7 +133,7 @@ int sendDataToOutputBuffer(OutputBuffer * cb, InputStream * inStream,
 				}
 				if (!inStream ||
 				    bufferInputStream(inStream) <= 0) {
-					my_usleep(10000);
+					waitNotify(&cb->notify);
 				}
 			}
 			if (dc->stop)
diff --git a/src/outputBuffer.h b/src/outputBuffer.h
index 9bd9d48c8..99d3010f0 100644
--- a/src/outputBuffer.h
+++ b/src/outputBuffer.h
@@ -26,6 +26,7 @@
 #include "inputStream.h"
 #include "metadataChunk.h"
 #include "replayGain.h"
+#include "notify.h"
 
 #define OUTPUT_BUFFER_DC_STOP   -1
 #define OUTPUT_BUFFER_DC_SEEK   -2
@@ -45,6 +46,7 @@ typedef struct _OutputBuffer {
 	mpd_sint8 metaChunkSet[BUFFERED_METACHUNKS];
 	mpd_sint8 *volatile metaChunk;
 	volatile mpd_sint8 acceptMetadata;
+	Notify notify;
 } OutputBuffer;
 
 void initOutputBuffer(OutputBuffer * cb, char *chunks);