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https://issues.apache.org/jira/browse/ZOOKEEPER-761?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15669747#comment-15669747
]
ASF GitHub Bot commented on ZOOKEEPER-761:
------------------------------------------
Github user rgs1 commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/90#discussion_r88183747
--- Diff: src/c/src/zookeeper.c ---
@@ -4052,6 +3958,76 @@ int zoo_amulti(zhandle_t *zh, int count, const
zoo_op_t *ops,
return (rc < 0) ? ZMARSHALLINGERROR : ZOK;
}
+
+int zoo_aremove_watchers(zhandle_t *zh, const char *path, ZooWatcherType
wtype,
+ watcher_fn watcher, void *watcherCtx, int local,
+ void_completion_t *completion, const void *data)
+{
+ char *server_path = prepend_string(zh, path);
+ int rc;
+ struct oarchive *oa;
+ struct RequestHeader h = { get_xid(), ZOO_REMOVE_WATCHES };
+ struct RemoveWatchesRequest req = { (char*)server_path, wtype };
+ watcher_deregistration_t *wdo;
+
+ if (!zh || !isValidPath(server_path, 0)) {
+ rc = ZBADARGUMENTS;
+ goto done;
+ }
+
+ if (!local && is_unrecoverable(zh)) {
+ rc = ZINVALIDSTATE;
+ goto done;
+ }
+
+ if (!pathHasWatcher(zh, server_path, wtype, watcher, watcherCtx)) {
+ rc = ZNOWATCHER;
+ goto done;
+ }
+
+ if (local) {
+ removeWatchers(zh, server_path, wtype, watcher, watcherCtx);
+#ifdef THREADED
+ notify_sync_completion((struct sync_completion *)data);
--- End diff --
@breed @fpj btw -- sorry for the confusing code. `zoo_aremove_watchers` is
sui generis given that it's the only public method that can return `ZOK`
without scheduling a remote call (for which then, the callback would be
naturally dispatched). Thus, this horrible hack of calling
`notify_sync_completion()`.
> Remove *synchronous* calls from the *single-threaded* C clieant API, since
> they are documented not to work
> ----------------------------------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-761
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-761
> Project: ZooKeeper
> Issue Type: Improvement
> Components: c client
> Affects Versions: 3.1.1, 3.2.2
> Environment: RHEL 4u8 (Linux). The issue is not OS-specific though.
> Reporter: Jozef Hatala
> Assignee: Benjamin Reed
> Priority: Minor
> Fix For: 3.5.3, 3.6.0
>
> Attachments: fix-sync-apis-in-st-adaptor.patch,
> fix-sync-apis-in-st-adaptor.v2.patch
>
>
> Since the synchronous calls are
> [known|http://hadoop.apache.org/zookeeper/docs/current/zookeeperProgrammers.html#Using+the+C+Client]
> to be unimplemented in the single threaded version of the client library
> libzookeeper_st.so, I believe that it would be helpful towards users of the
> library if that information was also obvious from the header file.
> Anecdotally more than one of us here made the mistake of starting by using
> the synchronous calls with the single-threaded library, and we found
> ourselves debugging it. An early warning would have been greatly appreciated.
> 1. Could you please add warnings to the doxygen blocks of all synchronous
> calls saying that they are not available in the single-threaded API. This
> cannot be safely done with {{#ifdef THREADED}}, obviously, because the same
> header file is included whichever client library implementation one is
> compiling for.
> 2. Could you please bracket the implementation of all synchronous calls in
> zookeeper.c with {{#ifdef THREADED}} and {{#endif}}, so that those symbols
> are not present in libzookeeper_st.so?
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