From 89527b80ebc1f58240b03a5cd86f6c48f462a728 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Sun, 8 Jul 2012 10:37:35 +0100
Subject: [PATCH] fix odd tile height + no overlap

dzsave with zero overlap and odd height was broken

also, fix cache init
---
 ChangeLog                       |  2 ++
 TODO                            |  8 ++++++++
 libvips/foreign/dzsave.c        | 19 ++++++++++++++-----
 libvips/include/vips/internal.h |  2 ++
 libvips/iofuncs/cache.c         |  6 ++----
 libvips/iofuncs/init.c          |  4 ++++
 6 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 73eb7c2d..0174a868 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -9,6 +9,8 @@
 - much more gentle sharpening in thumbnails
 - added "minimise" signal, used by tilecache to drop
 - add :seq support to im_tiff2vips(), im_jpeg2vips() ... helps ruby-vips
+- better thread safety for vips8 operation dispatch
+- better thread safety for upstream / downstream image linking
 
 18/6/12 started 7.28.9
 - slightly more memory debugging output
diff --git a/TODO b/TODO
index 80599d85..2bdba7cf 100644
--- a/TODO
+++ b/TODO
@@ -4,6 +4,14 @@
 
   have "rs" mode? ie. open for sequential read?
 
+- need a flag on operations for "is sequential"
+
+  should be on the object, not the class, since it can change with params
+
+- we probably have more threading issues :-( 
+
+  look through image and operation init and unref and see what gets called
+
 blocking bugs
 =============
 
diff --git a/libvips/foreign/dzsave.c b/libvips/foreign/dzsave.c
index bb04e6dd..5ff88742 100644
--- a/libvips/foreign/dzsave.c
+++ b/libvips/foreign/dzsave.c
@@ -168,13 +168,16 @@ pyramid_build( VipsForeignSaveDz *dz, Layer *above, int w, int h )
 
 	/* Build a line of tiles here. Normally strips are height + 2 *
 	 * overlap, but the first row is missing the top edge.
+	 *
+	 * We add one so that we will have the extra scan line for the shrink 
+	 * in case tile_height is odd and there's no overlap. 
 	 */
 	layer->y = 0;
 	layer->write_y = 0;
 	strip.left = 0;
 	strip.top = 0;
 	strip.width = w;
-	strip.height = dz->tile_height + dz->overlap;
+	strip.height = dz->tile_height + dz->overlap + 1;
 	if( vips_region_buffer( layer->strip, &strip ) ) {
 		layer_free( layer );
 		return( NULL );
@@ -506,6 +509,9 @@ strip_shrink( Layer *layer )
 		source.top = target.top * 2;
 		source.width = target.width * 2;
 		source.height = target.height * 2;
+
+		/* Of which we have these available.
+		 */
 		vips_rect_intersectrect( &source, &from->valid, &source );
 
 		/* So these are the pixels in the layer below we can provide.
@@ -515,7 +521,7 @@ strip_shrink( Layer *layer )
 		target.width = source.width / 2;
 		target.height = source.height / 2;
 
-		/* Are we empty? All done. 
+		/* None? All done.
 		 */
 		if( source.height < 2 ) 
 			break;
@@ -558,13 +564,15 @@ strip_arrived( Layer *layer )
 		strip_shrink( layer ) )
 		return( -1 );
 
-	/* Position our strip down the image. 
+	/* Position our strip down the image.  We add one to the strip height
+	 * to make sure we will have enough pixels for any shrinking even if
+	 * tile_height is odd and there's no overlap.
 	 */
 	layer->y += dz->tile_height;
 	new_strip.left = 0;
 	new_strip.top = layer->y - dz->overlap;
 	new_strip.width = layer->image->Xsize;
-	new_strip.height = dz->tile_height + 2 * dz->overlap;
+	new_strip.height = dz->tile_height + 2 * dz->overlap + 1;
 
 	/* What pixels that we will need do we already have? Save them in 
 	 * overlap.
@@ -622,7 +630,8 @@ pyramid_strip( VipsRegion *region, VipsRect *area, void *a )
 		/* And copy those pixels in.
 		 *
 		 * FIXME: If the strip fits inside the region we've just 
-		 * received, we could skip the copy. 
+		 * received, we could skip the copy. Will this happen very
+		 * often? Unclear.
 		 */
 		vips_region_copy( region, layer->strip, 
 			&target, target.left, target.top );
diff --git a/libvips/include/vips/internal.h b/libvips/include/vips/internal.h
index 118b88b9..937a60fa 100644
--- a/libvips/include/vips/internal.h
+++ b/libvips/include/vips/internal.h
@@ -83,6 +83,8 @@ extern char *vips__cache_max_files;
 extern gboolean vips__cache_dump;
 extern gboolean vips__cache_trace;
 
+void vips__cache_init( void );
+
 typedef int (*im__fftproc_fn)( VipsImage *, VipsImage *, VipsImage * );
 
 /* iofuncs
diff --git a/libvips/iofuncs/cache.c b/libvips/iofuncs/cache.c
index a4af6e61..bab52246 100644
--- a/libvips/iofuncs/cache.c
+++ b/libvips/iofuncs/cache.c
@@ -409,8 +409,8 @@ vips_operation_equal( VipsOperation *a, VipsOperation *b )
 	return( FALSE );
 }
 
-static void
-vips_cache_init( void )
+void
+vips__cache_init( void )
 {
 	if( !vips_cache_table ) {
 		vips_cache_lock = g_mutex_new();
@@ -670,8 +670,6 @@ vips_cache_operation_buildp( VipsOperation **operation )
 	vips_object_print_dump( VIPS_OBJECT( *operation ) );
 #endif /*VIPS_DEBUG*/
 
-	vips_cache_init();
-
 	vips_cache_trim();
 
 	g_mutex_lock( vips_cache_lock );
diff --git a/libvips/iofuncs/init.c b/libvips/iofuncs/init.c
index c4e5d5af..e4961237 100644
--- a/libvips/iofuncs/init.c
+++ b/libvips/iofuncs/init.c
@@ -227,6 +227,10 @@ vips_init( const char *argv0 )
 	vips__interpolate_init();
 	im__format_init();
 
+	/* Start up operator cache.
+	 */
+	vips__cache_init();
+
 	/* Start up packages.
 	 */
 	vips_arithmetic_operation_init();