Implemented a primitive single tile cache for image reading

libisoburn/data_source.c

@@ -4,8 +4,10 @@
   Copyright 2007 Vreixo Formoso Lopes <metalpain2002@yahoo.es>
 */
 
-#include <assert.h>
 #include <stdlib.h>
+#include <string.h>
+
+#include <stdio.h>
 
 
 #ifndef Xorriso_standalonE
@@ -24,6 +26,81 @@
 
 #include "isoburn.h"
 
+
+/* Cached reading of image tree data */
+/* Current implementation : single tile 128 kB */
+
+/* powers of 2 only ! */
+#define Libisoburn_cache_blockS 64
+
+struct isoburn_cached_drive {
+ struct burn_drive *drive;
+
+ char cache_data[Libisoburn_cache_blockS * 2048];
+ uint32_t cache_lba;
+ int cache_hits;
+};
+
+
+/* Debugging only: This reports cache loads on stderr.
+#define Libisoburn_read_cache_reporT 1
+*/
+#define Libisoburn_read_cache_experimenT
+
+#ifdef Libisoburn_read_cache_experimenT
+
+int 
+ds_read_block(IsoDataSource *src, uint32_t lba, uint8_t *buffer)
+{
+ int ret;
+ struct burn_drive *d;
+ off_t count;
+ uint32_t aligned_lba;
+
+ struct isoburn_cached_drive *icd;
+
+ if(src == NULL || buffer == NULL)
+   return -1;
+
+ icd = (struct isoburn_cached_drive *) src->data;
+ d = (struct burn_drive*) icd->drive;
+
+ aligned_lba= lba & ~(Libisoburn_cache_blockS - 1);
+ if(aligned_lba == icd->cache_lba && icd->cache_lba != 0xffffffff) {
+   (icd->cache_hits)++;
+   memcpy(buffer, icd->cache_data + (lba - aligned_lba) * 2048, 2048);
+   count= 2048;
+   return 1;
+ } 
+
+ icd->cache_lba= 0xffffffff; /* invalidate cache */
+ ret = burn_read_data(d, (off_t) aligned_lba * (off_t) 2048,
+                      (char *) icd->cache_data,
+                      Libisoburn_cache_blockS * 2048, &count, 0);
+ if (ret <= 0 ) {
+   /* Read-ahead failure ? Try to read 2048 directly. */
+   ret = burn_read_data(d, (off_t) lba * (off_t) 2048, (char *) buffer,
+                        2048, &count, 0);
+   if (ret > 0)
+     return 1;
+   return -1;
+ }
+
+#ifdef Libisoburn_read_cache_reporT
+ fprintf(stderr, "After %3d hits, new load from %8x , count= %d\n",
+         icd->cache_hits, aligned_lba, (int) count);
+#endif
+
+ icd->cache_lba= aligned_lba;
+ icd->cache_hits= 1;
+ memcpy(buffer, icd->cache_data + (lba - aligned_lba) * 2048, 2048);
+ count= 2048;
+
+ return 1;
+}
+
+#else /* Libisoburn_read_cache_experimenT */
+
 static int 
 ds_read_block(IsoDataSource *src, uint32_t lba, uint8_t *buffer)
 {
@@ -31,9 +108,10 @@ ds_read_block(IsoDataSource *src, uint32_t lba, uint8_t *buffer)
  struct burn_drive *d;
  off_t count;
 
- assert(src && buffer);
+ if(src == NULL || buffer == NULL)
+   return -1;
 
- d = (struct burn_drive*)src->data;
+ d = (struct burn_drive*) ((struct isoburn_cached_drive *) src->data)->drive;
 
  ret = burn_read_data(d, (off_t) lba * (off_t) 2048, (char *) buffer,
                       2048, &count, 0);
@@ -42,6 +120,9 @@ ds_read_block(IsoDataSource *src, uint32_t lba, uint8_t *buffer)
 
  return 1;
 }
+
+#endif /* ! Libisoburn_read_cache_experimenT */
+
 	
 static int
 ds_open(IsoDataSource *src)
@@ -67,17 +148,23 @@ IsoDataSource *
 isoburn_data_source_new(struct burn_drive *d)
 {
  IsoDataSource *ret;
+ struct isoburn_cached_drive *icd= NULL;
+
  if (d==NULL)
    return NULL;
  ret = malloc(sizeof(IsoDataSource));
- if (!ret)
+ icd = calloc(1,sizeof(struct isoburn_cached_drive));
+ if (ret == NULL || icd == NULL)
    return NULL;
  ret->refcount = 1;
  ret->read_block = ds_read_block;
  ret->open = ds_open;
  ret->close = ds_close;
  ret->free_data = ds_free_data;
- ret->data = d;
+ ret->data = icd;
+ icd->drive = d;
+ icd->cache_lba = 0xffffffff;
+ icd->cache_hits = 0;
  return ret;
 }
 

xorriso/xorriso_timestamp.h

@@ -1 +1 @@
-#define Xorriso_timestamP "2008.02.07.074248"
+#define Xorriso_timestamP "2008.02.07.154947"