write_kafka: ensure key is properly hashed to select partition

[collectd.git] / src / write_kafka.c

diff --git a/src/write_kafka.c b/src/write_kafka.c
index e881593..614ce0f 100644 (file)
--- a/src/write_kafka.c
+++ b/src/write_kafka.c
@@ -73,11 +73,19 @@ static void kafka_log(const rd_kafka_t *rkt, int level,
 }
 #endif
 
+static uint32_t kafka_hash(const char *keydata, size_t keylen)
+{
+    uint32_t hash = 5381;
+    for (; keylen > 0; keylen--)
+        hash = ((hash << 5) + hash) + keydata[keylen - 1];
+    return hash;
+}
+
 static int32_t kafka_partition(const rd_kafka_topic_t *rkt,
                                const void *keydata, size_t keylen,
                                int32_t partition_cnt, void *p, void *m)
 {
-    uint32_t key = *((uint32_t *)keydata );
+    uint32_t key = kafka_hash(keydata, keylen);
     uint32_t target = key % partition_cnt;
     int32_t  i = partition_cnt;