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hdf5/src/H5Fefc.c
Quincey Koziol 9c9ee2008c [svn-r21919] Description: 
Refactor function name macros and simplify the FUNC_ENTER macros, to clear
away the cruft and prepare for further cleanups.

Tested on:
    Mac OSX/64 10.7.3 (amazon) w/debug, production & parallel
2012-02-08 22:13:27 -05:00

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the files COPYING and Copyright.html. COPYING can be found at the root *
* of the source code distribution tree; Copyright.html can be found at the *
* root level of an installed copy of the electronic HDF5 document set and *
* is linked from the top-level documents page. It can also be found at *
* http://hdfgroup.org/HDF5/doc/Copyright.html. If you do not have *
* access to either file, you may request a copy from help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*-------------------------------------------------------------------------
*
* Created: H5Defc.c
* December 13, 2010
* Neil Fortner <nfortne2@hdfgroup.org>
*
* Purpose: External file caching routines - implements a
* cache of external files to minimize the number of
* file opens and closes.
*
*-------------------------------------------------------------------------
*/
#define H5F_PACKAGE /*suppress error about including H5Fpkg */
/* Packages needed by this file... */
#include "H5private.h" /* Generic Functions */
#include "H5Eprivate.h" /* Error handling */
#include "H5Fpkg.h" /* File access */
#include "H5MMprivate.h" /* Memory management */
#include "H5Pprivate.h" /* Property lists */
/* Special values for the "tag" field below */
#define H5F_EFC_TAG_DEFAULT -1
#define H5F_EFC_TAG_LOCK -2
#define H5F_EFC_TAG_CLOSE -3
#define H5F_EFC_TAG_DONTCLOSE -4
/* Structure for each entry in a file's external file cache */
typedef struct H5F_efc_ent_t {
char *name; /* Name of the file */
H5F_t *file; /* File object */
struct H5F_efc_ent_t *LRU_next; /* Next item in LRU list */
struct H5F_efc_ent_t *LRU_prev; /* Previous item in LRU list */
unsigned nopen; /* Number of times this file is currently opened by an EFC client */
} H5F_efc_ent_t;
/* Structure for a shared file struct's external file cache */
struct H5F_efc_t {
H5SL_t *slist; /* Skip list of cached external files */
H5F_efc_ent_t *LRU_head; /* Head of LRU list. This is the least recently used file */
H5F_efc_ent_t *LRU_tail; /* Tail of LRU list. This is the most recently used file */
unsigned nfiles; /* Size of the external file cache */
unsigned max_nfiles; /* Maximum size of the external file cache */
unsigned nrefs; /* Number of times this file appears in another file's EFC */
int tag; /* Temporary variable used by H5F_efc_try_close() */
H5F_file_t *tmp_next; /* Next file in temporary list used by H5F_efc_try_close() */
};
/* Private prototypes */
static herr_t H5F_efc_remove_ent(H5F_efc_t *efc, H5F_efc_ent_t *ent);
static void H5F_efc_try_close_tag1(H5F_file_t *sf, H5F_file_t **tail);
static void H5F_efc_try_close_tag2(H5F_file_t *sf, H5F_file_t **tail);
/* Free lists */
H5FL_DEFINE_STATIC(H5F_efc_ent_t);
H5FL_DEFINE_STATIC(H5F_efc_t);
/*-------------------------------------------------------------------------
* Function: H5F_efc_create
*
* Purpose: Allocate and initialize a new external file cache object,
* which can the be used to cache open external files.
* the object must be freed with H5F_efc_destroy.
*
* Return: Pointer to new external file cache object on success
* NULL on failure
*
* Programmer: Neil Fortner
* Tuesday, December 14, 2010
*
*-------------------------------------------------------------------------
*/
H5F_efc_t *
H5F_efc_create(unsigned max_nfiles)
{
H5F_efc_t *efc = NULL; /* EFC object */
H5F_efc_t *ret_value; /* Return value */
FUNC_ENTER_NOAPI(NULL)
/* Sanity checks */
HDassert(max_nfiles > 0);
/* Allocate EFC struct */
if(NULL == (efc = H5FL_CALLOC(H5F_efc_t)))
HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
/* Initialize maximum number of files */
efc->max_nfiles = max_nfiles;
/* Initialize temporary ref count */
efc->tag = H5F_EFC_TAG_DEFAULT;
/* Set the return value */
ret_value = efc;
done:
if(ret_value == NULL && efc)
efc = H5FL_FREE(H5F_efc_t, efc);
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_efc_create() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_open
*
* Purpose: Opens a file using the external file cache. The target
* file is added to the external file cache of the parent
* if it is not already present. If the target file is in
* the parent's EFC, simply returns the target file. When
* the file object is no longer in use, it should be closed
* with H5F_efc_close (will not actually close the file
* until it is evicted from the EFC).
*
* Return: Pointer to open file on success
* NULL on failure
*
* Programmer: Neil Fortner
* Tuesday, December 14, 2010
*
*-------------------------------------------------------------------------
*/
H5F_t *
H5F_efc_open(H5F_t *parent, const char *name, unsigned flags, hid_t fcpl_id,
hid_t fapl_id, hid_t dxpl_id)
{
H5F_efc_t *efc = NULL; /* External file cache for parent file */
H5F_efc_ent_t *ent = NULL; /* Entry for target file in efc */
hbool_t open_file = FALSE; /* Whether ent->file needs to be closed in case of error */
H5F_t *ret_value = NULL; /* Return value */
FUNC_ENTER_NOAPI_NOINIT
/* Sanity checks */
HDassert(parent);
HDassert(parent->shared);
HDassert(name);
/* Get external file cache */
efc = parent->shared->efc;
/* Check if the EFC exists. If it does not, just call H5F_open(). We
* support this so clients do not have to make 2 different calls depending
* on the state of the efc. */
if(!efc) {
if(NULL == (ret_value = H5F_open(name, flags, fcpl_id, fapl_id,
dxpl_id)))
HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "can't open file")
/* Increment the number of open objects to prevent the file from being
* closed out from under us - "simulate" having an open file id. Note
* that this behaviour replaces the calls to H5F_incr_nopen_objs() and
* H5F_decr_nopen_objs() in H5L_extern_traverse(). */
ret_value->nopen_objs++;
HGOTO_DONE(ret_value)
} /* end if */
/* Search the skip list for name if the skip list exists, create the skip
* list otherwise */
if(efc->slist) {
if(efc->nfiles > 0)
ent = (H5F_efc_ent_t *)H5SL_search(efc->slist, name);
} /* end if */
else {
HDassert(efc->nfiles == 0);
if(NULL == (efc->slist = H5SL_create(H5SL_TYPE_STR, NULL)))
HGOTO_ERROR(H5E_FILE, H5E_CANTCREATE, NULL, "can't create skip list")
} /* end else */
/* If we found the file update the LRU list and return the cached file,
* otherwise open the file and cache it */
if(ent) {
HDassert(efc->LRU_head);
HDassert(efc->LRU_tail);
/* Move ent to the head of the LRU list, if it is not already there */
if(ent->LRU_prev) {
HDassert(efc->LRU_head != ent);
/* Remove from current position. Note that once we touch the LRU
* list we cannot revert to the previous state. Make sure there can
* be no errors between when we first touch the LRU list and when
* the cache is in a consistent state! */
if(ent->LRU_next)
ent->LRU_next->LRU_prev = ent->LRU_prev;
else {
HDassert(efc->LRU_tail == ent);
efc->LRU_tail = ent->LRU_prev;
} /* end else */
ent->LRU_prev->LRU_next = ent->LRU_next;
/* Add to head of LRU list */
ent->LRU_next = efc->LRU_head;
ent->LRU_next->LRU_prev = ent;
ent->LRU_prev = NULL;
efc->LRU_head = ent;
} /* end if */
/* Mark the file as open */
ent->nopen++;
} /* end if */
else {
/* Check if we need to evict something */
if(efc->nfiles == efc->max_nfiles) {
/* Search for an unopened file from the tail */
for(ent = efc->LRU_tail; ent && ent->nopen; ent = ent->LRU_prev);
/* Evict the file if found, otherwise just open the target file and
* do not add it to cache */
if(ent) {
if(H5F_efc_remove_ent(efc, ent) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTREMOVE, NULL, "can't remove entry from external file cache")
/* Do not free ent, we will recycle it below */
} /* end if */
else {
/* Cannot cache file, just open file and return */
if(NULL == (ret_value = H5F_open(name, flags, fcpl_id, fapl_id,
dxpl_id)))
HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "can't open file")
/* Increment the number of open objects to prevent the file from
* being closed out from under us - "simulate" having an open
* file id */
ret_value->nopen_objs++;
HGOTO_DONE(ret_value)
} /* end else */
} /* end if */
else
/* Allocate new entry */
if(NULL == (ent = H5FL_MALLOC(H5F_efc_ent_t)))
HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
/* Build new entry */
if(NULL == (ent->name = H5MM_strdup(name)))
HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
/* Open the file */
if(NULL == (ent->file = H5F_open(name, flags, fcpl_id, fapl_id,
dxpl_id)))
HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "can't open file")
open_file = TRUE;
/* Increment the number of open objects to prevent the file from being
* closed out from under us - "simulate" having an open file id */
ent->file->nopen_objs++;
/* Add the file to the cache */
/* Skip list */
if(H5SL_insert(efc->slist, ent, ent->name) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTINSERT, NULL, "can't insert entry into skip list")
/* Add to head of LRU list and update tail if necessary */
ent->LRU_next = efc->LRU_head;
if(ent->LRU_next)
ent->LRU_next->LRU_prev = ent;
ent->LRU_prev = NULL;
efc->LRU_head = ent;
if(!efc->LRU_tail) {
HDassert(!ent->LRU_next);
efc->LRU_tail = ent;
} /* end if */
/* Mark the file as open */
ent->nopen = 1;
/* Update nfiles and nrefs */
efc->nfiles++;
if(ent->file->shared->efc)
ent->file->shared->efc->nrefs++;
} /* end else */
HDassert(ent);
HDassert(ent->file);
HDassert(ent->name);
HDassert(ent->nopen);
/* Set the return value */
ret_value = ent->file;
done:
if(!ret_value)
if(ent) {
if(open_file) {
ent->file->nopen_objs--;
if(H5F_try_close(ent->file) < 0)
HDONE_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, NULL, "can't close external file")
} /* end if */
ent->name = (char *)H5MM_xfree(ent->name);
ent = H5FL_FREE(H5F_efc_ent_t, ent);
} /* end if */
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_efc_open() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_close
*
* Purpose: Closes (unlocks) a file opened using the external file
* cache. The target file is not immediately closed unless
* there is no external file cache for the parent file.
*
* Return: Non-negative on success
* Negative on failure
*
* Programmer: Neil Fortner
* Wednesday, December 15, 2010
*
*-------------------------------------------------------------------------
*/
herr_t
H5F_efc_close(H5F_t *parent, H5F_t *file)
{
H5F_efc_t *efc = NULL; /* External file cache for parent file */
H5F_efc_ent_t *ent = NULL; /* Entry for target file in efc */
herr_t ret_value = SUCCEED; /* Return value */
FUNC_ENTER_NOAPI_NOINIT
/* Sanity checks */
HDassert(parent);
HDassert(parent->shared);
HDassert(file);
HDassert(file->shared);
/* Get external file cache */
efc = parent->shared->efc;
/* Check if the EFC exists. If it does not, just call H5F_try_close(). We
* support this so clients do not have to make 2 different calls depending
* on the state of the efc. */
if(!efc) {
file->nopen_objs--;
if(H5F_try_close(file) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "can't close external file")
HGOTO_DONE(SUCCEED)
} /* end if */
/* Scan the parent's LRU list from the head to file file. We do this
* instead of a skip list lookup because the file will almost always be at
* the head. In the unlikely case that the file is not found, just call
* H5F_try_close(). This could happen if the EFC was full of open files
* when the file was opened. */
for(ent = efc->LRU_head; ent && ent->file != file; ent = ent->LRU_next);
if(!ent) {
file->nopen_objs--;
if(H5F_try_close(file) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "can't close external file")
} /* end if */
else
/* Reduce the open count on this entry */
ent->nopen--;
done:
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_efc_close() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_max_nfiles
*
* Purpose: Returns the maximum number of files in the provided
* external file cache.
*
* Return: Maximum number of files (never fails)
*
* Programmer: Neil Fortner
* Wednesday, December 15, 2010
*
*-------------------------------------------------------------------------
*/
unsigned
H5F_efc_max_nfiles(H5F_efc_t *efc)
{
FUNC_ENTER_NOAPI_NOINIT_NOERR
HDassert(efc);
HDassert(efc->max_nfiles > 0);
FUNC_LEAVE_NOAPI(efc->max_nfiles)
} /* end H5F_efc_max_nfiles */
/*-------------------------------------------------------------------------
* Function: H5F_efc_release
*
* Purpose: Releases the external file cache, potentially closing any
* cached files unless they are held open from somewhere
* else (or are currently opened by a client).
*
* Return: Non-negative on success
* Negative on failure
*
* Programmer: Neil Fortner
* Wednesday, December 15, 2010
*
*-------------------------------------------------------------------------
*/
herr_t
H5F_efc_release(H5F_efc_t *efc)
{
H5F_efc_ent_t *ent = NULL; /* EFC entry */
H5F_efc_ent_t *prev_ent = NULL; /* Previous EFC entry */
herr_t ret_value = SUCCEED; /* Return value */
FUNC_ENTER_NOAPI_NOINIT
/* Sanity checks */
HDassert(efc);
/* Lock the EFC to prevent manipulation of the EFC wile we are releasing it.
* The EFC should never be locked when we enter this function because that
* would require a cycle, a cycle would necessarily invoke
* H5F_efc_try_close(), and that function checks the status of the lock
* before calling this one. */
HDassert((efc->tag == H5F_EFC_TAG_DEFAULT)
|| (efc->tag == H5F_EFC_TAG_CLOSE));
efc->tag = H5F_EFC_TAG_LOCK;
/* Walk down the LRU list, releasing any files that are not opened by an EFC
* client */
ent = efc->LRU_head;
while(ent)
if(!ent->nopen) {
if(H5F_efc_remove_ent(efc, ent) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTREMOVE, FAIL, "can't remove entry from external file cache")
/* Free the entry and move to next entry in LRU list */
prev_ent = ent;
ent = ent->LRU_next;
prev_ent = H5FL_FREE(H5F_efc_ent_t, prev_ent);
} /* end if */
else
/* Can't release file because it's open; just advance the pointer */
ent = ent->LRU_next;
/* Reset tag. No need to reset to CLOSE if that was the original tag, as in
* that case the file must be getting closed anyways. */
efc->tag = H5F_EFC_TAG_DEFAULT;
done:
FUNC_LEAVE_NOAPI(ret_value);
} /* end H5F_efc_release() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_destroy
*
* Purpose: Frees an external file cache object, releasing it first
* if necessary. If it cannot be fully released, for example
* if there are open files, returns an error.
*
* Return: Non-negative on success
* Negative on failure
*
* Programmer: Neil Fortner
* Wednesday, December 15, 2010
*
*-------------------------------------------------------------------------
*/
herr_t
H5F_efc_destroy(H5F_efc_t *efc)
{
herr_t ret_value = SUCCEED; /* Return value */
FUNC_ENTER_NOAPI_NOINIT
/* Sanity checks */
HDassert(efc);
if(efc->nfiles > 0) {
/* Release (clear) the efc */
if(H5F_efc_release(efc) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "can't release external file cache")
/* If there are still cached files, return an error */
if(efc->nfiles > 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTFREE, FAIL, "can't destroy EFC after incomplete release")
} /* end if */
HDassert(efc->nfiles == 0);
HDassert(efc->LRU_head == NULL);
HDassert(efc->LRU_tail == NULL);
/* Close skip list */
if(efc->slist)
if(H5SL_close(efc->slist) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTFREE, FAIL, "can't close skip list")
/* Free EFC object */
(void)H5FL_FREE(H5F_efc_t, efc);
done:
FUNC_LEAVE_NOAPI(ret_value);
} /* end H5F_efc_destroy() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_remove_ent
*
* Purpose: Removes the specified entry from the specified EFC,
* closing the file if requested. Does not free the entry.
*
* Return: Non-negative on success
* Negative on failure
*
* Programmer: Neil Fortner
* Wednesday, December 15, 2010
*
*-------------------------------------------------------------------------
*/
static herr_t
H5F_efc_remove_ent(H5F_efc_t *efc, H5F_efc_ent_t *ent)
{
herr_t ret_value = SUCCEED; /* Return value */
FUNC_ENTER_NOAPI_NOINIT
/* Sanity checks */
HDassert(efc);
HDassert(efc->slist);
HDassert(ent);
/* Remove from skip list */
if(ent != H5SL_remove(efc->slist, ent->name))
HGOTO_ERROR(H5E_FILE, H5E_CANTDELETE, FAIL, "can't delete entry from skip list")
/* Remove from LRU list */
if(ent->LRU_next)
ent->LRU_next->LRU_prev = ent->LRU_prev;
else {
HDassert(efc->LRU_tail == ent);
efc->LRU_tail = ent->LRU_prev;
} /* end else */
if(ent->LRU_prev)
ent->LRU_prev->LRU_next = ent->LRU_next;
else {
HDassert(efc->LRU_head == ent);
efc->LRU_head = ent->LRU_next;
} /* end else */
/* Update nfiles and nrefs */
efc->nfiles--;
if(ent->file->shared->efc)
ent->file->shared->efc->nrefs--;
/* Free the name */
ent->name = (char *)H5MM_xfree(ent->name);
/* Close the file. Note that since H5F_t structs returned from H5F_open()
* are *always* unique, there is no need to reference count this struct.
* However we must still manipulate the nopen_objs field to prevent the file
* from being closed out from under us. */
ent->file->nopen_objs--;
if(H5F_try_close(ent->file) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "can't close external file")
ent->file = NULL;
done:
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_efc_remove_ent() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_try_close_tag1
*
* Purpose: Recursively traverse the EFC tree, keeping a temporary
* reference count on each file that assumes all reachable
* files will eventually be closed.
*
* Return: void (never fails)
*
* Programmer: Neil Fortner
* Monday, January 10, 2011
*
*-------------------------------------------------------------------------
*/
static void
H5F_efc_try_close_tag1(H5F_file_t *sf, H5F_file_t **tail)
{
H5F_efc_ent_t *ent = NULL; /* EFC entry */
H5F_file_t *esf; /* Convenience pointer to ent->file->shared */
FUNC_ENTER_NOAPI_NOINIT_NOERR
/* Sanity checks */
HDassert(sf);
HDassert(sf->efc);
HDassert((sf->efc->tag > 0) || (sf->nrefs == sf->efc->nrefs));
HDassert(sf->efc->tag != H5F_EFC_TAG_LOCK);
HDassert(tail);
HDassert(*tail);
/* Recurse into this file's cached files */
for(ent = sf->efc->LRU_head; ent; ent = ent->LRU_next) {
esf = ent->file->shared;
if(esf->efc) {
/* If tag were 0, that would mean there are more actual references
* than are counted by nrefs */
HDassert(esf->efc->tag != 0);
/* If tag has been set, we have already visited this file so just
* decrement tag and continue */
if(esf->efc->tag > 0)
esf->efc->tag--;
/* If there are references that are not from an EFC, it will never
* be possible to close the file. Just continue. Also continue if
* the EFC is locked or the file is open (through the EFC). Note
* that the reference counts will never match for the root file, but
* that's ok because the root file will always have a tag and enter
* the branch above. */
else if((esf->nrefs == esf->efc->nrefs)
&& (esf->efc->tag != H5F_EFC_TAG_LOCK) && !(ent->nopen)) {
/* If we get here, this file's "tmp_next" pointer must be NULL
*/
HDassert(esf->efc->tmp_next == NULL);
/* If nrefs > 1, Add this file to the list of files with nrefs >
* 1 and initialize tag to the number of references (except this
* one) */
if(esf->nrefs > 1) {
(*tail)->efc->tmp_next = esf;
*tail = esf;
esf->efc->tag = (int)esf->nrefs - 1;
} /* end if */
/* Recurse into the entry */
H5F_efc_try_close_tag1(ent->file->shared, tail);
} /* end if */
} /* end if */
} /* end for */
FUNC_LEAVE_NOAPI_VOID
} /* end H5F_efc_try_close_tag1() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_try_close_tag2
*
* Purpose: Recuresively mark all files reachable through this one as
* uncloseable, and add newly uncloseable files to the tail
* of the provided linked list.
*
* Return: void (never fails)
*
* Programmer: Neil Fortner
* Monday, January 10, 2011
*
*-------------------------------------------------------------------------
*/
static void
H5F_efc_try_close_tag2(H5F_file_t *sf, H5F_file_t **tail)
{
H5F_efc_ent_t *ent = NULL; /* EFC entry */
H5F_file_t *esf; /* Convenience pointer to ent->file->shared */
FUNC_ENTER_NOAPI_NOINIT_NOERR
/* Sanity checks */
HDassert(sf);
HDassert(sf->efc);
/* Recurse into this file's cached files */
for(ent = sf->efc->LRU_head; ent; ent = ent->LRU_next) {
esf = ent->file->shared;
/* Only recurse if the file is tagged CLOSE or DEFAULT. If it is tagged
* DONTCLOSE, we have already visited this file *or* it will be the
* start point of another iteration. No files should be tagged with a
* nonegative value at this point. If it is tagged as DEFAULT, we must
* apply the same conditions as in cb1 above for recursion in order to
* make sure we do not go off into somewhere cb1 didn't touch. The
* root file should never be tagged DEFAULT here, so the reference check
* is still appropriate. */
if((esf->efc) && ((esf->efc->tag == H5F_EFC_TAG_CLOSE)
|| ((esf->efc->tag == H5F_EFC_TAG_DEFAULT)
&& (esf->nrefs == esf->efc->nrefs) && !(ent->nopen)))) {
/* tag should always be CLOSE is nrefs > 1 or DEFAULT if nrefs == 1
* here */
HDassert(((esf->nrefs > 1)
&& ((esf->efc->tag == H5F_EFC_TAG_CLOSE)))
|| ((esf->nrefs == 1)
&& (esf->efc->tag == H5F_EFC_TAG_DEFAULT)));
/* If tag is set to DONTCLOSE, we have already visited this file
* *or* it will be the start point of another iteration so just
* continue */
if(esf->efc->tag != H5F_EFC_TAG_DONTCLOSE) {
/* If tag is CLOSE, set to DONTCLOSE and add to the list of
* uncloseable files. */
if(esf->efc->tag == H5F_EFC_TAG_CLOSE) {
esf->efc->tag = H5F_EFC_TAG_DONTCLOSE;
esf->efc->tmp_next = NULL;
(*tail)->efc->tmp_next = esf;
*tail = esf;
} /* end if */
/* Recurse into the entry */
H5F_efc_try_close_tag2(esf, tail);
} /* end if */
} /* end if */
} /* end for */
FUNC_LEAVE_NOAPI_VOID
} /* end H5F_efc_try_close_tag2() */
/*-------------------------------------------------------------------------
* Function: H5F_efc_try_close
*
* Purpose: Attempts to close the provided (shared) file by checking
* to see if the releasing the EFC would cause its reference
* count to drop to 0. Necessary to handle the case where
* chained EFCs form a cycle. Note that this function does
* not actually close the file (though it closes all children
* as appropriate), as that is left up to the calling
* function H5F_try_close().
*
* Because H5F_try_close() has no way of telling if it is
* called recursively from within this function, this
* function serves as both the root of iteration and the
* "callback" for the final pass (the one where the files are
* actually closed). The code for the callback case is at
* the top of this function; luckily it only consists of a
* (possible) call to H5F_efc_release().
*
* The algorithm basically consists of 3 passes over the EFC
* tree. The first pass assumes that every reachable file is
* closed, and keeps track of what the final reference count
* would be for every reachable file. The files are then
* tagged as either closeable or uncloseable based on whether
* this reference count drops to 0.
*
* The second pass initiates a traversal from each file
* marked as uncloseable in the first pass, and marks every
* file reachable from the initial uncloseable file as
* uncloseable. This eliminates files that were marked as
* closeable only because the first pass assumed that an
* uncloseable file would be closed.
*
* The final pass exploits the H5F_efc_release()->
* H5F_efc_remove_ent()->H5F_try_close()->H5F_efc_try_close()
* calling chain to recursively close the tree, but only the
* files that are still marked as closeable. All files
* marked as closeable have their EFCs released, and will
* eventually be closed when their last parent EFC is
* released (the last part is guaranteed to be true by the
* first 2 passes).
*
* Return: Non-negative on success
* Negative on failure
*
* Programmer: Neil Fortner
* Thursday, January 6, 2011
*
*-------------------------------------------------------------------------
*/
herr_t
H5F_efc_try_close(H5F_t *f)
{
H5F_file_t *tail; /* Tail of linked list of found files. Head will be f->shared. */
H5F_file_t *uncloseable_head = NULL; /* Head of linked list of files found to be uncloseable by the first pass */
H5F_file_t *uncloseable_tail = NULL; /* Tail of linked list of files found to be uncloseable by the first pass */
H5F_file_t *sf; /* Temporary file pointer */
H5F_file_t *next; /* Temporary file pointer */
herr_t ret_value = SUCCEED; /* Return value */
FUNC_ENTER_NOAPI_NOINIT
/* Sanity checks */
HDassert(f);
HDassert(f->shared);
HDassert(f->shared->efc);
HDassert(f->shared->nrefs > f->shared->efc->nrefs);
HDassert(f->shared->nrefs > 1);
HDassert(f->shared->efc->tag < 0);
if(f->shared->efc->tag == H5F_EFC_TAG_CLOSE) {
/* We must have reentered this function, and we should close this file.
* In actuality, we just release the EFC, the recursion should
* eventually reduce this file's reference count to 1 (though possibly
* not from this call to H5F_efc_release()). */
if(H5F_efc_release(f->shared->efc) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "can't release external file cache")
/* If we marked the file as closeable, there must be no open files in
* its EFC. This is because, in order to close an open child file, the
* client must keep a copy of the parent file open. The algorithm
* detect that the parent file is open (directly or through an EFC) and
* refuse to close it. Verify that all files were released from this
* EFC (i.e. none were open). */
HDassert(f->shared->efc->nfiles == 0);
HGOTO_DONE(SUCCEED)
} /* end if */
/* Conditions where we should not do anything and just return immediately */
/* If there are references that are not from an EFC or f, it will never
* be possible to close the file. Just return. Note that this holds true
* for the case that this file is being closed through H5F_efc_release()
* because that function (through H5F_efc_remove_ent()) decrements the EFC
* reference count before it calls H5F_try_close(). This may occur if this
* function is reentered. */
/* If the tag is H5F_EFC_TAG_DONTCLOSE, then we have definitely reentered
* this function, and this file has been marked as uncloseable, so we should
* not close/release it */
/* If nfiles is 0, then there is nothing to do. Just return. This may also
* occur on reentry (for example if this file was previously released). */
if((f->shared->nrefs != f->shared->efc->nrefs + 1)
|| (f->shared->efc->tag == H5F_EFC_TAG_DONTCLOSE)
|| (f->shared->efc->nfiles == 0))
/* We must have reentered this function, and we should not close this
* file. Just return. */
HGOTO_DONE(SUCCEED)
/* If the file EFC were locked, that should always mean that there exists
* a reference to this file that is not in an EFC (it may have just been
* removed from an EFC), and should have been caught by the above check */
/* If we get here then we must be beginning a new run. Make sure that the
* temporary variables in f->shared->efc are at the default value */
HDassert(f->shared->efc->tag == H5F_EFC_TAG_DEFAULT);
HDassert(f->shared->efc->tmp_next == NULL);
/* Set up linked list for traversal into EFC tree. f->shared is guaranteed
* to always be at the head. */
tail = f->shared;
/* Set up temporary reference count on root file */
f->shared->efc->tag = (int)f->shared->efc->nrefs;
/* First Pass: simulate closing all files reachable from this one, use "tag"
* field to keep track of final reference count for each file (including
* this one). Keep list of files with starting reference count > 1 (head is
* f->shared). */
H5F_efc_try_close_tag1(f->shared, &tail);
/* Check if f->shared->efc->tag dropped to 0. If it did not,
* we cannot close anything. Just reset temporary values and return. */
if(f->shared->efc->tag > 0) {
sf = f->shared;
while(sf) {
next = sf->efc->tmp_next;
sf->efc->tag = H5F_EFC_TAG_DEFAULT;
sf->efc->tmp_next = NULL;
sf = next;
} /* end while */
HGOTO_DONE(SUCCEED)
} /* end if */
/* Run through the linked list , separating into two lists, one with tag ==
* 0 and one with tag > 0. Mark them as either H5F_EFC_TAG_CLOSE or
* H5F_EFC_TAG_DONTCLOSE as appropriate. */
sf = f->shared;
tail = NULL;
while(sf) {
HDassert(sf->efc->tag >= 0);
next = sf->efc->tmp_next;
if(sf->efc->tag > 0) {
/* Remove from main list */
HDassert(tail);
tail->efc->tmp_next = sf->efc->tmp_next;
sf->efc->tmp_next = NULL;
/* Add to uncloseable list */
if(!uncloseable_head)
uncloseable_head = sf;
else
uncloseable_tail->efc->tmp_next = sf;
uncloseable_tail = sf;
/* Mark as uncloseable */
sf->efc->tag = H5F_EFC_TAG_DONTCLOSE;
} /* end if */
else {
sf->efc->tag = H5F_EFC_TAG_CLOSE;
tail = sf;
} /* end else */
sf = next;
} /* end while */
/* Second pass: Determine which of the reachable files found in pass 1
* cannot be closed by releasing the root file's EFC. Run through the
* uncloseable list, for each item traverse the files reachable through the
* EFC, mark the file as uncloseable, and add it to the list of uncloseable
* files (for cleanup). Use "tail" to store the original uncloseable tail
* so we know when to stop. We do not need to keep track of the closeable
* list any more. */
sf = uncloseable_head;
if(sf) {
tail = uncloseable_tail;
HDassert(tail);
while(sf != tail->efc->tmp_next) {
H5F_efc_try_close_tag2(sf, &uncloseable_tail);
sf = sf->efc->tmp_next;
} /* end while */
} /* end if */
/* If the root file's tag is still H5F_EFC_TAG_CLOSE, release its EFC. This
* should start the recursive release that should close all closeable files.
* Also, see the top of this function. */
if(f->shared->efc->tag == H5F_EFC_TAG_CLOSE) {
if(H5F_efc_release(f->shared->efc) < 0)
HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "can't release external file cache")
/* Make sure the file's reference count is now 1 and will be closed by
* H5F_dest(). */
HDassert(f->shared->nrefs == 1);
} /* end if */
/* Clean up uncloseable files (reset tag and tmp_next). All closeable files
* should have been closed, and therefore do not need to be cleaned up. */
if(uncloseable_head) {
sf = uncloseable_head;
while(sf) {
next = sf->efc->tmp_next;
HDassert(sf->efc->tag == H5F_EFC_TAG_DONTCLOSE);
sf->efc->tag = H5F_EFC_TAG_DEFAULT;
sf->efc->tmp_next = NULL;
sf = next;
} /* end while */
} /* end if */
done:
FUNC_LEAVE_NOAPI(ret_value)
} /* end H5F_efc_try_close() */
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