sequential needs a strip size param

strip tiff can only read in strip-sized chunks

libvips/conversion/sequential.c

@@ -64,7 +64,7 @@ typedef struct _VipsSequential {
 	VipsConversion parent_instance;
 
 	VipsImage *in;
-
+	int tile_height;
 	gboolean trace;
 
 	/* Lock access to y_pos with this, use the cond to wake up stalled
@@ -175,6 +175,7 @@ vips_sequential_build( VipsObject *object )
 		return( -1 );
 
 	if( vips_linecache( sequential->in, &t, 
+		"tile_height", sequential->tile_height,
 		"strategy", VIPS_CACHE_SEQUENTIAL,
 		NULL ) )
 		return( -1 );
@@ -221,6 +222,13 @@ vips_sequential_class_init( VipsSequentialClass *class )
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsSequential, trace ),
 		TRUE );
+
+	VIPS_ARG_INT( class, "tile_height", 3, 
+		_( "Tile height" ), 
+		_( "Tile height in pixels" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsSequential, tile_height ),
+		1, 1000000, 1 );
 }
 
 static void
@@ -229,6 +237,7 @@ vips_sequential_init( VipsSequential *sequential )
 	sequential->trace = FALSE;
 	sequential->lock = g_mutex_new();
 	sequential->ready = g_cond_new();
+	sequential->tile_height = 1;
 }
 
 /**
@@ -240,18 +249,23 @@ vips_sequential_init( VipsSequential *sequential )
  * Optional arguments:
  *
  * @trace: trace requests
+ * @strip_height: height of cache strips
  *
  * This operation behaves rather like vips_copy() between images
  * @in and @out, except that it checks that pixels are only requested
- * top-to-bottom. If an out of order request is made, it throws an exception.
+ * top-to-bottom. If a thread makes an out of order request, it is stalled
+ * until the pack catches up.
  *
- * This operation is handy with tilecache for loading file formats which are 
+ * 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.
+ *
  * See also: vips_image_cache().
  *
  * Returns: 0 on success, -1 on error.

libvips/conversion/tilecache.c

@@ -357,6 +357,13 @@ vips_block_cache_class_init( VipsBlockCacheClass *class )
 		VIPS_ARGUMENT_REQUIRED_INPUT,
 		G_STRUCT_OFFSET( VipsBlockCache, in ) );
 
+	VIPS_ARG_INT( class, "tile_height", 3, 
+		_( "Tile height" ), 
+		_( "Tile height in pixels" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsBlockCache, tile_height ),
+		1, 1000000, 128 );
+
 	VIPS_ARG_ENUM( class, "strategy", 3, 
 		_( "Strategy" ), 
 		_( "Expected access pattern" ),
@@ -538,13 +545,6 @@ vips_tile_cache_class_init( VipsTileCacheClass *class )
 		G_STRUCT_OFFSET( VipsBlockCache, tile_width ),
 		1, 1000000, 128 );
 
-	VIPS_ARG_INT( class, "tile_height", 3, 
-		_( "Tile height" ), 
-		_( "Tile height in pixels" ),
-		VIPS_ARGUMENT_OPTIONAL_INPUT,
-		G_STRUCT_OFFSET( VipsBlockCache, tile_height ),
-		1, 1000000, 128 );
-
 	VIPS_ARG_INT( class, "max_tiles", 3, 
 		_( "Max tiles" ), 
 		_( "Maximum number of tiles to cache" ),
@@ -646,7 +646,6 @@ vips_line_cache_build( VipsObject *object )
 	int tile_width;
 	int tile_height;
 	int nlines;
-	int nstrips;
 
 	VIPS_DEBUG_MSG( "vips_line_cache_build\n" );
 
@@ -654,10 +653,9 @@ vips_line_cache_build( VipsObject *object )
 		build( object ) )
 		return( -1 );
 
-	/* Set the cache geometry from the image size ... a set of scanlines.
+	/* tile_height is set by a param, or defaulted below.
 	 */
 	block_cache->tile_width = block_cache->in->Xsize;
-	block_cache->tile_height = 1;
 
 	/* Enough lines for two complete buffers.
 	 *
@@ -665,7 +663,7 @@ vips_line_cache_build( VipsObject *object )
 	 */
 	vips_get_tile_size( block_cache->in, 
 		&tile_width, &tile_height, &nlines );
-	block_cache->max_tiles = 2 * nlines;
+	block_cache->max_tiles = 2 * (1 + nlines / block_cache->tile_height);
 
 	VIPS_DEBUG_MSG( "vips_line_cache_build: max_tiles = %d\n",
 		block_cache->max_tiles );
@@ -717,6 +715,7 @@ vips_line_cache_init( VipsLineCache *cache )
  * Optional arguments:
  *
  * @strategy: hint expected access pattern #VipsCacheStrategy
+ * @tile_height: height of tiles in cache
  *
  * This operation behaves rather like vips_copy() between images
  * @in and @out, except that it keeps a cache of computed pixels. 
@@ -731,6 +730,9 @@ vips_line_cache_init( VipsLineCache *cache )
  * @strategy is #VIPS_CACHE_SEQUENTIAL, the top-most tile is reused.
  * @strategy defaults to #VIPS_CACHE_RANDOM.
  *
+ * @tile_height can be used to set the size of the strips that
+ * vips_linecache() uses. The default is 1 (a single scanline).
+ *
  * This is a lower-level operation than vips_image_cache() since it does no 
  * subdivision and it single-threads its callee. It is suitable for caching 
  * the output of operations like png load. 

libvips/foreign/jpeg2vips.c

@@ -861,6 +861,11 @@ read_jpeg_generate( VipsRegion *or,
 	 */
 	g_assert( r->top % 8 == 0 );
 
+	/* Tiles should always be a strip in height, unless it's the final
+	 * strip.
+	 */
+	g_assert( r->height == VIPS_MIN( 8, or->im->Ysize - r->top ) ); 
+
 	/* Here for longjmp() from vips__new_error_exit().
 	 */
 	if( setjmp( jpeg->eman.jmp ) ) 
@@ -917,7 +922,9 @@ read_jpeg_image( ReadJpeg *jpeg, VipsImage *out )
 	if( vips_image_generate( t[0], 
 		NULL, read_jpeg_generate, NULL, 
 		jpeg, NULL ) ||
-		vips_sequential( t[0], &t[1], NULL ) ||
+		vips_sequential( t[0], &t[1], 
+			"tile_height", 8,
+			NULL ) ||
 		vips_image_write( t[1], out ) )
 		return( -1 );
 

libvips/foreign/tiff2vips.c

@@ -1319,6 +1319,12 @@ tiff2vips_stripwise_generate( VipsRegion *or,
 	 */
 	g_assert( r->top % rtiff->rows_per_strip == 0 );
 
+	/* Tiles should always be a strip in height, unless it's the final
+	 * strip.
+	 */
+	g_assert( r->height == 
+		VIPS_MIN( rtiff->rows_per_strip, or->im->Ysize - r->top ) ); 
+
 	for( y = 0; y < r->height; y += rtiff->rows_per_strip ) {
 		tdata_t dst;
 		tstrip_t strip;
@@ -1419,7 +1425,9 @@ read_stripwise( ReadTiff *rtiff, VipsImage *out )
 		vips_image_generate( t[0], 
 			NULL, tiff2vips_stripwise_generate, NULL, 
 			rtiff, tbuf ) ||
-		vips_sequential( t[0], &t[1], NULL ) ||
+		vips_sequential( t[0], &t[1], 
+			"tile_height", rtiff->rows_per_strip,
+			NULL ) ||
 		vips_image_write( t[1], out ) )
 		return( -1 );
 

libvips/foreign/vipspng.c

@@ -416,6 +416,11 @@ png2vips_generate( VipsRegion *or,
 	g_assert( r->width == or->im->Xsize );
 	g_assert( VIPS_RECT_BOTTOM( r ) <= or->im->Ysize );
 
+	/* Tiles should always be a strip in height, unless it's the final
+	 * strip.
+	 */
+	g_assert( r->height == VIPS_MIN( 8, or->im->Ysize - r->top ) ); 
+
 	if( setjmp( png_jmpbuf( read->pPng ) ) ) {
 #ifdef DEBUG
 		printf( "png2vips_generate: failing in setjmp\n" ); 
@@ -488,7 +493,9 @@ vips__png_read( const char *name, VipsImage *out )
 			vips_image_generate( t[0], 
 				NULL, png2vips_generate, NULL, 
 				read, NULL ) ||
-			vips_sequential( t[0], &t[1], NULL ) ||
+			vips_sequential( t[0], &t[1], 
+				"tile_height", 8,
+				NULL ) ||
 			vips_image_write( t[1], out ) )
 			return( -1 );
 	}