The various Architecture::nextFrame implementations were not walking
the stack correctly when a StackOverflowError was thrown. The
throwStackOverflow thunk is called before the frame of the most
recently called method has been fully created, and because tails=true
builds use a different calling convention, we need to treat this
situation carefully when building a stack trace or unwinding.
Otherwise, we will skip past all the java frames to the next native
frame, which is what was happening.
Tail call and dead code optimizations can cause code after a throw to
be eliminated, which confuses findUnwindTarget because it doesn't know
what code is throwing the exception. So we need at least one
instruction to follow the call to the throw_ thunk. Previously, we
only added such an instruction when we knew the throw was the last
instruction in the bytecode, but it turns out there are other cases
where it is needed, including certain try/finally situations.
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
getDeclaredMethods was returning methods which were inherited from
interfaces but not (re)declared in the class itself, due to the VM's
internal use of VMClass.methodTable differing from its role in
reflection. For reflection, we must only include the declared
methods, not the inherited but un-redeclared ones.
Previously, we saved the original method table in
ClassAddendum.methodTable before creating a new one which contains
both declared and inherited methods. That wasted space, so this patch
replaces ClassAddendum.methodTable with
ClassAddendum.declaredMethodCount, which specifies how many of the
methods in VMClass.methodTable were declared in that class.
Alternatively, we could ensure that undeclared methods always have
their VMMethod.class_ field set to the declaring class instead of the
inheriting class. I tried this, but it led to subtle crashes in
interface method lookup. The rest of the VM relies not only on
VMClass.methodTable containing all inherited interface methods but
also that those methods point to the inheriting class, not the
declaring class. Changing those assumptions would be a much bigger
(and more dangerous in terms of regression potential) effort than I
care to take on right now. The solution I chose is a bit ugly, but
it's safe.
An inner class has two sets of modifier flags: one is declared in the
usual place in the class file and the other is part of the
InnerClasses attribute. Not only is that redundant, but they can
contradict, and the VM can't just pick one and roll with it. Instead,
Class.getModifiers must return the InnerClasses version, whereas
reflection must check the top-level version. So even if
Class.getModifiers says the class is protected, it might still be
public for the purpose of reflection depending on what the
InnerClasses attribute says. Crazy? Yes.
This also changes ConcurrentLinkedQueue to implement the Queue interface, and just throw exceptions for operations which are not currently implemented.
This makes them available in all class libraries, not just the OpenJDK
library. Note that I've also removed the unecessary idle statements,
per ab4adef.
We were decrementing the "remaining" field twice for each byte read
using the no-arg read method, which resulted in available() returning
a value that was too small.
