Change H5F_open to perform deduplication of open VFDs in a more flexible way,

using the new routine H5FDdeduplicate().

Simplify H5F_open() a bit, pushing some of the configuration checks into the
SMWR VFD.  For example, check that page buffering is enabled in
H5FD_vfd_swmr_open() instead of in H5F_open().  Compare VFD SWMR configurations
in H5FD_vfd_swmr_dedup() instead of in H5F_open().

Clone the default file-access property list at a new file-access property list
ID, H5P_FILE_ACCESS_ANY_VFD.  The new ID is used to indicate that if the file
that's being opened is already open under an existing virtual file, and if that
virtual file would not ordinarily be opened with the default FAPL, then it's ok
to use that virtual file.

Add a new optional method, `dedup`, to H5FD_class_t, and use it to customize a
VFD's deduplication.

Customize the SWMR VFD's deduplication.  Make it honor H5P_FILE_ACCESS_ANY_VFD
Embed the VFD SWMR configuration in the H5FD_vfd_swmr_t to facilitate
comparison of configuration between new and old SWMR virtual files.

In H5F__sfile_search(), match using a pointer comparison instead of H5FD_cmp(),
because we will only ever enter H5F__sfile_search() with a deduplicated
H5FD_t *.

1 files changed, 89 insertions, 27 deletions

diff --git a/src/H5FDvfd_swmr.c b/src/H5FDvfd_swmr.c
index a7b6d33..f0e0cfd 100644
--- a/src/H5FDvfd_swmr.c
+++ b/src/H5FDvfd_swmr.c
@@ -58,6 +58,7 @@ typedef struct H5FD_vfd_swmr_t {
                                                 /* when the page buffer is    */
                                                 /* and to FALSE otherwise.    */
                                                 /* Used for sanity checking.  */
+    H5F_vfd_swmr_config_t config;
     bool writer;                            /* True iff configured to write. */
 } H5FD_vfd_swmr_t;
 
@@ -69,6 +70,7 @@ static H5FD_t *H5FD_vfd_swmr_open(const char *name, unsigned flags,
     hid_t fapl_id, haddr_t maxaddr);
 static herr_t H5FD_vfd_swmr_close(H5FD_t *_file);
 static int H5FD_vfd_swmr_cmp(const H5FD_t *_f1, const H5FD_t *_f2);
+static H5FD_t *H5FD_vfd_swmr_dedup(H5FD_t *, H5FD_t *, hid_t);
 static herr_t H5FD_vfd_swmr_query(const H5FD_t *_f1, unsigned long *flags);
 static haddr_t H5FD_vfd_swmr_get_eoa(const H5FD_t *_file, H5FD_mem_t type);
 static herr_t H5FD_vfd_swmr_set_eoa(H5FD_t *_file, H5FD_mem_t type,
@@ -130,6 +132,7 @@ static const H5FD_class_t H5FD_vfd_swmr_g = {
     H5FD_vfd_swmr_truncate,     /* truncate             */
     H5FD_vfd_swmr_lock,         /* lock                 */
     H5FD_vfd_swmr_unlock,       /* unlock               */
+    H5FD_vfd_swmr_dedup,        /* dedup               */
     H5FD_FLMAP_DICHOTOMY        /* fl_map               */
 };
 
@@ -250,15 +253,14 @@ done:
 } /* end H5Pset_fapl_vfd_swmr() */
 
 static herr_t
-H5FD__swmr_reader_open(H5FD_vfd_swmr_t *file, H5F_vfd_swmr_config_t *vfd_swmr_config)
+H5FD__swmr_reader_open(H5FD_vfd_swmr_t *file)
 {
     h5_retry_t retry;                        /* retry state */
     bool do_try;                             /* more tries remain */
     herr_t      ret_value = SUCCEED;
-
     FUNC_ENTER_STATIC
 
-    file->api_elapsed_nslots = vfd_swmr_config->max_lag + 1;
+    file->api_elapsed_nslots = file->config.max_lag + 1;
 
     file->api_elapsed_ticks =
         calloc(file->api_elapsed_nslots, sizeof(*file->api_elapsed_ticks));
@@ -311,30 +313,30 @@ static H5FD_t *
 H5FD_vfd_swmr_open(const char *name, unsigned flags, hid_t fapl_id,
     haddr_t maxaddr)
 {
-    H5FD_vfd_swmr_t *file = NULL;            /* VFD SWMR driver info        */
-    H5P_genplist_t *plist;                   /* Property list pointer       */
-    H5F_vfd_swmr_config_t *vfd_swmr_config = /* Points to VFD SWMR          */
-        NULL;                                /* configuration               */
+    H5FD_vfd_swmr_t *file = NULL;
+    size_t page_buf_size;
+    H5P_genplist_t *plist;
+    H5F_vfd_swmr_config_t *vfd_swmr_config;
     H5FD_t *ret_value  = NULL;               /* Return value     */
 
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Get file access property list */
-    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
-
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, \
-                    "not a file access property list")
-
-    /* Allocate buffer for reading the VFD SWMR configuration */
-    if(NULL == (vfd_swmr_config = H5MM_malloc(sizeof(H5F_vfd_swmr_config_t)))) {
-        HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, NULL,
-                    "memory allocation failed for H5F_vfd_swmr_config_t");
+    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id))) {
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL,
+                    "not a file access property list");
     }
 
-    /* Get VFD SWMR configuration */
-    if(H5P_get(plist, H5F_ACS_VFD_SWMR_CONFIG_NAME, vfd_swmr_config) < 0) {
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL,
-                    "can't get VFD SWMR config info");
+    if (H5P_get(plist, H5F_ACS_PAGE_BUFFER_SIZE_NAME, &page_buf_size) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "can't get page buffer size");
+
+    /* Paged allocation, too, has to be enabled, but the page buffer
+     * initialization (H5PB_create) will detect a conflicting configuration
+     * and return an error.
+     */
+    if (page_buf_size == 0) {
+        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL,
+            "page buffering must be enabled");
     }
 
     /* Create the new driver struct */
@@ -343,6 +345,14 @@ H5FD_vfd_swmr_open(const char *name, unsigned flags, hid_t fapl_id,
                     "unable to allocate file struct");
     }
 
+    vfd_swmr_config = &file->config;
+
+    /* Get VFD SWMR configuration */
+    if(H5P_get(plist, H5F_ACS_VFD_SWMR_CONFIG_NAME, vfd_swmr_config) < 0) {
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL,
+                    "can't get VFD SWMR config info");
+    }
+
     file->md_fd = -1;
     file->hdf5_file_lf = NULL;
     file->md_pages_reserved = vfd_swmr_config->md_pages_reserved;
@@ -359,8 +369,7 @@ H5FD_vfd_swmr_open(const char *name, unsigned flags, hid_t fapl_id,
     file->writer = vfd_swmr_config->writer;
 
     /* Ensure that this is the reader */
-    if (!vfd_swmr_config->writer &&
-        H5FD__swmr_reader_open(file, vfd_swmr_config) < 0) {
+    if (!vfd_swmr_config->writer && H5FD__swmr_reader_open(file) < 0) {
         HGOTO_ERROR(H5E_VFL, H5E_OPENERROR, NULL,
                    "perform reader-specific opening steps failed");
     }
@@ -384,13 +393,9 @@ H5FD_vfd_swmr_open(const char *name, unsigned flags, hid_t fapl_id,
     file->pb_configured = FALSE;
 
     /* Set return value */
-    ret_value = (H5FD_t*)file;
+    ret_value = &file->pub;
 
 done:
-    /* Free the buffer */
-    if(vfd_swmr_config)
-        vfd_swmr_config = H5MM_xfree(vfd_swmr_config);
-
     /* Handle closing if error */
     if(NULL == ret_value && file) {
 
@@ -503,6 +508,63 @@ H5FD_vfd_swmr_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_vfd_swmr_cmp() */
 
+static H5FD_t *
+H5FD_vfd_swmr_dedup(H5FD_t *_self, H5FD_t *_other, hid_t fapl)
+{
+    H5FD_vfd_swmr_t *self = (H5FD_vfd_swmr_t *)_self;
+
+    assert(_self->driver_id == H5FD_VFD_SWMR_g);
+
+    if (_self->cls == _other->cls) {
+        H5FD_vfd_swmr_t *other = (H5FD_vfd_swmr_t *)_other;
+        H5P_genplist_t *plist;
+        H5F_vfd_swmr_config_t *config;
+        bool equal_configs;
+
+        if (H5FD_cmp(self->hdf5_file_lf, other->hdf5_file_lf) != 0)
+            return _other;
+
+        /* If fapl == _ANY_VFD, then the match between lower files is
+         * sufficient.
+         */
+        if (fapl == H5P_FILE_ACCESS_ANY_VFD)
+            return _self;
+
+        /* If fapl != _ANY_VFD, then we have either a duplicate or
+         * a conflict.  If the VFD SWMR parameters match, then
+         * return `self` to indicate a duplicate.  Otherwise, return
+         * NULL to indicate a mismatch.
+         */
+        if (NULL == (plist = H5I_object(fapl))) {
+            HERROR(H5E_ARGS, H5E_BADTYPE, "could not get fapl");
+            return NULL;
+        }
+
+        if ((config = malloc(sizeof(*config))) == NULL) {
+            HERROR(H5E_ARGS, H5E_BADTYPE, "could not allocate config");
+            return NULL;
+        }
+        if (H5P_get(plist, H5F_ACS_VFD_SWMR_CONFIG_NAME, config) < 0) {
+           HERROR(H5E_PLIST, H5E_CANTGET, "cannot get VFD SWMR config");
+           return NULL;
+        }
+
+        equal_configs = memcmp(&self->config, config, sizeof(*config)) == 0;
+
+        free(config);
+
+        if (equal_configs)
+            return _self;
+
+        HERROR(H5E_PLIST, H5E_CANTGET, "inconsistent VFD SWMR config");
+        return NULL;
+    } else if (H5FD_cmp(self->hdf5_file_lf, _other) == 0) {
+        return (fapl == H5P_FILE_ACCESS_ANY_VFD) ? _self : NULL;
+    } else {
+        return _other;
+    }
+}
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5FD_vfd_swmr_query