[svn-r1585] Changes since 19990820

----------------------

./src/H5D.c
	Added additional elements to a variable initializer in
	H5Dvlen_get_buf_size() to shut up a warning message. Also
	added the API tracing call.

./src/H5F.c
	Added file opening optimizations. If the driver doesn't
	support the ability to determine when two file handles refer
	to the same file (like MPIO and GASS) then H5F_open() makes
	fewer calls to the driver's open callback.  Also, if the
	tentative file access flags are the same as the original flags
	then H5F_open() makes fewer calls to the file device.

./src/H5FD.c
./src/H5FDprivate.h
./src/H5FDpublic.h
	Added H5FD_get_class() so the library can get information
	about what file driver callbacks are defined. This will be
	useful when more optimization functions are added to the VFL,
	such as for MPIO derived datatype I/O.

./src/H5FDcore.c
./src/H5FDfamily.c
./src/H5FDmpio.c
./src/H5FDmulti.c
./src/H5FDsec2.c
	The driver symbols (like H5FD_CORE, etc) are actually function
	calls. The functions were fixed to return correct values even
	after calling H5close().

./src/H5FDmulti.c
./src/H5FDmulti.h
	Added support for opening a file when parts are missing (only
	if the caller explicitly allows that in the file access
	property list).

	Moved some common code sequences into macros or functions.

	Added better support for reopening files.  All the application
	has to know is that the file is a multi file and the base name
	from which all the member names are created.

	More debugging output when the file is opened with the
	H5F_ACC_DEBUG flag.

	Fixed various bugs.

./src/H5Fistore.c
	Chunked raw data was accidently allocated as meta data instead
	of raw data.

./src/H5I.c
	The H5Iget_type() function fails when invoked with an old
	object ID (an ID which has been closed down).

./test/h5test.c
	Added an extra argument when setting the multi file access
	property lists so the test fails if it can't open one of the
	sub-files.

./tools/h5ls.c
	Improved the algorithm for deciding what file driver to
	use. It basically tries all of the predefined drivers and is
	now able to open family, split, and multi files without
	looking for special characters in the file name.

	Added `-e' and `--errors' switches which cause errors from
	libhdf5 to be reported on stderr in addition to the simple
	error message displayed by h5ls.

1 files changed, 38 insertions, 9 deletions

diff --git a/src/H5F.c b/src/H5F.c
index e908625..dcbea3c 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -566,6 +566,7 @@ H5F_locate_signature(H5FD_t *file)
 		      "unable to obtain EOF/EOA value");
     }
     for (maxpow=0; addr; maxpow++) addr>>=1;
+    maxpow = MAX(maxpow, 9);
 
     /*
      * Search for the file signature at format address zero followed by
@@ -906,6 +907,13 @@ H5F_dest(H5F_t *f)
  *		Added decoding of file driver information block, which uses a
  *		formerly reserved address slot in the boot block in order to
  *		be compatible with previous versions of the file format.
+ *
+ * 		Robb Matzke, 1999-08-20
+ *		Optimizations for opening a file. If the driver can't
+ *		determine when two file handles refer to the same file then
+ *		we open the file in one step.  Otherwise if the first attempt
+ *		to open the file fails then we skip the second attempt if the
+ *		arguments would be the same.
  *-------------------------------------------------------------------------
  */
 H5F_t *
@@ -925,17 +933,41 @@ H5F_open(const char *name, uintn flags, hid_t fcpl_id, hid_t fapl_id)
     haddr_t		stored_eoa;	/*relative end-of-addr in file	*/
     uintn		tent_flags;	/*tentative flags		*/
     char		driver_name[9];	/*file driver name/version	*/
+    hbool_t		driver_has_cmp;	/*`cmp' callback defined?	*/
     
     FUNC_ENTER(H5F_open, NULL);
 
     /*
-     * Open the file very carefully because we don't want to wipe out a file
-     * which is currently open (which is possible if this call specifies
-     * truncation of an existing file).  So turn off truncation and file
-     * creation and try opening it. If that fails then open as normal.
+     * If the driver has a `cmp' method then the driver is capable of
+     * determining when two file handles refer to the same file and the
+     * library can insure that when the application opens a file twice that
+     * the two handles coordinate their operations appropriately. Otherwise
+     * it is the application's responsibility to never open the same file
+     * more than once at a time.
+     */
+    driver_has_cmp = H5FD_has_cmp(fapl_id);
+
+    /*
+     * Opening a file is a two step process. First we try to open the file in
+     * a way which doesn't affect its state (like not truncating or creating
+     * it) so we can compare it with files that are already open. If that
+     * fails then we try again with the full set of flags (only if they're
+     * different than the original failed attempt). However, if the file
+     * driver can't distinquish between files then there's no reason to open
+     * the file tentatively because it's the application's responsibility to
+     * prevent this situation (there's no way for us to detect it here
+     * anyway).
      */
-    tent_flags = flags & ~(H5F_ACC_CREAT|H5F_ACC_TRUNC|H5F_ACC_EXCL);
+    if (driver_has_cmp) {
+	tent_flags = flags & ~(H5F_ACC_CREAT|H5F_ACC_TRUNC|H5F_ACC_EXCL);
+    } else {
+	tent_flags = flags;
+    }
     if (NULL==(lf=H5FD_open(name, tent_flags, fapl_id, HADDR_UNDEF))) {
+	if (tent_flags == flags) {
+	    HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL,
+			"unable to open file");
+	}
 	H5E_clear();
 	tent_flags = flags;
 	if (NULL==(lf=H5FD_open(name, tent_flags, fapl_id, HADDR_UNDEF))) {
@@ -1223,10 +1255,7 @@ H5F_open(const char *name, uintn flags, hid_t fcpl_id, hid_t fapl_id)
     ret_value = file;
 
  done:
-    if (!ret_value) {
-	if (file) H5F_dest(file);
-	if (lf) H5FD_close(lf);
-    }
+    if (!ret_value && file) H5F_dest(file);
     FUNC_LEAVE(ret_value);
 }