From 1cfa33e4fb4c227c16582c6740046fb2e6263889 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Mon, 15 Aug 2011 16:24:46 +0100
Subject: [PATCH] better termination handling

setting and detecting ->kill is now treated more like a message ... you
can now cancel calculation in nip2 without breaking calculation
---
 ChangeLog               |  1 +
 libvips/iofuncs/image.c | 25 +++++++++++++++++++++----
 libvips/iofuncs/sink.c  |  5 +++++
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a48305d0..290657e3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 10/8/11 started 7.26.3
 - don't use G_VALUE_COLLECT_INIT(), many platforms do not have a glib this
   recent
+- don't leave image->kill set when we detect termination
 
 10/8/11 started 7.26.2
 - oops, im_benchmark.c had some stuff turned off
diff --git a/libvips/iofuncs/image.c b/libvips/iofuncs/image.c
index 328d2b6f..3a0aff70 100644
--- a/libvips/iofuncs/image.c
+++ b/libvips/iofuncs/image.c
@@ -1348,20 +1348,33 @@ vips_image_set_progress( VipsImage *image, gboolean progress )
 gboolean
 vips_image_get_kill( VipsImage *image )
 {
+	gboolean kill;
+
+	kill = image->kill;
+
 	/* Has kill been set for this image? If yes, abort evaluation.
 	 */
-	if( image->kill ) 
+	if( image->kill ) {
+		VIPS_DEBUG_MSG( "vips_image_get_kill: %s (%p) killed\n", 
+			image->filename, image );
 		vips_error( "VipsImage", 
 			_( "killed for image \"%s\"" ), image->filename );
 
-	return( image->kill );
+		/* We've picked up the kill message, it's now our caller's
+		 * responsibility to pass the message up the chain.
+		 */
+		vips_image_set_kill( image, FALSE );
+	}
+
+	return( kill );
 }
 
 void
 vips_image_set_kill( VipsImage *image, gboolean kill )
 {
-	if( !image->kill ) 
-		VIPS_DEBUG_MSG( "vips_image_set_kill: %s\n", image->filename );
+	if( image->kill != kill ) 
+		VIPS_DEBUG_MSG( "vips_image_set_kill: %s (%p) %d\n", 
+			image->filename, image, kill );
 
 	image->kill = kill;
 }
@@ -1880,6 +1893,10 @@ vips_image_write_line( VipsImage *image, int ypos, PEL *linebuffer )
 	/* Is this the start of eval?
 	 */
 	if( ypos == 0 ) {
+		/* Always clear kill before we start looping. See the 
+		 * call to vips_image_get_kill() below.
+		 */
+		vips_image_set_kill( image, FALSE );
 		vips__image_write_prepare( image );
 		vips_image_preeval( image );
 	}
diff --git a/libvips/iofuncs/sink.c b/libvips/iofuncs/sink.c
index 0106d8e8..81741231 100644
--- a/libvips/iofuncs/sink.c
+++ b/libvips/iofuncs/sink.c
@@ -203,6 +203,11 @@ sink_free( Sink *sink )
 void
 vips_sink_base_init( SinkBase *sink_base, VipsImage *image )
 {
+	/* Always clear kill before we start looping. See the 
+	 * call to vips_image_get_kill() below.
+	 */
+	vips_image_set_kill( image, FALSE );
+
 	sink_base->im = image;
 	sink_base->x = 0;
 	sink_base->y = 0;