dalvik.system.VMRuntime Maven / Gradle / Ivy
/*
* Copyright (C) 2007 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 dalvik.system;
import java.lang.reflect.Array;
import libcore.util.EmptyArray;
import com.bugvm.rt.VM;
/**
* Provides an interface to VM-global, Dalvik-specific features.
* An application cannot create its own Runtime instance, and must obtain
* one from the getRuntime method.
*
* @hide
*/
public final class VMRuntime {
/**
* Holds the VMRuntime singleton.
*/
private static final VMRuntime THE_ONE = new VMRuntime();
/**
* Prevents this class from being instantiated.
*/
private VMRuntime() {
}
/**
* Returns the object that represents the VM instance's Dalvik-specific
* runtime environment.
*
* @return the runtime object
*/
public static VMRuntime getRuntime() {
return THE_ONE;
}
/**
* Returns a copy of the VM's command-line property settings.
* These are in the form "name=value" rather than "-Dname=value".
*/
public String[] properties() {
// BugVM note: This is native Android.
// TODO: Support command-line supplied properties?
return EmptyArray.STRING;
}
/**
* Returns the VM's boot class path.
*/
public String bootClassPath() {
// BugVM note: This is native Android.
return VM.bootClassPath();
}
/**
* Returns the VM's class path.
*/
public String classPath() {
// BugVM note: This is native Android.
return VM.classPath();
}
/**
* Gets the current ideal heap utilization, represented as a number
* between zero and one. After a GC happens, the Dalvik heap may
* be resized so that (size of live objects) / (size of heap) is
* equal to this number.
*
* @return the current ideal heap utilization
*/
public native float getTargetHeapUtilization();
/**
* Sets the current ideal heap utilization, represented as a number
* between zero and one. After a GC happens, the Dalvik heap may
* be resized so that (size of live objects) / (size of heap) is
* equal to this number.
*
* This is only a hint to the garbage collector and may be ignored.
*
* @param newTarget the new suggested ideal heap utilization.
* This value may be adjusted internally.
* @return the previous ideal heap utilization
* @throws IllegalArgumentException if newTarget is <= 0.0 or >= 1.0
*/
public float setTargetHeapUtilization(float newTarget) {
if (newTarget <= 0.0f || newTarget >= 1.0f) {
throw new IllegalArgumentException(newTarget +
" out of range (0,1)");
}
/* Synchronize to make sure that only one thread gets
* a given "old" value if both update at the same time.
* Allows for reliable save-and-restore semantics.
*/
synchronized (this) {
float oldTarget = getTargetHeapUtilization();
nativeSetTargetHeapUtilization(newTarget);
return oldTarget;
}
}
/**
* Sets the target SDK version. Should only be called before the
* app starts to run, because it may change the VM's behavior in
* dangerous ways. Use 0 to mean "current" (since callers won't
* necessarily know the actual current SDK version, and the
* allocated version numbers start at 1).
*/
public void setTargetSdkVersion(int targetSdkVersion) {
// BugVM note: This is native in Android. In BugVM this is a nop.
}
/**
* This method exists for binary compatibility. It was part of a
* heap sizing API which was removed in Android 3.0 (Honeycomb).
*/
@Deprecated
public long getMinimumHeapSize() {
return 0;
}
/**
* This method exists for binary compatibility. It was part of a
* heap sizing API which was removed in Android 3.0 (Honeycomb).
*/
@Deprecated
public long setMinimumHeapSize(long size) {
return 0;
}
/**
* This method exists for binary compatibility. It used to
* perform a garbage collection that cleared SoftReferences.
*/
@Deprecated
public void gcSoftReferences() {}
/**
* This method exists for binary compatibility. It is equivalent
* to {@link System#runFinalization}.
*/
@Deprecated
public void runFinalizationSync() {
System.runFinalization();
}
/**
* Implements setTargetHeapUtilization().
*
* @param newTarget the new suggested ideal heap utilization.
* This value may be adjusted internally.
*/
private void nativeSetTargetHeapUtilization(float newTarget) {
// BugVM note: This is native in Android. In BugVM this is a nop.
}
/**
* This method exists for binary compatibility. It was part of
* the external allocation API which was removed in Android 3.0 (Honeycomb).
*/
@Deprecated
public boolean trackExternalAllocation(long size) {
return true;
}
/**
* This method exists for binary compatibility. It was part of
* the external allocation API which was removed in Android 3.0 (Honeycomb).
*/
@Deprecated
public void trackExternalFree(long size) {}
/**
* This method exists for binary compatibility. It was part of
* the external allocation API which was removed in Android 3.0 (Honeycomb).
*/
@Deprecated
public long getExternalBytesAllocated() {
return 0;
}
/**
* Tells the VM to enable the JIT compiler. If the VM does not have a JIT
* implementation, calling this method should have no effect.
*/
public void startJitCompilation() {
// BugVM note: This is native in Android. In BugVM there's no JIT so this is a nop.
}
/**
* Tells the VM to disable the JIT compiler. If the VM does not have a JIT
* implementation, calling this method should have no effect.
*/
public void disableJitCompilation() {
// BugVM note: This is native in Android. In BugVM there's no JIT so this is a nop.
}
/**
* Returns an array allocated in an area of the Java heap where it will never be moved.
* This is used to implement native allocations on the Java heap, such as DirectByteBuffers
* and Bitmaps.
*/
public Object newNonMovableArray(Class componentType, int length) {
// BugVM note: This is native in Android. In BugVM the GC never moves around objects on
// the heap so we can use Array.newInstance().
return Array.newInstance(componentType, length);
}
/**
* Returns the address of array[0]. This differs from using JNI in that JNI might lie and
* give you the address of a copy of the array when in forcecopy mode.
*/
public long addressOf(Object array) {
// BugVM note: This is native in Android.
return VM.getArrayValuesAddress(array);
}
/**
* Removes any growth limits, allowing the application to allocate
* up to the maximum heap size.
*/
public native void clearGrowthLimit();
/**
* Returns true if either a Java debugger or native debugger is active.
*/
public boolean isDebuggerActive() {
// BugVM note: This is native in Android. Called by the FinalizerWatchdogDaemon thread to check whether a
// debugger is attached. If there is a debugger the FinalizerWatchdogDaemon thread will not exit the VM if a
// finalizer takes more time than the allowed MAX_FINALIZE_MILLIS.
return false;
}
/**
* Registers a native allocation so that the heap knows about it and performs GC as required.
* If the number of native allocated bytes exceeds the native allocation watermark, the
* function requests a concurrent GC. If the native bytes allocated exceeds a second higher
* watermark, it is determined that the application is registering native allocations at an
* unusually high rate and a GC is performed inside of the function to prevent memory usage
* from excessively increasing.
*/
public void registerNativeAllocation(int bytes) {
// BugVM note: This is native in Android. In BugVM this is a nop.
}
/**
* Registers a native free by reducing the number of native bytes accounted for.
*/
public void registerNativeFree(int bytes) {
// BugVM note: This is native in Android. In BugVM this is a nop.
}
/**
* Fill in dex caches with classes, fields, and methods that are already loaded.
*/
public void preloadDexCaches() {
// BugVM note: This is native in Android. In BugVM this is a nop.
}
}