Dump ziplist hex value on failed assertion.

The ziplist -> hashtable conversion code is triggered every time an hash
value must be promoted to a full hash table because the number or size of
elements reached the threshold.

If a problem in the ziplist causes the same field to be present
multiple times, the assertion of successful addition of the element
inside the hash table will fail, crashing server with a failed
assertion, but providing little information about the problem.

This code adds a new logging function to perform the hex dump of binary
data, and makes sure that the ziplist -> hashtable conversion code uses
this new logging facility to dump the content of the ziplist when the
assertion fails.

This change was originally made in order to investigate issue #547.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/t_hash.c b/src/t_hash.c
index 5b7a347ab..aa021b038 100644
--- a/src/t_hash.c
+++ b/src/t_hash.c
@@ -403,7 +403,11 @@ void hashTypeConvertZiplist(robj *o, int enc) {
             value = hashTypeCurrentObject(hi, REDIS_HASH_VALUE);
             value = tryObjectEncoding(value);
             ret = dictAdd(dict, field, value);
-            redisAssert(ret == DICT_OK);
+            if (ret != DICT_OK) {
+                redisLogHexDump(REDIS_WARNING,"ziplist with dup elements dump",
+                    o->ptr,ziplistBlobLen(o->ptr));
+                redisAssert(ret == DICT_OK);
+            }
         }
 
         hashTypeReleaseIterator(hi);