Initial checkin of page buffer re-implementation to support VFD SWMR.

Tested serial / debug on Charis and Jelly.

Two known issues:

1) New page buffer seems to expose issues in the accumulator code.

   For whatever reason, fheap with the new page buffer exposes corruption
   issues if the page buffer uses H5F__accum_read/write(), but the problems
   go away if the page buffers uses H5FD_read/write() instead.

   Need to either chase this or dis-able page bufffer in combination with
   the accumulator.

2) Encountered a number of assertion failures that are explainable by the
   free space manager code not telling the page buffer to discard pages
   when they are freed.

   Wrote code to handle this -- once the free space manager is modified,
   this code should be removed and the original assertions restored.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/H5C.c b/src/H5C.c
index a22eca0..52c8dfa 100644
--- a/src/H5C.c
+++ b/src/H5C.c
@@ -6412,8 +6412,8 @@ H5C__flush_single_entry(H5F_t *f, H5C_cache_entry_t *entry_ptr, unsigned flags)
         HDassert(!destroy);
         HDassert(entry_ptr->image_ptr);
 
-        if(f->shared->page_buf && f->shared->page_buf->page_size >= entry_ptr->size)
-            if(H5PB_update_entry(f->shared->page_buf, entry_ptr->addr, entry_ptr->size, entry_ptr->image_ptr) > 0)
+        if(f->shared->pb_ptr && f->shared->pb_ptr->page_size >= entry_ptr->size)
+            if(H5PB_update_entry(f->shared->pb_ptr, entry_ptr->addr, entry_ptr->size, entry_ptr->image_ptr) > 0)
                 HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Failed to update PB with metadata cache")
     } /* end if */