| /* |
| * Copyright (C) 2008 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 org.apache.harmony.kernel.vm; |
| |
| import dalvik.system.VMStack; |
| |
| /** |
| * Bridge into <code>java.lang</code> from other trusted parts of the |
| * core library. Trusted packages either get seeded with an instance |
| * of this class directly or may call {@link #getInstance} on this |
| * class, to allow them to call into what would otherwise be |
| * package-scope functionality in <code>java.lang</code>. |
| */ |
| public abstract class LangAccess { |
| /** unique instance of this class */ |
| private static LangAccess theInstance = null; |
| |
| /** |
| * Sets the unique instance of this class. This may only be done once. |
| * |
| * @param instance non-null; the instance |
| */ |
| public static void setInstance(LangAccess instance) { |
| if (theInstance != null) { |
| throw new UnsupportedOperationException("already initialized"); |
| } |
| |
| theInstance = instance; |
| } |
| |
| /** |
| * Gets the unique instance of this class. This is only allowed in |
| * very limited situations. |
| */ |
| public static LangAccess getInstance() { |
| /* |
| * Only code on the bootclasspath is allowed to get at the |
| * instance. |
| */ |
| ClassLoader calling = VMStack.getCallingClassLoader2(); |
| ClassLoader current = LangAccess.class.getClassLoader(); |
| |
| if ((calling != null) && (calling != current)) { |
| throw new SecurityException("LangAccess access denied"); |
| } |
| |
| if (theInstance == null) { |
| throw new UnsupportedOperationException("not yet initialized"); |
| } |
| |
| return theInstance; |
| } |
| |
| /** |
| * Gets a shared array of the enum constants of a given class in |
| * declaration (ordinal) order. It is not safe to hand out this |
| * array to any user code. |
| * |
| * @param clazz non-null; the class in question |
| * @return null-ok; the class's list of enumerated constants in |
| * declaration order or <code>null</code> if the given class is |
| * not an enumeration |
| */ |
| public abstract <T> T[] getEnumValuesInOrder(Class<T> clazz); |
| |
| /** |
| * Unparks the given thread. This unblocks the thread it if it was |
| * previously parked, or indicates that the thread is "preemptively |
| * unparked" if it wasn't already parked. The latter means that the |
| * next time the thread is told to park, it will merely clear its |
| * latent park bit and carry on without blocking. |
| * |
| * <p>See {@link java.util.concurrent.locks.LockSupport} for more |
| * in-depth information of the behavior of this method.</p> |
| * |
| * @param thread non-null; the thread to unpark |
| */ |
| public abstract void unpark(Thread thread); |
| |
| /** |
| * Parks the current thread for a particular number of nanoseconds, or |
| * indefinitely. If not indefinitely, this method unparks the thread |
| * after the given number of nanoseconds if no other thread unparks it |
| * first. If the thread has been "preemptively unparked," this method |
| * cancels that unparking and returns immediately. This method may |
| * also return spuriously (that is, without the thread being told to |
| * unpark and without the indicated amount of time elapsing). |
| * |
| * <p>See {@link java.util.concurrent.locks.LockSupport} for more |
| * in-depth information of the behavior of this method.</p> |
| * |
| * @param nanos number of nanoseconds to park for or <code>0</code> |
| * to park indefinitely |
| * @throws IllegalArgumentException thrown if <code>nanos < 0</code> |
| */ |
| public abstract void parkFor(long nanos); |
| |
| /** |
| * Parks the current thread until the specified system time. This |
| * method attempts to unpark the current thread immediately after |
| * <code>System.currentTimeMillis()</code> reaches the specified |
| * value, if no other thread unparks it first. If the thread has |
| * been "preemptively unparked," this method cancels that |
| * unparking and returns immediately. This method may also return |
| * spuriously (that is, without the thread being told to unpark |
| * and without the indicated amount of time elapsing). |
| * |
| * <p>See {@link java.util.concurrent.locks.LockSupport} for more |
| * in-depth information of the behavior of this method.</p> |
| * |
| * @param time the time after which the thread should be unparked, |
| * in absolute milliseconds-since-the-epoch |
| */ |
| public abstract void parkUntil(long time); |
| } |