[svn-r15821] Purpose: Global heap metadata cache client conversion

Description: Converted the global heap metadata cache clients over to
             use the new journaling cache callbacks.

             Separated cache clients into new H5HGcache.c file. Added 
             H5HGcache.c to MANIFEST, added into src/Makefile.am, and
             ran bin/reconfigure to regenerate Makefile.in file.

Tested: kagiso, smirom, linew, duty

8 files changed, 619 insertions, 418 deletions

diff --git a/MANIFEST b/MANIFEST
index 590fd2b..e5e53ca 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -589,6 +589,7 @@
 ./src/H5HFtest.c
 ./src/H5HFtiny.c
 ./src/H5HG.c
+./src/H5HGcache.c
 ./src/H5HGdbg.c
 ./src/H5HGpkg.h
 ./src/H5HGprivate.h
diff --git a/configure b/configure
index a47df09..a659d59 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Id: configure.in 15564 2008-08-31 09:28:03Z acheng .
+# From configure.in Id: configure.in 15569 2008-09-01 06:34:44Z acheng .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.61 for HDF5 1.9.8-MDJ_a2.
 #
diff --git a/src/H5HG.c b/src/H5HG.c
index 4ee63d1..c741b91 100644
--- a/src/H5HG.c
+++ b/src/H5HG.c
@@ -42,7 +42,6 @@
 
 
 #include "H5private.h"		/* Generic Functions			*/
-#include "H5ACprivate.h"	/* Metadata cache			*/
 #include "H5Eprivate.h"		/* Error handling		  	*/
 #include "H5Fpkg.h"             /* File access				*/
 #include "H5FLprivate.h"	/* Free lists                           */
@@ -52,69 +51,6 @@
 
 /* Private macros */
 
-/*
- * Global heap collection version.
- */
-#define H5HG_VERSION	1
-
-/*
- * All global heap collections are at least this big.  This allows us to read
- * most collections with a single read() since we don't have to read a few
- * bytes of header to figure out the size.  If the heap is larger than this
- * then a second read gets the rest after we've decoded the header.
- */
-#define H5HG_MINSIZE	4096
-
-/*
- * Limit global heap collections to the some reasonable size.  This is
- * fairly arbitrary, but needs to be small enough that no more than H5HG_MAXIDX
- * objects will be allocated from a single heap.
- */
-#define H5HG_MAXSIZE	65536
-
-/*
- * Maximum length of the CWFS list, the list of remembered collections that
- * have free space.
- */
-#define H5HG_NCWFS	16
-
-/*
- * The maximum number of links allowed to a global heap object.
- */
-#define H5HG_MAXLINK	65535
-
-/*
- * The maximum number of indices allowed in a global heap object.
- */
-#define H5HG_MAXIDX	65535
-
-/*
- * The size of the collection header, always a multiple of the alignment so
- * that the stuff that follows the header is aligned.
- */
-#define H5HG_SIZEOF_HDR(f)						      \
-    H5HG_ALIGN(4 +			/*magic number		*/	      \
-	       1 +			/*version number	*/	      \
-	       3 +			/*reserved		*/	      \
-	       H5F_SIZEOF_SIZE(f))	/*collection size	*/
-
-/*
- * The initial guess for the number of messages in a collection.  We assume
- * that all objects in that collection are zero length, giving the maximum
- * possible number of objects in the collection.  The collection itself has
- * some overhead and each message has some overhead.  The `+2' accounts for
- * rounding and for the free space object.
- */
-#define H5HG_NOBJS(f,z) (int)((((z)-H5HG_SIZEOF_HDR(f))/		      \
-			       H5HG_SIZEOF_OBJHDR(f)+2))
-
-/*
- * Makes a global heap object pointer undefined, or checks whether one is
- * defined.
- */
-#define H5HG_undef(HGP)	((HGP)->idx=0)
-#define H5HG_defined(HGP) ((HGP)->idx!=0)
-
 /* Private typedefs */
 
 /* PRIVATE PROTOTYPES */
@@ -123,35 +59,14 @@ static haddr_t H5HG_create(H5F_t *f, hid_t dxpl_id, size_t size);
 static void *H5HG_peek(H5F_t *f, hid_t dxpl_id, H5HG_t *hobj);
 #endif /* NOT_YET */
 
-/* Metadata cache callbacks */
-static H5HG_heap_t *H5HG_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *udata1,
-			      void *udata2);
-static herr_t H5HG_flush(H5F_t *f, hid_t dxpl_id, hbool_t dest, haddr_t addr,
-			 H5HG_heap_t *heap, unsigned UNUSED * flags_ptr);
-static herr_t H5HG_dest(H5F_t *f, H5HG_heap_t *heap);
-static herr_t H5HG_clear(H5F_t *f, H5HG_heap_t *heap, hbool_t destroy);
-static herr_t H5HG_compute_size(const H5F_t *f, const H5HG_heap_t *heap, size_t *size_ptr);
-
-/*
- * H5HG inherits cache-like properties from H5AC
- */
-const H5AC_class_t H5AC_GHEAP[1] = {{
-    H5AC_GHEAP_ID,
-    (H5AC_load_func_t)H5HG_load,
-    (H5AC_flush_func_t)H5HG_flush,
-    (H5AC_dest_func_t)H5HG_dest,
-    (H5AC_clear_func_t)H5HG_clear,
-    (H5AC_size_func_t)H5HG_compute_size,
-}};
-
 /* Declare a free list to manage the H5HG_t struct */
-H5FL_DEFINE_STATIC(H5HG_heap_t);
+H5FL_DEFINE(H5HG_heap_t);
 
 /* Declare a free list to manage sequences of H5HG_obj_t's */
-H5FL_SEQ_DEFINE_STATIC(H5HG_obj_t);
+H5FL_SEQ_DEFINE(H5HG_obj_t);
 
 /* Declare a PQ free list to manage heap chunks */
-H5FL_BLK_DEFINE_STATIC(heap_chunk);
+H5FL_BLK_DEFINE(heap_chunk);
 
 
 /*-------------------------------------------------------------------------
@@ -177,16 +92,16 @@ H5FL_BLK_DEFINE_STATIC(heap_chunk);
  *		Modified function to return the disk address of the new
  *		global heap collection, or HADDR_UNDEF on failure.  This
  *		is necessary, as in some cases (i.e. flexible parallel)
- *		H5AC_set() will imediately flush and destroy the in memory
+ *		H5AC2_set() will imediately flush and destroy the in memory
  *		version of the new collection.  For the same reason, I
  *		moved the code which places the new collection on the cwfs
- *		list to just before the call to H5AC_set().
+ *		list to just before the call to H5AC2_set().
  *
  *		John Mainzer 6/8/05
  *		Removed code setting the is_dirty field of the cache info.
  *		This is no longer pemitted, as the cache code is now
  *		manageing this field.  Since this function uses a call to
- *		H5AC_set() (which marks the entry dirty automaticly), no
+ *		H5AC2_set() (which marks the entry dirty automaticly), no
  *		other change is required.
  *
  *-------------------------------------------------------------------------
@@ -199,6 +114,7 @@ H5HG_create (H5F_t *f, hid_t dxpl_id, size_t size)
     uint8_t	*p = NULL;
     haddr_t	addr;
     size_t	n;
+    int i;
 
     FUNC_ENTER_NOAPI_NOINIT(H5HG_create)
 
@@ -219,6 +135,7 @@ H5HG_create (H5F_t *f, hid_t dxpl_id, size_t size)
                      "memory allocation failed");
     heap->addr = addr;
     heap->size = size;
+    heap->shared = f->shared;
 
     if (NULL==(heap->chunk = H5FL_BLK_MALLOC (heap_chunk,size)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, HADDR_UNDEF, \
@@ -283,7 +200,7 @@ HDmemset(heap->chunk, 0, size);
     }
 
     /* Add the heap to the cache */
-    if (H5AC_set (f, dxpl_id, H5AC_GHEAP, addr, heap, H5AC__NO_FLAGS_SET)<0)
+    if (H5AC2_set (f, dxpl_id, H5AC2_GHEAP, addr, (size_t)size, heap, H5AC2__NO_FLAGS_SET)<0)
 	HGOTO_ERROR (H5E_HEAP, H5E_CANTINIT, HADDR_UNDEF, \
                      "unable to cache global heap collection");
 
@@ -291,7 +208,7 @@ HDmemset(heap->chunk, 0, size);
 
 done:
     if ( ! ( H5F_addr_defined(addr) ) && heap) {
-        if ( H5HG_dest(f,heap) < 0 )
+        if ( H5HG_dest(heap) < 0 )
 	    HDONE_ERROR(H5E_HEAP, H5E_CANTFREE, HADDR_UNDEF, \
                         "unable to destroy global heap collection");
     }
@@ -301,294 +218,6 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HG_load
- *
- * Purpose:	Loads a global heap collection from disk.
- *
- * Return:	Success:	Ptr to a global heap collection.
- *
- *		Failure:	NULL
- *
- * Programmer:	Robb Matzke
- *              Friday, March 27, 1998
- *
- * Modifications:
- *		Robb Matzke, 1999-07-28
- *		The ADDR argument is passed by value.
- *
- *	Quincey Koziol, 2002-7-180
- *	Added dxpl parameter to allow more control over I/O from metadata
- *      cache.
- *-------------------------------------------------------------------------
- */
-static H5HG_heap_t *
-H5HG_load (H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * udata1,
-	   void UNUSED * udata2)
-{
-    H5HG_heap_t	*heap = NULL;
-    uint8_t	*p = NULL;
-    int	i;
-    size_t	nalloc, need;
-    size_t      max_idx=0;              /* The maximum index seen */
-    H5HG_heap_t	*ret_value = NULL;      /* Return value */
-
-    FUNC_ENTER_NOAPI(H5HG_load, NULL);
-
-    /* check arguments */
-    assert (f);
-    assert (H5F_addr_defined (addr));
-    assert (!udata1);
-    assert (!udata2);
-
-    /* Read the initial 4k page */
-    if(NULL == (heap = H5FL_CALLOC (H5HG_heap_t)))
-	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-    heap->addr = addr;
-    if(NULL == (heap->chunk = H5FL_BLK_MALLOC(heap_chunk, (size_t)H5HG_MINSIZE)))
-	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-    if(H5F_block_read(f, H5FD_MEM_GHEAP, addr, (size_t)H5HG_MINSIZE, dxpl_id, heap->chunk)<0)
-	HGOTO_ERROR (H5E_HEAP, H5E_READERROR, NULL, "unable to read global heap collection");
-
-    /* Magic number */
-    if(HDmemcmp(heap->chunk, H5HG_MAGIC, (size_t)H5HG_SIZEOF_MAGIC))
-	HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, NULL, "bad global heap collection signature");
-    p = heap->chunk + H5HG_SIZEOF_MAGIC;
-
-    /* Version */
-    if (H5HG_VERSION!=*p++)
-	HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, NULL, "wrong version number in global heap");
-
-    /* Reserved */
-    p += 3;
-
-    /* Size */
-    H5F_DECODE_LENGTH (f, p, heap->size);
-    assert (heap->size>=H5HG_MINSIZE);
-
-    /*
-     * If we didn't read enough in the first try, then read the rest of the
-     * collection now.
-     */
-    if (heap->size > H5HG_MINSIZE) {
-	haddr_t next_addr = addr + (hsize_t)H5HG_MINSIZE;
-	if (NULL==(heap->chunk = H5FL_BLK_REALLOC (heap_chunk, heap->chunk, heap->size)))
-	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-	if (H5F_block_read (f, H5FD_MEM_GHEAP, next_addr, (heap->size-H5HG_MINSIZE), dxpl_id, heap->chunk+H5HG_MINSIZE)<0)
-	    HGOTO_ERROR (H5E_HEAP, H5E_READERROR, NULL, "unable to read global heap collection");
-    }
-
-    /* Decode each object */
-    p = heap->chunk + H5HG_SIZEOF_HDR (f);
-    nalloc = H5HG_NOBJS (f, heap->size);
-    if (NULL==(heap->obj = H5FL_SEQ_MALLOC (H5HG_obj_t,nalloc)))
-	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-    heap->obj[0].size=heap->obj[0].nrefs=0;
-    heap->obj[0].begin=NULL;
-
-    heap->nalloc = nalloc;
-    while (p<heap->chunk+heap->size) {
-	if (p+H5HG_SIZEOF_OBJHDR(f)>heap->chunk+heap->size) {
-	    /*
-	     * The last bit of space is too tiny for an object header, so we
-	     * assume that it's free space.
-	     */
-	    assert (NULL==heap->obj[0].begin);
-	    heap->obj[0].size = (heap->chunk+heap->size) - p;
-	    heap->obj[0].begin = p;
-	    p += heap->obj[0].size;
-	} else {
-	    unsigned idx;
-	    uint8_t *begin = p;
-
-	    UINT16DECODE (p, idx);
-
-            /* Check if we need more room to store heap objects */
-            if(idx>=heap->nalloc) {
-                size_t new_alloc;       /* New allocation number */
-                H5HG_obj_t *new_obj;	/* New array of object descriptions */
-
-                /* Determine the new number of objects to index */
-                new_alloc=MAX(heap->nalloc*2,(idx+1));
-
-                /* Reallocate array of objects */
-                if (NULL==(new_obj = H5FL_SEQ_REALLOC (H5HG_obj_t, heap->obj, new_alloc)))
-                    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-
-                /* Update heap information */
-                heap->nalloc=new_alloc;
-                heap->obj=new_obj;
-            } /* end if */
-
-	    UINT16DECODE (p, heap->obj[idx].nrefs);
-	    p += 4; /*reserved*/
-	    H5F_DECODE_LENGTH (f, p, heap->obj[idx].size);
-	    heap->obj[idx].begin = begin;
-	    /*
-	     * The total storage size includes the size of the object header
-	     * and is zero padded so the next object header is properly
-	     * aligned. The last bit of space is the free space object whose
-	     * size is never padded and already includes the object header.
-	     */
-	    if (idx>0) {
-		need = H5HG_SIZEOF_OBJHDR(f) + H5HG_ALIGN(heap->obj[idx].size);
-
-                /* Check for "gap" in index numbers (caused by deletions) and fill in heap object values */
-                if(idx>(max_idx+1))
-                    HDmemset(&heap->obj[max_idx+1],0,sizeof(H5HG_obj_t)*(idx-(max_idx+1)));
-                max_idx=idx;
-	    } else {
-		need = heap->obj[idx].size;
-	    }
-	    p = begin + need;
-	}
-    }
-    assert(p==heap->chunk+heap->size);
-    assert(H5HG_ISALIGNED(heap->obj[0].size));
-
-    /* Set the next index value to use */
-    if(max_idx>0)
-        heap->nused=max_idx+1;
-    else
-        heap->nused=1;
-
-    /*
-     * Add the new heap to the CWFS list, removing some other entry if
-     * necessary to make room. We remove the right-most entry that has less
-     * free space than this heap.
-     */
-    if (!f->shared->cwfs) {
-        f->shared->cwfs = H5MM_malloc (H5HG_NCWFS*sizeof(H5HG_heap_t*));
-        if (NULL==f->shared->cwfs)
-            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-        f->shared->ncwfs = 1;
-        f->shared->cwfs[0] = heap;
-    } else if (H5HG_NCWFS==f->shared->ncwfs) {
-        for (i=H5HG_NCWFS-1; i>=0; --i) {
-            if (f->shared->cwfs[i]->obj[0].size < heap->obj[0].size) {
-                HDmemmove (f->shared->cwfs+1, f->shared->cwfs, i * sizeof(H5HG_heap_t*));
-                f->shared->cwfs[0] = heap;
-                break;
-            }
-        }
-    } else {
-        HDmemmove (f->shared->cwfs+1, f->shared->cwfs, f->shared->ncwfs*sizeof(H5HG_heap_t*));
-        f->shared->ncwfs += 1;
-        f->shared->cwfs[0] = heap;
-    }
-
-    ret_value = heap;
-
-done:
-    if (!ret_value && heap) {
-        if(H5HG_dest(f,heap)<0)
-	    HDONE_ERROR(H5E_HEAP, H5E_CANTFREE, NULL, "unable to destroy global heap collection");
-    }
-    FUNC_LEAVE_NOAPI(ret_value);
-}
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5HG_flush
- *
- * Purpose:	Flushes a global heap collection from memory to disk if it's
- *		dirty.  Optionally deletes teh heap from memory.
- *
- * Return:	Non-negative on success/Negative on failure
- *
- * Programmer:	Robb Matzke
- *              Friday, March 27, 1998
- *
- * Modifications:
- *		Robb Matzke, 1999-07-28
- *		The ADDR argument is passed by value.
- *
- *	Quincey Koziol, 2002-7-180
- *	Added dxpl parameter to allow more control over I/O from metadata
- *      cache.
- *
- *      JRM -- 8/21/06
- *      Added the flags_ptr parameter.  This parameter exists to
- *      allow the flush routine to report to the cache if the
- *      entry is resized or renamed as a result of the flush.
- *      *flags_ptr is set to H5C_CALLBACK__NO_FLAGS_SET on entry.
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5HG_flush (H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HG_heap_t *heap, unsigned UNUSED * flags_ptr)
-{
-    herr_t      ret_value=SUCCEED;       /* Return value */
-
-    FUNC_ENTER_NOAPI(H5HG_flush, FAIL);
-
-    /* Check arguments */
-    assert (f);
-    assert (H5F_addr_defined (addr));
-    assert (H5F_addr_eq (addr, heap->addr));
-    assert (heap);
-
-    if (heap->cache_info.is_dirty) {
-	if (H5F_block_write (f, H5FD_MEM_GHEAP, addr, heap->size, dxpl_id, heap->chunk)<0)
-	    HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, FAIL, "unable to write global heap collection to file");
-	heap->cache_info.is_dirty = FALSE;
-    }
-
-    if (destroy) {
-        if(H5HG_dest(f,heap)<0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy global heap collection");
-    }
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value);
-}
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5HG_dest
- *
- * Purpose:	Destroys a global heap collection in memory
- *
- * Return:	Non-negative on success/Negative on failure
- *
- * Programmer:	Quincey Koziol
- *              Wednesday, January 15, 2003
- *
- * Modifications:
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5HG_dest (H5F_t *f, H5HG_heap_t *heap)
-{
-    int		i;
-
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HG_dest);
-
-    /* Check arguments */
-    assert (heap);
-
-    /* Verify that node is clean */
-    assert (heap->cache_info.is_dirty==FALSE);
-
-    for (i=0; i<f->shared->ncwfs; i++) {
-        if (f->shared->cwfs[i]==heap) {
-            f->shared->ncwfs -= 1;
-            HDmemmove (f->shared->cwfs+i, f->shared->cwfs+i+1, (f->shared->ncwfs-i) * sizeof(H5HG_heap_t*));
-            break;
-        }
-    }
-
-    if(heap->chunk)
-        heap->chunk = H5FL_BLK_FREE(heap_chunk,heap->chunk);
-    if(heap->obj)
-        heap->obj = H5FL_SEQ_FREE(H5HG_obj_t,heap->obj);
-    H5FL_FREE (H5HG_heap_t,heap);
-
-    FUNC_LEAVE_NOAPI(SUCCEED);
-} /* H5HG_dest() */
-
-
-/*-------------------------------------------------------------------------
  * Function:	H5HG_clear
  *
  * Purpose:	Mark a global heap in memory as non-dirty.
@@ -616,7 +245,7 @@ H5HG_clear(H5F_t *f, H5HG_heap_t *heap, hbool_t destroy)
     heap->cache_info.is_dirty = FALSE;
 
     if (destroy)
-        if (H5HG_dest(f, heap) < 0)
+        if (H5HG_dest(heap) < 0)
 	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy global heap collection");
 
 done:
@@ -675,7 +304,7 @@ H5HG_compute_size(const H5F_t UNUSED *f, const H5HG_heap_t *heap, size_t *size_p
  *
  *		John Mainzer, 6/8/05
  *		Modified the function to use the new dirtied parameter of
- *		of H5AC_unprotect() instead of modifying the is_dirty
+ *		of H5AC2_unprotect() instead of modifying the is_dirty
  *		field of the cache info.
  *
  *		In this case, that required adding the new heap_dirtied_ptr
@@ -772,7 +401,7 @@ H5HG_alloc (H5F_t *f, H5HG_heap_t *heap, size_t size, unsigned * heap_flags_ptr)
     }
 
     /* Mark the heap as dirty */
-    *heap_flags_ptr |= H5AC__DIRTIED_FLAG;
+    *heap_flags_ptr |= H5AC2__DIRTIED_FLAG;
 
     /* Set the return value */
     ret_value=idx;
@@ -801,7 +430,7 @@ done:
  *
  *		John Mainzer, 6/8/05
  *		Modified the function to use the new dirtied parameter of
- *		of H5AC_unprotect() instead of modifying the is_dirty
+ *		of H5AC2_unprotect() instead of modifying the is_dirty
  *		field of the cache info.
  *
  *		In this case, that required adding the new heap_dirtied_ptr
@@ -875,7 +504,7 @@ HDmemset(new_chunk + heap->size, 0, need);
     assert(H5HG_ISALIGNED(heap->obj[0].size));
 
     /* Mark the heap as dirty */
-    *heap_flags_ptr |= H5AC__DIRTIED_FLAG;
+    *heap_flags_ptr |= H5AC2__DIRTIED_FLAG;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value);
@@ -918,12 +547,12 @@ done:
  *		new collection, instead of the address of its
  *		representation in core.  This was necessary as in FP
  *		mode, the cache will immediately flush and destroy any
- *		entry inserted in it via H5AC_set().  I then modified
+ *		entry inserted in it via H5AC2_set().  I then modified
  *		this function to account for the change in H5HG_create().
  *
  *		John Mainzer - 6/8/05
  *		Modified function to use the dirtied parameter of
- *		H5AC_unprotect() instead of modifying the is_dirty
+ *		H5AC2_unprotect() instead of modifying the is_dirty
  *		field of the cache info.
  *
  *-------------------------------------------------------------------------
@@ -936,7 +565,7 @@ H5HG_insert (H5F_t *f, hid_t dxpl_id, size_t size, void *obj, H5HG_t *hobj/*out*
     size_t	idx;
     haddr_t	addr = HADDR_UNDEF;
     H5HG_heap_t	*heap = NULL;
-    unsigned 	heap_flags = H5AC__NO_FLAGS_SET;
+    unsigned 	heap_flags = H5AC2__NO_FLAGS_SET;
     hbool_t     found=0;        /* Flag to indicate a heap with enough space was found */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
@@ -1035,9 +664,10 @@ H5HG_insert (H5F_t *f, hid_t dxpl_id, size_t size, void *obj, H5HG_t *hobj/*out*
     } /* end else */
 
     HDassert(H5F_addr_defined(addr));
-
-    if ( NULL == (heap = H5AC_protect(f, dxpl_id, H5AC_GHEAP, addr, NULL, NULL, H5AC_WRITE)) )
+    if ( NULL == (heap = H5AC2_protect(f, dxpl_id, H5AC2_GHEAP, addr, (size_t)H5HG_SPEC_READ_SIZE, f, H5AC2_WRITE)) )
         HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
+    
+    HDassert(heap->obj[0].size);
 
     /* Split the free space to make room for the new object */
     idx = H5HG_alloc (f, heap, size, &heap_flags);
@@ -1051,14 +681,14 @@ H5HG_insert (H5F_t *f, hid_t dxpl_id, size_t size, void *obj, H5HG_t *hobj/*out*
                  need-(H5HG_SIZEOF_OBJHDR(f)+size));
 #endif /* OLD_WAY */
     } /* end if */
-    heap_flags |= H5AC__DIRTIED_FLAG;
+    heap_flags |= H5AC2__DIRTIED_FLAG;
 
     /* Return value */
     hobj->addr = heap->addr;
     hobj->idx = idx;
 
 done:
-    if ( heap && H5AC_unprotect(f, dxpl_id, H5AC_GHEAP, heap->addr, heap, heap_flags) < 0 )
+    if ( heap && H5AC2_unprotect(f, dxpl_id, H5AC2_GHEAP, heap->addr, (size_t)0, heap, heap_flags) < 0 )
         HDONE_ERROR(H5E_HEAP, H5E_PROTECT, FAIL, "unable to unprotect heap.");
 
     FUNC_LEAVE_NOAPI(ret_value);
@@ -1084,7 +714,7 @@ done:
  *
  *              John Mainzer, 6/8/05
  *              Modified the function to use the new dirtied parameter of
- *              of H5AC_unprotect() instead of modifying the is_dirty
+ *              of H5AC2_unprotect() instead of modifying the is_dirty
  *              field of the cache info.
  *
  *-------------------------------------------------------------------------
@@ -1105,7 +735,7 @@ H5HG_read(H5F_t *f, hid_t dxpl_id, H5HG_t *hobj, void *object/*out*/,
     HDassert(hobj);
 
     /* Load the heap */
-    if(NULL == (heap = H5AC_protect(f, dxpl_id, H5AC_GHEAP, hobj->addr, NULL, NULL, H5AC_READ)))
+    if(NULL == (heap = H5AC2_protect(f, dxpl_id, H5AC2_GHEAP, hobj->addr, (size_t)H5HG_SPEC_READ_SIZE, f, H5AC2_READ)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "unable to load heap")
 
     HDassert(hobj->idx < heap->nused);
@@ -1119,7 +749,7 @@ H5HG_read(H5F_t *f, hid_t dxpl_id, H5HG_t *hobj, void *object/*out*/,
 
     /*
      * Advance the heap in the CWFS list. We might have done this already
-     * with the H5AC_protect(), but it won't hurt to do it twice.
+     * with the H5AC2_protect(), but it won't hurt to do it twice.
      */
     if(heap->obj[0].begin) {
         int	i;
@@ -1142,7 +772,7 @@ H5HG_read(H5F_t *f, hid_t dxpl_id, H5HG_t *hobj, void *object/*out*/,
     ret_value = object;
 
 done:
-    if(heap && H5AC_unprotect(f, dxpl_id, H5AC_GHEAP, hobj->addr, heap, H5AC__NO_FLAGS_SET)<0)
+    if(heap && H5AC2_unprotect(f, dxpl_id, H5AC2_GHEAP, hobj->addr, (size_t)0, heap, H5AC2__NO_FLAGS_SET)<0)
         HDONE_ERROR(H5E_HEAP, H5E_PROTECT, NULL, "unable to release object header")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1169,7 +799,7 @@ done:
  *
  *		John Mainzer - 6/8/05
  *		Modified function to use the dirtied parameter of
- *		H5AC_unprotect() instead of modifying the is_dirty
+ *		H5AC2_unprotect() instead of modifying the is_dirty
  *		field of the cache info.
  *
  *-------------------------------------------------------------------------
@@ -1178,7 +808,7 @@ int
 H5HG_link (H5F_t *f, hid_t dxpl_id, const H5HG_t *hobj, int adjust)
 {
     H5HG_heap_t *heap = NULL;
-    unsigned heap_flags = H5AC__NO_FLAGS_SET;
+    unsigned heap_flags = H5AC2__NO_FLAGS_SET;
     int ret_value;              /* Return value */
 
     FUNC_ENTER_NOAPI(H5HG_link, FAIL);
@@ -1190,8 +820,9 @@ H5HG_link (H5F_t *f, hid_t dxpl_id, const H5HG_t *hobj, int adjust)
 	HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, FAIL, "no write intent on file");
 
     if(adjust!=0) {
+
         /* Load the heap */
-        if (NULL == (heap = H5AC_protect(f, dxpl_id, H5AC_GHEAP, hobj->addr, NULL, NULL, H5AC_WRITE)))
+        if (NULL == (heap = H5AC2_protect(f, dxpl_id, H5AC2_GHEAP, hobj->addr, (size_t)H5HG_SPEC_READ_SIZE, f, H5AC2_WRITE)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
 
         assert (hobj->idx<heap->nused);
@@ -1201,14 +832,14 @@ H5HG_link (H5F_t *f, hid_t dxpl_id, const H5HG_t *hobj, int adjust)
         if (heap->obj[hobj->idx].nrefs+adjust>H5HG_MAXLINK)
             HGOTO_ERROR (H5E_HEAP, H5E_BADVALUE, FAIL, "new link count would be out of range");
         heap->obj[hobj->idx].nrefs += adjust;
-        heap_flags |= H5AC__DIRTIED_FLAG;
+        heap_flags |= H5AC2__DIRTIED_FLAG;
     } /* end if */
 
     /* Set return value */
     ret_value=heap->obj[hobj->idx].nrefs;
 
 done:
-    if (heap && H5AC_unprotect(f, dxpl_id, H5AC_GHEAP, hobj->addr, heap, heap_flags)<0)
+    if (heap && H5AC2_unprotect(f, dxpl_id, H5AC2_GHEAP, hobj->addr, (size_t)0, heap, heap_flags)<0)
         HDONE_ERROR(H5E_HEAP, H5E_PROTECT, FAIL, "unable to release object header");
 
     FUNC_LEAVE_NOAPI(ret_value);
@@ -1229,7 +860,7 @@ done:
  *
  *		John Mainzer - 6/8/05
  *		Modified function to use the dirtied parameter of
- *		H5AC_unprotect() instead of modifying the is_dirty
+ *		H5AC2_unprotect() instead of modifying the is_dirty
  *		field of the cache info.
  *
  *-------------------------------------------------------------------------
@@ -1242,7 +873,7 @@ H5HG_remove (H5F_t *f, hid_t dxpl_id, H5HG_t *hobj)
     size_t	need;
     int	i;
     unsigned	u;
-    unsigned    flags=H5AC__NO_FLAGS_SET;/* Whether the heap gets deleted */
+    unsigned    flags=H5AC2__NO_FLAGS_SET;/* Whether the heap gets deleted */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5HG_remove, FAIL);
@@ -1254,7 +885,7 @@ H5HG_remove (H5F_t *f, hid_t dxpl_id, H5HG_t *hobj)
         HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, FAIL, "no write intent on file");
 
     /* Load the heap */
-    if (NULL == (heap = H5AC_protect(f, dxpl_id, H5AC_GHEAP, hobj->addr, NULL, NULL, H5AC_WRITE)))
+    if (NULL == (heap = H5AC2_protect(f, dxpl_id, H5AC2_GHEAP, hobj->addr, (size_t)H5HG_SPEC_READ_SIZE, f, H5AC2_WRITE)))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
 
     assert (hobj->idx<heap->nused);
@@ -1275,8 +906,10 @@ H5HG_remove (H5F_t *f, hid_t dxpl_id, H5HG_t *hobj)
     } else {
         heap->obj[0].size += need;
     }
+
     HDmemmove (obj_start, obj_start+need,
 	       heap->size-((obj_start+need)-heap->chunk));
+
     if (heap->obj[0].size>=H5HG_SIZEOF_OBJHDR (f)) {
         p = heap->obj[0].begin;
         UINT16ENCODE(p, 0); /*id*/
@@ -1285,7 +918,7 @@ H5HG_remove (H5F_t *f, hid_t dxpl_id, H5HG_t *hobj)
         H5F_ENCODE_LENGTH (f, p, heap->obj[0].size);
     }
     HDmemset (heap->obj+hobj->idx, 0, sizeof(H5HG_obj_t));
-    flags |= H5AC__DIRTIED_FLAG;
+    flags |= H5AC2__DIRTIED_FLAG;
 
     if (heap->obj[0].size+H5HG_SIZEOF_HDR(f)==heap->size) {
         /*
@@ -1298,7 +931,7 @@ H5HG_remove (H5F_t *f, hid_t dxpl_id, H5HG_t *hobj)
     } else {
         /*
          * If the heap is in the CWFS list then advance it one position.  The
-         * H5AC_protect() might have done that too, but that's okay.  If the
+         * H5AC2_protect() might have done that too, but that's okay.  If the
          * heap isn't on the CWFS list then add it to the end.
          */
         for (i=0; i<f->shared->ncwfs; i++) {
@@ -1317,8 +950,55 @@ H5HG_remove (H5F_t *f, hid_t dxpl_id, H5HG_t *hobj)
     }
 
 done:
-    if (heap && H5AC_unprotect(f, dxpl_id, H5AC_GHEAP, hobj->addr, heap, flags) != SUCCEED)
+    if (heap && H5AC2_unprotect(f, dxpl_id, H5AC2_GHEAP, hobj->addr, (size_t)0, heap, flags) != SUCCEED)
         HDONE_ERROR(H5E_HEAP, H5E_PROTECT, FAIL, "unable to release object header");
 
     FUNC_LEAVE_NOAPI(ret_value);
 }
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HG_dest
+ *
+ * Purpose:	Destroys a global heap collection in memory
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Wednesday, January 15, 2003
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5HG_dest (H5HG_heap_t *heap)
+{
+    int		i;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HG_dest);
+
+    /* Check arguments */
+    assert (heap);
+
+    /* Verify that node is clean */
+    assert (heap->cache_info.is_dirty==FALSE);
+
+
+    /* Remove the heap from the CWFS list */
+    for (i=0; i<heap->shared->ncwfs; i++) {
+        if (heap->shared->cwfs[i]==heap) {
+            heap->shared->ncwfs -= 1;
+            HDmemmove (heap->shared->cwfs+i, heap->shared->cwfs+i+1, (heap->shared->ncwfs-i) * sizeof(H5HG_heap_t*));
+            break;
+        }
+    }
+
+    if(heap->chunk)
+        heap->chunk = H5FL_BLK_FREE(heap_chunk,heap->chunk);
+    if(heap->obj)
+        heap->obj = H5FL_SEQ_FREE(H5HG_obj_t,heap->obj);
+    H5FL_FREE (H5HG_heap_t,heap);
+
+    FUNC_LEAVE_NOAPI(SUCCEED);
+} /* H5HG_dest() */
diff --git a/src/H5HGcache.c b/src/H5HGcache.c
new file mode 100755
index 0000000..6f4cf45
--- /dev/null
+++ b/src/H5HGcache.c
@@ -0,0 +1,437 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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:		H5HGcache.c
+ *			October 6, 2008
+ *                      Mike McGreevy <mamcgree@hdfgroup.org>
+ *
+ * Purpose:		Implement gloabl heap metadata cache methods.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/****************/
+/* Module Setup */
+/****************/
+
+#define H5F_PACKAGE		/*suppress error about including H5Fpkg	  */
+#define H5HG_PACKAGE		/*suppress error about including H5HGpkg  */
+
+/***********/
+/* Headers */
+/***********/
+
+#include "H5private.h"		/* Generic Functions			*/
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5Fpkg.h"             /* File access				*/
+#include "H5FLprivate.h"	/* Free lists                           */
+#include "H5HGpkg.h"		/* Global heaps				*/
+#include "H5MMprivate.h"	/* Memory management			*/
+
+/****************/
+/* Local Macros */
+/****************/
+
+/******************/
+/* Local Typedefs */
+/******************/
+
+/********************/
+/* Package Typedefs */
+/********************/
+
+/********************/
+/* Local Prototypes */
+/********************/
+
+/* Metadata cache callbacks */
+static void *H5HG_deserialize(haddr_t addr, size_t len, const void *image, 
+    const void *udata, hbool_t *dirty);
+static herr_t H5HG_serialize(const H5F_t *f, hid_t dxpl_id, haddr_t addr, size_t len,
+    void *image, void *thing, unsigned *flags, haddr_t *new_addr,
+    size_t *new_len, void **new_image);
+static herr_t H5HG_free_icr(haddr_t addr, size_t len, void *thing);
+static herr_t H5HG_image_len(const void *thing, size_t *image_len_ptr);
+
+/*********************/
+/* Package Variables */
+/*********************/
+
+/*
+ * H5HG inherits cache-like properties from H5AC2
+ */
+const H5AC2_class_t H5AC2_GHEAP[1] = {{
+    H5AC2_GHEAP_ID,
+    "global heap",
+    H5FD_MEM_GHEAP,
+    H5HG_deserialize,
+    H5HG_image_len,
+    H5HG_serialize,
+    H5HG_free_icr,
+    NULL,
+}};
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+/*******************/
+/* Local Variables */
+/*******************/
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HG_deserialize
+ *
+ * Purpose:	Deserialize the data structure from disk.
+ *
+ * Return:	Success:	SUCCESS
+ *		Failure:	FAIL
+ *
+ * Programmer:	Robb Matzke
+ *              Friday, March 27, 1998
+ *
+ * Modifications:
+ *		Robb Matzke, 1999-07-28
+ *		The ADDR argument is passed by value.
+ *
+ *	Quincey Koziol, 2002-7-180
+ *	Added dxpl parameter to allow more control over I/O from metadata
+ *      cache.
+ *
+ *              Mike McGreevy
+ *              mcgreevy@hdfgroup.org
+ *              July 28, 2008
+ *              Converted from H5HG_load 
+ * 
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5HG_deserialize(haddr_t addr, size_t UNUSED len, const void *image,
+    const void *_udata, hbool_t UNUSED *dirty)
+{
+
+    H5HG_heap_t	*heap = NULL;
+    uint8_t	*p = NULL;
+    int	i;
+    size_t	nalloc, need;
+    size_t      max_idx=0;              /* The maximum index seen */
+    H5HG_heap_t	*ret_value = NULL;      /* Return value */
+    H5F_t *f = (H5F_t *)_udata;
+
+    FUNC_ENTER_NOAPI(H5HG_deserialize, NULL);
+
+    /* check arguments */
+    HDassert(image);
+
+    /* Allocate space for heap */
+    if(NULL == (heap = H5FL_CALLOC (H5HG_heap_t)))
+	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+    heap->addr = addr;
+    heap->shared = f->shared;
+
+    p = image;
+
+    /* Magic number */
+    if(HDmemcmp(p, H5HG_MAGIC, (size_t)H5HG_SIZEOF_MAGIC))
+	HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, NULL, "bad global heap collection signature");
+    p += H5HG_SIZEOF_MAGIC;
+
+    /* Version */
+    if (H5HG_VERSION!=*p++)
+	HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, NULL, "wrong version number in global heap");
+
+    /* Reserved */
+    p += 3;
+
+    /* Size */
+    H5F_DECODE_LENGTH (f, p, heap->size);
+    assert (heap->size>=H5HG_MINSIZE);
+
+    /* if heap->size is more than the allocated image size, then we need to do nothing and wait for correctly sized image to come in */
+    if (heap->size <= len) {
+
+        /* Allocate space for the heap->chunk */
+        if(NULL == (heap->chunk = H5FL_BLK_MALLOC(heap_chunk, (size_t)heap->size)))
+    	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+        
+        /* Copy image into chunk */
+        HDmemcpy(heap->chunk, image, heap->size);
+
+        /* Decode each object */
+        p = heap->chunk + H5HG_SIZEOF_HDR(f);
+        nalloc = H5HG_NOBJS (f, heap->size);
+        if (NULL==(heap->obj = H5FL_SEQ_MALLOC (H5HG_obj_t,nalloc)))
+    	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+        heap->obj[0].size=heap->obj[0].nrefs=0;
+        heap->obj[0].begin=NULL;
+        heap->nalloc = nalloc;
+        while (p<heap->chunk+heap->size) {
+	    if (p+H5HG_SIZEOF_OBJHDR(f)>heap->chunk+heap->size) {
+	        /*
+	         * The last bit of space is too tiny for an object header, so we
+	         * assume that it's free space.
+	         */
+	        assert (NULL==heap->obj[0].begin);
+	        heap->obj[0].size = ((const uint8_t *)heap->chunk+heap->size) - p;
+	        heap->obj[0].begin = p;
+	        p += heap->obj[0].size;
+	    } else {
+	        unsigned idx;
+	        uint8_t *begin = p;
+
+	        UINT16DECODE (p, idx);
+
+                /* Check if we need more room to store heap objects */
+                if(idx>=heap->nalloc) {
+                    size_t new_alloc;       /* New allocation number */
+                    H5HG_obj_t *new_obj;	/* New array of object descriptions */
+
+                    /* Determine the new number of objects to index */
+                    new_alloc=MAX(heap->nalloc*2,(idx+1));
+
+                    /* Reallocate array of objects */
+                    if (NULL==(new_obj = H5FL_SEQ_REALLOC (H5HG_obj_t, heap->obj, new_alloc)))
+                        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
+                    /* Update heap information */
+                    heap->nalloc=new_alloc;
+                    heap->obj=new_obj;
+                } /* end if */
+
+	        UINT16DECODE (p, heap->obj[idx].nrefs);
+	        p += 4; /*reserved*/
+	        H5F_DECODE_LENGTH (f, p, heap->obj[idx].size);
+	        heap->obj[idx].begin = begin;
+	        /*
+	         * The total storage size includes the size of the object header
+	         * and is zero padded so the next object header is properly
+	         * aligned. The last bit of space is the free space object whose
+	         * size is never padded and already includes the object header.
+	         */
+	        if (idx>0) {
+		    need = H5HG_SIZEOF_OBJHDR(f) + H5HG_ALIGN(heap->obj[idx].size);
+
+                    /* Check for "gap" in index numbers (caused by deletions) and fill in heap object values */
+                    if(idx>(max_idx+1))
+                        HDmemset(&heap->obj[max_idx+1],0,sizeof(H5HG_obj_t)*(idx-(max_idx+1)));
+                    max_idx=idx;
+	        } else {
+		    need = heap->obj[idx].size;
+	        }
+	        p = begin + need;
+	    }
+        }
+        assert(p==heap->chunk+heap->size);
+        assert(H5HG_ISALIGNED(heap->obj[0].size));
+
+
+        /* Set the next index value to use */
+        if(max_idx>0)
+            heap->nused=max_idx+1;
+        else
+            heap->nused=1;
+
+        /*
+         * Add the new heap to the CWFS list, removing some other entry if
+         * necessary to make room. We remove the right-most entry that has less
+         * free space than this heap.
+         */
+        if (!f->shared->cwfs) {
+            f->shared->cwfs = H5MM_malloc (H5HG_NCWFS*sizeof(H5HG_heap_t*));
+            if (NULL==f->shared->cwfs)
+                HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+            f->shared->ncwfs = 1;
+            f->shared->cwfs[0] = heap;
+        } else if (H5HG_NCWFS==f->shared->ncwfs) {
+            for (i=H5HG_NCWFS-1; i>=0; --i) {
+                if (f->shared->cwfs[i]->obj[0].size < heap->obj[0].size) {
+                    HDmemmove (f->shared->cwfs+1, f->shared->cwfs, i * sizeof(H5HG_heap_t*));
+                    f->shared->cwfs[0] = heap;
+                    break;
+                }
+            }
+        } else {
+            HDmemmove (f->shared->cwfs+1, f->shared->cwfs, f->shared->ncwfs*sizeof(H5HG_heap_t*));
+            f->shared->ncwfs += 1;
+            f->shared->cwfs[0] = heap;
+        }
+
+        /* Sanity check */    
+        HDassert((size_t)((const uint8_t *)p - (const uint8_t *)heap->chunk) <= len);
+
+    } /* end if heap->size <= len */
+
+    ret_value = heap;
+
+done:
+    if (!ret_value && heap) {
+        if(H5HG_dest(heap)<0)
+	    HDONE_ERROR(H5E_HEAP, H5E_CANTFREE, NULL, "unable to destroy global heap collection");
+    }
+    FUNC_LEAVE_NOAPI(ret_value);
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HG_serialize
+ *
+ * Purpose:	Serialize the data structure for writing to disk.
+ *
+ * Return:	Success:        SUCCESS
+ *              Failure:        FAIL
+ *
+ * Programmer:	Robb Matzke
+ *              Friday, March 27, 1998
+ *
+ * Modifications:
+ *		Robb Matzke, 1999-07-28
+ *		The ADDR argument is passed by value.
+ *
+ *	Quincey Koziol, 2002-7-180
+ *	Added dxpl parameter to allow more control over I/O from metadata
+ *      cache.
+ *
+ *      JRM -- 8/21/06
+ *      Added the flags_ptr parameter.  This parameter exists to
+ *      allow the flush routine to report to the cache if the
+ *      entry is resized or renamed as a result of the flush.
+ *      *flags_ptr is set to H5C_CALLBACK__NO_FLAGS_SET on entry.
+ *
+ *      Mike McGreevy
+ *      mcgreevy@hdfgroup.org
+ *      July 28, 2008
+ *      Converted from H5HG_flush
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5HG_serialize (const H5F_t *f, hid_t dxpl_id, haddr_t UNUSED addr, size_t UNUSED len,
+    void *image, void *_thing, unsigned *flags, haddr_t UNUSED *new_addr,
+    size_t UNUSED *new_len, void UNUSED **new_image)
+{
+    herr_t      ret_value=SUCCEED;       /* Return value */
+    H5HG_heap_t *heap = (H5HG_heap_t *)_thing;
+
+    FUNC_ENTER_NOAPI(H5HG_serialize, FAIL);
+
+    /* Check arguments */
+    assert (f);
+    assert (H5F_addr_defined (addr));
+    assert (H5F_addr_eq (addr, heap->addr));
+    assert (heap);
+
+
+    /* Need to increase image size if we need to copy a bigger thing into it */
+    if (heap->size > len) {
+        /* free old image buffer */
+        H5MM_free(image);
+    
+        /* allocate new image buffer */
+        *new_image = H5MM_malloc(heap->size);
+        if (*new_image == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "new image null after H5MM_realloc()\n");
+
+        /* copy the heap->chunk into the new image buffer */
+        HDmemcpy(*new_image, heap->chunk, heap->size);
+
+        /* set new length of image */
+        *new_len = heap->size;
+
+        /* specify in flags that image has been resized */
+        *flags = H5C2__SERIALIZE_RESIZED_FLAG;
+
+    } else {
+
+        /* copy the heap->chunk into the image buffer */
+        HDmemcpy(image, heap->chunk, heap->size);
+
+        /* Reset the cache flags for this operation */
+        *flags = 0;
+
+    }
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value);
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5HG_image_len
+ *
+ * Purpose:     Tell the metadata cache about the actual size 
+ *              of the global heap
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Mike McGreevy
+ *              mcgreevy@hdfgroup.org
+ *              July 28, 2008
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5HG_image_len(const void *thing, size_t *image_len_ptr)
+{
+
+    const H5HG_heap_t    *heap = (const H5HG_heap_t *)thing;    /* Global heap */
+    
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HG_image_len)
+
+    /* Check arguments */
+    HDassert(heap);
+    HDassert(image_len_ptr);
+    
+    /* Report the global heap's total size */
+    *image_len_ptr = heap->size;
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+
+} /* end H5HG_image_len() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HG_free_icr
+ *
+ * Purpose:	Destroy/release an "in core representation" of a data structure
+ *
+ * Return:	Success:        SUCCEED
+ *              Failure:        FAIL
+ *
+ * Programmer:	Mike McGreevy
+ *		mcgreevy@hdfgroup.org
+ *		July 28, 2008
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5HG_free_icr(haddr_t UNUSED addr, size_t UNUSED len, void *thing)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HG_free_icr)
+
+    /* Check arguments */
+    HDassert(thing);
+
+    /* Destroy B-tree node */
+    H5HG_dest(thing);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5HG_free_icr() */
+
+
+
+
diff --git a/src/H5HGdbg.c b/src/H5HGdbg.c
index 0e5aff8..d21e1f4 100644
--- a/src/H5HGdbg.c
+++ b/src/H5HGdbg.c
@@ -48,7 +48,7 @@
  *
  *              John Mainzer, 6/17/05
  *              Modified the function to use the new dirtied parameter of
- *              of H5AC_unprotect() instead of modifying the is_dirty
+ *              of H5AC2_unprotect() instead of modifying the is_dirty
  *              field of the cache info.
  *
  *-------------------------------------------------------------------------
@@ -73,7 +73,7 @@ H5HG_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     assert(indent >= 0);
     assert(fwidth >= 0);
 
-    if (NULL == (h = H5AC_protect(f, dxpl_id, H5AC_GHEAP, addr, NULL, NULL, H5AC_READ)))
+    if (NULL == (h = H5AC2_protect(f, dxpl_id, H5AC2_GHEAP, addr, fwidth, f, H5AC2_READ)))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load global heap collection");
 
     fprintf(stream, "%*sGlobal Heap Collection...\n", indent, "");
@@ -132,7 +132,7 @@ H5HG_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     }
 
 done:
-    if (h && H5AC_unprotect(f, dxpl_id, H5AC_GHEAP, addr, h, H5AC__NO_FLAGS_SET) != SUCCEED)
+    if (h && H5AC2_unprotect(f, dxpl_id, H5AC2_GHEAP, addr, (size_t)0, h, H5AC2__NO_FLAGS_SET) != SUCCEED)
         HDONE_ERROR(H5E_HEAP, H5E_PROTECT, FAIL, "unable to release object header");
 
     FUNC_LEAVE_NOAPI(ret_value);
diff --git a/src/H5HGpkg.h b/src/H5HGpkg.h
index e814367..f526d00 100644
--- a/src/H5HGpkg.h
+++ b/src/H5HGpkg.h
@@ -32,13 +32,17 @@
 #include "H5HGprivate.h"
 
 /* Other private headers needed by this file */
+#include "H5AC2private.h"	/* Metadata cache			*/
+
+#define H5F_PACKAGE
+#include "H5Fpkg.h"	       
 
 /*****************************/
 /* Package Private Variables */
 /*****************************/
 
 /* The cache subclass */
-H5_DLLVAR const H5AC_class_t H5AC_GHEAP[1];
+H5_DLLVAR const H5AC2_class_t H5AC2_GHEAP[1];
 
 /**************************/
 /* Package Private Macros */
@@ -65,6 +69,71 @@ H5_DLLVAR const H5AC_class_t H5AC_GHEAP[1];
 	       4 +			/*reserved		*/	      \
 	       H5F_SIZEOF_SIZE(f))	/*object data size	*/
 
+/*
+ * Global heap collection version.
+ */
+#define H5HG_VERSION	1
+
+/*
+ * All global heap collections are at least this big.  This allows us to read
+ * most collections with a single read() since we don't have to read a few
+ * bytes of header to figure out the size.  If the heap is larger than this
+ * then a second read gets the rest after we've decoded the header.
+ */
+#define H5HG_MINSIZE	4096
+
+/*
+ * Limit global heap collections to the some reasonable size.  This is
+ * fairly arbitrary, but needs to be small enough that no more than H5HG_MAXIDX
+ * objects will be allocated from a single heap.
+ */
+#define H5HG_MAXSIZE	65536
+
+/*
+ * Maximum length of the CWFS list, the list of remembered collections that
+ * have free space.
+ */
+#define H5HG_NCWFS	16
+
+/*
+ * The maximum number of links allowed to a global heap object.
+ */
+#define H5HG_MAXLINK	65535
+
+/*
+ * The maximum number of indices allowed in a global heap object.
+ */
+#define H5HG_MAXIDX	65535
+
+/*
+ * The size of the collection header, always a multiple of the alignment so
+ * that the stuff that follows the header is aligned.
+ */
+#define H5HG_SIZEOF_HDR(f)						      \
+    H5HG_ALIGN(4 +			/*magic number		*/	      \
+	       1 +			/*version number	*/	      \
+	       3 +			/*reserved		*/	      \
+	       H5F_SIZEOF_SIZE(f))	/*collection size	*/
+
+/*
+ * The initial guess for the number of messages in a collection.  We assume
+ * that all objects in that collection are zero length, giving the maximum
+ * possible number of objects in the collection.  The collection itself has
+ * some overhead and each message has some overhead.  The `+2' accounts for
+ * rounding and for the free space object.
+ */
+#define H5HG_NOBJS(f,z) (int)((((z)-H5HG_SIZEOF_HDR(f))/		      \
+			       H5HG_SIZEOF_OBJHDR(f)+2))
+
+/*
+ * Makes a global heap object pointer undefined, or checks whether one is
+ * defined.
+ */
+#define H5HG_undef(HGP)	((HGP)->idx=0)
+#define H5HG_defined(HGP) ((HGP)->idx!=0)
+
+#define H5HG_SPEC_READ_SIZE 4096
+
 /****************************/
 /* Package Private Typedefs */
 /****************************/
@@ -76,7 +145,7 @@ typedef struct H5HG_obj_t {
 } H5HG_obj_t;
 
 struct H5HG_heap_t {
-    H5AC_info_t cache_info; /* Information for H5AC cache functions, _must_ be */
+    H5AC2_info_t cache_info; /* Information for H5AC2 cache functions, _must_ be */
                             /* first field in structure */
     haddr_t		addr;		/*collection address		*/
     size_t		size;		/*total size of collection	*/
@@ -86,6 +155,7 @@ struct H5HG_heap_t {
                                         /* If this value is >65535 then all indices */
                                         /* have been used at some time and the */
                                         /* correct new index should be searched for */
+    H5F_file_t          *shared;        /* shared file */
     H5HG_obj_t	*obj;		/*array of object descriptions	*/
 };
 
@@ -93,5 +163,17 @@ struct H5HG_heap_t {
 /* Package Private Prototypes */
 /******************************/
 
+H5_DLL herr_t H5HG_dest(H5HG_heap_t *heap);
+
+/* Declare a free list to manage the H5HG_t struct */
+H5FL_EXTERN(H5HG_heap_t);
+
+/* Declare a free list to manage sequences of H5HG_obj_t's */
+H5FL_SEQ_EXTERN(H5HG_obj_t);
+
+/* Declare a PQ free list to manage heap chunks */
+H5FL_BLK_EXTERN(heap_chunk);
+
+
 #endif
 
diff --git a/src/Makefile.am b/src/Makefile.am
index a010cb3..8a77070 100755
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -63,7 +63,7 @@ libhdf5_la_SOURCES= H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5HF.c H5HFbtree2.c H5HFcache.c H5HFdbg.c H5HFdblock.c H5HFdtable.c \
         H5HFhdr.c H5HFhuge.c H5HFiblock.c H5HFiter.c H5HFman.c H5HFsection.c \
         H5HFspace.c H5HFstat.c H5HFtest.c H5HFtiny.c \
-        H5HG.c H5HGdbg.c H5HL.c H5HLdbg.c H5HP.c H5I.c H5L.c H5Lexternal.c \
+        H5HG.c H5HGcache.c H5HGdbg.c H5HL.c H5HLdbg.c H5HP.c H5I.c H5L.c H5Lexternal.c \
         H5MF.c H5MM.c H5MP.c H5MPtest.c \
         H5O.c H5Oainfo.c H5Oalloc.c H5Oattr.c \
         H5Oattribute.c H5Obogus.c H5Obtreek.c H5Ocache.c H5Ochunk.c \
diff --git a/src/Makefile.in b/src/Makefile.in
index 51417eb..cf79748 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -98,8 +98,8 @@ am_libhdf5_la_OBJECTS = H5.lo H5checksum.lo H5dbg.lo H5system.lo \
 	H5HFcache.lo H5HFdbg.lo H5HFdblock.lo H5HFdtable.lo H5HFhdr.lo \
 	H5HFhuge.lo H5HFiblock.lo H5HFiter.lo H5HFman.lo \
 	H5HFsection.lo H5HFspace.lo H5HFstat.lo H5HFtest.lo \
-	H5HFtiny.lo H5HG.lo H5HGdbg.lo H5HL.lo H5HLdbg.lo H5HP.lo \
-	H5I.lo H5L.lo H5Lexternal.lo H5MF.lo H5MM.lo H5MP.lo \
+	H5HFtiny.lo H5HG.lo H5HGcache.lo H5HGdbg.lo H5HL.lo H5HLdbg.lo \
+	H5HP.lo H5I.lo H5L.lo H5Lexternal.lo H5MF.lo H5MM.lo H5MP.lo \
 	H5MPtest.lo H5O.lo H5Oainfo.lo H5Oalloc.lo H5Oattr.lo \
 	H5Oattribute.lo H5Obogus.lo H5Obtreek.lo H5Ocache.lo \
 	H5Ochunk.lo H5Ocont.lo H5Ocopy.lo H5Odbg.lo H5Odrvinfo.lo \
@@ -442,7 +442,7 @@ libhdf5_la_SOURCES = H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5HF.c H5HFbtree2.c H5HFcache.c H5HFdbg.c H5HFdblock.c H5HFdtable.c \
         H5HFhdr.c H5HFhuge.c H5HFiblock.c H5HFiter.c H5HFman.c H5HFsection.c \
         H5HFspace.c H5HFstat.c H5HFtest.c H5HFtiny.c \
-        H5HG.c H5HGdbg.c H5HL.c H5HLdbg.c H5HP.c H5I.c H5L.c H5Lexternal.c \
+        H5HG.c H5HGcache.c H5HGdbg.c H5HL.c H5HLdbg.c H5HP.c H5I.c H5L.c H5Lexternal.c \
         H5MF.c H5MM.c H5MP.c H5MPtest.c \
         H5O.c H5Oainfo.c H5Oalloc.c H5Oattr.c \
         H5Oattribute.c H5Obogus.c H5Obtreek.c H5Ocache.c H5Ochunk.c \
@@ -702,6 +702,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5HFtest.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5HFtiny.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5HG.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5HGcache.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5HGdbg.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5HL.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5HLdbg.Plo@am__quote@