Add a flag for H5C__flush_single_entry() to allow the parallel code to request

that images for entries be generated, even when not writing the entry from an
MPI rank.

3 files changed, 65 insertions, 37 deletions

diff --git a/src/H5C.c b/src/H5C.c
index 147489b..31f887d 100644
--- a/src/H5C.c
+++ b/src/H5C.c
@@ -5739,6 +5739,7 @@ H5C__flush_single_entry(const H5F_t *f, hid_t dxpl_id, H5C_cache_entry_t *entry_
     hbool_t		during_flush;		/* external flag */
     hbool_t		write_entry;		/* internal flag */
     hbool_t		destroy_entry;		/* internal flag */
+    hbool_t		generate_image;		/* internal flag */
     hbool_t		was_dirty;
     haddr_t             entry_addr = HADDR_UNDEF;
     herr_t		ret_value = SUCCEED;      /* Return value */
@@ -5759,6 +5760,7 @@ H5C__flush_single_entry(const H5F_t *f, hid_t dxpl_id, H5C_cache_entry_t *entry_
     take_ownership         = ((flags & H5C__TAKE_OWNERSHIP_FLAG) != 0);
     del_from_slist_on_destroy = ((flags & H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG) != 0);
     during_flush           = ((flags & H5C__DURING_FLUSH_FLAG) != 0);
+    generate_image         = ((flags & H5C__GENERATE_IMAGE_FLAG) != 0);
 
     /* Set the flag for destroying the entry, based on the 'take ownership'
      * and 'destroy' flags
@@ -5818,29 +5820,13 @@ H5C__flush_single_entry(const H5F_t *f, hid_t dxpl_id, H5C_cache_entry_t *entry_
     entry_ptr->flush_in_progress = TRUE;
     entry_ptr->flush_marker = FALSE;
 
-    /* serialize the entry if necessary, and then write it to disk. */
-    if(write_entry) {
-
-	/* The entry is dirty, and we are doing either a flush,
-	 * or a flush destroy.  In either case, serialize the
-	 * entry and write it to disk.
-         *
-         * Note that this may cause the entry to be re-sized and/or
-         * moved in the cache.  
-	 *
-         * As we will not update the metadata cache's data structures 
-         * until we we finish the write, we must touch up these 
-         * data structures for size and location changes even if we 
-         * are about to delete the entry from the cache (i.e. on a 
-         * flush destroy).
-         */
+    /* The entry is dirty, and we are doing a flush, a flush destroy or have
+     * been requested to generate an image.  In those cases, serialize the
+     * entry.
+     */
+    if(write_entry || generate_image) {
         HDassert(entry_ptr->is_dirty);
 
-#if H5C_DO_SANITY_CHECKS
-        if(cache_ptr->check_write_permitted && !(cache_ptr->write_permitted))
-            HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Write when writes are always forbidden!?!?!")
-#endif /* H5C_DO_SANITY_CHECKS */
-
         if(NULL == entry_ptr->image_ptr) {
             if(NULL == (entry_ptr->image_ptr = H5MM_malloc(entry_ptr->size + H5C_IMAGE_EXTRA_SPACE)))
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTALLOC, FAIL, "memory allocation failed for on disk image buffer")
@@ -5854,13 +5840,22 @@ H5C__flush_single_entry(const H5F_t *f, hid_t dxpl_id, H5C_cache_entry_t *entry_
             if(H5C__generate_image(f, cache_ptr, entry_ptr, dxpl_id) < 0)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTGET, FAIL, "can't generate entry's image")
         } /* end if ( ! (entry_ptr->image_up_to_date) ) */
+    } /* end if */
+
+    /* Finally, write the image to disk.  
+     * 
+     * Note that if the H5AC__CLASS_SKIP_WRITES flag is set in the 
+     * in the entry's type, we silently skip the write.  This
+     * flag should only be used in test code. 
+     */
+    if(write_entry) {
+        HDassert(entry_ptr->is_dirty);
+
+#if H5C_DO_SANITY_CHECKS
+        if(cache_ptr->check_write_permitted && !(cache_ptr->write_permitted))
+            HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Write when writes are always forbidden!?!?!")
+#endif /* H5C_DO_SANITY_CHECKS */
 
-        /* Finally, write the image to disk.  
-         * 
-         * Note that if the H5AC__CLASS_SKIP_WRITES flag is set in the 
-         * in the entry's type, we silently skip the write.  This
-         * flag should only be used in test code. 
-         */
         if(((entry_ptr->type->flags) & H5C__CLASS_SKIP_WRITES) == 0) {
 #ifdef H5_HAVE_PARALLEL
             if(collective_write_list) {
@@ -7600,6 +7595,15 @@ H5C__assert_flush_dep_nocycle(const H5C_cache_entry_t * entry,
  *
  * Purpose:     Serialize an entry and generate its image.
  *
+ * Note:	This may cause the entry to be re-sized and/or moved in
+ *              the cache.  
+ *
+ *              As we will not update the metadata cache's data structures 
+ *              until we we finish the write, we must touch up these 
+ *              data structures for size and location changes even if we 
+ *              are about to delete the entry from the cache (i.e. on a 
+ *              flush destroy).
+ *
  * Return:      Non-negative on success/Negative on failure
  *
  * Programmer:  Mohamad Chaarawi
diff --git a/src/H5Cmpio.c b/src/H5Cmpio.c
index 8a28f88..72de4d0 100644
--- a/src/H5Cmpio.c
+++ b/src/H5Cmpio.c
@@ -454,13 +454,37 @@ H5C_apply_candidate_list(H5F_t * f,
               (long long)clear_ptr->addr);
 #endif /* H5C_APPLY_CANDIDATE_LIST__DEBUG */
 
-	    /* No need to check for the next entry in the scan being 
-             * removed from the cache, as this call to H5C__flush_single_entry()
-             * will not call either the pre_serialize or serialize callbacks.
+            /* reset entries_removed_counter and
+             * last_entry_removed_ptr prior to the call to
+             * H5C__flush_single_entry() so that we can spot
+             * unexpected removals of entries from the cache,
+             * and set the restart_scan flag if proceeding
+             * would be likely to cause us to scan an entry
+             * that is no longer in the cache.
+             *
+             * Note that as of this writing (April 2015) this 
+             * case cannot occur in the parallel case.  However 
+             * Quincey is making noises about changing this, hence 
+             * the insertion of this test.
+             *
+             * Note also that there is no test code to verify 
+             * that this code actually works (although similar code
+             * in the serial version exists and is tested).  
+             * 
+             * Implementing a test will likely require implementing
+             * flush op like facilities in the parallel tests.  At
+             * a guess this will not be terribly painful, but it 
+             * will take a bit of time.
              */
+            cache_ptr->entries_removed_counter = 0;
+            cache_ptr->last_entry_removed_ptr  = NULL;
 
-            if(H5C__flush_single_entry(f, dxpl_id, clear_ptr, H5C__FLUSH_CLEAR_ONLY_FLAG | H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG, NULL) < 0)
+            if(H5C__flush_single_entry(f, dxpl_id, clear_ptr, H5C__FLUSH_CLEAR_ONLY_FLAG | H5C__GENERATE_IMAGE_FLAG | H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG, NULL) < 0)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "Can't clear entry.")
+
+            if((cache_ptr->entries_removed_counter > 1) ||
+                    (cache_ptr->last_entry_removed_ptr == entry_ptr))
+                restart_scan = TRUE;
         } /* end if */
 
         /* Else, if this process needs to flush this entry. */
@@ -508,11 +532,9 @@ H5C_apply_candidate_list(H5F_t * f,
             if(H5C__flush_single_entry(f, dxpl_id, flush_ptr, H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG, collective_write_list) < 0)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "Can't flush entry.")
 
-            if ( ( cache_ptr->entries_removed_counter > 1 ) ||
-                 ( cache_ptr->last_entry_removed_ptr == entry_ptr ) )
-
+            if((cache_ptr->entries_removed_counter > 1) ||
+                    (cache_ptr->last_entry_removed_ptr == entry_ptr))
                 restart_scan = TRUE;
-
         } /* end else-if */
 
         /* Otherwise, no action to be taken on this entry. Grab the next. */
@@ -663,7 +685,7 @@ H5C_apply_candidate_list(H5F_t * f,
                           (long long)clear_ptr->addr);
 #endif /* H5C_APPLY_CANDIDATE_LIST__DEBUG */
 
-                if(H5C__flush_single_entry(f, dxpl_id, clear_ptr, H5C__FLUSH_CLEAR_ONLY_FLAG | H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG, NULL) < 0)
+                if(H5C__flush_single_entry(f, dxpl_id, clear_ptr, H5C__FLUSH_CLEAR_ONLY_FLAG | H5C__GENERATE_IMAGE_FLAG | H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG, NULL) < 0)
                     HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "Can't clear entry.")
             } /* end else-if */
 
@@ -714,7 +736,7 @@ H5C_apply_candidate_list(H5F_t * f,
     if (delayed_ptr) {
 
         if (delayed_ptr->clear_on_unprotect) {
-            if(H5C__flush_single_entry(f, dxpl_id, delayed_ptr, H5C__FLUSH_CLEAR_ONLY_FLAG, NULL) < 0)
+            if(H5C__flush_single_entry(f, dxpl_id, delayed_ptr, H5C__FLUSH_CLEAR_ONLY_FLAG | H5C__GENERATE_IMAGE_FLAG, NULL) < 0)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "Can't flush entry.")
 
             entry_ptr->clear_on_unprotect = FALSE;
diff --git a/src/H5Cprivate.h b/src/H5Cprivate.h
index c03e2e7..923083f 100644
--- a/src/H5Cprivate.h
+++ b/src/H5Cprivate.h
@@ -183,6 +183,7 @@
  * 	H5C__FLUSH_MARKED_ENTRIES_FLAG
  *      H5C__TAKE_OWNERSHIP_FLAG
  *      H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG
+ *      H5C__GENERATE_IMAGE_FLAG
  */
 #define H5C__NO_FLAGS_SET			0x00000
 #define H5C__SET_FLUSH_MARKER_FLAG		0x00001
@@ -202,6 +203,7 @@
 #define H5C__EVICT_ALLOW_LAST_PINS_FLAG         0x04000
 #define H5C__DEL_FROM_SLIST_ON_DESTROY_FLAG     0x08000
 #define H5C__DURING_FLUSH_FLAG                  0x10000 /* Set when the entire cache is being flushed */
+#define H5C__GENERATE_IMAGE_FLAG                0x20000 /* Set during parallel I/O */
 
 /* Debugging/sanity checking/statistics settings */
 #ifndef NDEBUG