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/*
* Copyright (C) 2020 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.android.tools.metalava;
import java.lang.reflect.Method;
import java.util.List;
/**
* A collection of wrapper functions for java.lang.management APIs. Unfortunately we need to
* use reflections for them due to b/151224432.
*
* TODO(b/151224432) Resolve the device-side dependency and stop using reflections here.
*
* To avoid extra possible allocations around casts in kotlin, it's written in Java.
*/
final class ManagementWrapper {
private static Class<?>[] EMPTY_CLASSES = new Class[]{};
private static Object[] EMPTY_ARGS = new Object[]{};
private static void onReflectionException(Exception e) {
throw new RuntimeException(e);
}
private abstract static class Lazy<T> {
private boolean mInitialized;
private T mValue;
abstract T init();
public T get() {
if (!mInitialized) {
mValue = init();
mInitialized = true;
}
return mValue;
}
}
private static class LazyClass extends Lazy<Class<?>> {
private final String mName;
private LazyClass(String name) {
mName = name;
}
@Override
Class<?> init() {
try {
return Class.forName(mName);
} catch (Exception e) {
onReflectionException(e);
return null;
}
}
}
private static class LazyMethod<TV> extends Lazy<Method> {
private final LazyClass mClazz;
private final String mName;
private TV mCachedInvokeResult;
private TV mDefault;
private LazyMethod(LazyClass clazz, String name) {
this(clazz, name, null);
}
private LazyMethod(LazyClass clazz, String name, TV defaultValue) {
mClazz = clazz;
mName = name;
mDefault = defaultValue;
}
@Override
Method init() {
try {
final Class<?> clazz = mClazz.get();
final Method m = clazz.getMethod(mName, EMPTY_CLASSES);
m.setAccessible(true);
return m;
} catch (Exception e) {
onReflectionException(e);
return null;
}
}
@SuppressWarnings("unchecked")
public TV invoke(Object target) {
try {
return (TV) get().invoke(target, EMPTY_ARGS);
} catch (Exception e) {
onReflectionException(e);
return mDefault;
}
}
public TV invokeOnce(Object target) {
if (mCachedInvokeResult == null) {
mCachedInvokeResult = invoke(target);
}
return mCachedInvokeResult;
}
}
private static LazyClass sFactoryClazz = new LazyClass("java.lang.management.ManagementFactory");
private static LazyClass sThreadMxClazz = new LazyClass("java.lang.management.ThreadMXBean");
private static LazyClass sRuntimeMxClazz = new LazyClass("java.lang.management.RuntimeMXBean");
private static LazyClass sMemoryMxClazz = new LazyClass("java.lang.management.MemoryMXBean");
private static LazyClass sMemoryUsageClazz = new LazyClass("java.lang.management.MemoryUsage");
private static LazyMethod<Object> sRuntimeMxGetter = new LazyMethod<>(sFactoryClazz, "getRuntimeMXBean");
private static LazyMethod<Object> sThreadMxGetter = new LazyMethod<>(sFactoryClazz, "getThreadMXBean");
private static LazyMethod<Object> sMemoryMxGetter = new LazyMethod<>(sFactoryClazz, "getMemoryMXBean");
// RuntimeMxBean functions
private static LazyMethod<List<String>> sGetInputArguments = new LazyMethod<>(sRuntimeMxClazz, "getInputArguments");
/** This corresponds to RuntimeMxBean.getInputArguments() */
public static List<String> getVmArguments() {
return sGetInputArguments.invoke(sRuntimeMxGetter.invokeOnce(null));
}
// ThreadMxBean functions
private static LazyMethod<Long> sUserTime = new LazyMethod<>(sThreadMxClazz, "getCurrentThreadUserTime", 0L);
private static LazyMethod<Long> sCpuTime = new LazyMethod<>(sThreadMxClazz, "getCurrentThreadCpuTime", 0L);
/** This corresponds to ThreadMxBean.getCurrentThreadUserTime() */
public static long getUserTimeNano() {
return sUserTime.invoke(sThreadMxGetter.invokeOnce(null));
}
/** This corresponds to ThreadMxBean.getCurrentThreadCpuTime() */
public static long getCpuTimeNano() {
return sCpuTime.invoke(sThreadMxGetter.invokeOnce(null));
}
// MemoryMxBean functions
/** Corresponds to java.lang.management.MemoryUsage */
public static final class MemoryUsage {
public final long init;
public final long used;
public final long committed;
public final long max;
public MemoryUsage(long init, long used, long committed, long max) {
this.init = init;
this.used = used;
this.committed = committed;
this.max = max;
}
}
// This returns a java.lang.management.MemoryUsage instance.
private static LazyMethod<Object> sGetHeapMemoryUsage = new LazyMethod<>(sMemoryMxClazz, "getHeapMemoryUsage");
private static LazyMethod<Long> sGetInitMemory = new LazyMethod<>(sMemoryUsageClazz, "getInit", 0L);
private static LazyMethod<Long> sGetUsedMemory = new LazyMethod<>(sMemoryUsageClazz, "getUsed", 0L);
private static LazyMethod<Long> sGetCommittedMemory = new LazyMethod<>(sMemoryUsageClazz, "getCommitted", 0L);
private static LazyMethod<Long> sGetMaxMemory = new LazyMethod<>(sMemoryUsageClazz, "getMax", 0L);
/** Corresponds to java.lang.management.MemoryUsage.getHeapMemoryUsage() */
public static MemoryUsage getHeapUsage() {
final Object heapUsage = sGetHeapMemoryUsage.invoke(sMemoryMxGetter.invokeOnce(null));
return new MemoryUsage(
sGetInitMemory.invoke(heapUsage),
sGetUsedMemory.invoke(heapUsage),
sGetCommittedMemory.invoke(heapUsage),
sGetMaxMemory.invoke(heapUsage)
);
}
}
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