Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.os; |
| 18 | |
| 19 | /** |
Olivier Gaillard | a50fdae | 2018-11-14 17:15:02 +0000 | [diff] [blame] | 20 | * Tracks who triggered the work currently executed on this thread. |
| 21 | * |
| 22 | * <p>ThreadLocalWorkSource is automatically updated inside system server for incoming/outgoing |
| 23 | * binder calls and messages posted to handler threads. |
| 24 | * |
| 25 | * <p>ThreadLocalWorkSource can also be set manually if needed to refine the WorkSource. |
| 26 | * |
| 27 | * <p>Example: |
| 28 | * <ul> |
| 29 | * <li>Bluetooth process calls {@link PowerManager#isInteractive()} API on behalf of app foo. |
| 30 | * <li>ThreadLocalWorkSource will be automatically set to the UID of foo. |
| 31 | * <li>Any code on the thread handling {@link PowerManagerService#isInteractive()} can call |
| 32 | * {@link ThreadLocalWorkSource#getUid()} to blame any resource used to handle this call. |
| 33 | * <li>If a message is posted from the binder thread, the code handling the message can also call |
| 34 | * {@link ThreadLocalWorkSource#getUid()} and it will return the UID of foo since the work source is |
| 35 | * automatically propagated. |
| 36 | * </ul> |
| 37 | * |
Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 38 | * @hide Only for use within system server. |
| 39 | */ |
Olivier Gaillard | d542b1c | 2018-11-14 15:24:35 +0000 | [diff] [blame] | 40 | public final class ThreadLocalWorkSource { |
Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 41 | public static final int UID_NONE = Message.UID_NONE; |
| 42 | private static final ThreadLocal<Integer> sWorkSourceUid = |
| 43 | ThreadLocal.withInitial(() -> UID_NONE); |
| 44 | |
Olivier Gaillard | a50fdae | 2018-11-14 17:15:02 +0000 | [diff] [blame] | 45 | /** |
| 46 | * Returns the UID to blame for the code currently executed on this thread. |
| 47 | * |
| 48 | * <p>This UID is set automatically by common frameworks (e.g. Binder and Handler frameworks) |
| 49 | * and automatically propagated inside system server. |
| 50 | * <p>It can also be set manually using {@link #setUid(int)}. |
| 51 | */ |
Olivier Gaillard | d542b1c | 2018-11-14 15:24:35 +0000 | [diff] [blame] | 52 | public static int getUid() { |
Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 53 | return sWorkSourceUid.get(); |
| 54 | } |
| 55 | |
Olivier Gaillard | a50fdae | 2018-11-14 17:15:02 +0000 | [diff] [blame] | 56 | /** |
| 57 | * Sets the UID to blame for the code currently executed on this thread. |
| 58 | * |
| 59 | * <p>Inside system server, this UID will be automatically propagated. |
| 60 | * <p>It will be used to attribute future resources used on this thread (e.g. binder |
| 61 | * transactions or processing handler messages) and on any other threads the UID is propagated |
| 62 | * to. |
| 63 | * |
| 64 | * @return a token that can be used to restore the state. |
| 65 | */ |
Olivier Gaillard | d542b1c | 2018-11-14 15:24:35 +0000 | [diff] [blame] | 66 | public static long setUid(int uid) { |
| 67 | final long token = getToken(); |
Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 68 | sWorkSourceUid.set(uid); |
Olivier Gaillard | d542b1c | 2018-11-14 15:24:35 +0000 | [diff] [blame] | 69 | return token; |
| 70 | } |
| 71 | |
Olivier Gaillard | a50fdae | 2018-11-14 17:15:02 +0000 | [diff] [blame] | 72 | /** |
| 73 | * Restores the state using the provided token. |
| 74 | */ |
Olivier Gaillard | d542b1c | 2018-11-14 15:24:35 +0000 | [diff] [blame] | 75 | public static void restore(long token) { |
| 76 | sWorkSourceUid.set(parseUidFromToken(token)); |
Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 77 | } |
| 78 | |
Olivier Gaillard | a50fdae | 2018-11-14 17:15:02 +0000 | [diff] [blame] | 79 | /** |
| 80 | * Clears the stored work source uid. |
| 81 | * |
| 82 | * <p>This method should be used when we do not know who to blame. If the UID to blame is the |
| 83 | * UID of the current process, it is better to attribute the work to the current process |
| 84 | * explicitly instead of clearing the work source: |
| 85 | * |
| 86 | * <pre> |
| 87 | * ThreadLocalWorkSource.setUid(Process.myUid()); |
| 88 | * </pre> |
| 89 | * |
| 90 | * @return a token that can be used to restore the state. |
| 91 | **/ |
Olivier Gaillard | d542b1c | 2018-11-14 15:24:35 +0000 | [diff] [blame] | 92 | public static long clear() { |
| 93 | return setUid(UID_NONE); |
Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 94 | } |
| 95 | |
Olivier Gaillard | d542b1c | 2018-11-14 15:24:35 +0000 | [diff] [blame] | 96 | private static int parseUidFromToken(long token) { |
| 97 | return (int) token; |
| 98 | } |
| 99 | |
| 100 | private static long getToken() { |
| 101 | return sWorkSourceUid.get(); |
| 102 | } |
| 103 | |
| 104 | private ThreadLocalWorkSource() { |
Marcin Oczeretko | ec75872 | 2018-09-12 12:53:47 +0100 | [diff] [blame] | 105 | } |
| 106 | } |