Parallel streams returning boolean that fail on first or succeed on all - code evaluation

Question

Okay, working with Java 8, need to know if my code below does what I need it to do.

• I have three methods. Each do an operation and return success or failure as a boolean.
• I need to have all three operate at the same time.
• If any return a false, the first one to do so will cause the entire process to short-circuit and the master method to return a false.
• If none of them return a false, all three need to run to completion and return a true for the master method to return a true.

My code:

private boolean checkProcess1(){
    //does stuff, mostly DB schema checking
}

private boolean checkProcess2(){
    //does stuff, mostly queries on a different DB
}

private boolean checkProcess3(){
    //does stuff, checking files and versioning
}

public boolean checkProcessesForSuccess(){
    final List<Supplier<Boolean>> checkList = Arrays.asList(
        this::checkProcess1,
        this::checkProcess2,
        this::checkProcess3
    );
    return checkList.parallelStream().allMatch( Supplier :: get );
}

My main sticking point concerns the .allMatch(). It is supposed to take a predicate that determines how each item in the list is evaluated. By passing in the Supplier :: get, does it not return a true on any full set of matches, such as all false values, or does it require all values to be true in order to return a true?

Additionally, if the first method to return a result is false, does this short-circuit the entire master method, or does it continue processing until all three are complete? My worry is that if a short-running method returns a false, the entire system will be bound by the longest-running method.

I had previously tried to utilize CompletableFuture for this problem, and I did come up with a solution, but it was quite a bit more complex and - honestly - quite inelegant and ugly. I turned to Streams in an attempt to see if the problem could be resolved in a simpler and more elegant manner.

Suggestions?

Answer 1

By passing in the Supplier :: get, does it not return a true on any full set of matches, such as all false values, or does it require all values to be true in order to return a true?

It requires all supplier.get to return true to eventually return true as a complete result from checkProcessesForSuccess.

Additionally, if the first method to return a result is false, does this short-circuit the entire master method, or does it continue processing until all three are complete?

It does short-circuit, as mentioned in the javadoc.