# HG changeset patch
# User dnsimon
# Date 1465345011 25200
# Node ID 6f1681fea93729844892023ca78841a52ff6d2a7
# Parent  d139a133ba270086ecf4dc863663b3841c470dd6
8158985: [JVMCI] access to HotSpotJVMCIRuntime.vmEventListeners must be thread safe
Reviewed-by: iveresov, kvn

diff -r d139a133ba27 -r 6f1681fea937 hotspot/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java
--- a/hotspot/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java	Tue Jun 07 18:20:44 2016 +0200
+++ b/hotspot/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java	Tue Jun 07 17:16:51 2016 -0700
@@ -31,10 +31,13 @@
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.ServiceLoader;
 import java.util.TreeMap;
 
 import jdk.internal.misc.VM;
@@ -213,7 +216,22 @@
 
     private final Map<Class<? extends Architecture>, JVMCIBackend> backends = new HashMap<>();
 
-    private final Iterable<HotSpotVMEventListener> vmEventListeners;
+    private volatile List<HotSpotVMEventListener> vmEventListeners;
+
+    private Iterable<HotSpotVMEventListener> getVmEventListeners() {
+        if (vmEventListeners == null) {
+            synchronized (this) {
+                if (vmEventListeners == null) {
+                    List<HotSpotVMEventListener> listeners = new ArrayList<>();
+                    for (HotSpotVMEventListener vmEventListener : ServiceLoader.load(HotSpotVMEventListener.class)) {
+                        listeners.add(vmEventListener);
+                    }
+                    vmEventListeners = listeners;
+                }
+            }
+        }
+        return vmEventListeners;
+    }
 
     /**
      * Stores the result of {@link HotSpotJVMCICompilerFactory#getTrivialPrefixes()} so that it can
@@ -240,8 +258,6 @@
             hostBackend = registerBackend(factory.createJVMCIBackend(this, null));
         }
 
-        vmEventListeners = Services.load(HotSpotVMEventListener.class);
-
         metaAccessContext = new HotSpotJVMCIMetaAccessContext();
 
         boolean printFlags = Option.PrintFlags.getBoolean();
@@ -370,7 +386,7 @@
      */
     @SuppressWarnings({"unused"})
     private void shutdown() throws Exception {
-        for (HotSpotVMEventListener vmEventListener : vmEventListeners) {
+        for (HotSpotVMEventListener vmEventListener : getVmEventListeners()) {
             vmEventListener.notifyShutdown();
         }
     }
@@ -382,7 +398,7 @@
      */
     @SuppressWarnings({"unused"})
     private void bootstrapFinished() throws Exception {
-        for (HotSpotVMEventListener vmEventListener : vmEventListeners) {
+        for (HotSpotVMEventListener vmEventListener : getVmEventListeners()) {
             vmEventListener.notifyBootstrapFinished();
         }
     }
@@ -395,7 +411,7 @@
      * @param compiledCode
      */
     void notifyInstall(HotSpotCodeCacheProvider hotSpotCodeCacheProvider, InstalledCode installedCode, CompiledCode compiledCode) {
-        for (HotSpotVMEventListener vmEventListener : vmEventListeners) {
+        for (HotSpotVMEventListener vmEventListener : getVmEventListeners()) {
             vmEventListener.notifyInstall(hotSpotCodeCacheProvider, installedCode, compiledCode);
         }
     }