phunt commented on a change in pull request #831: ZOOKEEPER-3286: xid
wrap-around causes connection loss/segfault when hitting predefined XIDs
URL: https://github.com/apache/zookeeper/pull/831#discussion_r264012775
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File path: zookeeper-client/zookeeper-client-c/src/st_adaptor.c
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@@ -77,11 +77,11 @@ int32_t inc_ref_counter(zhandle_t* zh,int i)
int32_t get_xid()
{
- static int32_t xid = -1;
- if (xid == -1) {
- xid = time(0);
- }
- return xid++;
+ static int32_t xid = 1;
+
+ // The XID returned should not be negative to avoid collisions
+ // with reserved XIDs, such as AUTH_XID or SET_WATCHES_XID.
+ return xid++ & ~(1<<31);
Review comment:
I realize this will sound very boring but why not just reset xid to 1 prior
to it rolling over? a) the xid actually represents the next xid to send and b)
much easier to read/grok for someone new to the code.
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