This is the simplest possible ConcurrentHashMap I could come up with
that works and is actually concurrent in the way one would expect.
It's pretty unconventional, being based on a persistent red-black
tree, and not particularly memory-efficient or cache-friendly. I
think this is a good place to start, though, and it should perform
reasonably well for most workloads. Patches for a more efficient
implementation are welcome!
I also implemented AtomicReferenceArray, since I was using it in my
first, naive attempt to implement ConcurrentHashMap.
I had to do a bit of refactoring, including moving some non-standard
stuff from java.util.Collections to avian.Data so I could make it
available to code outside the java.util package, which is why I had to
modify several unrelated files.
I had to implement a blocking queue for ExecutorCompletionService. LinkedBlockingQueue could be very easily extended right now to implement the java 7 LinkedBlockingDeque. Right now LinkedBlockingQueue just synchronizes and depends on LinkedList implementation. But I wrote a very complete unit test suite so we if we want to put a more concurrent design here, we have a complete test suite to verify against.# Please enter the commit message for your changes. Lines starting
We added a 4th state, so we have "Canceling and Canceled". We are in canceling state if we previously were running, and will not transition to canceled till after the interrupt has been sent. So at the end if we are not running, or already canceled, we will sleep, waiting for the interrupt to occur so we can be sure we handle it before we let the thread complete.
This also fixes a condition where we returned true on a cancel after a task has already been canceled
This also changes ConcurrentLinkedQueue to implement the Queue interface, and just throw exceptions for operations which are not currently implemented.
Previously, I used a shell script to extract modification date ranges
from the Git history, but that was complicated and unreliable, so now
every file just gets the same year range in its copyright header. If
someone needs to know when a specific file was modified and by whom,
they can look at the Git history themselves; no need to include it
redundantly in the header.
