[svn-r117] Added "seek position caching" code to shared file-records, which trimmed 20%

off the run-time for the current tests.  (4.77s down to 3.89s)

2 files changed, 36 insertions, 8 deletions

diff --git a/src/H5F.c b/src/H5F.c
index 88e4581..25cb336 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -1295,14 +1295,20 @@ H5F_block_read (H5F_t *f, haddr_t addr, size_t size, void *buf)
    if (0==size) return 0;
    addr += f->shared->file_create_parms.userblock_size;
    
-   if (H5F_SEEK (f->shared->file_handle, addr)<0) {
-      /* low-level seek failure */
-      HRETURN_ERROR (H5E_IO, H5E_SEEKERROR, FAIL);
-   }
+  /* Check for switching file access operations or mis-placed seek offset */
+  if(f->shared->last_op!=OP_READ || f->shared->f_cur_off!=addr)
+    {
+      f->shared->last_op=OP_READ;
+      if (H5F_SEEK (f->shared->file_handle, addr)<0) {
+          /* low-level seek failure */
+          HRETURN_ERROR (H5E_IO, H5E_SEEKERROR, FAIL);
+        } /* end if */
+    } /* end if */
    if (H5F_READ (f->shared->file_handle, buf, size)<0) {
       /* low-level read failure */
       HRETURN_ERROR (H5E_IO, H5E_READERROR, FAIL);
    }
+   f->shared->f_cur_off=addr+size;
 
    FUNC_LEAVE (SUCCEED);
 }
@@ -1343,14 +1349,22 @@ H5F_block_write (H5F_t *f, haddr_t addr, size_t size, void *buf)
       /* no write intent */
       HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL);
    }
-   if (H5F_SEEK (f->shared->file_handle, addr)<0) {
-      /* low-level seek failure */
-      HRETURN_ERROR (H5E_IO, H5E_SEEKERROR, FAIL);
-   }
+
+  /* Check for switching file access operations or mis-placed seek offset */
+  if(f->shared->last_op!=OP_WRITE || f->shared->f_cur_off!=addr)
+    {
+      f->shared->last_op=OP_WRITE;
+      if (H5F_SEEK (f->shared->file_handle, addr)<0) {
+         /* low-level seek failure */
+         HRETURN_ERROR (H5E_IO, H5E_SEEKERROR, FAIL);
+      }
+    } /* end if */
+
    if (H5F_WRITE (f->shared->file_handle, buf, size)<0) {
       /* low-level write failure */
       HRETURN_ERROR (H5E_IO, H5E_WRITEERROR, FAIL);
    }
+   f->shared->f_cur_off=addr+size;
 
    FUNC_LEAVE (SUCCEED);
 }
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index 4165b1e..81f43ce 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -351,11 +351,25 @@ typedef struct H5F_search_t {
    ino_t	ino;		/* Unique file number on device		*/
 } H5F_search_t;
 
+/* For determining what the last file operation was */
+typedef enum
+  {
+      OP_UNKNOWN = 0,   /* Don't know what the last operation was (after fopen frex) */
+      OP_SEEK,          /* Last operation was a seek */
+      OP_WRITE,         /* Last operation was a write */
+      OP_READ           /* Last operation was a read */
+  }
+H5F_fileop_t;
+
 /*
  * Define the structure to store the file information for HDF5 files. One of
  * these structures is allocated per file, not per H5Fopen().
  */
 typedef struct H5F_file_t {
+   /* Seek caching info */
+   haddr_t       f_cur_off; /* Current location in the file */
+   H5F_fileop_t  last_op;   /* the last file operation performed */
+
    H5F_search_t	key;		/* The key for looking up files		*/
    uintn	flags;         	/* Access Permissions for file		*/
    hdf_file_t 	file_handle; 	/* File handle for actual I/O 		*/