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fix(runtime): route Java->JS calls to the runtime that created the binding - #2015
SBG generates real Java classes for JS code, but those classes carried no record of which runtime they belong to. com.tns.Runtime therefore re-derived the target of every Java→JS call from the calling thread: the currentRuntime thread-local, then the entered V8 isolate, then getObjectRuntime(), a linear scan probing every live runtime's object→id maps until one contained the instance.
That had four problems:
Ownership was inferred from the wrong signal. "This runtime has an id for the object" only means the instance crossed into that isolate, not that the isolate implements it. An instance created by a worker and later wrapped by main lived in both maps, and a call on main dispatched into main's plain wrapper. Main resolved the method to the Java override, which called back into callJSMethod, and the call recursed.
Cross-thread calls mutated another runtime's maps. With enableMultithreadedJavascript off (the default) the object maps are a plain NativeScriptHashMap/NativeScriptWeakHashMap. Every cross-thread call looked the object up on the calling thread, and NativeScriptWeakHashMap.get() isn't read-only: it expunges stale entries. So a callback arriving on an OkHttp, executor or Binder thread changed main's map with no lock while main mutated it too. The owner scan did the same to every runtime.
A worker ending could hang the caller.WorkerWrapper stops a worker with Looper.quit(), which discards queued messages. A call posted just before that never ran and nothing woke the caller, so the caller blocked in wait() forever (an ANR if it was the main thread). A post that failed outright returned null with no log.
initInstance off a runtime thread dereferenced a null runtime and threw a bare NPE.
What this changes
Bindings carry their owner. Both generators now emit com.tns.NativeScriptRuntimeBound, a volatile int tag with an accessor pair:
the static binding generator, in Java source;
the runtime binding generator (Dump.java), which dexes the proxies behind new java.lang.Runnable({...}), in asmdex alongside the existing __initialized field and equals__super.
initInstance writes the tag once, after the instance is registered. Later registrations by other runtimes (getOrCreateJavaObjectID, when the instance crosses isolates) never overwrite it, because only the creating runtime holds the JS implementation. Runtime ids are monotonic and never reused, so a stale tag can't match a newer runtime.
The tag is the runtime id plus one, encoded and decoded only inside Runtime. That way the field's zero default means "no owner yet": nothing has to seed it, and the field still reads "no owner" while the superclass constructor runs, before initInstance can record anything. Runtime id 0 is main's and stays load-bearing; JsV8InspectorClient hard-codes GetRuntime(0).
Routing.callJSMethod dispatches to the tagged runtime. An untagged instance is still being constructed or registered: a generated method called from the superclass constructor, or re-entered from JS during initInstance. Those go to the calling thread's runtime, which is the only one that can be registering it. getObjectRuntime() and its scan are removed. Bindings are always regenerated by the SBG that ships with the runtime, so no untagged binding outlives a build.
The object id is resolved on the owner's thread. The lookup moved from the caller into the posted Runnable, next to the argument packaging that already ran there. With multithreaded JS off, nothing outside a runtime's thread touches its object maps any more. A missing id is still reported to the caller as a NativeScriptException, now naming the class instead of calling a possibly JS-overridden toString().
Calls with nowhere left to run are dropped and logged, not thrown or left waiting. These calls arrive on Android callbacks (lifecycle, listeners, draw), so throwing would take down the process just because a worker ended. Primitive returns get the existing default-value substitution so the generated cast can still unbox. This covers:
a call against a terminated owner;
a failed post() to a quitting looper;
a call that was queued when the worker quit. The caller re-checks every 100 ms whether the owner is still running and gives up once it has left runtimeCache (or its thread has died);
with multithreaded JS, an owner torn down between the routing check and the native call. TryGetRuntime then throws Cannot find runtime for id:N, which is dropped once the owner is confirmed gone.
Two cases still throw, because they are programming errors rather than lifecycle races: an untagged instance called from a thread with no runtime, and an instance its owner has no object id for.
initInstance with no runtime on the thread is the one case that throws, with a message that says what to do. It was already a crash (the NPE), and dropping there would leave an unregistered instance whose later calls all fail further from the cause.
Suppressed exceptions go to the owner.passSuppressedExceptionToJs reported to the calling thread's runtime, and the message it built was never used. The generated code now passes the instance, and the report goes to the owner on the owner's own thread without blocking. If the owner has terminated, the report is logged and dropped instead of surfacing in an unrelated runtime. The two-argument overload remains for callers with no instance.
Cost: two methods and one int field per generated binding class.
Notes for review
The hand-written asmdex in Dump.java is now just the field declaration and the two accessors. The constructor emits nothing new. The accessors follow the register conventions of equals__super/hashCode__super (parameters occupy the last registers). Mistakes here show up as dex verification failures at runtime, which the device suite would hit, since nearly every listener in the specs is one of these proxies.
The native side is unchanged. With multithreaded JS, a teardown that lands after TryGetRuntime succeeds but before the v8::Locker is taken is still a native race; this PR doesn't touch it.
Routing calls to the real owner means a call to another runtime's object now blocks until that runtime runs it, where before it ran (wrongly) in the caller's isolate. Two live runtimes making synchronous calls on each other's objects at the same time can therefore deadlock. The bounded wait only covers an owner that terminates, not one that is busy waiting on the caller.
A call to an object owned by a terminated worker no-ops with a log. Falling back to main would run main's wrapper rather than the worker's implementation, so it would run the wrong code instead of none.
Related Pull Requests
None yet. iOS has the same static-binding shape and would want a matching change.
Does your pull request have unit tests?
Yes.
testRuntimeBoundDispatch.js (device, new). A worker creates JS-implemented Runnable and Comparable objects and hands them to main through a Java holder (com.tns.tests.RuntimeBoundHolder). Main then checks that:
calls from main JS (with main also holding a wrapper), from main via Java, and from a plain Java thread all run on the worker;
after terminate(), calls are dropped and a primitive return comes back as 0, with no throw;
a call queued on the worker's looper while the worker sleeps and then close()s returns 0 instead of hanging the caller.
GeneratorTest checks that a generated binding implements NativeScriptRuntimeBound, that its tag defaults to 0 and round-trips, that the field is volatile, and that the exception-suppressing variant compiles and passes this to passSuppressedExceptionToJs. That path had no compile coverage before; it needed an android.util.Log test stub, added here.
testsForRuntimeBindingGenerator.js asserts the exact interface list of a runtime-generated proxy; updated for the added interface.
Verification (Pixel 3a, API 36, arm64 emulator):
The full Jasmine suite as committed (the test app enables enableMultithreadedJavascript): 1483 specs, 0 failures, 4 skipped.
The full suite again with enableMultithreadedJavascript temporarily set to false, which is the runtime's default. The test app's own setting never exercises the post-to-looper path that most of this changes. All four new specs pass, including the queued-call/close() case. The only failures were the two specs that require multithreaded JS (testEventLoop.js:114 and testMultithreadedJavascript.js:7 expect a JS Runnable to run off the main thread).
:static-binding-generator:test: 19 tests pass.
The new specs read the flag from the app's package.json. With multithreaded JS on, a Java→JS call runs on the calling thread under the owner isolate's lock, so they assert which isolate ran the call rather than which thread. The queued-call spec runs only when the flag is off, since that is the only mode with a queue.
Summary by CodeRabbit
New Features
Java-to-JavaScript calls now run on the runtime that created the object, including calls originating from other threads.
Calls targeting a runtime that has stopped are discarded safely, with appropriate default return values. Waiting calls can also finish when the runtime stops accepting work.
Generated bindings now track their creating runtime.
Tests
Added coverage for runtime-bound dispatch across worker modes, thread calls, comparisons, and worker shutdown.
Generated bindings now include runtime tags. Runtime dispatch uses each bound instance’s recorded owner for Java-to-JavaScript calls and handles calls when that runtime stops. New tests exercise dispatch across threads, worker termination, and queued calls during worker shutdown.
Changes: Runtime-bound dispatch
Layer / File(s)
Summary
Runtime-tag contract and binding generation test-app/runtime-binding-generator/src/main/java/com/tns/NativeScriptRuntimeBound.java, test-app/runtime-binding-generator/src/main/java/com/tns/bindings/Dump.java, test-app/build-tools/static-binding-generator/src/main/java/org/nativescript/staticbindinggenerator/..., test-app/build-tools/static-binding-generator/src/test/java/..., test-app/app/src/main/assets/app/tests/testsForRuntimeBindingGenerator.js
Both binding generators add the NativeScriptRuntimeBound interface, a private volatile runtime-tag field, and getter and setter methods. Generator tests check the generated members and suppressed-exception call. JavaScript and TypeScript tests expect the new interface.
Owner-runtime dispatch and shutdown handling test-app/runtime/src/main/java/com/tns/Runtime.java
Runtime records ownership on bound instances and routes Java-to-JavaScript calls to that owner. Queued calls check runtime liveness; calls that cannot run are discarded with a default result. Suppressed exceptions use the instance owner when available.
Cross-thread dispatch and worker shutdown tests test-app/app/src/main/java/com/tns/tests/RuntimeBoundHolder.java, test-app/app/src/main/assets/app/mainpage.js, test-app/app/src/main/assets/app/tests/*
The test runner loads new worker dispatch tests. The tests check worker-thread execution, calls from a Java thread, comparison results, and calls after termination or during worker shutdown.
sequenceDiagram
participant JavaCaller
participant Runtime
participant OwnerRuntime
participant JavaScriptObject
JavaCaller->>Runtime: callJSMethod(instance, method)
Runtime->>JavaScriptObject: Read recorded runtime tag
Runtime->>OwnerRuntime: Dispatch call to recorded owner
OwnerRuntime->>JavaScriptObject: Invoke JavaScript method
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Merge Risk: Minimal · up to 129de
The change routes Java-to-JavaScript calls to the runtime that created each binding and handles calls to stopped runtimes. No actionable merge-blocking issue was found in the supplied context, and the PR reports device and generator tests passing.
Pre-merge checks: 4 · 1
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The title names the primary change: Java-to-JS calls are now routed to the runtime that created the binding. The raw summary confirms this: generated bindings carry a runtime tag (NativeScriptRuntimeB…
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The title names the primary change: Java-to-JS calls are now routed to the runtime that created the binding. The raw summary confirms this: generated bindings carry a runtime tag (NativeScriptRuntimeBound), and Runtime.java now uses the recorded owner for call routing and suppressed-exception reports. The PR objectives state the same aim. The title is specific and accurate, and it follows the conventional commit format.
Full details: Docstring Coverage
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A rabbit checks the runtime tag, Then sends a call along its path. The worker answers from its thread, Or leaves a safe default instead. I hop through tests as workers close, And find the owner each call knows.
…tance
Binding classes carried no runtime identity, so com.tns.Runtime had to re-derive
the target of every Java->JS call from the calling thread: the currentRuntime
thread-local, then the entered V8 isolate, then a linear scan of every live
runtime's object maps (getObjectRuntime). That is wrong in two ways and racy in
a third.
Ownership was inferred from "some runtime has a wrapper for this object", but a
wrapper only records that the instance crossed into that isolate. An instance
created by one runtime and later passed into another exists in both maps, so a
call could dispatch into an isolate that holds a wrapper but not the user's JS
implementation. The scan also reads other runtimes' strongJavaObjectToID /
weakJavaObjectToID from a foreign thread; with enableMultithreadedJavascript
off (the default) those are plain HashMap/NativeScriptHashMap being mutated
concurrently by their owning threads.
Both generators now emit com.tns.NativeScriptRuntimeBound: the static binding
generator in Java source, and the runtime binding generator - which dexes the
proxies behind new java.lang.Runnable({...}) and is the more common of the two -
in asmdex alongside the __initialized field and equals__super it already emits.
initInstance stamps the id once; later registrations by other runtimes
(getOrCreateJavaObjectID, when the instance crosses into another isolate) must
not overwrite it, because only the creating runtime holds the JS implementation
behind the generated overrides.
INVALID_RUNTIME_ID is -1, so both generators seed the field rather than rely on
its zero default: 0 is the main runtime's id, and JsV8InspectorClient hard-codes
it as such. The dex proxies seed it as early as a constructor may touch the
instance - the verifier rejects field access on an uninitialized reference, so
not before the superclass constructor. A proxied method invoked from within that
superclass constructor therefore still reads 0 and resolves to the main runtime,
which finds no object id registered for the instance and reports that; before
this change the same call reported that no runtime held the instance.
A call with nowhere left to run is dropped and logged rather than executed
against an unrelated runtime. These arrive on Android callbacks - lifecycle,
listeners, draw - so throwing would take down the process because a worker
ended; the loss stays contained to the one call. Primitive returns reuse the
existing default-value substitution so the generated cast can still unbox.
- callJSMethod against a terminated owner drops instead of scanning and
landing on whichever runtime happens to hold a wrapper.
- dispatchCallJSMethodNative ignored the result of threadScheduler.post(); a
post to a quitting worker looper already returned null silently, and now
says so in the log.
initInstance is the one case that still throws: it dereferenced a null runtime,
so constructing a binding off a runtime thread produced a bare NPE. Dropping
there would leave an unregistered instance whose every later call fails anyway,
further from the cause, so it reports instead.
passSuppressedExceptionToJs routed by calling thread, so an exception suppressed
on behalf of another runtime was reported to the wrong one - and the message it
built was never passed to passDiscardedExceptionToJs. It now takes the instance,
resolves the same owner, and reports on that runtime's own thread without
blocking. The two-argument overload stays for already-generated bindings.
Bindings from an older generator carry no id and keep the previous thread-based
resolution. Costs two methods and one int field per binding class; noted for dex
budgets.
…ng on dead workers
Follow-up to the runtime-bound routing, from review.
The object id was still looked up on the calling thread before a
cross-thread call hopped to the owner. With multithreaded JS off the
owner's maps are unsynchronized, and NativeScriptWeakHashMap.get()
expunges stale entries, so every callback arriving on an OkHttp,
executor or Binder thread mutated main's map concurrently. The lookup
now runs inside the posted Runnable, next to argument packaging; a
missing id is still rethrown on the caller.
WorkerWrapper ends a worker with Looper.quit(), which discards queued
messages. A call posted just before that never ran and its caller
waited forever. The caller now re-checks the owner every 100ms and
drops the call once the runtime has left runtimeCache or its thread
has died.
The owner tag is now the runtime id plus one, so the field's zero
default means "no owner yet". Neither generator seeds it any more, and
a generated method called from the superclass constructor reads "no
owner" and stays on the constructing thread instead of being posted to
main, which could deadlock against main waiting on that worker. The
field is volatile, since it is read on whichever thread a call arrives.
getObjectRuntime() and its scan of every runtime's maps are removed:
an untagged instance is only one still being constructed or
registered, which only the calling thread's runtime can hold.
initInstance tags the instance after it is registered, and
passSuppressedExceptionToJs drops reports whose owner has terminated
rather than delivering them to an unrelated runtime.
Adds device specs for routing across runtimes and threads, dropped
calls after terminate(), and the queued-call-on-close() case.
edusperoni
changed the title
Route Java to JS calls to the runtime that created the binding
fix(runtime): route Java->JS calls to the runtime that created the binding
Nov 8, 2026
…call
With enableMultithreadedJavascript a cross-thread call runs directly
on the caller. If the owning worker detaches between the routing check
and the JNI call, TryGetRuntime throws "Cannot find runtime for id"
back to Java, and the caller crashed on what is the same lifecycle race
the other dead-owner paths already drop. Drop it too once the owner is
confirmed gone.
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Write docstrings for the functions missing them to satisfy the coverage
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Description
SBG generates real Java classes for JS code, but those classes carried no record of which runtime they belong to.
com.tns.Runtimetherefore re-derived the target of every Java→JS call from the calling thread: thecurrentRuntimethread-local, then the entered V8 isolate, thengetObjectRuntime(), a linear scan probing every live runtime's object→id maps until one contained the instance.That had four problems:
callJSMethod, and the call recursed.enableMultithreadedJavascriptoff (the default) the object maps are a plainNativeScriptHashMap/NativeScriptWeakHashMap. Every cross-thread call looked the object up on the calling thread, andNativeScriptWeakHashMap.get()isn't read-only: it expunges stale entries. So a callback arriving on an OkHttp, executor or Binder thread changed main's map with no lock while main mutated it too. The owner scan did the same to every runtime.WorkerWrapperstops a worker withLooper.quit(), which discards queued messages. A call posted just before that never ran and nothing woke the caller, so the caller blocked inwait()forever (an ANR if it was the main thread). A post that failed outright returnednullwith no log.initInstanceoff a runtime thread dereferenced a null runtime and threw a bare NPE.What this changes
Bindings carry their owner. Both generators now emit
com.tns.NativeScriptRuntimeBound, avolatile inttag with an accessor pair:Dump.java), which dexes the proxies behindnew java.lang.Runnable({...}), in asmdex alongside the existing__initializedfield andequals__super.initInstancewrites the tag once, after the instance is registered. Later registrations by other runtimes (getOrCreateJavaObjectID, when the instance crosses isolates) never overwrite it, because only the creating runtime holds the JS implementation. Runtime ids are monotonic and never reused, so a stale tag can't match a newer runtime.The tag is the runtime id plus one, encoded and decoded only inside
Runtime. That way the field's zero default means "no owner yet": nothing has to seed it, and the field still reads "no owner" while the superclass constructor runs, beforeinitInstancecan record anything. Runtime id 0 is main's and stays load-bearing;JsV8InspectorClienthard-codesGetRuntime(0).Routing.
callJSMethoddispatches to the tagged runtime. An untagged instance is still being constructed or registered: a generated method called from the superclass constructor, or re-entered from JS duringinitInstance. Those go to the calling thread's runtime, which is the only one that can be registering it.getObjectRuntime()and its scan are removed. Bindings are always regenerated by the SBG that ships with the runtime, so no untagged binding outlives a build.The object id is resolved on the owner's thread. The lookup moved from the caller into the posted
Runnable, next to the argument packaging that already ran there. With multithreaded JS off, nothing outside a runtime's thread touches its object maps any more. A missing id is still reported to the caller as aNativeScriptException, now naming the class instead of calling a possibly JS-overriddentoString().Calls with nowhere left to run are dropped and logged, not thrown or left waiting. These calls arrive on Android callbacks (lifecycle, listeners, draw), so throwing would take down the process just because a worker ended. Primitive returns get the existing default-value substitution so the generated cast can still unbox. This covers:
post()to a quitting looper;runtimeCache(or its thread has died);TryGetRuntimethen throwsCannot find runtime for id:N, which is dropped once the owner is confirmed gone.Two cases still throw, because they are programming errors rather than lifecycle races: an untagged instance called from a thread with no runtime, and an instance its owner has no object id for.
initInstancewith no runtime on the thread is the one case that throws, with a message that says what to do. It was already a crash (the NPE), and dropping there would leave an unregistered instance whose later calls all fail further from the cause.Suppressed exceptions go to the owner.
passSuppressedExceptionToJsreported to the calling thread's runtime, and the message it built was never used. The generated code now passes the instance, and the report goes to the owner on the owner's own thread without blocking. If the owner has terminated, the report is logged and dropped instead of surfacing in an unrelated runtime. The two-argument overload remains for callers with no instance.Cost: two methods and one int field per generated binding class.
Notes for review
Dump.javais now just the field declaration and the two accessors. The constructor emits nothing new. The accessors follow the register conventions ofequals__super/hashCode__super(parameters occupy the last registers). Mistakes here show up as dex verification failures at runtime, which the device suite would hit, since nearly every listener in the specs is one of these proxies.TryGetRuntimesucceeds but before thev8::Lockeris taken is still a native race; this PR doesn't touch it.Related Pull Requests
None yet. iOS has the same static-binding shape and would want a matching change.
Does your pull request have unit tests?
Yes.
testRuntimeBoundDispatch.js(device, new). A worker creates JS-implementedRunnableandComparableobjects and hands them to main through a Java holder (com.tns.tests.RuntimeBoundHolder). Main then checks that:terminate(), calls are dropped and a primitive return comes back as 0, with no throw;close()s returns 0 instead of hanging the caller.GeneratorTestchecks that a generated binding implementsNativeScriptRuntimeBound, that its tag defaults to 0 and round-trips, that the field isvolatile, and that the exception-suppressing variant compiles and passesthistopassSuppressedExceptionToJs. That path had no compile coverage before; it needed anandroid.util.Logtest stub, added here.testsForRuntimeBindingGenerator.jsasserts the exact interface list of a runtime-generated proxy; updated for the added interface.Verification (Pixel 3a, API 36, arm64 emulator):
enableMultithreadedJavascript): 1483 specs, 0 failures, 4 skipped.enableMultithreadedJavascripttemporarily set tofalse, which is the runtime's default. The test app's own setting never exercises the post-to-looper path that most of this changes. All four new specs pass, including the queued-call/close()case. The only failures were the two specs that require multithreaded JS (testEventLoop.js:114andtestMultithreadedJavascript.js:7expect a JSRunnableto run off the main thread).:static-binding-generator:test: 19 tests pass.The new specs read the flag from the app's
package.json. With multithreaded JS on, a Java→JS call runs on the calling thread under the owner isolate's lock, so they assert which isolate ran the call rather than which thread. The queued-call spec runs only when the flag is off, since that is the only mode with a queue.Summary by CodeRabbit
New Features
Tests