ZOOKEEPER-4299: Use lock free subroutines for clist in zoo_amulti since it is not multithreaded

[Gowrima]

No description provided.

[kezhuw]

I checked code related to zoo_amulti and did not find concurrent usage of this list. The list is constructed in zoo_amulti and deconstructed in deserialize_multi. I would recommend to use queue_completion_nolock and dequeue_completion_nolock in these two places. Regarding the fix, the inited mutex/cond will leak as they are not destroyed.

[Gowrima]

@kezhuw https://github.com/apache/zookeeper/blob/master/zookeeper-client/zookeeper-client-c/src/mt_adaptor.c#L63
https://github.com/apache/zookeeper/blob/aeadf574c0463e7e3db092b588033d8347989d4c/zookeeper-client/zookeeper-client-c/src/zookeeper.c#L3142

Please take a look at this code. Mutex lock is already being called without proper initialization. This will lead to EINVAL error at some point in the future. Do you recommend restructuring this code to remove the mutex and condition variable from completion_head_t?

[kezhuw]

Do you recommend restructuring this code to remove the mutex and condition variable from completion_head_t?

No.

I checked code related to zoo_amulti and did not find concurrent usage of this list. The list is constructed in zoo_amulti and deconstructed in deserialize_multi. I would recommend to use queue_completion_nolock and dequeue_completion_nolock in these two places.

This is what I recommend. To be specific, I mean those two places:

zookeeper/zookeeper-client/zookeeper-client-c/src/zookeeper.c

Line 4731 in aeadf57

queue_completion(&clist, entry, 0);

,

zookeeper/zookeeper-client/zookeeper-client-c/src/zookeeper.c

Line 3177 in aeadf57

completion_list_t *entry = dequeue_completion(clist);

[Gowrima]

@kezhuw there is no dequeue_completion_nolock().

[kezhuw]

@Gowrima You could write one. queue_completion is an good example for rewriting.

[kezhuw]

cleanup_failed_multi should also be updated.