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-rw-r--r--src/H5Cprivate.h58
1 files changed, 50 insertions, 8 deletions
diff --git a/src/H5Cprivate.h b/src/H5Cprivate.h
index 28eacf2..3408839 100644
--- a/src/H5Cprivate.h
+++ b/src/H5Cprivate.h
@@ -1066,9 +1066,9 @@ typedef int H5C_ring_t;
*
* is_read_only: Boolean flag that is only meaningful if is_protected is
* TRUE. In this circumstance, it indicates whether the
- * entry has been protected read only, or read/write.
+ * entry has been protected read-only, or read/write.
*
- * If the entry has been protected read only (i.e. is_protected
+ * If the entry has been protected read-only (i.e. is_protected
* and is_read_only are both TRUE), we allow the entry to be
* protected more than once.
*
@@ -1078,7 +1078,7 @@ typedef int H5C_ring_t;
* the entry is actually unprotected.
*
* ro_ref_count: Integer field used to maintain a count of the number of
- * outstanding read only protects on this entry. This field
+ * outstanding read-only protects on this entry. This field
* must be zero whenever either is_protected or is_read_only
* are TRUE.
*
@@ -1458,13 +1458,13 @@ typedef int H5C_ring_t;
* the load of a cache image block, although other scenarios
* are contemplated for the use of this feature. Note that
* unlike the usual prefetch situation, this means that a
- * pre fetched entry can be dirty, and/or can be a party to
+ * prefetched entry can be dirty, and/or can be a party to
* flush dependency relationship(s). This complicates matters
* somewhat.
*
- * The essential feature of a pre-fetched entry is that it
+ * The essential feature of a prefetched entry is that it
* consists only of a buffer containing the on disk image of
- * the entry. Thus it must be deserialized before it can
+ * the entry. Thus it must be deserialized before it can
* be passed back to the library on a protect call. This
* task is handled by H5C_deserialized_prefetched_entry().
* In essence, this routine calls the deserialize callback
@@ -1475,7 +1475,7 @@ typedef int H5C_ring_t;
*
* Further, if the prefetched entry is a flush dependency parent,
* all its flush dependency children (which must also be
- * pre-fetched entries), must be tranfered to the new cache
+ * prefetched entries), must be tranfered to the new cache
* entry returned by the deserailization callback.
*
* Finally, if the prefetched entry is a flush dependency child,
@@ -1511,6 +1511,46 @@ typedef int H5C_ring_t;
*
* This field must be zero if prefetched is FALSE.
*
+ * prefetched_dirty: Boolean field that must be set to FALSE unless the
+ * following conditions hold:
+ *
+ * 1) The file has been opened R/O.
+ *
+ * 2) The entry is either a prefetched entry, or was
+ * re-constructed from a prefetched entry.
+ *
+ * 3) The base prefetched entry was marked dirty.
+ *
+ * This field exists to solve the following problem with
+ * files containing cache images that are opened R/O.
+ *
+ * If the cache image contains a dirty entry, that entry
+ * must be marked clean when it is inserted into the cache
+ * in the read-only case, as otherwise the metadata cache
+ * will attempt to flush it on file close -- which is poor
+ * form in the read-only case.
+ *
+ * However, since the entry is marked clean, it is possible
+ * that the metadata cache will evict it if the size of the
+ * metadata in the file exceeds the size of the metadata cache,
+ * and the application visits much of this data.
+ *
+ * If this happens, and the metadata cache is then asked for
+ * this entry, it will attempt to read it from file, and will
+ * obtain either obsolete or invalid data depending on whether
+ * the entry has ever been written to it assigned location in
+ * the file.
+ *
+ * With this background, the purpose of this field should be
+ * obvious -- when set, it allows the eviction candidate
+ * selection code to skip over the entry, thus avoiding the
+ * issue.
+ *
+ * Since the issue only arises in the R/O case, there is
+ * no possible interaction with SWMR. There are also
+ * potential interactions with Evict On Close -- at present,
+ * we deal with this by disabling EOC in the R/O case.
+ *
* serialization_count: Integer field used to maintain a count of the
* number of times each entry is serialized during cache
* serialization. While no entry should be serialized more than
@@ -1627,6 +1667,7 @@ typedef struct H5C_cache_entry_t {
hbool_t prefetched;
int prefetch_type_id;
int32_t age;
+ hbool_t prefetched_dirty;
#ifndef NDEBUG /* debugging field */
int serialization_count;
@@ -2259,7 +2300,6 @@ H5_DLL herr_t H5C_set_trace_file_ptr(H5C_t *cache_ptr, FILE *trace_file_ptr);
H5_DLL herr_t H5C_stats(H5C_t *cache_ptr, const char *cache_name,
hbool_t display_detailed_stats);
H5_DLL void H5C_stats__reset(H5C_t *cache_ptr);
-H5_DLL herr_t H5C_dump_cache(H5C_t *cache_ptr, const char *cache_name);
H5_DLL herr_t H5C_unpin_entry(void *thing);
H5_DLL herr_t H5C_destroy_flush_dependency(void *parent_thing, void *child_thing);
H5_DLL herr_t H5C_unprotect(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *thing,
@@ -2289,6 +2329,8 @@ H5_DLL herr_t H5C_mark_entries_as_clean(H5F_t *f, hid_t dxpl_id, unsigned ce_arr
#endif /* H5_HAVE_PARALLEL */
#ifndef NDEBUG /* debugging functions */
+H5_DLL herr_t H5C_dump_cache(H5C_t *cache_ptr, const char *cache_name);
+H5_DLL herr_t H5C_dump_cache_LRU(H5C_t *cache_ptr, const char *cache_name);
H5_DLL hbool_t H5C_get_serialization_in_progress(const H5C_t *cache_ptr);
H5_DLL hbool_t H5C_cache_is_clean(const H5C_t *cache_ptr, H5C_ring_t inner_ring);
H5_DLL herr_t H5C_dump_cache_skip_list(H5C_t *cache_ptr, char *calling_fcn);