* Use thread local in Generator to detach automatically native thr…

…eads on exit for Windows as well (pull #562)
bytedeco · Mar 15, 2022 · e8aacb2 · e8aacb2
1 parent 8d0547b
commit e8aacb2
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Showing 3 changed files with 27 additions and 7 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,4 +1,5 @@
 
+ * Use thread local in `Generator` to detach automatically native threads on exit for Windows as well ([pull #562](https://github.com/bytedeco/javacpp/pull/562))
  * Add compiler options for C++14 and C++17 to platform properties files for Visual Studio
  * Fix `Parser` incorrectly shortening type names for nested class template instances
  * Make `Parser` output `boolean has_value()` methods for basic containers like `std::optional`

diff --git a/src/main/java/org/bytedeco/javacpp/tools/Generator.java b/src/main/java/org/bytedeco/javacpp/tools/Generator.java
@@ -523,7 +523,16 @@ boolean classes(boolean handleExceptions, boolean defineAdapters, boolean conver
         out.println("    va_end(ap);");
         out.println("}");
         out.println();
-        out.println("#if !defined(NO_JNI_DETACH_THREAD) && (defined(__linux__) || defined(__APPLE__))");
+        out.println("#if !defined(NO_JNI_DETACH_THREAD) && defined(_WIN32)");
+        out.println("   static __declspec(thread) struct JavaCPP_thread_local {");
+        out.println("       JNIEnv* env = NULL;");
+        out.println("       ~JavaCPP_thread_local() {");
+        out.println("           if (env && JavaCPP_vm) {");
+        out.println("               JavaCPP_vm->DetachCurrentThread();");
+        out.println("           }");
+        out.println("       }");
+        out.println("   } JavaCPP_thread_local; ");
+        out.println("#elif !defined(NO_JNI_DETACH_THREAD) && (defined(__linux__) || defined(__APPLE__))");
         out.println("    static pthread_key_t JavaCPP_current_env;");
         out.println("    static JavaCPP_noinline void JavaCPP_detach_env(void *data) {");
         out.println("        if (JavaCPP_vm) {");
@@ -1431,7 +1440,7 @@ boolean classes(boolean handleExceptions, boolean defineAdapters, boolean conver
             out.println("#endif");
             out.println();
             out.println("static JavaCPP_noinline void JavaCPP_detach(bool detach) {");
-            out.println("#if !defined(NO_JNI_DETACH_THREAD) && !defined(__linux__) && !defined(__APPLE__)");
+            out.println("#if !defined(NO_JNI_DETACH_THREAD) && !defined(__linux__) && !defined(__APPLE__) && !defined(_WIN32)");
             out.println("    if (detach && JavaCPP_vm->DetachCurrentThread() != JNI_OK) {");
             out.println("        JavaCPP_log(\"Could not detach the JavaVM from the current thread.\");");
             out.println("    }");
@@ -1462,7 +1471,12 @@ boolean classes(boolean handleExceptions, boolean defineAdapters, boolean conver
                 out.println("#endif");
             }
             out.println("    }");
-            out.println("#if !defined(NO_JNI_DETACH_THREAD) && (defined(__linux__) || defined(__APPLE__))");
+            out.println("#if !defined(NO_JNI_DETACH_THREAD) && defined(_WIN32)");
+            out.println("    if ((*env = JavaCPP_thread_local.env) != NULL) {");
+            out.println("        attached = true;");
+            out.println("        goto done;");
+            out.println("    }");
+            out.println("#elif !defined(NO_JNI_DETACH_THREAD) && (defined(__linux__) || defined(__APPLE__))");
             out.println("    pthread_once(&JavaCPP_once, JavaCPP_create_pthread_key);");
             out.println("    if ((*env = (JNIEnv *)pthread_getspecific(JavaCPP_current_env)) != NULL) {");
             out.println("        attached = true;");
@@ -1492,7 +1506,9 @@ boolean classes(boolean handleExceptions, boolean defineAdapters, boolean conver
             out.println("            *env = NULL;");
             out.println("            goto done;");
             out.println("        }");
-            out.println("#if !defined(NO_JNI_DETACH_THREAD) && (defined(__linux__) || defined(__APPLE__))");
+            out.println("#if !defined(NO_JNI_DETACH_THREAD) && defined(_WIN32)");
+            out.println("        JavaCPP_thread_local.env = *env;");
+            out.println("#elif !defined(NO_JNI_DETACH_THREAD) && (defined(__linux__) || defined(__APPLE__))");
             out.println("        pthread_setspecific(JavaCPP_current_env, *env);");
             out.println("#endif");
             out.println("        attached = true;");

diff --git a/src/test/java/org/bytedeco/javacpp/ThreadTest.java b/src/test/java/org/bytedeco/javacpp/ThreadTest.java
@@ -25,7 +25,7 @@
  * @author Dan Avila
  *
  */
-@Platform(compiler = "cpp11", define = "NO_JNI_DETACH_THREAD", include = "ThreadTest.h")
+@Platform(compiler = "cpp11", include = "ThreadTest.h")
 public class ThreadTest {
     public static class Callback extends Pointer {
         /** Default native constructor. */
@@ -76,8 +76,8 @@ public static class Callback extends Pointer {
 
         run(callback, count);
 
-        assertTrue(callbackValueRefs.size() == count);
-        assertTrue(threadRefs.size() == count);
+        assertEquals(callbackValueRefs.size(), count);
+        assertEquals(threadRefs.size(), count);
 
         for (int i = 0; i < count; i++) {
             int value = callbackValueRefs.get(i);
@@ -95,5 +95,8 @@ public static class Callback extends Pointer {
 
             assertEquals(cbThread1, cbThread2);
         }
+
+        // thread should be automatically detached upon completion
+        assertFalse(threadRefs.get(0).isAlive());
     }
 }