Merge "Bound the SourceRead size to the block size."
diff --git a/syspatch.c b/syspatch.c
index 44b609d..4d9dbc3 100644
--- a/syspatch.c
+++ b/syspatch.c
@@ -35,22 +35,25 @@
// SOURCE_WINDOW_SIZE probably don't make any sense, but this is untested. The
// primary tradeoff made here is between memory and extra calls to the decoder.
#define XZ_OUTPUT_SIZE (1U<<23)
+// BLOCK_SIZE is the base I/O size for xdelta. See the variables below for how
+// this impacts performance.
+#define BLOCK_SIZE (1U<<23)
// TARGET_WINDOW_SIZE determines how large writes to the target file are. There
// isn't a lot of science behind this yet, excepting the notes about the write
// queue below.
-#define TARGET_WINDOW_SIZE (1U<<23)
+#define TARGET_WINDOW_SIZE (1 * BLOCK_SIZE)
// SOURCE_WINDOW_SIZE is one of the primary tunables. Higher values increase
// compression ratios and improve decoder speed, but consume more memory.
-#define SOURCE_WINDOW_SIZE (1U<<26)
+#define SOURCE_WINDOW_SIZE (8 * BLOCK_SIZE)
// WRITE_QUEUE_LENGTH * TARGET_WINDOW_SIZE must be >= SOURCE_WINDOW_SIZE / 2.
// This ensures that writes will always happen behind an area where a read
// might occur. This is enforced by the READ_FRONTIER check.
#define WRITE_QUEUE_LENGTH (4)
// READ_CACHE_LENGTH is defined based on the acceptability of a time/memory
-// tradeoff. A value of at least one is necessary to not completely suck, and
-// two or higher is recommended. Higher than 8 will probably not yield
+// tradeoff. A value of at least 6 is necessary to not completely suck, and
+// 8 or higher is recommended. Higher than 16 will probably not yield
// reasonable returns for realistic patches.
-#define READ_CACHE_LENGTH (2)
+#define READ_CACHE_LENGTH (8)
static uint8_t in[XZ_OUTPUT_SIZE];
static uint8_t out[XZ_OUTPUT_SIZE];
@@ -66,7 +69,7 @@
struct SourceRead {
size_t blkno;
size_t length;
- uint8_t data[SOURCE_WINDOW_SIZE];
+ uint8_t data[BLOCK_SIZE];
};
static SourceRead* READ_CACHE[READ_CACHE_LENGTH];
@@ -111,7 +114,7 @@
static size_t read_source_file(uint8_t *data, FILE *file) {
size_t size;
fflush(file);
- size = fread((void*)data, 1, SOURCE_WINDOW_SIZE, file);
+ size = fread((void*)data, 1, BLOCK_SIZE, file);
fflush(file);
return size;
}
@@ -333,7 +336,7 @@
memset(source, 0, sizeof(*source));
source->name = "source";
source->ioh = source_file;
- source->blksize = SOURCE_WINDOW_SIZE;
+ source->blksize = BLOCK_SIZE;
source->curblkno = 0;
source->curblk = NULL;
source->onblk = 0;
