argh reapply seq removal

TODO

@@ -1,14 +1,6 @@
- 
+- check initial cache sizing in vips_line_cache_build
-- VIPS_META_SEQUENTIAL will be saved to vips files, then loaded back again argh
 
-  we need to set a value that can't be saved
+  what about dynamic cache sizing?
-
-  maybe a NULL boxed pointer?
-
-  looks like vips_image_set_area(im, "poop", NULL, NULL); might work
-
-- do we need a seq cache for reducev as well? we could have up to a 3x
-  reduction there
 
 
 

libvips/arithmetic/arithmetic.c

@@ -633,7 +633,7 @@ vips_arithmetic_class_init( VipsArithmeticClass *class )
 	vobject_class->description = _( "arithmetic operations" );
 	vobject_class->build = vips_arithmetic_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "out", 100, 
 		_( "Output" ), 

libvips/arithmetic/statistic.c

@@ -161,7 +161,7 @@ vips_statistic_class_init( VipsStatisticClass *class )
 	vobject_class->description = _( "VIPS statistic operations" );
 	vobject_class->build = vips_statistic_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 0, 
 		_( "Input" ), 

libvips/colour/colour.c

@@ -421,7 +421,7 @@ vips_colour_class_init( VipsColourClass *class )
 	vobject_class->description = _( "color operations" );
 	vobject_class->build = vips_colour_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "out", 100, 
 		_( "Output" ), 

libvips/colour/colourspace.c

@@ -580,7 +580,7 @@ vips_colourspace_class_init( VipsColourspaceClass *class )
 	vobject_class->description = _( "convert to a new colorspace" );
 	vobject_class->build = vips_colourspace_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/colour/sRGB2scRGB.c

@@ -237,7 +237,7 @@ vips_sRGB2scRGB_class_init( VipssRGB2scRGBClass *class )
 	object_class->description = _( "convert an sRGB image to scRGB" );
 	object_class->build = vips_sRGB2scRGB_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/colour/scRGB2BW.c

@@ -231,7 +231,7 @@ vips_scRGB2BW_class_init( VipsscRGB2BWClass *class )
 	object_class->description = _( "convert scRGB to BW" ); 
 	object_class->build = vips_scRGB2BW_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/colour/scRGB2sRGB.c

@@ -259,7 +259,7 @@ vips_scRGB2sRGB_class_init( VipsscRGB2sRGBClass *class )
 	object_class->description = _( "convert an scRGB image to sRGB" ); 
 	object_class->build = vips_scRGB2sRGB_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/arrayjoin.c

@@ -298,7 +298,7 @@ vips_arrayjoin_class_init( VipsArrayjoinClass *class )
 	vobject_class->description = _( "join an array of images" );
 	vobject_class->build = vips_arrayjoin_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_BOXED( class, "in", -1, 
 		_( "Input" ), 

libvips/conversion/bandary.c

@@ -186,7 +186,7 @@ vips_bandary_class_init( VipsBandaryClass *class )
 	vobject_class->description = _( "operations on image bands" );
 	vobject_class->build = vips_bandary_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 }
 
 static void

libvips/conversion/bandfold.c

@@ -154,7 +154,7 @@ vips_bandfold_class_init( VipsBandfoldClass *class )
 	vobject_class->description = _( "fold up x axis into bands" );
 	vobject_class->build = vips_bandfold_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/bandunfold.c

@@ -157,7 +157,7 @@ vips_bandunfold_class_init( VipsBandunfoldClass *class )
 	vobject_class->description = _( "unfold image bands into x axis" );
 	vobject_class->build = vips_bandunfold_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/byteswap.c

@@ -200,7 +200,7 @@ vips_byteswap_class_init( VipsByteswapClass *class )
 	vobject_class->description = _( "byteswap an image" );
 	vobject_class->build = vips_byteswap_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/cast.c

@@ -542,7 +542,7 @@ vips_cast_class_init( VipsCastClass *class )
 	vobject_class->description = _( "cast an image" );
 	vobject_class->build = vips_cast_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/copy.c

@@ -264,7 +264,7 @@ vips_copy_class_init( VipsCopyClass *class )
 	 * cache it. Plus copy is cheap.
 	 */
 	operation_class->flags = 
-		VIPS_OPERATION_SEQUENTIAL_UNBUFFERED | 
+		VIPS_OPERATION_SEQUENTIAL | 
 		VIPS_OPERATION_NOCACHE;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 

libvips/conversion/embed.c

@@ -557,7 +557,7 @@ vips_embed_class_init( VipsEmbedClass *class )
 	vobject_class->description = _( "embed an image in a larger image" );
 	vobject_class->build = vips_embed_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", -1, 
 		_( "Input" ), 

libvips/conversion/extract.c

@@ -188,7 +188,7 @@ 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;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "input", 0, 
 		_( "Input" ), 

libvips/conversion/falsecolour.c

@@ -375,7 +375,7 @@ vips_falsecolour_class_init( VipsFalsecolourClass *class )
 	vobject_class->description = _( "false-color an image" );
 	vobject_class->build = vips_falsecolour_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 0, 
 		_( "in" ), 

libvips/conversion/flatten.c

@@ -380,7 +380,7 @@ vips_flatten_class_init( VipsFlattenClass *class )
 	vobject_class->description = _( "flatten alpha out of an image" );
 	vobject_class->build = vips_flatten_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/gamma.c

@@ -137,7 +137,7 @@ vips_gamma_class_init( VipsGammaClass *class )
 	vobject_class->description = _( "gamma an image" );
 	vobject_class->build = vips_gamma_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", -1, 
 		_( "in" ), 

libvips/conversion/msb.c

@@ -238,7 +238,7 @@ vips_msb_class_init( VipsMsbClass *class )
 		_( "pick most-significant byte from an image" );
 	vobject_class->build = vips_msb_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 0, 
 		_( "Input" ), 

libvips/conversion/premultiply.c

@@ -253,7 +253,7 @@ vips_premultiply_class_init( VipsPremultiplyClass *class )
 	vobject_class->description = _( "premultiply image alpha" );
 	vobject_class->build = vips_premultiply_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/recomb.c

@@ -201,7 +201,7 @@ vips_recomb_class_init( VipsRecombClass *class )
 	object_class->description = _( "linear recombination with matrix" );
 	object_class->build = vips_recomb_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 0, 
 		_( "Input" ), 

libvips/conversion/sequential.c

@@ -21,6 +21,8 @@
  * 	  this broke on some busy, many-core systems, see comment below
  * 10/6/14
  * 	- re-enable skipahead now we have the single-thread-first-tile idea
+ * 6/3/17
+ * 	- deprecate @trace, @access now seq is much simpler
  */
 
 /*
@@ -70,15 +72,6 @@
 
 #include "pconversion.h"
 
-/* Stall threads that run ahead for up to this long, in seconds. Normally they
- * will be woken once their data is ready and long before this. The timeout is
- * just to prevent a total crash in the case of accidental deadlock. 
- *
- * This has to be a long time: if we're trying to use all cores on a busy 
- * system, it could be ages until all the other threads get a chance to run. 
- */
-#define STALL_TIME (60.0)
-
 typedef struct _VipsSequential {
 	VipsConversion parent_instance;
 
@@ -87,11 +80,9 @@ typedef struct _VipsSequential {
 	VipsAccess access;
 	gboolean trace;
 
-	/* Lock access to y_pos with this, use the cond to wake up stalled
+	/* Lock access to y_pos with this.
-	 * threads.
 	 */
 	GMutex *lock;
-	GCond *ready;
 
 	/* The next read from our source will fetch this scanline, ie. it's 0
 	 * when we start.
@@ -114,7 +105,6 @@ vips_sequential_dispose( GObject *gobject )
 	VipsSequential *sequential = (VipsSequential *) gobject;
 
 	VIPS_FREEF( vips_g_mutex_free, sequential->lock );
-	VIPS_FREEF( vips_g_cond_free, sequential->ready );
 
 	G_OBJECT_CLASS( vips_sequential_parent_class )->dispose( gobject );
 }
@@ -130,18 +120,12 @@ vips_sequential_generate( VipsRegion *or,
 	VIPS_DEBUG_MSG_GREEN( "thread %p request for line %d, height %d\n", 
 		g_thread_self(), r->top, r->height );
 
-	if( sequential->trace )
-		g_info( "request for line %d, height %d", 
-			r->top, r->height );
-
 	VIPS_GATE_START( "vips_sequential_generate: wait" );
 
 	g_mutex_lock( sequential->lock );
 
 	VIPS_GATE_STOP( "vips_sequential_generate: wait" );
 
-	VIPS_DEBUG_MSG_GREEN( "thread %p has lock ...\n", g_thread_self() ); 
-
 	/* If we've seen an error, everything must stop.
 	 */
 	if( sequential->error ) {
@@ -149,68 +133,8 @@ vips_sequential_generate( VipsRegion *or,
 		return( -1 );
 	}
 
-	if( r->top > sequential->y_pos &&
-		sequential->y_pos > 0 ) {
-		/* This request is for stuff beyond the current read position, 
-		 * and this is not the first request. We 
-		 * stall for a while to give other threads time to catch up.
-		 * 
-		 * The stall can be cancelled by a signal on @ready.
-		 *
-		 * We don't stall forever, since an error would be better than
-		 * deadlock, and we don't fail on timeout, since the timeout 
-		 * may be harmless.
-		 */
-
-#ifdef HAVE_COND_INIT
-		gint64 time;
-
-		time = g_get_monotonic_time() + 
-			STALL_TIME * G_TIME_SPAN_SECOND;
-#else
-		GTimeVal time;
-
-		g_get_current_time( &time );
-		g_time_val_add( &time, STALL_TIME * 1000000 );
-#endif
-
-		VIPS_DEBUG_MSG_GREEN( "thread %p stalling for up to %gs ...\n", 
-			g_thread_self(), STALL_TIME ); 
-
-		VIPS_GATE_START( "vips_sequential_generate: wait" );
-
-		/* Exit the loop on timeout or condition passes. We have to
-		 * be wary of spurious wakeups. 
-		 */
-		while( r->top > sequential->y_pos ) {
-#ifdef HAVE_COND_INIT
-			if( !g_cond_wait_until( sequential->ready, 
-				sequential->lock, time ) )
-				break;
-#else
-			if( !g_cond_timed_wait( sequential->ready, 
-				sequential->lock, &time ) )
-				break;
-#endif
-
-			/* We may have woken up because of an eval error.
-			 */
-			if( sequential->error ) {
-				g_mutex_unlock( sequential->lock );
-				return( -1 );
-			}
-		}
-
-		VIPS_GATE_STOP( "vips_sequential_generate: wait" );
-
-		VIPS_DEBUG_MSG_GREEN( "thread %p awake again ...\n", 
-			g_thread_self() ); 
-	}
-
 	if( r->top > sequential->y_pos ) {
-		/* This is a request for something some way down the image, 
+		/* This is a request for something some way down the image. 
-		 * and we've fallen through from the stall above. 
-		 *
 		 * Probably the operation is something like extract_area and 
 		 * we should skip the initial part of the image. In fact, 
 		 * we read to cache, since it may be useful.
@@ -226,10 +150,7 @@ vips_sequential_generate( VipsRegion *or,
 		area.width = 1;
 		area.height = r->top - sequential->y_pos;
 		if( vips_region_prepare( ir, &area ) ) {
-			VIPS_DEBUG_MSG( "thread %p error, unlocking #1 ...\n", 
-				g_thread_self() ); 
 			sequential->error = -1;
-			g_cond_broadcast( sequential->ready );
 			g_mutex_unlock( sequential->lock );
 			return( -1 );
 		}
@@ -240,32 +161,14 @@ vips_sequential_generate( VipsRegion *or,
 	/* This is a request for old or present pixels -- serve from cache.
 	 * This may trigger further, sequential reads.
 	 */
-	VIPS_DEBUG_MSG_GREEN( "thread %p reading ...\n", g_thread_self() ); 
 	if( vips_region_prepare( ir, r ) ||
 		vips_region_region( or, ir, r, r->left, r->top ) ) {
-		VIPS_DEBUG_MSG( "thread %p error, unlocking #2 ...\n", 
-			g_thread_self() ); 
 		sequential->error = -1;
-		g_cond_broadcast( sequential->ready );
 		g_mutex_unlock( sequential->lock );
 		return( -1 );
 	}
 
-	if( VIPS_RECT_BOTTOM( r ) > sequential->y_pos ) {
+	sequential->y_pos = VIPS_MAX( sequential->y_pos, VIPS_RECT_BOTTOM( r ) );
-		/* This request has moved the read point. Update it, and wake 
-		 * up all stalled threads for a retry.
-		 */
-		sequential->y_pos = VIPS_RECT_BOTTOM( r );
-
-		VIPS_DEBUG_MSG_GREEN( "thread %p updating y_pos to %d and "
-			"waking stalled\n", 
-			g_thread_self(),
-			sequential->y_pos ); 
-
-		g_cond_broadcast( sequential->ready );
-	}
-
-	VIPS_DEBUG_MSG_GREEN( "thread %p unlocking ...\n", g_thread_self() ); 
 
 	g_mutex_unlock( sequential->lock );
 
@@ -285,12 +188,9 @@ vips_sequential_build( VipsObject *object )
 	if( VIPS_OBJECT_CLASS( vips_sequential_parent_class )->build( object ) )
 		return( -1 );
 
-	if( vips_image_pio_input( sequential->in ) )
-		return( -1 );
-
 	if( vips_linecache( sequential->in, &t, 
 		"tile_height", sequential->tile_height,
-		"access", sequential->access,
+		"access", VIPS_ACCESS_SEQUENTIAL,
 		NULL ) )
 		return( -1 );
 
@@ -329,13 +229,6 @@ vips_sequential_class_init( VipsSequentialClass *class )
 		VIPS_ARGUMENT_REQUIRED_INPUT,
 		G_STRUCT_OFFSET( VipsSequential, in ) );
 
-	VIPS_ARG_BOOL( class, "trace", 2, 
-		_( "trace" ), 
-		_( "trace pixel requests" ),
-		VIPS_ARGUMENT_OPTIONAL_INPUT,
-		G_STRUCT_OFFSET( VipsSequential, trace ),
-		TRUE );
-
 	VIPS_ARG_INT( class, "tile_height", 3, 
 		_( "Tile height" ), 
 		_( "Tile height in pixels" ),
@@ -343,21 +236,27 @@ vips_sequential_class_init( VipsSequentialClass *class )
 		G_STRUCT_OFFSET( VipsSequential, tile_height ),
 		1, 1000000, 1 );
 
+
 	VIPS_ARG_ENUM( class, "access", 6, 
 		_( "Strategy" ), 
 		_( "Expected access pattern" ),
-		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
 		G_STRUCT_OFFSET( VipsSequential, access ),
 		VIPS_TYPE_ACCESS, VIPS_ACCESS_SEQUENTIAL );
+
+	VIPS_ARG_BOOL( class, "trace", 2, 
+		_( "trace" ), 
+		_( "trace pixel requests" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
+		G_STRUCT_OFFSET( VipsSequential, trace ),
+		TRUE );
+
 }
 
 static void
 vips_sequential_init( VipsSequential *sequential )
 {
-	sequential->trace = FALSE;
-	sequential->access = VIPS_ACCESS_SEQUENTIAL;
 	sequential->lock = vips_g_mutex_new();
-	sequential->ready = vips_g_cond_new();
 	sequential->tile_height = 1;
 	sequential->error = 0;
 }
@@ -370,28 +269,16 @@ vips_sequential_init( VipsSequential *sequential )
  *
  * Optional arguments:
  *
- * * @trace: trace requests
  * * @strip_height: height of cache strips
- * * @access: access pattern
  *
  * This operation behaves rather like vips_copy() between images
- * @in and @out, except that it checks that pixels are only requested
+ * @in and @out, except that it checks that pixels on @in are only requested
- * top-to-bottom. If a thread makes an out of order request, it is stalled
+ * top-to-bottom. This operation is useful for loading file formats which are 
- * until the pack catches up.
- *
- * This operation is useful for loading file formats which are 
  * strictly top-to-bottom, like PNG. 
  *
- * If @trace is true, the operation will print diagnostic messages for each
- * block of pixels which are processed. This can help find the cause of
- * non-sequential accesses. 
- *
  * @strip_height can be used to set the size of the tiles that
  * vips_sequential() uses. The default value is 1.
  *
- * @access can be set to #VIPS_ACCESS_SEQUENTIAL_UNBUFFERED, meaning don't
- * keep a large cache behind the read point. This can save some memory. 
- *
  * See also: vips_cache(), vips_linecache(), vips_tilecache().
  *
  * Returns: 0 on success, -1 on error.

libvips/conversion/tilecache.c

@@ -842,7 +842,7 @@ vips_tile_cache_init( VipsTileCache *cache )
  *
  * When the cache fills, a tile is chosen for reuse. If @access is
  * #VIPS_ACCESS_RANDOM, then the least-recently-used tile is reused. If 
- * @access is #VIPS_ACCESS_SEQUENTIAL or #VIPS_ACCESS_SEQUENTIAL_UNBUFFERED, 
+ * @access is #VIPS_ACCESS_SEQUENTIAL 
  * the top-most tile is reused.
  *
  * By default, @tile_width and @tile_height are 128 pixels, and the operation
@@ -917,6 +917,10 @@ vips_line_cache_build( VipsObject *object )
 	VipsBlockCache *block_cache = (VipsBlockCache *) object;
 	VipsLineCache *cache = (VipsLineCache *) object;
 
+	int tile_width;
+	int tile_height;
+	int n_lines;
+
 	VIPS_DEBUG_MSG( "vips_line_cache_build\n" );
 
 	if( VIPS_OBJECT_CLASS( vips_line_cache_parent_class )->
@@ -929,31 +933,13 @@ vips_line_cache_build( VipsObject *object )
 
 	block_cache->access = cache->access; 
 
-	if( cache->access == VIPS_ACCESS_SEQUENTIAL_UNBUFFERED )
+	/* This can go up with request size, see vips_line_cache_gen().
-		/* A tile per thread. 
+	 */
-		 *
+	vips_get_tile_size( block_cache->in, 
-		 * Imagine scanline tiles and four threads. And add a bit for
+		&tile_width, &tile_height, &n_lines );
-		 * slop. 
+	block_cache->max_tiles = 1 + 2 * n_lines / block_cache->tile_height;
-		 */
-		block_cache->max_tiles = 2 * vips_concurrency_get();
-	else { 
-		/* Enough lines for two complete buffers would be exactly 
-		 * right. Make it 4 to give us some slop room. 
-		 *
-		 * This can go up with request size, see vips_line_cache_gen().
-		 */
-		int tile_width;
-		int tile_height;
-		int n_lines;
 
-		vips_get_tile_size( block_cache->in, 
+	VIPS_DEBUG_MSG( "vips_line_cache_build: n_lines = %d\n", n_lines );
-			&tile_width, &tile_height, &n_lines );
-		block_cache->max_tiles = 4 * 
-			(1 + n_lines / block_cache->tile_height);
-
-		VIPS_DEBUG_MSG( "vips_line_cache_build: n_lines = %d\n", 
-			n_lines );
-	}
 
 	VIPS_DEBUG_MSG( "vips_line_cache_build: "
 		"max_tiles = %d, tile_height = %d\n", 
@@ -1026,15 +1012,14 @@ vips_line_cache_init( VipsLineCache *cache )
  * @in and @out, except that it keeps a cache of computed scanlines. 
  *
  * The number of lines cached is enough for a small amount of non-local
- * access. If you know you will not be making any non-local access, you can
+ * access. 
- * save some memory and set @access to #VIPS_ACCESS_SEQUENTIAL_UNBUFFERED. 
  *
  * Each cache tile is made with a single call to 
  * vips_region_prepare(). 
  *
  * When the cache fills, a tile is chosen for reuse. If @access is
  * #VIPS_ACCESS_RANDOM, then the least-recently-used tile is reused. If 
- * @access is #VIPS_ACCESS_SEQUENTIAL or #VIPS_ACCESS_SEQUENTIAL_UNBUFFERED, 
+ * @access is #VIPS_ACCESS_SEQUENTIAL, then 
  * the top-most tile is reused. @access defaults to #VIPS_ACCESS_RANDOM.
  *
  * @tile_height can be used to set the size of the strips that

libvips/conversion/unpremultiply.c

@@ -262,7 +262,7 @@ vips_unpremultiply_class_init( VipsUnpremultiplyClass *class )
 	vobject_class->description = _( "unpremultiply image alpha" );
 	vobject_class->build = vips_unpremultiply_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/conversion/zoom.c

@@ -372,7 +372,7 @@ vips_zoom_class_init( VipsZoomClass *class )
 	vobject_class->description = _( "zoom an image" );
 	vobject_class->build = vips_zoom_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "input", 0, 
 		_( "Input" ), 

libvips/deprecated/im_jpeg2vips.c

@@ -111,7 +111,7 @@ jpeg2vips( const char *name, IMAGE *out, gboolean header_only )
 
 #ifdef HAVE_JPEG
 	if( vips__jpeg_read_file( filename, out, 
-		header_only, shrink, fail_on_warn, TRUE, FALSE ) )
+		header_only, shrink, fail_on_warn, FALSE ) )
 		return( -1 );
 #else
 	vips_error( "im_jpeg2vips", 

libvips/deprecated/im_png2vips.c

@@ -87,7 +87,7 @@ png2vips( const char *name, IMAGE *out, gboolean header_only )
 			return( -1 );
 	}
 	else {
-		if( vips__png_read( filename, out, TRUE ) )
+		if( vips__png_read( filename, out ) )
 			return( -1 );
 	}
 #else

libvips/deprecated/im_tiff2vips.c

@@ -98,7 +98,7 @@ tiff2vips( const char *name, IMAGE *out, gboolean header_only )
 			return( -1 );
 	}
 	else {
-		if( vips__tiff_read( filename, out, page, 1, FALSE, TRUE ) )
+		if( vips__tiff_read( filename, out, page, 1, FALSE ) )
 			return( -1 );
 	}
 #else

libvips/foreign/foreign.c

@@ -1502,7 +1502,7 @@ vips_foreign_save_class_init( VipsForeignSaveClass *class )
 	 * write and interlaced png write, which are not, add extra caches 
 	 * on their input. 
 	 */
-	operation_class->flags |= VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags |= VIPS_OPERATION_SEQUENTIAL;
 
 	/* Must not cache savers.
 	 */

libvips/foreign/jpeg2vips.c

@@ -152,10 +152,6 @@ typedef struct _ReadJpeg {
 	 */
 	gboolean fail;
 
-	/* Use a read behind buffer.
-	 */
-	gboolean readbehind; 
-
 	/* Used for file input only.
 	 */
 	char *filename;
@@ -216,8 +212,7 @@ readjpeg_close( VipsObject *object, ReadJpeg *jpeg )
 }
 
 static ReadJpeg *
-readjpeg_new( VipsImage *out, 
+readjpeg_new( VipsImage *out, int shrink, gboolean fail, gboolean autorotate )
-	int shrink, gboolean fail, gboolean readbehind, gboolean autorotate )
 {
 	ReadJpeg *jpeg;
 
@@ -227,7 +222,6 @@ readjpeg_new( VipsImage *out,
 	jpeg->out = out;
 	jpeg->shrink = shrink;
 	jpeg->fail = fail;
-	jpeg->readbehind = readbehind;
 	jpeg->filename = NULL;
         jpeg->cinfo.err = jpeg_std_error( &jpeg->eman.pub );
 	jpeg->eman.pub.error_exit = vips__new_error_exit;
@@ -516,7 +510,7 @@ read_jpeg_header( ReadJpeg *jpeg, VipsImage *out )
 
 	/* Tell downstream we are reading sequentially.
 	 */
-	vips_image_set_int( out, VIPS_META_SEQUENTIAL, 1 ); 
+	vips_image_set_area( out, VIPS_META_SEQUENTIAL, NULL, NULL ); 
 
 	return( 0 );
 }
@@ -680,9 +674,6 @@ read_jpeg_image( ReadJpeg *jpeg, VipsImage *out )
 		jpeg, NULL ) ||
 		vips_sequential( t[0], &t[1], 
 			"tile_height", 8,
-			"access", jpeg->readbehind ? 
-				VIPS_ACCESS_SEQUENTIAL : 
-				VIPS_ACCESS_SEQUENTIAL_UNBUFFERED,
 			NULL ) )
 		return( -1 );
 
@@ -751,13 +742,12 @@ vips__jpeg_read( ReadJpeg *jpeg, VipsImage *out, gboolean header_only )
  */
 int
 vips__jpeg_read_file( const char *filename, VipsImage *out, 
-	gboolean header_only, int shrink, gboolean fail, gboolean readbehind,
+	gboolean header_only, int shrink, gboolean fail, 
 	gboolean autorotate )
 {
 	ReadJpeg *jpeg;
 
-	if( !(jpeg = readjpeg_new( out, 
+	if( !(jpeg = readjpeg_new( out, shrink, fail, autorotate )) )
-		shrink, fail, readbehind, autorotate )) )
 		return( -1 );
 
 	/* Here for longjmp() from vips__new_error_exit() during startup.
@@ -958,13 +948,11 @@ readjpeg_buffer (ReadJpeg *jpeg, const void *buf, size_t len)
 
 int
 vips__jpeg_read_buffer( const void *buf, size_t len, VipsImage *out, 
-	gboolean header_only, int shrink, int fail, gboolean readbehind, 
+	gboolean header_only, int shrink, int fail, gboolean autorotate )
-	gboolean autorotate )
 {
 	ReadJpeg *jpeg;
 
-	if( !(jpeg = readjpeg_new( out, 
+	if( !(jpeg = readjpeg_new( out, shrink, fail, autorotate )) )
-		shrink, fail, readbehind, autorotate )) )
 		return( -1 );
 
 	if( setjmp( jpeg->eman.jmp ) ) 

libvips/foreign/jpegload.c

@@ -182,7 +182,7 @@ vips_foreign_load_jpeg_file_header( VipsForeignLoad *load )
 	VipsForeignLoadJpegFile *file = (VipsForeignLoadJpegFile *) load;
 
 	if( vips__jpeg_read_file( file->filename, load->out, 
-		TRUE, jpeg->shrink, load->fail, FALSE, jpeg->autorotate ) ) 
+		TRUE, jpeg->shrink, load->fail, jpeg->autorotate ) ) 
 		return( -1 );
 
 	return( 0 );
@@ -195,8 +195,7 @@ vips_foreign_load_jpeg_file_load( VipsForeignLoad *load )
 	VipsForeignLoadJpegFile *file = (VipsForeignLoadJpegFile *) load;
 
 	if( vips__jpeg_read_file( file->filename, load->real, 
-		FALSE, jpeg->shrink, load->fail,
+		FALSE, jpeg->shrink, load->fail, jpeg->autorotate ) )
-		load->access == VIPS_ACCESS_SEQUENTIAL, jpeg->autorotate ) )
 		return( -1 );
 
 	return( 0 );
@@ -262,8 +261,7 @@ vips_foreign_load_jpeg_buffer_header( VipsForeignLoad *load )
 	VipsForeignLoadJpegBuffer *buffer = (VipsForeignLoadJpegBuffer *) load;
 
 	if( vips__jpeg_read_buffer( buffer->buf->data, buffer->buf->length, 
-		load->out, TRUE, jpeg->shrink, load->fail, FALSE, 
+		load->out, TRUE, jpeg->shrink, load->fail, jpeg->autorotate ) )
-		jpeg->autorotate ) )
 		return( -1 );
 
 	return( 0 );
@@ -276,8 +274,7 @@ vips_foreign_load_jpeg_buffer_load( VipsForeignLoad *load )
 	VipsForeignLoadJpegBuffer *buffer = (VipsForeignLoadJpegBuffer *) load;
 
 	if( vips__jpeg_read_buffer( buffer->buf->data, buffer->buf->length, 
-		load->real, FALSE, jpeg->shrink, load->fail,
+		load->real, FALSE, jpeg->shrink, load->fail, jpeg->autorotate ) )
-		load->access == VIPS_ACCESS_SEQUENTIAL, jpeg->autorotate ) )
 		return( -1 );
 
 	return( 0 );

libvips/foreign/pforeign.h

@@ -68,7 +68,7 @@ int vips__tiff_write_buf( VipsImage *in,
 int vips__tiff_read_header( const char *filename, VipsImage *out, 
 	int page, int n, gboolean autorotate );
 int vips__tiff_read( const char *filename, VipsImage *out, 
-	int page, int n, gboolean autorotate, gboolean readbehind );
+	int page, int n, gboolean autorotate ); 
 
 gboolean vips__istiff( const char *filename );
 gboolean vips__istifftiled( const char *filename );
@@ -79,7 +79,7 @@ gboolean vips__istifftiled_buffer( const void *buf, size_t len );
 int vips__tiff_read_header_buffer( const void *buf, size_t len, VipsImage *out, 
 	int page, int n, gboolean autorotate );
 int vips__tiff_read_buffer( const void *buf, size_t len, VipsImage *out, 
-	int page, int n, gboolean autorotate, gboolean readbehind );
+	int page, int n, gboolean autorotate );
 
 extern const char *vips__foreign_tiff_suffs[];
 
@@ -149,7 +149,7 @@ int vips__ppm_save( VipsImage *in, const char *filename,
 
 int vips__rad_israd( const char *filename );
 int vips__rad_header( const char *filename, VipsImage *out );
-int vips__rad_load( const char *filename, VipsImage *out, gboolean readbehind );
+int vips__rad_load( const char *filename, VipsImage *out );
 
 int vips__rad_save( VipsImage *in, const char *filename );
 int vips__rad_save_buf( VipsImage *in, void **obuf, size_t *olen );
@@ -172,21 +172,18 @@ int vips__jpeg_write_buffer( VipsImage *in,
 int vips__isjpeg_buffer( const void *buf, size_t len );
 int vips__isjpeg( const char *filename );
 int vips__jpeg_read_file( const char *name, VipsImage *out, 
-	gboolean header_only, int shrink, gboolean fail, gboolean readbehind,
+	gboolean header_only, int shrink, gboolean fail, gboolean autorotate );
-	gboolean autorotate );
 int vips__jpeg_read_buffer( const void *buf, size_t len, VipsImage *out, 
-	gboolean header_only, int shrink, int fail, gboolean readbehind,
+	gboolean header_only, int shrink, int fail, gboolean autorotate );
-	gboolean autorotate );
 
 int vips__png_header( const char *name, VipsImage *out );
-int vips__png_read( const char *name, VipsImage *out, gboolean readbehind );
+int vips__png_read( const char *name, VipsImage *out );
 gboolean vips__png_ispng_buffer( const void *buf, size_t len );
 int vips__png_ispng( const char *filename );
 gboolean vips__png_isinterlaced( const char *filename );
 gboolean vips__png_isinterlaced_buffer( const void *buffer, size_t length );
 extern const char *vips__png_suffs[];
-int vips__png_read_buffer( const void *buffer, size_t length, 
+int vips__png_read_buffer( const void *buffer, size_t length, VipsImage *out );
-	VipsImage *out, gboolean readbehind  );
 int vips__png_header_buffer( const void *buffer, size_t length, 
 	VipsImage *out );
 

libvips/foreign/pngload.c

@@ -106,8 +106,7 @@ vips_foreign_load_png_load( VipsForeignLoad *load )
 {
 	VipsForeignLoadPng *png = (VipsForeignLoadPng *) load;
 
-	if( vips__png_read( png->filename, load->real, 
+	if( vips__png_read( png->filename, load->real ) )
-		load->access == VIPS_ACCESS_SEQUENTIAL ) )
 		return( -1 );
 
 	return( 0 );
@@ -202,7 +201,7 @@ vips_foreign_load_png_buffer_load( VipsForeignLoad *load )
 	VipsForeignLoadPngBuffer *buffer = (VipsForeignLoadPngBuffer *) load;
 
 	if( vips__png_read_buffer( buffer->buf->data, buffer->buf->length, 
-		load->real, load->access == VIPS_ACCESS_SEQUENTIAL ) )
+		load->real ) )
 		return( -1 );
 
 	return( 0 );

libvips/foreign/radiance.c

@@ -1084,7 +1084,7 @@ rad2vips_get_header( Read *read, VipsImage *out )
 
 	/* Tell downstream we are reading sequentially.
 	 */
-	vips_image_set_int( out, VIPS_META_SEQUENTIAL, 1 ); 
+	vips_image_set_area( out, VIPS_META_SEQUENTIAL, NULL, NULL ); 
 
 	return( 0 );
 }
@@ -1140,7 +1140,7 @@ rad2vips_generate( VipsRegion *or,
 }
 
 int
-vips__rad_load( const char *filename, VipsImage *out, gboolean readbehind )
+vips__rad_load( const char *filename, VipsImage *out )
 {
 	VipsImage **t = (VipsImage **) 
 		vips_object_local_array( VIPS_OBJECT( out ), 3 );
@@ -1159,14 +1159,8 @@ vips__rad_load( const char *filename, VipsImage *out, gboolean readbehind )
 		return( -1 );
 
 	if( vips_image_generate( t[0], 
-		NULL, rad2vips_generate, NULL, 
+		NULL, rad2vips_generate, NULL, read, NULL ) ||
-		read, NULL ) ||
+		vips_sequential( t[0], &t[1], "tile_height", 8, NULL ) ||
-		vips_sequential( t[0], &t[1], 
-			"tile_height", 8,
-			"access", readbehind ? 
-				VIPS_ACCESS_SEQUENTIAL : 
-				VIPS_ACCESS_SEQUENTIAL_UNBUFFERED,
-			NULL ) ||
 		vips_image_write( t[1], out ) )
 		return( -1 );
 

libvips/foreign/radload.c

@@ -100,8 +100,7 @@ vips_foreign_load_rad_load( VipsForeignLoad *load )
 {
 	VipsForeignLoadRad *rad = (VipsForeignLoadRad *) load;
 
-	if( vips__rad_load( rad->filename, load->real,
+	if( vips__rad_load( rad->filename, load->real ) )
-		load->access == VIPS_ACCESS_SEQUENTIAL ) )
 		return( -1 );
 
 	return( 0 );

libvips/foreign/tiff2vips.c

@@ -274,7 +274,6 @@ typedef struct _Rtiff {
 	int page;
 	int n;
 	gboolean autorotate;
-	gboolean readbehind; 
 
 	/* The TIFF we read.
 	 */
@@ -1337,7 +1336,7 @@ rtiff_set_header( Rtiff *rtiff, VipsImage *out )
 	/* Tell downstream if we are reading sequentially.
 	 */
 	if( !rtiff->header.tiled ) 
-		vips_image_set_int( out, VIPS_META_SEQUENTIAL, 1 ); 
+		vips_image_set_area( out, VIPS_META_SEQUENTIAL, NULL, NULL ); 
 
 	return( 0 );
 }
@@ -1931,9 +1930,6 @@ rtiff_read_stripwise( Rtiff *rtiff, VipsImage *out )
 			rtiff, NULL ) ||
 		vips_sequential( t[0], &t[1], 
 			"tile_height", rtiff->header.rows_per_strip,
-			"access", rtiff->readbehind ? 
-				VIPS_ACCESS_SEQUENTIAL : 
-				VIPS_ACCESS_SEQUENTIAL_UNBUFFERED,
 			NULL ) ||
 		rtiff_autorotate( rtiff, t[1], &t[2] ) ||
 		vips_image_write( t[2], out ) )
@@ -1957,8 +1953,7 @@ rtiff_close( VipsObject *object, Rtiff *rtiff )
 }
 
 static Rtiff *
-rtiff_new( VipsImage *out, 
+rtiff_new( VipsImage *out, int page, int n, gboolean autorotate )
-	int page, int n, gboolean autorotate, gboolean readbehind )
 {
 	Rtiff *rtiff;
 
@@ -1970,7 +1965,6 @@ rtiff_new( VipsImage *out,
 	rtiff->page = page;
 	rtiff->n = n;
 	rtiff->autorotate = autorotate;
-	rtiff->readbehind = readbehind;
 	rtiff->tiff = NULL;
 	rtiff->current_page = -1;
 	rtiff->sfn = NULL;
@@ -2174,11 +2168,11 @@ rtiff_header_read_all( Rtiff *rtiff )
 
 static Rtiff *
 rtiff_new_filename( const char *filename, VipsImage *out, 
-	int page, int n, gboolean autorotate, gboolean readbehind )
+	int page, int n, gboolean autorotate )
 {
 	Rtiff *rtiff;
 
-	if( !(rtiff = rtiff_new( out, page, n, autorotate, readbehind )) ||
+	if( !(rtiff = rtiff_new( out, page, n, autorotate )) ||
 		!(rtiff->tiff = vips__tiff_openin( filename )) || 
 		rtiff_header_read_all( rtiff ) )
 		return( NULL );
@@ -2190,11 +2184,11 @@ rtiff_new_filename( const char *filename, VipsImage *out,
 
 static Rtiff *
 rtiff_new_buffer( const void *buf, size_t len, VipsImage *out, 
-	int page, int n, gboolean autorotate, gboolean readbehind )
+	int page, int n, gboolean autorotate )
 {
 	Rtiff *rtiff;
 
-	if( !(rtiff = rtiff_new( out, page, n, autorotate, readbehind )) ||
+	if( !(rtiff = rtiff_new( out, page, n, autorotate )) ||
 		!(rtiff->tiff = vips__tiff_openin_buffer( out, buf, len )) ||
 		rtiff_header_read_all( rtiff ) )
 		return( NULL );
@@ -2225,7 +2219,7 @@ istiffpyramid( const char *name )
 
 int
 vips__tiff_read( const char *filename, VipsImage *out, 
-	int page, int n, gboolean autorotate, gboolean readbehind )
+	int page, int n, gboolean autorotate )
 {
 	Rtiff *rtiff;
 
@@ -2236,8 +2230,7 @@ vips__tiff_read( const char *filename, VipsImage *out,
 
 	vips__tiff_init();
 
-	if( !(rtiff = rtiff_new_filename( filename, 
+	if( !(rtiff = rtiff_new_filename( filename, out, page, n, autorotate )) )
-		out, page, n, autorotate, readbehind )) )
 		return( -1 );
 
 	if( rtiff->header.tiled ) {
@@ -2283,8 +2276,7 @@ vips__tiff_read_header( const char *filename, VipsImage *out,
 
 	vips__tiff_init();
 
-	if( !(rtiff = rtiff_new_filename( filename, out, 
+	if( !(rtiff = rtiff_new_filename( filename, out, page, n, autorotate )) )
-		page, n, autorotate, FALSE )) )
 		return( -1 );
 
 	if( rtiff_set_header( rtiff, out ) )
@@ -2352,8 +2344,7 @@ vips__tiff_read_header_buffer( const void *buf, size_t len, VipsImage *out,
 
 	vips__tiff_init();
 
-	if( !(rtiff = rtiff_new_buffer( buf, len, out, 
+	if( !(rtiff = rtiff_new_buffer( buf, len, out, page, n, autorotate )) )
-		page, n, autorotate, FALSE )) )
 		return( -1 );
 
 	if( rtiff_set_header( rtiff, out ) )
@@ -2366,8 +2357,7 @@ vips__tiff_read_header_buffer( const void *buf, size_t len, VipsImage *out,
 
 int
 vips__tiff_read_buffer( const void *buf, size_t len, 
-	VipsImage *out, int page, int n, gboolean autorotate, 
+	VipsImage *out, int page, int n, gboolean autorotate )
-	gboolean readbehind )
 {
 	Rtiff *rtiff;
 
@@ -2378,8 +2368,7 @@ vips__tiff_read_buffer( const void *buf, size_t len,
 
 	vips__tiff_init();
 
-	if( !(rtiff = rtiff_new_buffer( buf, len, out, 
+	if( !(rtiff = rtiff_new_buffer( buf, len, out, page, n, autorotate )) )
-		page, n, autorotate, readbehind )) )
 		return( -1 );
 
 	if( rtiff->header.tiled ) {

libvips/foreign/tiffload.c

@@ -183,8 +183,7 @@ vips_foreign_load_tiff_file_load( VipsForeignLoad *load )
 	VipsForeignLoadTiffFile *file = (VipsForeignLoadTiffFile *) load;
 
 	if( vips__tiff_read( file->filename, load->real, 
-		tiff->page, tiff->n,  tiff->autorotate, 
+		tiff->page, tiff->n,  tiff->autorotate ) )
-		load->access == VIPS_ACCESS_SEQUENTIAL ) )
 		return( -1 );
 
 	return( 0 );
@@ -284,8 +283,7 @@ vips_foreign_load_tiff_buffer_load( VipsForeignLoad *load )
 
 	if( vips__tiff_read_buffer( 
 		buffer->buf->data, buffer->buf->length, load->real, 
-		tiff->page, tiff->n, tiff->autorotate,
+		tiff->page, tiff->n, tiff->autorotate ) )
-		load->access == VIPS_ACCESS_SEQUENTIAL ) )
 		return( -1 );
 
 	return( 0 );

libvips/foreign/vipspng.c

@@ -140,7 +140,6 @@ user_warning_function( png_structp png_ptr, png_const_charp warning_msg )
 typedef struct {
 	char *name;
 	VipsImage *out;
-	gboolean readbehind; 
 
 	int y_pos;
 	png_structp pPng;
@@ -177,7 +176,7 @@ read_close_cb( VipsImage *out, Read *read )
 }
 
 static Read *
-read_new( VipsImage *out, gboolean readbehind )
+read_new( VipsImage *out )
 {
 	Read *read;
 
@@ -185,7 +184,6 @@ read_new( VipsImage *out, gboolean readbehind )
 		return( NULL );
 
 	read->name = NULL;
-	read->readbehind = readbehind;
 	read->out = out;
 	read->y_pos = 0;
 	read->pPng = NULL;
@@ -223,11 +221,11 @@ read_new( VipsImage *out, gboolean readbehind )
 }
 
 static Read *
-read_new_filename( VipsImage *out, const char *name, gboolean readbehind )
+read_new_filename( VipsImage *out, const char *name )
 {
 	Read *read;
 
-	if( !(read = read_new( out, readbehind )) )
+	if( !(read = read_new( out )) )
 		return( NULL );
 
 	read->name = vips_strdup( VIPS_OBJECT( out ), name );
@@ -386,7 +384,7 @@ png2vips_header( Read *read, VipsImage *out )
 	 * read via a huge memory buffer.
 	 */
 	if( interlace_type == PNG_INTERLACE_NONE ) {
-		vips_image_set_int( out, VIPS_META_SEQUENTIAL, 1 ); 
+		vips_image_set_area( out, VIPS_META_SEQUENTIAL, NULL, NULL ); 
 
 		/* Sequential mode needs thinstrip to work with things like
 		 * vips_shrink().
@@ -439,7 +437,7 @@ vips__png_header( const char *name, VipsImage *out )
 {
 	Read *read;
 
-	if( !(read = read_new_filename( out, name, FALSE )) ||
+	if( !(read = read_new_filename( out, name )) ||
 		png2vips_header( read, out ) ) 
 		return( -1 );
 
@@ -568,7 +566,7 @@ vips__png_isinterlaced( const char *filename )
 	int interlace_type;
 
 	image = vips_image_new();
-	if( !(read = read_new_filename( image, filename, FALSE )) ) {
+	if( !(read = read_new_filename( image, filename )) ) {
 		g_object_unref( image );
 		return( -1 );
 	}
@@ -603,9 +601,6 @@ png2vips_image( Read *read, VipsImage *out )
 				read, NULL ) ||
 			vips_sequential( t[0], &t[1], 
 				"tile_height", 8,
-				"access", read->readbehind ? 
-					VIPS_ACCESS_SEQUENTIAL : 
-					VIPS_ACCESS_SEQUENTIAL_UNBUFFERED,
 				NULL ) ||
 			vips_image_write( t[1], out ) )
 			return( -1 );
@@ -615,7 +610,7 @@ png2vips_image( Read *read, VipsImage *out )
 }
 
 int
-vips__png_read( const char *filename, VipsImage *out, gboolean readbehind )
+vips__png_read( const char *filename, VipsImage *out )
 {
 	Read *read;
 
@@ -623,7 +618,7 @@ vips__png_read( const char *filename, VipsImage *out, gboolean readbehind )
 	printf( "vips__png_read: reading \"%s\"\n", filename );
 #endif /*DEBUG*/
 
-	if( !(read = read_new_filename( out, filename, readbehind )) ||
+	if( !(read = read_new_filename( out, filename )) ||
 		png2vips_image( read, out ) )
 		return( -1 ); 
 
@@ -670,12 +665,11 @@ vips_png_read_buffer( png_structp pPng, png_bytep data, png_size_t length )
 }
 
 static Read *
-read_new_buffer( VipsImage *out, const void *buffer, size_t length, 
+read_new_buffer( VipsImage *out, const void *buffer, size_t length )
-	gboolean readbehind )
 {
 	Read *read;
 
-	if( !(read = read_new( out, readbehind )) )
+	if( !(read = read_new( out )) )
 		return( NULL );
 
 	read->length = length;
@@ -701,7 +695,7 @@ vips__png_header_buffer( const void *buffer, size_t length, VipsImage *out )
 {
 	Read *read;
 
-	if( !(read = read_new_buffer( out, buffer, length, FALSE )) ||
+	if( !(read = read_new_buffer( out, buffer, length )) ||
 		png2vips_header( read, out ) ) 
 		return( -1 );
 
@@ -709,12 +703,11 @@ vips__png_header_buffer( const void *buffer, size_t length, VipsImage *out )
 }
 
 int
-vips__png_read_buffer( const void *buffer, size_t length, VipsImage *out, 
+vips__png_read_buffer( const void *buffer, size_t length, VipsImage *out )
-	gboolean readbehind  )
 {
 	Read *read;
 
-	if( !(read = read_new_buffer( out, buffer, length, readbehind )) ||
+	if( !(read = read_new_buffer( out, buffer, length )) ||
 		png2vips_image( read, out ) )
 		return( -1 ); 
 
@@ -733,7 +726,7 @@ vips__png_isinterlaced_buffer( const void *buffer, size_t length )
 
 	image = vips_image_new();
 
-	if( !(read = read_new_buffer( image, buffer, length, FALSE )) ) { 
+	if( !(read = read_new_buffer( image, buffer, length )) ) { 
 		g_object_unref( image );
 		return( -1 );
 	}

libvips/histogram/maplut.c

@@ -688,7 +688,7 @@ vips_maplut_class_init( VipsMaplutClass *class )
 	object_class->description = _( "map an image though a lut" );
 	object_class->build = vips_maplut_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_IMAGE( class, "in", 1, 
 		_( "Input" ), 

libvips/iofuncs/image.c

@@ -147,7 +147,6 @@
  * VipsAccess:
  * @VIPS_ACCESS_RANDOM: can read anywhere
  * @VIPS_ACCESS_SEQUENTIAL: top-to-bottom reading only, but with a small buffer
- * @VIPS_ACCESS_SEQUENTIAL_UNBUFFERED: top-to-bottom reading only
  *
  * The type of access an operation has to supply. See vips_tilecache()
  * and #VipsForeign. 
@@ -156,9 +155,6 @@
  *
  * @VIPS_ACCESS_SEQUENTIAL means requests will be top-to-bottom, but with some
  * amount of buffering behind the read point for small non-local accesses. 
- *
- * @VIPS_ACCESS_SEQUENTIAL_UNBUFFERED means requests will be strictly
- * top-to-bottom with no read-behind. This can save some memory. 
  */
 
 /** 
@@ -1856,9 +1852,7 @@ vips_filename_get_options( const char *vips_filename )
  * whole image exactly once, top-to-bottom. In this mode, vips can avoid
  * converting the whole image in one go, for a large memory saving. You are
  * allowed to make small non-local references, so area operations like 
- * convolution will work. #VIPS_ACCESS_SEQUENTIAL_UNBUFFERED does not allow
+ * convolution will work. 
- * non-local references, so will only work for very strict top-to-bottom
- * operations, but does have very low memory needs. 
  *
  * In #VIPS_ACCESS_RANDOM mode, small images are decompressed to memory and
  * then processed from there. Large images are decompressed to temporary

libvips/iofuncs/object.c

@@ -1830,9 +1830,8 @@ vips_object_set_argument_from_string( VipsObject *object,
 
 		/* Read the filename. 
 		 */
-		if( flags & VIPS_OPERATION_SEQUENTIAL_UNBUFFERED ) 
+		if( flags & (VIPS_OPERATION_SEQUENTIAL_UNBUFFERED |
-			access = VIPS_ACCESS_SEQUENTIAL_UNBUFFERED;
+			     VIPS_OPERATION_SEQUENTIAL) ) 
-		else if( flags & VIPS_OPERATION_SEQUENTIAL ) 
 			access = VIPS_ACCESS_SEQUENTIAL;
 		else
 			access = VIPS_ACCESS_RANDOM; 
@@ -1869,9 +1868,8 @@ vips_object_set_argument_from_string( VipsObject *object,
 			flags = vips_operation_get_flags( 
 				VIPS_OPERATION( object ) );
 
-		if( flags & VIPS_OPERATION_SEQUENTIAL_UNBUFFERED ) 
+		if( flags & (VIPS_OPERATION_SEQUENTIAL_UNBUFFERED |
-			access = VIPS_ACCESS_SEQUENTIAL_UNBUFFERED;
+			     VIPS_OPERATION_SEQUENTIAL) ) 
-		else if( flags & VIPS_OPERATION_SEQUENTIAL ) 
 			access = VIPS_ACCESS_SEQUENTIAL;
 		else
 			access = VIPS_ACCESS_RANDOM; 

libvips/iofuncs/operation.c

@@ -169,7 +169,6 @@
  * VipsOperationFlags:
  * @VIPS_OPERATION_NONE: no flags
  * @VIPS_OPERATION_SEQUENTIAL: can work sequentially with a small buffer
- * @VIPS_OPERATION_SEQUENTIAL_UNBUFFERED: can work sequentially with no buffer
  * @VIPS_OPERATION_NOCACHE: must not be cached
  * @VIPS_OPERATION_DEPRECATED: a compatibility thing
  *
@@ -184,10 +183,6 @@
  * not at the top of the image. In this case, the first part of the image will
  * be read and discarded
  *
- * @VIPS_OPERATION_SEQUENTIAL_UNBUFFERED means that the operation works like 
- * vips_copy(): it can process images top-to-bottom and makes no 
- * non-local references. 
- *
  * Every scan-line must be requested, you are not allowed to skip
  * ahead, but as a special case, the very first request can be for a region
  * not at the top of the image. In this case, the first part of the image will

libvips/resample/resize.c

@@ -22,6 +22,8 @@
  * 	- more accurate resizing
  * 9/9/16
  * 	- add @centre option
+ * 6/3/17	
+ * 	- moved the cache to shrinkv
  */
 
 /*

libvips/resample/shrinkh.c

@@ -316,7 +316,7 @@ vips_shrinkh_class_init( VipsShrinkhClass *class )
 	vobject_class->description = _( "shrink an image horizontally" );
 	vobject_class->build = vips_shrinkh_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_INT( class, "hshrink", 8, 
 		_( "Hshrink" ), 

libvips/resample/shrinkv.c

@@ -457,7 +457,7 @@ vips_shrinkv_class_init( VipsShrinkvClass *class )
 	vobject_class->description = _( "shrink an image vertically" );
 	vobject_class->build = vips_shrinkv_build;
 
-	operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
+	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;
 
 	VIPS_ARG_INT( class, "vshrink", 9, 
 		_( "Vshrink" ), 

libvips/resample/thumbnail.c

@@ -376,10 +376,6 @@ vips_thumbnail_build( VipsObject *object )
 	shrink = vips_thumbnail_calculate_shrink( thumbnail, 
 		in->Xsize, in->Ysize );
 
-
-
-
-
 	/* Use centre convention to better match imagemagick.
 	 */
 	if( vips_resize( in, &t[4], 1.0 / shrink, 

test/test_seq.sh

@@ -43,3 +43,12 @@ if ! $vipsheader $tmp/x.png > /dev/null 2>&1 ; then
 	exit 1
 fi
 echo "ok"
+
+printf "testing reduce does not make temps ... "
+rm -f $tmp/x.png
+$vips reduce $huge $tmp/x.png 3 3 
+if ! $vipsheader $tmp/x.png > /dev/null 2>&1 ; then
+	echo "reduce made a temp"
+	exit 1
+fi
+echo "ok"