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      1 /*
      2  * Copyright (C) 2017 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 com.android.server.timezone;
     18 
     19 import java.io.ByteArrayInputStream;
     20 import java.io.ByteArrayOutputStream;
     21 import java.io.DataInputStream;
     22 import java.io.DataOutputStream;
     23 import java.io.IOException;
     24 import java.util.Arrays;
     25 
     26 /**
     27  * A deserialized version of the byte[] sent to the time zone update application to identify a
     28  * triggered time zone update check. It encodes the optimistic lock ID used to detect
     29  * concurrent checks and the minimal package versions that will have been checked.
     30  */
     31 final class CheckToken {
     32 
     33     final int mOptimisticLockId;
     34     final PackageVersions mPackageVersions;
     35 
     36     CheckToken(int optimisticLockId, PackageVersions packageVersions) {
     37         this.mOptimisticLockId = optimisticLockId;
     38 
     39         if (packageVersions == null) {
     40             throw new NullPointerException("packageVersions == null");
     41         }
     42         this.mPackageVersions = packageVersions;
     43     }
     44 
     45     byte[] toByteArray() {
     46         ByteArrayOutputStream baos = new ByteArrayOutputStream(12 /* (3 * sizeof(int)) */);
     47         try (DataOutputStream dos = new DataOutputStream(baos)) {
     48             dos.writeInt(mOptimisticLockId);
     49             dos.writeLong(mPackageVersions.mUpdateAppVersion);
     50             dos.writeLong(mPackageVersions.mDataAppVersion);
     51         } catch (IOException e) {
     52             throw new RuntimeException("Unable to write into a ByteArrayOutputStream", e);
     53         }
     54         return baos.toByteArray();
     55     }
     56 
     57     static CheckToken fromByteArray(byte[] tokenBytes) throws IOException {
     58         ByteArrayInputStream bais = new ByteArrayInputStream(tokenBytes);
     59         try (DataInputStream dis = new DataInputStream(bais)) {
     60             int versionId = dis.readInt();
     61             long updateAppVersion = dis.readLong();
     62             long dataAppVersion = dis.readLong();
     63             return new CheckToken(versionId, new PackageVersions(updateAppVersion, dataAppVersion));
     64         }
     65     }
     66 
     67     @Override
     68     public boolean equals(Object o) {
     69         if (this == o) {
     70             return true;
     71         }
     72         if (o == null || getClass() != o.getClass()) {
     73             return false;
     74         }
     75 
     76         CheckToken checkToken = (CheckToken) o;
     77 
     78         if (mOptimisticLockId != checkToken.mOptimisticLockId) {
     79             return false;
     80         }
     81         return mPackageVersions.equals(checkToken.mPackageVersions);
     82     }
     83 
     84     @Override
     85     public int hashCode() {
     86         int result = mOptimisticLockId;
     87         result = 31 * result + mPackageVersions.hashCode();
     88         return result;
     89     }
     90 
     91     @Override
     92     public String toString() {
     93         return "Token{" +
     94                 "mOptimisticLockId=" + mOptimisticLockId +
     95                 ", mPackageVersions=" + mPackageVersions +
     96                 '}';
     97     }
     98 }
     99