GetOrSet method to handle case for atomic get and set if not exists #117
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This PR adds a new method
GetOrSetto handle the case where we run into a race when multiple threads do "if not found then set" sequence. Without usingGetOrSet, callers will have to use global locks, then perform 1-2 cache operations (Addfollowed byGetif already exists) which would be redundant and inefficient.There was a similar PR #82 but it tried to do it using a closure instead of a simple value. This PR takes a much simpler approach to avoid potential long held locks by external code.