Merge remote-tracking branch 'origin/7.38'

ChangeLog

@@ -13,6 +13,7 @@
 
 24/2/14 started 7.38.5
 - jpeg load from buffer could write to input, thanks Lovell
+- remove support for seq mode read for operations like extract
 
 13/2/14 started 7.38.4
 - --sharpen=none option to vipsthumbnail was broken, thanks ferryfax

libvips/conversion/extract.c

@@ -193,8 +193,6 @@ vips_extract_area_class_init( VipsExtractAreaClass *class )
 	vobject_class->description = _( "extract an area from an image" );
 	vobject_class->build = vips_extract_area_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
-
 	VIPS_ARG_IMAGE( class, "input", 0, 
 		_( "Input" ), 
 		_( "Input image" ),

libvips/conversion/ifthenelse.c

@@ -470,8 +470,6 @@ vips_ifthenelse_class_init( VipsIfthenelseClass *class )
 	vobject_class->description = _( "ifthenelse an image" );
 	vobject_class->build = vips_ifthenelse_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
-
 	VIPS_ARG_IMAGE( class, "cond", -2, 
 		_( "Condition" ), 
 		_( "Condition input image" ),

libvips/conversion/insert.c

@@ -472,8 +472,6 @@ vips_insert_class_init( VipsInsertClass *class )
 	vobject_class->description = _( "insert an image" );
 	vobject_class->build = vips_insert_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
-
 	VIPS_ARG_IMAGE( class, "main", -1, 
 		_( "Main" ), 
 		_( "Main input image" ),

libvips/conversion/join.c

@@ -228,8 +228,6 @@ vips_join_class_init( VipsJoinClass *class )
 	vobject_class->description = _( "join a pair of images" );
 	vobject_class->build = vips_join_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
-
 	VIPS_ARG_IMAGE( class, "in1", -1, 
 		_( "in1" ), 
 		_( "First input image" ),

libvips/conversion/sequential.c

@@ -16,6 +16,9 @@
  * 4/9/12
  * 	- stop all threads on error
  * 	- don't stall forever, just delay ahead threads
+ * 25/2/14
+ * 	- we were allowing skipahead if the first request was for y>0, but
+ * 	  this broke on some busy, many-core systems, see comment below
  */
 
 /*
@@ -144,11 +147,9 @@ vips_sequential_generate( VipsRegion *or,
 		return( -1 );
 	}
 
-	if( r->top > sequential->y_pos /* &&
+	if( r->top > sequential->y_pos ) {
-		sequential->y_pos > 0 */ ) {
+		/* This request is for stuff beyond the current read position, 
-		/* We have started reading (y_pos > 0) and this request is for
+		 * stall for a while to give other threads time to catch up.
-		 * stuff beyond that, stall for a while to give other
-		 * threads time to catch up.
 		 * 
 		 * The stall can be cancelled by a signal on @ready.
 		 *
@@ -156,6 +157,16 @@ vips_sequential_generate( VipsRegion *or,
 		 * deadlock, and we don't fail on timeout, since the timeout 
 		 * may be harmless.
 		 */
+
+		/* We used to not stall if the read position was zero, ie. if
+		 * the first request was for a line some way down the image,
+		 * and assume this was extract or somesuch. But this could
+		 * sometimes break on busy, many-core systems.
+		 *
+		 * Think of a better way to support eg. extract safely in
+		 * sequential mode.
+		 */
+
 #ifdef HAVE_COND_INIT
 		gint64 time;