blob: ee6a5a42baa2740cba927d663f61268667814cb2 [file] [log] [blame]
/*
* Copyright (C) 2020 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 com.android.launcher3.logging;
import static java.lang.Math.max;
import static java.lang.Math.min;
import androidx.annotation.VisibleForTesting;
import java.security.SecureRandom;
import java.util.Random;
/**
* Generates random InstanceIds in range [1, instanceIdMax] for passing to
* UiEventLogger.logWithInstanceId(). Holds a SecureRandom, which self-seeds on first use; try to
* give it a long lifetime. Safe for concurrent use.
*
* Copy of frameworks/base/core/java/com/android/internal/logging/InstanceIdSequence.java
*/
public class InstanceIdSequence {
protected final int mInstanceIdMax;
private final Random mRandom = new SecureRandom();
/**
* Constructs a sequence with identifiers [1, instanceIdMax]. Capped at INSTANCE_ID_MAX.
* @param instanceIdMax Limiting value of identifiers. Normally positive: otherwise you get
* an all-1 sequence.
*/
public InstanceIdSequence(int instanceIdMax) {
mInstanceIdMax = min(max(1, instanceIdMax), InstanceId.INSTANCE_ID_MAX);
}
/**
* Constructs a sequence with identifiers [1, InstanceId.INSTANCE_ID_MAX].
*/
public InstanceIdSequence() {
this(InstanceId.INSTANCE_ID_MAX);
}
/**
* Gets the next instance from the sequence. Safe for concurrent use.
* @return new InstanceId
*/
public InstanceId newInstanceId() {
return newInstanceIdInternal(1 + mRandom.nextInt(mInstanceIdMax));
}
/**
* Factory function for instance IDs, used for testing.
* @param id
* @return new InstanceId(id)
*/
@VisibleForTesting
protected InstanceId newInstanceIdInternal(int id) {
return new InstanceId(id);
}
}