/*
* Copyright 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 androidx.mediarouter.media;
import android.os.Handler;
import android.os.Looper;
import android.os.SystemClock;
/**
* Helper class for deciding whether active scan is allowed and when should active scan should be
* suppressed.
*/
class MediaRouterActiveScanThrottlingHelper {
// The constant is package visible for tests can set it to a shorter duration.
static final long MAX_ACTIVE_SCAN_DURATION_MS = 30000;
private final Handler mHandler = new Handler(Looper.getMainLooper());
private final Runnable mUpdateDiscoveryRequestRunnable;
private long mSuppressActiveScanTimeout;
private long mCurrentTime;
private boolean mActiveScan;
MediaRouterActiveScanThrottlingHelper(Runnable updateDiscoveryRequestRunnable) {
mUpdateDiscoveryRequestRunnable = updateDiscoveryRequestRunnable;
}
/** Resets the helper as if no active scan is requested. */
public void reset() {
mSuppressActiveScanTimeout = 0;
mActiveScan = false;
mCurrentTime = SystemClock.elapsedRealtime();
mHandler.removeCallbacks(mUpdateDiscoveryRequestRunnable);
}
/** Add an active scan request. */
public void requestActiveScan(boolean activeScanAsRequested, long requestTimestamp) {
if (!activeScanAsRequested) {
// Active scan not requested.
return;
}
if (mCurrentTime - requestTimestamp >= MAX_ACTIVE_SCAN_DURATION_MS) {
// Active scan should be suppressed.
return;
}
mSuppressActiveScanTimeout =
Math.max(
mSuppressActiveScanTimeout,
requestTimestamp + MAX_ACTIVE_SCAN_DURATION_MS - mCurrentTime);
mActiveScan = true;
}
/**
* Calculate whether active scan is needed based on all active scan requests since last
* {@link #reset()} and schedule a runnable to suppress active scan if needed.
*/
public boolean finalizeActiveScanAndScheduleSuppressActiveScanRunnable() {
if (mActiveScan && mSuppressActiveScanTimeout > 0) {
mHandler.postDelayed(mUpdateDiscoveryRequestRunnable, mSuppressActiveScanTimeout);
}
return mActiveScan;
}
}