Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  Rewrite OS bean provider to avoid using reflection

Change-Id: I8e6ad355a06bef294f7bd7589005e196d518f66b

java/com/google/gerrit/metrics/proc/OperatingSystemMXBeanFactory.java

@@ -0,0 +1,49 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.metrics.proc;
+
+import com.google.common.flogger.FluentLogger;
+import com.sun.management.UnixOperatingSystemMXBean;
+import java.lang.management.ManagementFactory;
+import java.lang.management.OperatingSystemMXBean;
+import java.util.Arrays;
+
+@SuppressWarnings("restriction")
+class OperatingSystemMXBeanFactory {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  static OperatingSystemMXBeanInterface create() {
+    OperatingSystemMXBean sys = ManagementFactory.getOperatingSystemMXBean();
+    if (sys instanceof UnixOperatingSystemMXBean) {
+      return new OperatingSystemMXBeanUnixNative((UnixOperatingSystemMXBean) sys);
+    }
+
+    for (String name :
+        Arrays.asList(
+            "com.sun.management.UnixOperatingSystemMXBean",
+            "com.ibm.lang.management.UnixOperatingSystemMXBean")) {
+      try {
+        Class<?> impl = Class.forName(name);
+        if (impl.isInstance(sys)) {
+          return new OperatingSystemMXBeanReflectionBased(sys);
+        }
+      } catch (ReflectiveOperationException e) {
+        logger.atFine().withCause(e).log("No implementation for %s", name);
+      }
+    }
+    logger.atWarning().log("No implementation of UnixOperatingSystemMXBean found");
+    return null;
+  }
+}

java/com/google/gerrit/metrics/proc/OperatingSystemMXBeanInterface.java

@@ -0,0 +1,21 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.metrics.proc;
+
+interface OperatingSystemMXBeanInterface {
+  long getProcessCpuTime();
+
+  long getOpenFileDescriptorCount();
+}

java/com/google/gerrit/metrics/proc/OperatingSystemMXBeanReflectionBased.java

@@ -1,4 +1,4 @@
-// Copyright (C) 2017 The Android Open Source Project
+// Copyright (C) 2019 The Android Open Source Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -14,50 +14,24 @@
 
 package com.google.gerrit.metrics.proc;
 
-import com.google.common.flogger.FluentLogger;
-import java.lang.management.ManagementFactory;
 import java.lang.management.OperatingSystemMXBean;
 import java.lang.reflect.Method;
-import java.util.Arrays;
-
-class OperatingSystemMXBeanProvider {
-  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
+class OperatingSystemMXBeanReflectionBased implements OperatingSystemMXBeanInterface {
   private final OperatingSystemMXBean sys;
   private final Method getProcessCpuTime;
   private final Method getOpenFileDescriptorCount;
 
-  static class Factory {
-    static OperatingSystemMXBeanProvider create() {
-      OperatingSystemMXBean sys = ManagementFactory.getOperatingSystemMXBean();
-      for (String name :
-          Arrays.asList(
-              "com.sun.management.UnixOperatingSystemMXBean",
-              "com.ibm.lang.management.UnixOperatingSystemMXBean")) {
-        try {
-          Class<?> impl = Class.forName(name);
-          if (impl.isInstance(sys)) {
-            return new OperatingSystemMXBeanProvider(sys);
-          }
-        } catch (ReflectiveOperationException e) {
-          logger.atFine().withCause(e).log("No implementation for %s", name);
-        }
-      }
-      logger.atWarning().log("No implementation of UnixOperatingSystemMXBean found");
-      return null;
-    }
-  }
-
-  private OperatingSystemMXBeanProvider(OperatingSystemMXBean sys)
+  OperatingSystemMXBeanReflectionBased(OperatingSystemMXBean sys)
       throws ReflectiveOperationException {
     this.sys = sys;
-    getProcessCpuTime = sys.getClass().getMethod("getProcessCpuTime", new Class<?>[] {});
+    getProcessCpuTime = sys.getClass().getMethod("getProcessCpuTime");
     getProcessCpuTime.setAccessible(true);
-    getOpenFileDescriptorCount =
-        sys.getClass().getMethod("getOpenFileDescriptorCount", new Class<?>[] {});
+    getOpenFileDescriptorCount = sys.getClass().getMethod("getOpenFileDescriptorCount");
     getOpenFileDescriptorCount.setAccessible(true);
   }
 
+  @Override
   public long getProcessCpuTime() {
     try {
       return (long) getProcessCpuTime.invoke(sys, new Object[] {});
@@ -66,6 +40,7 @@ class OperatingSystemMXBeanProvider {
     }
   }
 
+  @Override
   public long getOpenFileDescriptorCount() {
     try {
       return (long) getOpenFileDescriptorCount.invoke(sys, new Object[] {});

java/com/google/gerrit/metrics/proc/OperatingSystemMXBeanUnixNative.java

@@ -0,0 +1,36 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.metrics.proc;
+
+import com.sun.management.UnixOperatingSystemMXBean;
+
+@SuppressWarnings("restriction")
+class OperatingSystemMXBeanUnixNative implements OperatingSystemMXBeanInterface {
+  private final UnixOperatingSystemMXBean sys;
+
+  OperatingSystemMXBeanUnixNative(UnixOperatingSystemMXBean sys) {
+    this.sys = sys;
+  }
+
+  @Override
+  public long getProcessCpuTime() {
+    return sys.getProcessCpuTime();
+  }
+
+  @Override
+  public long getOpenFileDescriptorCount() {
+    return sys.getOpenFileDescriptorCount();
+  }
+}

java/com/google/gerrit/metrics/proc/ProcMetricModule.java

@@ -64,7 +64,7 @@ public class ProcMetricModule extends MetricModule {
   }
 
   private void procCpuUsage(MetricMaker metrics) {
-    final OperatingSystemMXBeanProvider provider = OperatingSystemMXBeanProvider.Factory.create();
+    OperatingSystemMXBeanInterface provider = OperatingSystemMXBeanFactory.create();
 
     if (provider == null) {
       return;