ParseObjectCoder.encode is not thread-safe

[hallucinogen]

ParseObjectCoder.encode signature accepts ParseObject.State, ParseOperationSet and ParseEncoder. While ParseObject.State and ParseEncoder is immutable and thread-safe, ParseOperationSet can be mutated anytime and is not guarded by any mutex. We need to either guard the ParseOperationSet with mutex or make a copy of this ParseOperationSet somewhere and pass the copy to ParseObjectCoder.encode.

[hallucinogen]

This is an example of how ParseObjectCoder.encode is not thread-safe: https://github.com/ParsePlatform/Parse-SDK-Android/blob/master/Parse/src/main/java/com/parse/NetworkUserController.java#L41

Though we can argue that every call to NetworkUserController will be guarded by ParseUser's taskQueue.

[lukas1994]

We could make a deep-copy of the operation set in encode() but that might not be very efficient. What do you think?

[hallucinogen]

Deep-copy won't solve the problem I mentioned in #78.

[lukas1994]

from #78 :
I checked all places where ParseOperationSet is used and couldn't find any concurrency issues.
The scenario you described above can't happen because if save() gets called a new ParseOperationSet gets enqueued (to operationSetQueue) and all methods mutate the top of the queue.

[hallucinogen]

Sounds good. Closing this one