I'd like to lazily initialize InvokeByName and dynamic method handles in
global instance. I am not sure of the refactoring in NativeArray that
you suggested.
Are you talking about these?
private final MethodHandle someInvoker =
getSOME_CALLBACK_INVOKER();
If I pass key to a refactored method, I've to do if..else on object
identity check.. Or am I missing something?
Also, on avoiding synchronized in Global.java. If we'd like to avoid
jdk8 specific API/syntax in nashorn, I can't use computeIfAbsent. But
putIfAbsent forces computing the value... Again, am I missing something?
thanks,
-Sundar
On Thursday 08 August 2013 08:56 AM, A. Sundararajan wrote:
On Thursday 08 August 2013 02:29 AM, Attila Szegedi wrote:
- CompileUnit: While making fields non-final and nulling out fields
is certainly a solution, I don't like it as it feels fragile - you
end up with an object that has a member nulled out, and what if
something later would want to depend on it etc. As an example,
consider CompileUnit, which now has its ClassEmitter nulled out.
Seems like architecturally it's a better idea is to remove the field
from the CompileUnit altogether, and use a composite object being a
tuple of (CompileUnit, ClassEmitter) in the compiler, and only pass
down the CompileUnit part of the tuple to things in the IR package
that require it.
While code can be refactored for a longer term, as of now, it does
leak memory. Moment class is loaded, we don't need lots of info
maintained by ASM's ClassEmitter. I suggest we go with short term
solution and revisit refactoring changes to
FunctionNode/CompileUnit/Compiler later.
- Another issue I have is with synchronization in the Global object;
I'd rather use a ConcurrentMap and the (new for Java 8)
computeIfAbsent() method.
<http://download.java.net/jdk8/docs/api/java/util/Map.html#computeIfAbsent(K,
java.util.function.Function)>. If you don't want to rely on
computeIfAbsent() (but I don't see why wouldn't you, frankly), you
could still use a composition of get() and putIfAbsent().
We still don't use any jdk8 specific API in nashorn codebase yet (I
believe). I'll restructure this with older API.
- In NativeArray, you could factor out the pattern of getting an
invoker for an iterator callback repeated across 4 methods into a
method taking a key and a return type.
Will do.
- Ostensibly, NativeObject could just use Global.TO_STRING instead of
having its own now. Not too convinced about this, as these things
sort-of represent call sites, so maybe it's okay as it is.
Yes - it is a different callsite (although I doubt how much
InvokeByName and dynamic invokers help now!)
- We still keep GlobalObject interface around?
Yes - we do. That calls for more refactorings. As I said, I'd like to
keep it minimal (as much as possible) for now.
- Why does RecompilableScriptFunctionData.ensureHasAllocator have to
be synchronized? If we absolutely need atomic updates to the
allocator field, I'd consider using an AtomicReference for it
instead. Having synchronization in path of every "new SomeClass()"
bothers me. Even if it's completely unsynced and the field is not
volatile, we only "risk" creating the method handle multiple times;
shouldn't be a big deal as we're (a) rarely multithreaded and (b)
it's idempotent. So, I'd rather choose a bit of a statistical
redundancy than a certain performance hit.
- Why does ensureCodeGenerated have to be synchronized? Can the
modifications of fields possibly occur on multiple threads? I mean,
functionNode.canSpecialize() will be determined at first execution
and fields nulled out. Also, wouldn't a second call to
ensureCodeGenerated() after functionNode was nulled out (if that's
possible) result in a NPE on functionNode.isLazy(), or is this
guarded by !code.isEmpty()? At least this synchronization only
happens once on every linking event and not on every invocation,
unlike allocate() but I still don't really see the necessity.
I'll check again.
-Sundar
Attila.
On Aug 7, 2013, at 6:56 PM, A. Sundararajan
<[email protected]> wrote:
Please review http://cr.openjdk.java.net/~sundar/8022524/
Thanks
-Sundar
