Modifications to:

A) Allow automatic generation of metadata file names for VDS support
B) Allow VFD SWMR reader to open an existing HDF5 file either before
the VFD SWMR writer has opened it or after it has closed.
C) Remove the usage of H5P_FILE_ACCESS_ANY_VFD.
D) Add H5FD_FEAT_SUPPORTS_VFD_SWMR feature flag.
E) Do not map H5FD_MEM_GHEAP to H5FD_MEM_DRAW when vfd swmr IS enabled;
   map H5FD_MEM_GHEAP to H5FD_MEM_DRAW when vfd swmr is NOT enabled.

For details regarding #A and #B above, see version 9 of the RFC.

1 files changed, 344 insertions, 34 deletions

diff --git a/src/H5FDvfd_swmr.c b/src/H5FDvfd_swmr.c
index fb88de3..ab74613 100644
--- a/src/H5FDvfd_swmr.c
+++ b/src/H5FDvfd_swmr.c
@@ -15,9 +15,10 @@
  */
 
 #include "H5FDdrvr_module.h" /* This source code file is part of the H5FD driver module */
+#define H5F_FRIEND           /* Suppress error about including H5Fpkg            */
 
 #include "H5Eprivate.h"      /* Error handling           */
-#include "H5Fprivate.h"      /* File access              */
+#include "H5Fpkg.h"          /* Files                    */
 #include "H5FDprivate.h"     /* File drivers             */
 #include "H5FDvfd_swmr.h"    /* VFD SWMR file driver     */
 #include "H5FLprivate.h"     /* Free Lists               */
@@ -40,7 +41,7 @@ typedef struct H5FD_vfd_swmr_t {
     /* Metadata file */
     int                     md_fd;             /* File descriptor for the metadata file */
     uint32_t                md_pages_reserved; /* # of pages reserved at the head of the metadata file */
-    char                    md_file_path[H5FD_MAX_FILENAME_LEN]; /* Name of the metadate file */
+    char                    md_file_path_name[H5FD_MAX_FILENAME_LEN+1]; /* Name of the metadate file */
     H5FD_vfd_swmr_md_header md_header;                           /* Metadata file header */
     H5FD_vfd_swmr_md_index  md_index;                            /* Metadata file index */
 
@@ -60,10 +61,15 @@ typedef struct H5FD_vfd_swmr_t {
      * to the lower VFD instance.
      */
     hbool_t writer;
+    /*
+     * Indicate whether we are in make_believe state or not
+     */
+    hbool_t make_believe;
 
 } H5FD_vfd_swmr_t;
 
 #define MAXADDR (((haddr_t)1 << (8 * sizeof(HDoff_t) - 1)) - 1)
+#define VFD_SWMR_MD_SUFFIX  ".md"
 
 /* Prototypes */
 static herr_t  H5FD__vfd_swmr_term(void);
@@ -217,6 +223,10 @@ done:
  *
  * Return:      SUCCEED/FAIL
  *
+ * Modifications:
+ *  Vailin Choi: 2/18/2022
+ *  VDS changes: Try opening metadata file and loading header/index if make_believe is FALSE.
+ *
  *-------------------------------------------------------------------------
  */
 static herr_t
@@ -235,30 +245,117 @@ H5FD__swmr_reader_open(H5FD_vfd_swmr_t *file)
     if (file->api_elapsed_ticks == NULL)
         HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, FAIL, "could not allocate API elapsed ticks")
 
-    /* Retry on opening the metadata file */
-    for (do_try         = H5_retry_init(&retry, H5FD_VFD_SWMR_MD_FILE_RETRY_MAX, H5_RETRY_DEFAULT_MINIVAL,
-                                H5_RETRY_DEFAULT_MAXIVAL);
-         do_try; do_try = H5_retry_next(&retry)) {
-        if ((file->md_fd = HDopen(file->md_file_path, O_RDONLY)) >= 0)
-            break;
-    }
+    if(!file->make_believe) {
+        /* Retry on opening the metadata file */
+        for (do_try         = H5_retry_init(&retry, H5FD_VFD_SWMR_MD_FILE_RETRY_MAX, H5_RETRY_DEFAULT_MINIVAL,
+                                    H5_RETRY_DEFAULT_MAXIVAL);
+             do_try; do_try = H5_retry_next(&retry)) {
+            if ((file->md_fd = HDopen(file->md_file_path_name, O_RDONLY)) >= 0)
+                break;
+        }
 
-    /* Exhaust all retries for opening the md file */
-    if (!do_try)
-        HGOTO_ERROR(H5E_VFL, H5E_OPENERROR, FAIL,
-                    "unable to open the metadata file after all retry attempts");
+        /* Exhaust all retries for opening the md file */
+        if (!do_try)
+            HGOTO_ERROR(H5E_VFL, H5E_OPENERROR, FAIL,
+                        "unable to open the metadata file after all retry attempts");
 
-    /* Retry on loading and decoding the header and index in the
-     *  metadata file
-     */
-    if (H5FD__vfd_swmr_load_hdr_and_idx(file, TRUE) < 0)
-        HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "unable to load/decode the md file header/index");
+        /* Retry on loading and decoding the header and index in the
+         *  metadata file
+         */
+        if (H5FD__vfd_swmr_load_hdr_and_idx(file, TRUE) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "unable to load/decode the md file header/index");
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD__swmr_reader_open() */
 
 /*-------------------------------------------------------------------------
+ *
+ * Function:    H5FD_vfd_swmr_build_md_path_name
+ *
+ * Purpose:     To construct the metadata file's full name based on config's 
+ *              md_file_path and md_file_name.  See RFC for details.
+ *              
+ *
+ * Return:      Success:        SUCCEED
+ *              Failure:        FAIL
+ *
+ * Programmer:  Vailin Choi -- 1/13/2022
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t 
+H5FD_vfd_swmr_build_md_path_name(H5F_vfd_swmr_config_t *config, const char *hdf5_filename, char *name /*out*/)
+{
+    size_t          tot_len = 0;
+    size_t          tmp_len = 0;
+    herr_t          ret_value = SUCCEED;                 /* Return value */
+
+    FUNC_ENTER_PACKAGE
+
+    if((tot_len = HDstrlen(config->md_file_path)) != 0) {
+
+        /* md_file_path + '/' */
+        if(++tot_len > H5F__MAX_VFD_SWMR_FILE_NAME_LEN)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTCOPY, FAIL, "md_file_path and md_file_name exceeds maximum");
+        HDstrcat(name, config->md_file_path);
+        HDstrcat(name, "/");
+    }
+
+    if((tmp_len = HDstrlen(config->md_file_name)) != 0) {
+        if((tot_len += tmp_len) > H5F__MAX_VFD_SWMR_FILE_NAME_LEN)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTCOPY, FAIL, "md_file_path and md_file_name exceeds maxiumum");
+        HDstrcat(name, config->md_file_name);
+    } else {
+        /* Automatic generation of metadata file name based on hdf5_filename + '.md' */
+        if((tot_len += (HDstrlen(hdf5_filename) + 3)) > H5F__MAX_VFD_SWMR_FILE_NAME_LEN)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTCOPY, FAIL, "md_file_path and md_file_name maxiumum");
+
+        HDstrcat(name, hdf5_filename);
+        HDstrcat(name, VFD_SWMR_MD_SUFFIX);
+    }
+
+done:
+
+    FUNC_LEAVE_NOAPI(ret_value)
+
+} /* H5FD_vfd_swmr_build_md_path_name() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_vfd_swmr_create_make_believe_data
+ *
+ * Purpose:     Set up pretend data when make_believe is true
+ *
+ * Return:      VOID
+ *
+ * Programmer:  Vailin Choi -- 1/13/2022
+ *
+ *-------------------------------------------------------------------------
+ */
+static void
+H5FD_vfd_swmr_create_make_believe_data(H5FD_vfd_swmr_t *_file)
+{
+    H5FD_vfd_swmr_t *file = (H5FD_vfd_swmr_t *)_file;
+
+    FUNC_ENTER_PACKAGE_NOERR
+
+    HDassert(file->make_believe);
+
+    /* Create make_believe data: empty header and index */
+    file->md_header.fs_page_size = 0;
+    file->md_header.tick_num = 0;
+    file->md_header.index_offset =  H5FD_MD_HEADER_SIZE;
+    file->md_header.index_length = H5FD_MD_INDEX_SIZE(0);
+
+    file->md_index.tick_num = 0;
+    file->md_index.num_entries = 0;
+
+    FUNC_LEAVE_NOAPI_VOID
+
+}  /* H5FD_vfd_swmr_create_make_believe_data() */
+
+/*-------------------------------------------------------------------------
  * Function:    H5FD__vfd_swmr_open
  *
  * Purpose:     Open the metadata file and the underlying HDF5 file
@@ -268,6 +365,11 @@ done:
  *                          caller, which is always H5FD_open().
  *              Failure:    NULL
  *
+ * Modifications:
+ *  Vailin Choi: 2/18/2022
+ *  VDS changes: --Build metadata file name
+ *               --Determine make_believe or not
+ *
  *-------------------------------------------------------------------------
  */
 static H5FD_t *
@@ -278,6 +380,7 @@ H5FD__vfd_swmr_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t max
     H5P_genplist_t *       plist;
     H5F_vfd_swmr_config_t *vfd_swmr_config;
     H5FD_t *               ret_value = NULL; /* Return value     */
+    htri_t is_hdf5;
 
     FUNC_ENTER_PACKAGE
 
@@ -314,16 +417,33 @@ H5FD__vfd_swmr_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t max
     file->hdf5_filename[sizeof(file->hdf5_filename) - 1] = '\0';
 
     /* Retain a copy of the metadata file name */
-    HDstrncpy(file->md_file_path, vfd_swmr_config->md_file_path, sizeof(file->md_file_path));
-    file->md_file_path[sizeof(file->md_file_path) - 1] = '\0';
+    if(H5FD_vfd_swmr_build_md_path_name(vfd_swmr_config, name, file->md_file_path_name) < 0)
+        HGOTO_ERROR(H5E_VFL, H5E_OPENERROR, NULL, "building md_file_path and md_file_name failed")
+    
+    file->md_file_path_name[sizeof(file->md_file_path_name) - 1] = '\0';
 
     file->writer = vfd_swmr_config->writer;
 
-    /* Ensure that this is the reader */
-    if (!vfd_swmr_config->writer && H5FD__swmr_reader_open(file) < 0)
-        HGOTO_ERROR(H5E_VFL, H5E_OPENERROR, NULL, "perform reader-specific opening steps failed")
+    /* Make sure the hdf5 file exists and is valid */
+    is_hdf5 = H5F__is_hdf5(name, H5P_FILE_ACCESS_DEFAULT);
+
+    /* Ensure reader */
+    if(!vfd_swmr_config->writer) {
+        /* Metadata file does not exist, presume_posix is true, HDF5 file exist */
+        if (HDaccess(file->md_file_path_name, F_OK) < 0 &&
+            vfd_swmr_config->presume_posix_semantics &&
+            is_hdf5 == TRUE) {
+
+            file->make_believe = TRUE;
+            H5FD_vfd_swmr_create_make_believe_data(file);
+        }
+        if (H5FD__swmr_reader_open(file) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_OPENERROR, NULL, "perform reader-specific opening steps failed")
+    }
 
     /* Hard-wired to open the underlying HDF5 file with SEC2 */
+    /* H5FD_SEC2 is the default driver for H5P_FILE_ACCESS_DEFAULT except when 
+       the environment variable HDF5_DRIVER is set to otherwise */
     if ((file->hdf5_file_lf = H5FD_open(name, flags, H5P_FILE_ACCESS_DEFAULT, maxaddr)) == NULL)
         HGOTO_ERROR(H5E_VFL, H5E_CANTOPENFILE, NULL, "can't set driver info");
 
@@ -456,7 +576,7 @@ H5FD__vfd_swmr_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
 } /* end H5FD_vfd__swmr_cmp() */
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_vfd_swmr_dedup
+ * Function:    H5FD_vfd_swmr_dedup (original description with H5P_FILE_ACCESS_ANY_VFD)
  *
  * Purpose:     Compare the already-opened VFD instance `_self` with the
  *              VFD instance `_other` newly-opened with file-access properties
@@ -497,6 +617,42 @@ H5FD__vfd_swmr_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
  *              Failure:    NULL
  *-------------------------------------------------------------------------
  */
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_vfd_swmr_dedup (modified version without H5P_FILE_ACCESS_ANY_VFD)
+ *
+ * Purpose:     Compare the already-opened VFD instance `_self` with the
+ *              VFD instance `_other` newly-opened with file-access properties
+ *              `fapl_id` and indicate whether the instances duplicate each
+ *              other, if they conflict with each other, or if they are
+ *              dissimilar.
+ *
+ *              If `_self` duplicates `_other`, return `_self`.
+ *
+ *              Return NULL on error, or if `_other` and `_self` refer to the
+ *              same file but the file-access properties, `fapl_id`, conflict
+ *              with the properties of `_self`.
+ *
+ *              If `_other` neither duplicates nor conflicts with `_self`,
+ *              then return `_other`.
+ *
+ * NOTE:        Judging duplicate/conflicting/dissimilar VFD instances
+ *
+ *              `_self` DUPLICATES `_other` if `_other` is also an instance
+ *              of SWMR class, the instances' lower files are equal under
+ *              `H5FD_cmp()`, and the file-access properties of `_self` match
+ *              `fapl_id`. 
+ *
+ *              `_self` and `_other` CONFLICT if both are SWMR instances
+ *              referring to the same lower file, and their file-access
+ *              properties differ.
+ *
+ *              `_self` and `_other` CONFLICT if `_other` is not a SWMR
+ *              instance, it equals the lower file of `_self`.
+ *
+ * Return:      Success:    `_self' or `_other', as described above
+ *              Failure:    NULL
+ *-------------------------------------------------------------------------
+ */
 H5FD_t *
 H5FD_vfd_swmr_dedup(H5FD_t *_self, H5FD_t *_other, hid_t fapl_id)
 {
@@ -523,11 +679,6 @@ H5FD_vfd_swmr_dedup(H5FD_t *_self, H5FD_t *_other, hid_t fapl_id)
         if (H5FD_cmp(self->hdf5_file_lf, other->hdf5_file_lf) != 0)
             HGOTO_DONE(_other)
 
-        /* If fapl_id == _ANY_VFD, then the match between lower files is
-         * sufficient.
-         */
-        if (fapl_id == H5P_FILE_ACCESS_ANY_VFD)
-            HGOTO_DONE(_self)
 
         /* If fapl_id != _ANY_VFD, then we have either a duplicate or
          * a conflict.  If the VFD SWMR parameters match, then
@@ -552,7 +703,7 @@ H5FD_vfd_swmr_dedup(H5FD_t *_self, H5FD_t *_other, hid_t fapl_id)
         HGOTO_ERROR(H5E_VFL, H5E_CANTGET, NULL, "inconsistent VFD SWMR config")
     }
     else if (H5FD_cmp(self->hdf5_file_lf, _other) == 0)
-        ret_value = (fapl_id == H5P_FILE_ACCESS_ANY_VFD) ? _self : NULL;
+        ret_value = NULL;
     else
         ret_value = _other;
 
@@ -752,6 +903,11 @@ done:
  *                          buffer BUF.
  *              Failure:    FAIL, Contents of buffer BUF are undefined.
  *
+ * Modifications:
+ *  Vailin Choi: 2/18/2022
+ *  VDS changes: If fs_page_size is 0, i.e. in make_believe state,
+ *               read from the underlying HDF5 file
+ *
  *-------------------------------------------------------------------------
  */
 static herr_t
@@ -780,10 +936,16 @@ H5FD__vfd_swmr_read(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id
     num_entries  = file->md_index.num_entries;
     fs_page_size = file->md_header.fs_page_size;
 
-    /* Try finding the addr from the index */
-    target_page = addr / fs_page_size;
+    if(!fs_page_size) {
+        HDassert(!num_entries);
+        HDassert(file->make_believe);
+        entry = NULL;
+    } else {
+        /* Try finding the addr from the index */
+        target_page = addr / fs_page_size;
 
-    entry = H5FD_vfd_swmr_pageno_to_mdf_idx_entry(index, num_entries, target_page, FALSE);
+        entry = H5FD_vfd_swmr_pageno_to_mdf_idx_entry(index, num_entries, target_page, FALSE);
+    }
 
     if (entry == NULL) {
         /* Cannot find addr in index, read from the underlying hdf5 file */
@@ -791,7 +953,7 @@ H5FD__vfd_swmr_read(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id
             HGOTO_ERROR(H5E_VFL, H5E_READERROR, FAIL, "file read request failed")
 
         HGOTO_DONE(SUCCEED);
-    }
+    } 
 
     /* Found in index, read from the metadata file */
     HDassert(addr >= target_page * fs_page_size);
@@ -1007,6 +1169,10 @@ done:
  *
  * Return:      Success:    SUCCEED
  *              Failure:    FAIL
+ *  
+ * Modifications:
+ *  Vailin Choi: 2/18/2022
+ *  VDS changes: Update the header's fs_page size if it is still 0
  *
  *-------------------------------------------------------------------------
  */
@@ -1113,6 +1279,14 @@ H5FD__vfd_swmr_load_hdr_and_idx(H5FD_vfd_swmr_t *file, hbool_t open)
     md_index.entries = NULL;
 
 done:
+    /* Need to update the header's fs_page_size if it is still 0
+       because it is possible that md_header.tick_num == file->md_header.tick_num 
+       and the loading is not done */
+    if(ret_value == SUCCEED && !file->md_header.fs_page_size) {
+        HDassert(md_header.fs_page_size);
+        HDassert(file->make_believe);
+        file->md_header.fs_page_size = md_header.fs_page_size;
+    }
 
     FUNC_LEAVE_NOAPI(ret_value)
 
@@ -1501,3 +1675,139 @@ H5FD_vfd_swmr_record_elapsed_ticks(H5FD_t *_file, uint64_t elapsed)
 
     FUNC_LEAVE_NOAPI_VOID
 } /* end H5FD_vfd_swmr_record_elapsed_ticks() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_vfd_swmr_get_md_name
+ *
+ * Purpose:     To retrieve the metadata file's full name
+ *
+ * Return:      VOID
+ *
+ * Programmer:  Vailin Choi; 02/18/2022
+ *
+ *-------------------------------------------------------------------------
+ *
+ */
+void
+H5FD_vfd_swmr_get_md_path_name(H5FD_t *_file, char **name)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    H5FD_vfd_swmr_t *file = (H5FD_vfd_swmr_t *)_file;
+
+    *name = H5MM_xstrdup(file->md_file_path_name);
+
+    FUNC_LEAVE_NOAPI_VOID
+
+}  /* H5FD_vfd_swmr_get_md_path_name() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_vfd_swmr_get_make_believe
+ *
+ * Purpose:     To retrieve the value of make_believe 
+ *
+ * Return:      TRUE/FALSE
+ *
+ * Programmer:  Vailin Choi; 02/18/2022
+ *
+ *-------------------------------------------------------------------------
+ *
+ */
+hbool_t
+H5FD_vfd_swmr_get_make_believe(H5FD_t *_file)
+{
+    H5FD_vfd_swmr_t *file = (H5FD_vfd_swmr_t *)_file;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    HDassert(file);
+
+    FUNC_LEAVE_NOAPI(file->make_believe)
+
+}  /* H5FD_vfd_swmr_get_make_believe() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_vfd_swmr_set_make_believe
+ *
+ * Purpose:     To set the VFD's make believe to the
+ *              parameter "make_believe"
+ *
+ * Return:      VOID
+ *
+ * Programmer:  Vailin Choi; 02/18/2022
+ *
+ *-------------------------------------------------------------------------
+ *
+ */
+void
+H5FD_vfd_swmr_set_make_believe(H5FD_t *_file, hbool_t make_believe)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    H5FD_vfd_swmr_t *file = (H5FD_vfd_swmr_t *)_file;
+
+    HDassert(file);
+
+    /* Set return value */
+    file->make_believe = make_believe;
+
+    FUNC_LEAVE_NOAPI_VOID
+
+}  /* H5FD_vfd_swmr_make_believe() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_vfd_swmr_assess_make_believe
+ *
+ * Purpose:     To determine whether continuing with make_believe or not.
+ *              Return TRUE:
+ *              --if metadata file does not exist, continue with make_believe
+ *              Return FALSE:
+ *              --if metadata file exists and can be opened successfully,
+ *                discontinue with make_believe 
+ *              Return FAIL:
+ *              --error in opening the metadata file
+ *              
+ *
+ * Return:      TRUE/FALSE/FAIL
+ *
+ * Programmer:  Vailin Choi; 02/18/2022
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5FD_vfd_swmr_assess_make_believe(H5FD_t *_file)
+{
+    H5FD_vfd_swmr_t *file      = (H5FD_vfd_swmr_t *)_file; /* VFD SWMR file struct */
+    h5_retry_t retry;
+    hbool_t    do_try;                      /* more tries remain */
+    htri_t     ret_value = TRUE;     /* Return value  */
+
+    FUNC_ENTER_NOAPI(FALSE)
+
+    HDassert(file->make_believe);
+
+    if (HDaccess(file->md_file_path_name, F_OK) >= 0) {
+        /* MD file exists now, proceed to open it */
+        HDassert(file->md_fd < 0);
+            
+        /* Retry on opening the metadata file */
+        for (do_try = H5_retry_init(&retry, H5FD_VFD_SWMR_MD_FILE_RETRY_MAX, H5_RETRY_DEFAULT_MINIVAL,
+                      H5_RETRY_DEFAULT_MAXIVAL);
+             do_try; do_try = H5_retry_next(&retry)) {
+            if ((file->md_fd = HDopen(file->md_file_path_name, O_RDONLY)) >= 0)
+                break;
+        }
+
+       /* Exhaust all retries for opening the md file */
+       if (!do_try)
+            HGOTO_ERROR(H5E_VFL, H5E_OPENERROR, FAIL,
+                        "unable to open the metadata file after all retry attempts");
+
+       /* Succeed in opening the MD file, discontinue make_believe */
+       ret_value = FALSE;
+    }
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+
+} /* end H5FD_vfd_swmr_assess_make_believe() */