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      1 /*
      2  * Copyright (C) 2016 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.health;
     18 
     19 import android.content.Context;
     20 import android.os.BatteryStats;
     21 import android.os.Process;
     22 import android.os.RemoteException;
     23 import android.os.ServiceManager;
     24 
     25 import com.android.internal.app.IBatteryStats;
     26 
     27 /**
     28  * Provides access to data about how various system resources are used by applications.
     29  * @more
     30  * <p>
     31  * If you are going to be using this class to log your application's resource usage,
     32  * please consider the amount of resources (battery, network, etc) that will be used
     33  * by the logging itself.  It can be substantial.
     34  * <p>
     35  * <b>Battery Usage</b><br>
     36  * The statistics related to power (battery) usage are recorded since the device
     37  * was last unplugged. It is expected that applications schedule more work to do
     38  * while the device is plugged in (e.g. using {@link android.app.job.JobScheduler
     39  * JobScheduler}), and while that can affect charging rates, it is still preferable
     40  * to actually draining the battery.
     41  */
     42 public class SystemHealthManager {
     43     private final IBatteryStats mBatteryStats;
     44 
     45     /**
     46      * Construct a new SystemHealthManager object.
     47      * @hide
     48      */
     49     public SystemHealthManager() {
     50         mBatteryStats = IBatteryStats.Stub.asInterface(
     51             ServiceManager.getService(BatteryStats.SERVICE_NAME));
     52     }
     53 
     54     /**
     55      * Obtain a SystemHealthManager object for the supplied context.
     56      *
     57      * @hide
     58      */
     59     public static SystemHealthManager from(Context context) {
     60         return (SystemHealthManager)context.getSystemService(Context.SYSTEM_HEALTH_SERVICE);
     61     }
     62 
     63     /**
     64      * Return a {@link HealthStats} object containing a snapshot of system health
     65      * metrics for the given uid (user-id, which in usually corresponds to application).
     66      * @more
     67      *
     68      * An application must hold the {@link android.Manifest.permission#BATTERY_STATS
     69      * android.permission.BATTERY_STATS} permission in order to retrieve any HealthStats
     70      * other than its own.
     71      *
     72      * @param uid User ID for a given application.
     73      * @return A {@link HealthStats} object containing the metrics for the requested
     74      * application. The keys for this HealthStats object will be from the {@link UidHealthStats}
     75      * class.
     76      * @see Process#myUid() Process.myUid()
     77      */
     78     public HealthStats takeUidSnapshot(int uid) {
     79         try {
     80             final HealthStatsParceler parceler = mBatteryStats.takeUidSnapshot(uid);
     81             return parceler.getHealthStats();
     82         } catch (RemoteException ex) {
     83             throw new RuntimeException(ex);
     84         }
     85     }
     86 
     87     /**
     88      * Return a {@link HealthStats} object containing a snapshot of system health
     89      * metrics for the application calling this API. This method is the same as calling
     90      * {@code takeUidSnapshot(Process.myUid())}.
     91      *
     92      * @return A {@link HealthStats} object containing the metrics for this application. The keys
     93      * for this HealthStats object will be from the {@link UidHealthStats} class.
     94      */
     95     public HealthStats takeMyUidSnapshot() {
     96         return takeUidSnapshot(Process.myUid());
     97     }
     98 
     99     /**
    100      * Return a {@link HealthStats} object containing a snapshot of system health
    101      * metrics for the given uids (user-id, which in usually corresponds to application).
    102      * @more
    103      *
    104      * An application must hold the {@link android.Manifest.permission#BATTERY_STATS
    105      * android.permission.BATTERY_STATS} permission in order to retrieve any HealthStats
    106      * other than its own.
    107      *
    108      * @param uids An array of User IDs to retrieve.
    109      * @return An array of {@link HealthStats} objects containing the metrics for each of
    110      * the requested uids. The keys for this HealthStats object will be from the
    111      * {@link UidHealthStats} class.
    112      */
    113     public HealthStats[] takeUidSnapshots(int[] uids) {
    114         try {
    115             final HealthStatsParceler[] parcelers = mBatteryStats.takeUidSnapshots(uids);
    116             final HealthStats[] results = new HealthStats[uids.length];
    117             final int N = uids.length;
    118             for (int i=0; i<N; i++) {
    119                 results[i] = parcelers[i].getHealthStats();
    120             }
    121             return results;
    122         } catch (RemoteException ex) {
    123             throw new RuntimeException(ex);
    124         }
    125     }
    126 
    127 }
    128 
    129