fix window cycling

we were repeatedly free-ing and new-ing input mmap windows ... this made
things like zoom out on large images in nip2 much slower than they
needed to be

ChangeLog

@@ -1,3 +1,6 @@
+10/12/17 started 8.6.1
+- stop window new/free cycling .. faster zoom out on large images in nip2
+
 15/4/17 started 8.6.0
 - supports fits images with leading non-image HDUs, thanks benepo
 - add vips_image_new_from_image() and vips_image_new_from_image1() ... make a

configure.ac

@@ -2,7 +2,7 @@
 
 # also update the version number in the m4 macros below
 
-AC_INIT([vips], [8.6.0], [vipsip@jiscmail.ac.uk])
+AC_INIT([vips], [8.6.1], [vipsip@jiscmail.ac.uk])
 # required for gobject-introspection
 AC_PREREQ(2.62)
 
@@ -18,7 +18,7 @@ AC_CONFIG_MACRO_DIR([m4])
 # user-visible library versioning
 m4_define([vips_major_version], [8])
 m4_define([vips_minor_version], [6])
-m4_define([vips_micro_version], [0])
+m4_define([vips_micro_version], [1])
 m4_define([vips_version],
           [vips_major_version.vips_minor_version.vips_micro_version])
 
@@ -38,7 +38,7 @@ VIPS_VERSION_STRING=$VIPS_VERSION-`date`
 #   binary interface changes not backwards compatible?: reset age to 0
 
 LIBRARY_CURRENT=50
-LIBRARY_REVISION=0
+LIBRARY_REVISION=1
 LIBRARY_AGE=8
 
 # patched into include/vips/version.h

libvips/include/vips/private.h

@@ -73,7 +73,8 @@ typedef struct {
 
 /* window manager.
  */
-VipsWindow *vips_window_ref( struct _VipsImage *im, int top, int height );
+VipsWindow *vips_window_ref( VipsWindow *window, 
+	struct _VipsImage *im, int top, int height );
 int vips_window_unref( VipsWindow *window );
 void vips_window_print( VipsWindow *window );
 

libvips/iofuncs/region.c

@@ -652,23 +652,21 @@ vips_region_image( VipsRegion *reg, const VipsRect *r )
 	all.height = image->Ysize;
 	vips_rect_intersectrect( r, &all, &clipped );
 
-	/* Test for empty.
-	 */
 	if( vips_rect_isempty( &clipped ) ) {
 		vips_error( "VipsRegion", 
 			"%s", _( "valid clipped to nothing" ) );
 		return( -1 );
 	}
 
-	VIPS_FREEF( vips_buffer_unref, reg->buffer );
-	VIPS_FREEF( vips_window_unref, reg->window );
 	reg->invalid = FALSE;
 
 	if( image->data ) {
 		/* We have the whole image available ... easy!
 		 */
+		VIPS_FREEF( vips_buffer_unref, reg->buffer );
+		VIPS_FREEF( vips_window_unref, reg->window );
 
-		/* We can't just set valid = clipped, since this may be an
+		/* We can't just set valid = whole image, since this may be an
 		 * incompletely calculated memory buffer. Just set valid to r.
 		 */
 		reg->valid = clipped;
@@ -677,20 +675,15 @@ vips_region_image( VipsRegion *reg, const VipsRect *r )
 		reg->type = VIPS_REGION_OTHER_IMAGE;
 	}
 	else if( image->dtype == VIPS_IMAGE_OPENIN ) {
+		VIPS_FREEF( vips_buffer_unref, reg->buffer );
+
 		/* No complete image data ... but we can use a rolling window.
 		 */
-		if( reg->type != VIPS_REGION_WINDOW || 
+		reg->type = VIPS_REGION_WINDOW;
-			!reg->window ||
+		if( !(reg->window = vips_window_ref( reg->window, image, 
-			reg->window->top > clipped.top ||
-			reg->window->top + reg->window->height < 
-				clipped.top + clipped.height ) {
-			if( !(reg->window = vips_window_ref( image, 
 			clipped.top, clipped.height )) )
 			return( -1 );
 
-			reg->type = VIPS_REGION_WINDOW;
-		}
-
 		/* Note the area the window actually represents.
 		 */
 		reg->valid.left = 0;
@@ -701,6 +694,9 @@ vips_region_image( VipsRegion *reg, const VipsRect *r )
 		reg->data = reg->window->data;
 	}
 	else {
+		VIPS_FREEF( vips_buffer_unref, reg->buffer );
+		VIPS_FREEF( vips_window_unref, reg->window );
+
 		vips_error( "VipsRegion", "%s", _( "bad image type" ) );
 		return( -1 );
 	}

libvips/iofuncs/window.c

@@ -53,7 +53,6 @@
 #ifdef HAVE_SYS_MMAN_H
 #include <sys/mman.h>
 #endif
-#include <assert.h>
 
 #include <vips/vips.h>
 #include <vips/internal.h>
@@ -96,7 +95,7 @@ vips_window_unmap( VipsWindow *window )
 #ifdef DEBUG_TOTAL
 		g_mutex_lock( vips__global_lock );
 		total_mmap_usage -= window->length;
-		assert( total_mmap_usage >= 0 );
+		g_assert( total_mmap_usage >= 0 );
 		g_mutex_unlock( vips__global_lock );
 #endif /*DEBUG_TOTAL*/
 
@@ -111,13 +110,20 @@ vips_window_unmap( VipsWindow *window )
 static int
 vips_window_free( VipsWindow *window )
 {
-	assert( window->ref_count == 0 );
+	VipsImage *im = window->im;
+
+	g_assert( window->ref_count == 0 );
 
 #ifdef DEBUG
 	printf( "** vips_window_free: window top = %d, height = %d (%p)\n",
 		window->top, window->height, window );
+	printf( "vips_window_unref: %d windows left\n",
+		g_slist_length( im->windows ) );
 #endif /*DEBUG*/
 
+	g_assert( g_slist_find( im->windows, window ) );
+	im->windows = g_slist_remove( im->windows, window );
+
 	if( vips_window_unmap( window ) )
 		return( -1 );
 
@@ -140,19 +146,11 @@ vips_window_unref( VipsWindow *window )
 		window->top, window->height, window->ref_count );
 #endif /*DEBUG*/
 
-	assert( window->ref_count > 0 );
+	g_assert( window->ref_count > 0 );
 
 	window->ref_count -= 1;
 
 	if( window->ref_count == 0 ) {
-		assert( g_slist_find( im->windows, window ) );
-		im->windows = g_slist_remove( im->windows, window );
-
-#ifdef DEBUG
-		printf( "vips_window_unref: %d windows left\n",
-			g_slist_length( im->windows ) );
-#endif /*DEBUG*/
-
 		if( vips_window_free( window ) ) {
 			g_mutex_unlock( im->sslock );
 			return( -1 );
@@ -276,22 +274,20 @@ vips_window_new( VipsImage *im, int top, int height )
 	if( !(window = VIPS_NEW( NULL, VipsWindow )) )
 		return( NULL );
 
-	window->ref_count = 0;
+	window->ref_count = 1;
 	window->im = im;
 	window->top = 0;
 	window->height = 0;
 	window->data = NULL;
 	window->baseaddr = NULL;
 	window->length = 0;
+	im->windows = g_slist_prepend( im->windows, window );
 
 	if( vips_window_set( window, top, height ) ) {
 		vips_window_free( window );
 		return( NULL );
 	}
 
-	im->windows = g_slist_prepend( im->windows, window );
-	window->ref_count += 1;
-
 #ifdef DEBUG
 	printf( "** vips_window_new: window top = %d, height = %d (%p)\n",
 		window->top, window->height, window );
@@ -343,27 +339,59 @@ vips_window_find( VipsImage *im, int top, int height )
 	return( window );
 }
 
-/* Return a ref to a window that encloses top/height.
+/* Update a ref to a window to make it enclose top/height.
  */
 VipsWindow *
-vips_window_ref( VipsImage *im, int top, int height )
+vips_window_ref( VipsWindow *window, VipsImage *im, int top, int height )
 {
-	VipsWindow *window;
+	int margin;
+
+	/* We have a window and it has the pixels we need.
+	 */
+	if( window &&
+		window->top <= top &&
+		window->top + window->height >= top + height ) 
+		return( window );
 
 	g_mutex_lock( im->sslock );
 
-	if( !(window = vips_window_find( im, top, height )) ) {
+	/* We have a window and we are the only ref to it ... scroll.
-		/* No existing window ... make a new one. Ask for a larger
-		 * window than we strictly need. There's no point making tiny
-		 * windows.
 	 */
-		int margin = VIPS_MIN( vips__window_margin_pixels,
+	if( window &&
-			vips__window_margin_bytes / 
+		window->ref_count == 1 ) {
-				VIPS_IMAGE_SIZEOF_LINE( im ) );
+		if( vips_window_set( window, top, height ) ) {
+			g_mutex_unlock( im->sslock );
+			vips_window_unref( window );
 
+			return( NULL );
+		}
+
+		g_mutex_unlock( im->sslock );
+
+		return( window );
+	}
+
+	/* There's more than one ref to the window. We can just decrement.
+	 * Don't call _unref, since we've inside the lock.
+	 */
+	if( window ) 
+		window->ref_count -= 1;
+
+	/* Is there an existing window we can reuse?
+	 */
+	if( (window = vips_window_find( im, top, height )) ) {
+		g_mutex_unlock( im->sslock );
+
+		return( window );
+	}
+
+	/* We have to make a new window. Make it a bit bigger than strictly 
+	 * necessary.
+	 */
+	margin = VIPS_MIN( vips__window_margin_pixels,
+		vips__window_margin_bytes / VIPS_IMAGE_SIZEOF_LINE( im ) );
 	top -= margin;
 	height += margin * 2;
-
 	top = VIPS_CLIP( 0, top, im->Ysize - 1 );
 	height = VIPS_CLIP( 0, height, im->Ysize - top );
 
@@ -371,7 +399,6 @@ vips_window_ref( VipsImage *im, int top, int height )
 		g_mutex_unlock( im->sslock );
 		return( NULL );
 	}
-	}
 
 	g_mutex_unlock( im->sslock );