| /* |
| * Copyright (C) 2018 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 android.os; |
| |
| /** |
| * Tracks who triggered the work currently executed on this thread. |
| * |
| * <p>ThreadLocalWorkSource is automatically updated inside system server for incoming/outgoing |
| * binder calls and messages posted to handler threads. |
| * |
| * <p>ThreadLocalWorkSource can also be set manually if needed to refine the WorkSource. |
| * |
| * <p>Example: |
| * <ul> |
| * <li>Bluetooth process calls {@link PowerManager#isInteractive()} API on behalf of app foo. |
| * <li>ThreadLocalWorkSource will be automatically set to the UID of foo. |
| * <li>Any code on the thread handling {@link PowerManagerService#isInteractive()} can call |
| * {@link ThreadLocalWorkSource#getUid()} to blame any resource used to handle this call. |
| * <li>If a message is posted from the binder thread, the code handling the message can also call |
| * {@link ThreadLocalWorkSource#getUid()} and it will return the UID of foo since the work source is |
| * automatically propagated. |
| * </ul> |
| * |
| * @hide Only for use within system server. |
| */ |
| public final class ThreadLocalWorkSource { |
| public static final int UID_NONE = Message.UID_NONE; |
| private static final ThreadLocal<Integer> sWorkSourceUid = |
| ThreadLocal.withInitial(() -> UID_NONE); |
| |
| /** |
| * Returns the UID to blame for the code currently executed on this thread. |
| * |
| * <p>This UID is set automatically by common frameworks (e.g. Binder and Handler frameworks) |
| * and automatically propagated inside system server. |
| * <p>It can also be set manually using {@link #setUid(int)}. |
| */ |
| public static int getUid() { |
| return sWorkSourceUid.get(); |
| } |
| |
| /** |
| * Sets the UID to blame for the code currently executed on this thread. |
| * |
| * <p>Inside system server, this UID will be automatically propagated. |
| * <p>It will be used to attribute future resources used on this thread (e.g. binder |
| * transactions or processing handler messages) and on any other threads the UID is propagated |
| * to. |
| * |
| * @return a token that can be used to restore the state. |
| */ |
| public static long setUid(int uid) { |
| final long token = getToken(); |
| sWorkSourceUid.set(uid); |
| return token; |
| } |
| |
| /** |
| * Restores the state using the provided token. |
| */ |
| public static void restore(long token) { |
| sWorkSourceUid.set(parseUidFromToken(token)); |
| } |
| |
| /** |
| * Clears the stored work source uid. |
| * |
| * <p>This method should be used when we do not know who to blame. If the UID to blame is the |
| * UID of the current process, it is better to attribute the work to the current process |
| * explicitly instead of clearing the work source: |
| * |
| * <pre> |
| * ThreadLocalWorkSource.setUid(Process.myUid()); |
| * </pre> |
| * |
| * @return a token that can be used to restore the state. |
| **/ |
| public static long clear() { |
| return setUid(UID_NONE); |
| } |
| |
| private static int parseUidFromToken(long token) { |
| return (int) token; |
| } |
| |
| private static long getToken() { |
| return sWorkSourceUid.get(); |
| } |
| |
| private ThreadLocalWorkSource() { |
| } |
| } |