Rule Request: AvoidNonAtomicIfPutOnConcurrentMap

[jborgers]

Check-Modify constructs are the most subtle and most occurring concurrency bugs. When using a ConcurrentMap, it is a multi-threading environment, so separate check and modify is a concurrency bug.

Example:

void foo(ConcurrentMap<String, Account> accountMap, String accKey) {
     if(!accountMap.containsKey(accKey)){
            accountMap.put(accKey, account);
      }
}

accountMap.putIfAbsent(accKey, account) should be used

[jborgers]

Note it needs support for local var (used in parallelStream), formal param and field.

[jborgers]

Not just put: Utilize an atomic if-combined-with-modify operation provided by the ConcurrentMap: putIfAbsent, computeIfAbsent, computeIfPresent, getOrDefault, remove and replace.