From 59653835ebdbce083697cfaf3b8188cb0d699013 Mon Sep 17 00:00:00 2001
From: Nikolay Igotti <olonho@users.noreply.github.com>
Date: Wed, 26 Sep 2018 12:25:44 +0300
Subject: [PATCH] Fix bug preventing return from worker value passed in it.
 (#2135)

---
 backend.native/tests/build.gradle             |  6 +++
 .../tests/runtime/workers/worker11.kt         | 48 +++++++++++++++++++
 runtime/src/main/cpp/Memory.h                 |  1 +
 runtime/src/main/cpp/Worker.cpp               |  1 +
 4 files changed, 56 insertions(+)
 create mode 100644 backend.native/tests/runtime/workers/worker11.kt

diff --git a/backend.native/tests/build.gradle b/backend.native/tests/build.gradle
index ac47869ac5b..f2e233fd950 100644
--- a/backend.native/tests/build.gradle
+++ b/backend.native/tests/build.gradle
@@ -663,6 +663,12 @@ task worker10(type: RunKonanTest) {
     source = "runtime/workers/worker10.kt"
 }
 
+task worker11(type: RunKonanTest) {
+    disabled = (project.testTarget == 'wasm32') // Workers need pthreads.
+    goldValue = "OK\n"
+    source = "runtime/workers/worker11.kt"
+}
+
 task freeze0(type: RunKonanTest) {
     disabled = (project.testTarget == 'wasm32') // No workers on WASM.
     goldValue = "frozen bit is true\n" +
diff --git a/backend.native/tests/runtime/workers/worker11.kt b/backend.native/tests/runtime/workers/worker11.kt
new file mode 100644
index 00000000000..91527808da3
--- /dev/null
+++ b/backend.native/tests/runtime/workers/worker11.kt
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package runtime.workers.worker11
+
+import kotlin.test.*
+
+import kotlin.native.concurrent.*
+import kotlinx.cinterop.convert
+
+data class Job(val index: Int, var input: Int, var counter: Int)
+
+fun initJobs(count: Int) = Array<Job?>(count) { i -> Job(i, i * 2, i)}
+
+@Test fun runTest() {
+    val COUNT = 100
+    val workers = Array(COUNT, { _ -> Worker.start() })
+    val jobs = initJobs(COUNT)
+    val futures = Array(workers.size, { workerIndex ->
+        workers[workerIndex].execute(TransferMode.SAFE, {
+            val job = jobs[workerIndex]
+            jobs[workerIndex] = null
+            job!!
+        }) { job ->
+            job.counter += job.input
+            job
+        }
+    })
+    val futureSet = futures.toSet()
+    var consumed = 0
+    while (consumed < futureSet.size) {
+        val ready = futureSet.waitForMultipleFutures(10000)
+        ready.forEach {
+            it.consume { job ->
+                assertEquals(job.index * 3, job.counter)
+                jobs[job.index] = job
+            }
+            consumed++
+        }
+    }
+    assertEquals(consumed, COUNT)
+    workers.forEach {
+        it.requestTermination().result
+    }
+    println("OK")
+}
\ No newline at end of file
diff --git a/runtime/src/main/cpp/Memory.h b/runtime/src/main/cpp/Memory.h
index d530d4b4490..a39984c3399 100644
--- a/runtime/src/main/cpp/Memory.h
+++ b/runtime/src/main/cpp/Memory.h
@@ -496,6 +496,7 @@ class ObjHolder {
    ObjHeader* obj() { return obj_; }
    const ObjHeader* obj() const { return obj_; }
    ObjHeader** slot() { return &obj_; }
+   void clear() { ::UpdateRef(&obj_, nullptr); }
 
   private:
    ObjHeader* obj_;
diff --git a/runtime/src/main/cpp/Worker.cpp b/runtime/src/main/cpp/Worker.cpp
index e4801e2276b..a941525efd9 100644
--- a/runtime/src/main/cpp/Worker.cpp
+++ b/runtime/src/main/cpp/Worker.cpp
@@ -379,6 +379,7 @@ void* workerRoutine(void* argument) {
     KNativePtr result = nullptr;
     try {
         job.function(argument, &resultRef);
+        argumentHolder.clear();
         // Transfer the result.
         result = transfer(resultRef, job.transferMode);
     } catch (ObjHolder& e) {