Hi,
So if scopeLocal.get() is called in a thread outside any .run() scope in
that thread, it will throw exception and scopeLocal.isBound() will
return false. Unless it was called on an inheritableScopeLocal which
inherited binding from parent thread.
What if I wanted to create and start a thread that would be "pristine" -
not have any ScopeLocal value bound? Is this intentionally not allowed
in order to make sure that inheritable ScopeLocal(s) can't be cleared by
code that has no access to ScopeLocal instance(s)?
Another question: Suppose there are two inheritable ScopeLocal variables
with bound values in scope (A and B) when I take a snapshot:
var snapshot = ScopeLocal.snapshot();
now I pass that snapshot to a thread which does the following:
ScopeLocal
.where(C, "value for C")
.run(() -> {
System.out.printf("A:%s B:%s C:%s\n", A.isBound(), B.isBound(),
C.isBound());
ScopeLocal.runWithSnapshot(() -> {
System.out.printf("A:%s B:%s C:%s\n", A.isBound(),
B.isBound(), C.isBound());
}, snapshot);
System.out.printf("A:%s B:%s C:%s\n", A.isBound(), B.isBound(),
C.isBound());
});
What would this code print?
...in other words, does runWithSnapshot replace the whole set of bound
values or does it merge it with existing set?
Peter
On 5/12/21 4:42 PM, Andrew Haley wrote:
There's been considerable discussion about scope locals on the loom-dev list,
and it's now time to open this to a wider audience. This subject is important
because. although scope locals were motivated by the the needs of Loom, they
have many potential applications outside that project.
The draft JEP is at
https://bugs.openjdk.java.net/browse/JDK-8263012
I've already received some very helpful suggestions for enhancements to
the API, and it'll take me a while to work through them all. In particular,
Paul Sandoz has suggested that I unify the classes Snapshot and Carrier,
and it will take me some time to understand the consequences of that.
In the meantime, please have a look at the JEP and comment here.
For reference, earlier discussions are at
https://mail.openjdk.java.net/pipermail/loom-dev/2021-March/002268.html
https://mail.openjdk.java.net/pipermail/loom-dev/2021-April/002287.html
https://mail.openjdk.java.net/pipermail/loom-dev/2021-May/002427.html
