[svn-r13449] Description:

	Add object creation property (H5P[s|g]et_obj_track_times) to disable
storing timestamps on objects, which makes the object's header size smaller.

	Also, added object header status flags to H5O_info_t struct (for
H5Oget_info/H5Oget_info_by_idx) and cleaned up other field names in the
struct as well.

Tested on:
	FreeBSD/32 6.2 (duty)
	Mac OS X/32 10.4.8 (amazon)

9 files changed, 269 insertions, 106 deletions

diff --git a/src/H5Gdeprec.c b/src/H5Gdeprec.c
index 5f7942e..5dbb1d2 100644
--- a/src/H5Gdeprec.c
+++ b/src/H5Gdeprec.c
@@ -905,8 +905,8 @@ H5G_get_objinfo_cb(H5G_loc_t *grp_loc/*in*/, const char UNUSED *name, const H5O_
             statbuf->mtime = oinfo.ctime;
 
             /* Retrieve the object header information */
-            statbuf->ohdr.size = oinfo.hdr.hdr_size;
-            statbuf->ohdr.free = oinfo.hdr.free_space;
+            statbuf->ohdr.size = oinfo.hdr.space.total;
+            statbuf->ohdr.free = oinfo.hdr.space.free;
             statbuf->ohdr.nmesgs = oinfo.hdr.nmesgs;
             statbuf->ohdr.nchunks = oinfo.hdr.nchunks;
         } /* end if */
diff --git a/src/H5O.c b/src/H5O.c
index 7b0584f..874b4c8 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -676,9 +676,6 @@ H5O_create(H5F_t *f, hid_t dxpl_id, size_t size_hint, hid_t ocpl_id,
     if(oh->version > H5O_VERSION_1) {
         H5P_genplist_t  *oc_plist;          /* Object creation property list */
 
-        /* Initialize all time fields with current time */
-        oh->atime = oh->mtime = oh->ctime = oh->btime = H5_now();
-
         /* Get the property list */
         if(NULL == (oc_plist = H5I_object(ocpl_id)))
             HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a property list")
@@ -695,12 +692,21 @@ H5O_create(H5F_t *f, hid_t dxpl_id, size_t size_hint, hid_t ocpl_id,
         if(H5P_get(oc_plist, H5O_CRT_OHDR_FLAGS_NAME, &oh->flags) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get object header flags")
 
+        /* Initialize all time fields with current time */
+        if(oh->flags & H5O_HDR_STORE_TIMES)
+            oh->atime = oh->mtime = oh->ctime = oh->btime = H5_now();
+        else
+            oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
+
         /* Set starting values for attribute info */
         oh->attr_fheap_addr = HADDR_UNDEF;
         oh->name_bt2_addr = HADDR_UNDEF;
         oh->corder_bt2_addr = HADDR_UNDEF;
     } /* end if */
     else {
+        /* Flags */
+        oh->flags = H5O_CRT_OHDR_FLAGS_DEF;
+
         /* Reset unused time fields */
         oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
 
@@ -1109,55 +1115,58 @@ H5O_touch_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh, hbool_t force)
     HDassert(f);
     HDassert(oh);
 
-    /* Get current time */
-    now = H5_now();
+    /* Check if this object header is tracking times */
+    if(oh->flags & H5O_HDR_STORE_TIMES) {
+        /* Get current time */
+        now = H5_now();
 
-    /* Check version, to determine how to store time information */
-    if(oh->version == H5O_VERSION_1) {
-        unsigned	idx;                    /* Index of modification time message to update */
+        /* Check version, to determine how to store time information */
+        if(oh->version == H5O_VERSION_1) {
+            unsigned	idx;                    /* Index of modification time message to update */
 
-        /* Look for existing message */
-        for(idx = 0; idx < oh->nmesgs; idx++)
-            if(H5O_MSG_MTIME == oh->mesg[idx].type || H5O_MSG_MTIME_NEW == oh->mesg[idx].type)
-                break;
+            /* Look for existing message */
+            for(idx = 0; idx < oh->nmesgs; idx++)
+                if(H5O_MSG_MTIME == oh->mesg[idx].type || H5O_MSG_MTIME_NEW == oh->mesg[idx].type)
+                    break;
 
-        /* Create a new message, if necessary */
-        if(idx == oh->nmesgs) {
-            unsigned mesg_flags = 0;        /* Flags for message in object header */
+            /* Create a new message, if necessary */
+            if(idx == oh->nmesgs) {
+                unsigned mesg_flags = 0;        /* Flags for message in object header */
 
-            /* If we would have to create a new message, but we aren't 'forcing' it, get out now */
-            if(!force)
-                HGOTO_DONE(SUCCEED);        /*nothing to do*/
+                /* If we would have to create a new message, but we aren't 'forcing' it, get out now */
+                if(!force)
+                    HGOTO_DONE(SUCCEED);        /*nothing to do*/
 
-            /* Allocate space for the modification time message */
-            if((idx = H5O_msg_alloc(f, dxpl_id, oh, H5O_MSG_MTIME_NEW, &mesg_flags, &now)) == UFAIL)
-                HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to allocate space for modification time message")
+                /* Allocate space for the modification time message */
+                if((idx = H5O_msg_alloc(f, dxpl_id, oh, H5O_MSG_MTIME_NEW, &mesg_flags, &now)) == UFAIL)
+                    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to allocate space for modification time message")
 
-            /* Set the message's flags if appropriate */
-            oh->mesg[idx].flags = mesg_flags;
-        } /* end if */
+                /* Set the message's flags if appropriate */
+                oh->mesg[idx].flags = mesg_flags;
+            } /* end if */
 
-        /* Allocate 'native' space, if necessary */
-        if(NULL == oh->mesg[idx].native) {
-            if(NULL == (oh->mesg[idx].native = H5FL_MALLOC(time_t)))
-                HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "memory allocation failed for modification time message")
-        } /* end if */
+            /* Allocate 'native' space, if necessary */
+            if(NULL == oh->mesg[idx].native) {
+                if(NULL == (oh->mesg[idx].native = H5FL_MALLOC(time_t)))
+                    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "memory allocation failed for modification time message")
+            } /* end if */
 
-        /* Update the message */
-        *((time_t *)(oh->mesg[idx].native)) = now;
+            /* Update the message */
+            *((time_t *)(oh->mesg[idx].native)) = now;
 
-        /* Mark the message as dirty */
-        oh->mesg[idx].dirty = TRUE;
-    } /* end if */
-    else {
-        /* XXX: For now, update access time & change fields in the object header */
-        /* (will need to add some code to update modification time appropriately) */
-        oh->atime = oh->ctime = now;
-    } /* end else */
+            /* Mark the message as dirty */
+            oh->mesg[idx].dirty = TRUE;
+        } /* end if */
+        else {
+            /* XXX: For now, update access time & change fields in the object header */
+            /* (will need to add some code to update modification time appropriately) */
+            oh->atime = oh->ctime = now;
+        } /* end else */
 
-    /* Mark object header as dirty in cache */
-    if(H5AC_mark_pinned_or_protected_entry_dirty(f, oh) < 0)
-        HGOTO_ERROR(H5E_OHDR, H5E_CANTMARKDIRTY, FAIL, "unable to mark object header as dirty")
+        /* Mark object header as dirty in cache */
+        if(H5AC_mark_pinned_or_protected_entry_dirty(f, oh) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTMARKDIRTY, FAIL, "unable to mark object header as dirty")
+    } /* end if */
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1857,13 +1866,16 @@ H5O_get_info(H5O_loc_t *oloc, H5O_info_t *oinfo, hid_t dxpl_id)
     oinfo->hdr.nmesgs = oh->nmesgs;
     oinfo->hdr.nchunks = oh->nchunks;
 
+    /* Set the status flags */
+    oinfo->hdr.flags = oh->flags;
+
     /* Iterate over all the messages, accumulating message size & type information */
     oinfo->num_attrs = 0;
-    oinfo->hdr.meta_space = H5O_SIZEOF_HDR(oh) + (H5O_SIZEOF_CHKHDR_OH(oh) * (oh->nchunks - 1));
-    oinfo->hdr.mesg_space = 0;
-    oinfo->hdr.free_space = 0;
-    oinfo->hdr.msg_present = 0;
-    oinfo->hdr.msg_shared = 0;
+    oinfo->hdr.space.meta = H5O_SIZEOF_HDR(oh) + (H5O_SIZEOF_CHKHDR_OH(oh) * (oh->nchunks - 1));
+    oinfo->hdr.space.mesg = 0;
+    oinfo->hdr.space.free = 0;
+    oinfo->hdr.mesg.present = 0;
+    oinfo->hdr.mesg.shared = 0;
     for(u = 0, curr_msg = &oh->mesg[0]; u < oh->nmesgs; u++, curr_msg++) {
         uint64_t type_flag;             /* Flag for message type */
 
@@ -1873,21 +1885,21 @@ H5O_get_info(H5O_loc_t *oloc, H5O_info_t *oinfo, hid_t dxpl_id)
 
         /* Accumulate information, based on the type of message */
 	if(H5O_NULL_ID == curr_msg->type->id)
-            oinfo->hdr.free_space += H5O_SIZEOF_MSGHDR_OH(oh) + curr_msg->raw_size;
+            oinfo->hdr.space.free += H5O_SIZEOF_MSGHDR_OH(oh) + curr_msg->raw_size;
         else if(H5O_CONT_ID == curr_msg->type->id)
-            oinfo->hdr.meta_space += H5O_SIZEOF_MSGHDR_OH(oh) + curr_msg->raw_size;
+            oinfo->hdr.space.meta += H5O_SIZEOF_MSGHDR_OH(oh) + curr_msg->raw_size;
         else {
-            oinfo->hdr.meta_space += H5O_SIZEOF_MSGHDR_OH(oh);
-            oinfo->hdr.mesg_space += curr_msg->raw_size;
+            oinfo->hdr.space.meta += H5O_SIZEOF_MSGHDR_OH(oh);
+            oinfo->hdr.space.mesg += curr_msg->raw_size;
         } /* end else */
 
-        /* Set flag to indicate present of message type */
+        /* Set flag to indicate presence of message type */
         type_flag = ((uint64_t)1) << curr_msg->type->id;
-        oinfo->hdr.msg_present |= type_flag;
+        oinfo->hdr.mesg.present |= type_flag;
 
         /* Set flag if the message is shared in some way */
         if(curr_msg->flags & H5O_MSG_FLAG_SHARED)                                   \
-            oinfo->hdr.msg_shared |= type_flag;
+            oinfo->hdr.mesg.shared |= type_flag;
     } /* end for */
 
     /* Sanity checking, etc. for # of attributes */
@@ -1901,17 +1913,17 @@ H5O_get_info(H5O_loc_t *oloc, H5O_info_t *oinfo, hid_t dxpl_id)
     } /* end if */
 
     /* Iterate over all the chunks, adding any gaps to the free space */
-    oinfo->hdr.hdr_size = 0;
+    oinfo->hdr.space.total = 0;
     for(u = 0, curr_chunk = &oh->chunk[0]; u < oh->nchunks; u++, curr_chunk++) {
         /* Accumulate the size of the header on header */
-        oinfo->hdr.hdr_size += curr_chunk->size;
+        oinfo->hdr.space.total += curr_chunk->size;
 
         /* If the chunk has a gap, add it to the free space */
-        oinfo->hdr.free_space += curr_chunk->gap;
+        oinfo->hdr.space.free += curr_chunk->gap;
     } /* end for */
 
     /* Sanity check that all the bytes are accounted for */
-    HDassert(oinfo->hdr.hdr_size == (oinfo->hdr.free_space + oinfo->hdr.meta_space + oinfo->hdr.mesg_space + oh->skipped_mesg_size));
+    HDassert(oinfo->hdr.space.total == (oinfo->hdr.space.free + oinfo->hdr.space.meta + oinfo->hdr.space.mesg + oh->skipped_mesg_size));
 
 done:
     if(oh && H5AC_unprotect(oloc->file, dxpl_id, H5AC_OHDR, oloc->addr, oh, H5AC__NO_FLAGS_SET) < 0)
diff --git a/src/H5Oattribute.c b/src/H5Oattribute.c
index 92c0887..ac76f78 100644
--- a/src/H5Oattribute.c
+++ b/src/H5Oattribute.c
@@ -671,6 +671,7 @@ herr_t
 H5O_attr_write(const H5O_loc_t *loc, hid_t dxpl_id, H5A_t *attr)
 {
     H5O_t *oh = NULL;                   /* Pointer to actual object header */
+    unsigned oh_flags = H5AC__NO_FLAGS_SET;     /* Metadata cache flags for object header */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5O_attr_write)
@@ -714,8 +715,11 @@ H5O_attr_write(const H5O_loc_t *loc, hid_t dxpl_id, H5A_t *attr)
     if(H5O_touch_oh(loc->file, dxpl_id, oh, FALSE) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update time on object")
 
+    /* Indicate that the object header was modified */
+    oh_flags |= H5AC__DIRTIED_FLAG;
+
 done:
-    if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, H5AC__NO_FLAGS_SET) < 0)
+    if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, oh_flags) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_PROTECT, FAIL, "unable to release object header")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -948,15 +952,15 @@ H5O_attr_rename(const H5O_loc_t *loc, hid_t dxpl_id, const char *old_name,
         /* Check that we found the attribute to rename */
         if(!udata.found)
             HGOTO_ERROR(H5E_ATTR, H5E_NOTFOUND, FAIL, "can't locate attribute with old name")
-
-        /* Indicate that the object header was modified */
-        oh_flags |= H5AC__DIRTIED_FLAG;
     } /* end else */
 
     /* Update the modification time, if any */
     if(H5O_touch_oh(loc->file, dxpl_id, oh, FALSE) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update time on object")
 
+    /* Indicate that the object header was modified */
+    oh_flags |= H5AC__DIRTIED_FLAG;
+
 done:
     if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, oh_flags) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_PROTECT, FAIL, "unable to release object header")
@@ -1175,10 +1179,6 @@ H5O_attr_remove_update(const H5O_loc_t *loc, H5O_t *oh, hid_t dxpl_id)
                 /* Remove the dense storage */
                 if(H5A_dense_delete(loc->file, dxpl_id, oh) < 0)
                     HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete dense attribute storage")
-
-                /* Update the modification time, if any */
-                if(H5O_touch_oh(loc->file, dxpl_id, oh, FALSE) < 0)
-                    HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update time on object")
             } /* end if */
 
             /* Free attribute table information */
@@ -1264,6 +1264,7 @@ herr_t
 H5O_attr_remove(const H5O_loc_t *loc, const char *name, hid_t dxpl_id)
 {
     H5O_t *oh = NULL;                   /* Pointer to actual object header */
+    unsigned oh_flags = H5AC__NO_FLAGS_SET;     /* Metadata cache flags for object header */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5O_attr_remove)
@@ -1310,8 +1311,15 @@ H5O_attr_remove(const H5O_loc_t *loc, const char *name, hid_t dxpl_id)
     if(H5O_attr_remove_update(loc, oh, dxpl_id) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update attribute info")
 
+    /* Update the modification time, if any */
+    if(H5O_touch_oh(loc->file, dxpl_id, oh, FALSE) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update time on object")
+
+    /* Indicate that the object header was modified */
+    oh_flags |= H5AC__DIRTIED_FLAG;
+
 done:
-    if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, H5AC__NO_FLAGS_SET) < 0)
+    if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, oh_flags) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_PROTECT, FAIL, "unable to release object header")
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1336,6 +1344,7 @@ H5O_attr_remove_by_idx(const H5O_loc_t *loc, H5_index_t idx_type,
     H5_iter_order_t order, hsize_t n, hid_t dxpl_id)
 {
     H5O_t *oh = NULL;                   /* Pointer to actual object header */
+    unsigned oh_flags = H5AC__NO_FLAGS_SET;     /* Metadata cache flags for object header */
     H5A_attr_table_t atable = {0, NULL};        /* Table of attributes */
     herr_t ret_value = SUCCEED;         /* Return value */
 
@@ -1390,8 +1399,15 @@ H5O_attr_remove_by_idx(const H5O_loc_t *loc, H5_index_t idx_type,
     if(H5O_attr_remove_update(loc, oh, dxpl_id) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update attribute info")
 
+    /* Update the modification time, if any */
+    if(H5O_touch_oh(loc->file, dxpl_id, oh, FALSE) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update time on object")
+
+    /* Indicate that the object header was modified */
+    oh_flags |= H5AC__DIRTIED_FLAG;
+
 done:
-    if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, H5AC__NO_FLAGS_SET) < 0)
+    if(oh && H5AC_unprotect(loc->file, dxpl_id, H5AC_OHDR, loc->addr, oh, oh_flags) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_PROTECT, FAIL, "unable to release object header")
     if(atable.attrs && H5A_attr_release_table(&atable) < 0)
         HDONE_ERROR(H5E_ATTR, H5E_CANTFREE, FAIL, "unable to release attribute table")
diff --git a/src/H5Ocache.c b/src/H5Ocache.c
index 194ebf4..48e3a6d 100644
--- a/src/H5Ocache.c
+++ b/src/H5Ocache.c
@@ -43,7 +43,9 @@
 /****************/
 
 /* Set the object header size to speculatively read in */
-/* (needs to be more than the default dataset header size) */
+/* (needs to be more than the object header prefix size to work at all and
+ *      should be larger than the default dataset object header to save the
+ *      extra I/O operations) */
 #define H5O_SPEC_READ_SIZE 512
 
 
@@ -281,6 +283,9 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
         if(H5O_VERSION_1 != oh->version)
             HGOTO_ERROR(H5E_OHDR, H5E_VERSION, NULL, "bad object header version number")
 
+        /* Flags */
+        oh->flags = H5O_CRT_OHDR_FLAGS_DEF;
+
         /* Reserved */
         p++;
     } /* end else */
@@ -294,10 +299,14 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
     /* Version-specific fields */
     if(oh->version > H5O_VERSION_1) {
         /* Time fields */
-        UINT32DECODE(p, oh->atime);
-        UINT32DECODE(p, oh->mtime);
-        UINT32DECODE(p, oh->ctime);
-        UINT32DECODE(p, oh->btime);
+        if(oh->flags & H5O_HDR_STORE_TIMES) {
+            UINT32DECODE(p, oh->atime);
+            UINT32DECODE(p, oh->mtime);
+            UINT32DECODE(p, oh->ctime);
+            UINT32DECODE(p, oh->btime);
+        } /* end if */
+        else
+            oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
 
         /* Attribute fields */
         UINT16DECODE(p, oh->max_compact);
@@ -331,6 +340,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
 
     /* Determine object header prefix length */
     prefix_size = (size_t)(p - read_buf);
+    HDassert((size_t)prefix_size == (size_t)(H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
 
     /* Compute first chunk address */
     chunk_addr = addr + (hsize_t)prefix_size;
@@ -385,6 +395,10 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
                 HDmemcpy(oh->chunk[0].image, read_buf, prefix_size);
 
                 /* Read the chunk raw data */
+                /* (probably re-reads some data we already retrieved, but since
+                 *      we have to do the I/O operation anyway, we might as
+                 *      well avoid memcpy()ing the data in our buffer already)
+                 */
                 if(H5F_block_read(f, H5FD_MEM_OHDR, chunk_addr, (oh->chunk[0].size - prefix_size),
                         dxpl_id, (oh->chunk[0].image + prefix_size)) < 0)
                     HGOTO_ERROR(H5E_OHDR, H5E_READERROR, NULL, "unable to read object header data")
@@ -634,10 +648,12 @@ H5O_assert(oh);
             UINT32ENCODE(p, oh->nlink);
 
             /* Time fields */
-            UINT32ENCODE(p, oh->atime);
-            UINT32ENCODE(p, oh->mtime);
-            UINT32ENCODE(p, oh->ctime);
-            UINT32ENCODE(p, oh->btime);
+            if(oh->flags & H5O_HDR_STORE_TIMES) {
+                UINT32ENCODE(p, oh->atime);
+                UINT32ENCODE(p, oh->mtime);
+                UINT32ENCODE(p, oh->ctime);
+                UINT32ENCODE(p, oh->btime);
+            } /* end if */
 
             /* Attribute fields */
             UINT16ENCODE(p, oh->max_compact);
diff --git a/src/H5Opkg.h b/src/H5Opkg.h
index 6ed310e..6825210 100644
--- a/src/H5Opkg.h
+++ b/src/H5Opkg.h
@@ -40,7 +40,7 @@
 #define H5O_VERSION_1		1
 
 /* Revised version - leaves out reserved bytes and alignment padding, and adds
- *      magic number as prefix and checksum
+ *      magic number as prefix and checksum as suffix for all chunks.
  */
 #define H5O_VERSION_2		2
 
@@ -78,6 +78,9 @@
 /* Size of checksum (on disk) */
 #define H5O_SIZEOF_CHKSUM               4
 
+/* Default value for object header status flags */
+#define H5O_CRT_OHDR_FLAGS_DEF          H5O_HDR_STORE_TIMES
+
 /*
  * Size of object header prefix.
  */
@@ -95,10 +98,12 @@
                 1 +		/*flags		 	*/		      \
                 2 +		/*number of messages	*/		      \
                 4 +		/*reference count	*/		      \
-                4 +		/*access time		*/		      \
-                4 +		/*modification time	*/		      \
-                4 +		/*change time		*/		      \
-                4 +		/*birth time		*/		      \
+                (((O)->flags & H5O_HDR_STORE_TIMES) ? (			      \
+                  4 +		/*access time		*/		      \
+                  4 +		/*modification time	*/		      \
+                  4 +		/*change time		*/		      \
+                  4		/*birth time		*/		      \
+                ) : 0) +						      \
                 2 +		/*max compact attributes */		      \
                 2 +		/*min dense attributes	*/		      \
                 (O)->sizeof_size + /*# of attributes	*/		      \
@@ -231,9 +236,9 @@ struct H5O_t {
     size_t      sizeof_addr;            /* Size of file addresses	     */
 
     /* Object information (stored) */
-    unsigned	version;		/*version number		     */
     unsigned	nlink;			/*link count			     */
-    unsigned	flags;			/*flags				     */
+    uint8_t	version;		/*version number		     */
+    uint8_t	flags;			/*flags				     */
 
     /* Time information (stored, for versions > 1) */
     time_t      atime;                  /*access time 			     */
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 0438101..c08b97d 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -414,8 +414,6 @@ typedef herr_t (*H5O_operator_t)(const void *mesg/*in*/, unsigned idx,
 
 /* Forward declarations for prototype arguments */
 struct H5P_genplist_t;
-struct H5SL_t;
-struct H5O_t;
 
 /* Object header routines */
 H5_DLL herr_t H5O_init(void);
diff --git a/src/H5Opublic.h b/src/H5Opublic.h
index 6395eec..0e64a93 100644
--- a/src/H5Opublic.h
+++ b/src/H5Opublic.h
@@ -48,7 +48,7 @@
 /* Flags for shared message indexes.
  * Pass these flags in using the mesg_type_flags parameter in
  * H5P_set_shared_mesg_index.
- * (Developers: These flags correspond to object header message type_ids,
+ * (Developers: These flags correspond to object header message type IDs,
  * but we need to assign each kind of message to a different bit so that
  * one index can hold multiple types.)
  */
@@ -60,6 +60,11 @@
 #define H5O_MESG_ATTR_FLAG     0x0010          /* Attribute Message.  */
 #define H5O_MESG_ALL_FLAG      (H5O_MESG_SDSPACE_FLAG | H5O_MESG_DTYPE_FLAG | H5O_MESG_FILL_FLAG | H5O_MESG_PLINE_FLAG | H5O_MESG_ATTR_FLAG)
 
+/* Object header status flag definitions */
+#define H5O_HDR_ATTR_CRT_ORDER_TRACKED  0x01    /* Attribute creation order is tracked */
+#define H5O_HDR_ATTR_CRT_ORDER_INDEXED  0x02    /* Attribute creation order has index */
+#define H5O_HDR_STORE_TIMES             0x04    /* Store access, modification, change & birth times for object */
+
 /* Maximum shared message values.  Number of indexes is 8 to allow room to add
  * new types of messages.
  */
@@ -100,12 +105,17 @@ typedef struct H5O_info_t {
         unsigned version;		/* Version number of header format in file */
         unsigned nmesgs;		/* Number of object header messages */
         unsigned nchunks;		/* Number of object header chunks */
-        hsize_t hdr_size;		/* Total size of object header in file */
-        hsize_t meta_space;		/* Space within header for object header metadata information */
-        hsize_t mesg_space;		/* Space within header for actual message information */
-        hsize_t free_space;		/* Free space within object header */
-        uint64_t msg_present;		/* Flags to indicate presence of message type in header */
-        uint64_t msg_shared;		/* Flags to indicate message type is shared in header */
+        unsigned flags;                 /* Object header status flags */
+        struct {
+            hsize_t total;		/* Total space for storing object header in file */
+            hsize_t meta;		/* Space within header for object header metadata information */
+            hsize_t mesg;		/* Space within header for actual message information */
+            hsize_t free;		/* Free space within object header */
+        } space;
+        struct {
+            uint64_t present;		/* Flags to indicate presence of message type in header */
+            uint64_t shared;		/* Flags to indicate message type is shared in header */
+        } mesg;
     } hdr;
     hsize_t             meta_size;      /* Size of additional metadata for an object */
                                         /* (B-tree & heap for groups, B-tree for chunked dataset, etc.) */
diff --git a/src/H5Pocpl.c b/src/H5Pocpl.c
index b454d08..974a6a0 100755
--- a/src/H5Pocpl.c
+++ b/src/H5Pocpl.c
@@ -27,6 +27,7 @@
 /****************/
 /* Module Setup */
 /****************/
+#define H5O_PACKAGE		/*suppress error about including H5Opkg	  */
 #define H5P_PACKAGE		/*suppress error about including H5Ppkg	  */
 
 
@@ -36,6 +37,7 @@
 #include "H5private.h"		/* Generic Functions			*/
 #include "H5Eprivate.h"		/* Error handling		  	*/
 #include "H5Iprivate.h"		/* IDs			  		*/
+#include "H5Opkg.h"             /* Object headers			*/
 #include "H5Ppkg.h"		/* Property lists		  	*/
 
 
@@ -50,9 +52,8 @@
 /* Definitions for the min. # of attributes to store densely */
 #define H5O_CRT_ATTR_MIN_DENSE_SIZE     sizeof(unsigned)
 #define H5O_CRT_ATTR_MIN_DENSE_DEF      6
-/* Definitions for the min. # of attributes to store densely */
-#define H5O_CRT_OHDR_FLAGS_SIZE         sizeof(unsigned)
-#define H5O_CRT_OHDR_FLAGS_DEF          0
+/* Definitions for object header flags */
+#define H5O_CRT_OHDR_FLAGS_SIZE         sizeof(uint8_t)
 
 
 /******************/
@@ -114,6 +115,7 @@ const H5P_libclass_t H5P_CLS_OCRT[1] = {{
  *
  * Programmer:  Quincey Koziol
  *              November 28, 2006
+ *
  *-------------------------------------------------------------------------
  */
 static herr_t
@@ -121,7 +123,7 @@ H5P_ocrt_reg_prop(H5P_genclass_t *pclass)
 {
     unsigned attr_max_compact = H5O_CRT_ATTR_MAX_COMPACT_DEF;   /* Default max. compact attribute storage settings */
     unsigned attr_min_dense = H5O_CRT_ATTR_MIN_DENSE_DEF;       /* Default min. dense attribute storage settings */
-    unsigned ohdr_flags = H5O_CRT_OHDR_FLAGS_DEF;               /* Default object header flag settings */
+    uint8_t ohdr_flags = H5O_CRT_OHDR_FLAGS_DEF;               /* Default object header flag settings */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5P_ocrt_reg_prop)
@@ -249,13 +251,14 @@ done:
  *
  * Programmer:  Quincey Koziol
  *              February  6, 2007
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
 H5Pset_attr_creation_order(hid_t plist_id, unsigned crt_order_flags)
 {
     H5P_genplist_t *plist;              /* Property list pointer */
-    unsigned ohdr_flags;                /* Object header flags */
+    uint8_t ohdr_flags;                 /* Object header flags */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_API(H5Pset_attr_creation_order, FAIL)
@@ -274,11 +277,11 @@ H5Pset_attr_creation_order(hid_t plist_id, unsigned crt_order_flags)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get object header flags")
 
     /* Mask off previous attribute creation order flag settings */
-    ohdr_flags &= ~(H5P_CRT_ORDER_TRACKED | H5P_CRT_ORDER_INDEXED);
+    ohdr_flags &= ~(H5O_HDR_ATTR_CRT_ORDER_TRACKED | H5O_HDR_ATTR_CRT_ORDER_INDEXED);
 
     /* Update with new attribute creation order flags */
-    ohdr_flags |= (crt_order_flags & H5P_CRT_ORDER_TRACKED);
-    ohdr_flags |= (crt_order_flags & H5P_CRT_ORDER_INDEXED);
+    ohdr_flags |= (crt_order_flags & H5P_CRT_ORDER_TRACKED) ? H5O_HDR_ATTR_CRT_ORDER_TRACKED : 0;
+    ohdr_flags |= (crt_order_flags & H5P_CRT_ORDER_INDEXED) ? H5O_HDR_ATTR_CRT_ORDER_INDEXED : 0;
 
     /* Set object header flags */
     if(H5P_set(plist, H5O_CRT_OHDR_FLAGS_NAME, &ohdr_flags) < 0)
@@ -298,7 +301,8 @@ done:
  * Return:      Non-negative on success/Negative on failure
  *
  * Programmer:  Quincey Koziol
- *              Ferbruary  6, 2007
+ *              February  6, 2007
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -312,7 +316,7 @@ H5Pget_attr_creation_order(hid_t plist_id, unsigned *crt_order_flags)
     /* Get values */
     if(crt_order_flags) {
         H5P_genplist_t *plist;      /* Property list pointer */
-        unsigned ohdr_flags;        /* Object header flags */
+        uint8_t ohdr_flags;         /* Object header flags */
 
         /* Reset the value to return */
         *crt_order_flags = 0;
@@ -326,10 +330,110 @@ H5Pget_attr_creation_order(hid_t plist_id, unsigned *crt_order_flags)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get object header flags")
 
         /* Set creation order flags to return */
-        *crt_order_flags = ohdr_flags & (H5P_CRT_ORDER_TRACKED | H5P_CRT_ORDER_INDEXED);
+        *crt_order_flags |= (ohdr_flags & H5O_HDR_ATTR_CRT_ORDER_TRACKED) ? H5P_CRT_ORDER_TRACKED : 0;
+        *crt_order_flags |= (ohdr_flags & H5O_HDR_ATTR_CRT_ORDER_INDEXED) ? H5P_CRT_ORDER_INDEXED : 0;
     } /* end if */
 
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Pget_attr_creation_order() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pset_obj_track_times
+ *
+ * Purpose:     Set whether the birth, access, modification & change times for
+ *              an object are stored.
+ *
+ *              Birth time is the time the object was created.  Access time is
+ *              the last time that metadata or raw data was read from this
+ *              object.  Modification time is the last time the data for
+ *              this object was changed (either writing raw data to a dataset
+ *              or inserting/modifying/deleting a link in a group).  Change
+ *              time is the last time the metadata for this object was written
+ *              (adding/modifying/deleting an attribute on an object, extending
+ *              the size of a dataset, etc).
+ *
+ *              If these times are not tracked, they will be reported as
+ *              12:00 AM UDT, Jan. 1, 1970 (i.e. 0 seconds past the UNIX
+ *              epoch) when queried.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              March  1, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_obj_track_times(hid_t plist_id, hbool_t track_times)
+{
+    H5P_genplist_t *plist;              /* Property list pointer */
+    uint8_t ohdr_flags;                 /* Object header flags */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_API(H5Pset_obj_track_times, FAIL)
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(plist_id, H5P_OBJECT_CREATE)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Get object header flags */
+    if(H5P_get(plist, H5O_CRT_OHDR_FLAGS_NAME, &ohdr_flags) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get object header flags")
+
+    /* Mask off previous time tracking flag settings */
+    ohdr_flags &= ~H5O_HDR_STORE_TIMES;
+
+    /* Update with new time tracking flag */
+    ohdr_flags |= track_times ? H5O_HDR_STORE_TIMES : 0;
+
+    /* Set object header flags */
+    if(H5P_set(plist, H5O_CRT_OHDR_FLAGS_NAME, &ohdr_flags) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set object header flags")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pset_obj_track_times() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5Pget_obj_track_times
+ *
+ * Purpose:     Returns whether times are tracked for an object.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              March  1, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_obj_track_times(hid_t plist_id, hbool_t *track_times)
+{
+    herr_t ret_value = SUCCEED;   /* return value */
+
+    FUNC_ENTER_API(H5Pget_obj_track_times, FAIL)
+
+    /* Get values */
+    if(track_times) {
+        H5P_genplist_t *plist;      /* Property list pointer */
+        uint8_t ohdr_flags;         /* Object header flags */
+
+        /* Get the plist structure */
+        if(NULL == (plist = H5P_object_verify(plist_id, H5P_OBJECT_CREATE)))
+            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+        /* Get object header flags */
+        if(H5P_get(plist, H5O_CRT_OHDR_FLAGS_NAME, &ohdr_flags) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get object header flags")
+
+        /* Set track times flag to return */
+        *track_times = (ohdr_flags & H5O_HDR_STORE_TIMES) ? TRUE : FALSE;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_obj_track_times() */
+
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index 5475fa0..637528d 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -224,6 +224,8 @@ H5_DLL herr_t H5Pset_attr_phase_change(hid_t plist_id, unsigned max_compact, uns
 H5_DLL herr_t H5Pget_attr_phase_change(hid_t plist_id, unsigned *max_compact, unsigned *min_dense);
 H5_DLL herr_t H5Pset_attr_creation_order(hid_t plist_id, unsigned crt_order_flags);
 H5_DLL herr_t H5Pget_attr_creation_order(hid_t plist_id, unsigned *crt_order_flags);
+H5_DLL herr_t H5Pset_obj_track_times(hid_t plist_id, hbool_t track_times);
+H5_DLL herr_t H5Pget_obj_track_times(hid_t plist_id, hbool_t *track_times);
 
 /* File creation property list (FCPL) routines */
 H5_DLL herr_t H5Pget_version(hid_t plist_id, unsigned *boot/*out*/,