| /* |
| * Copyright (C) 2016 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.documentsui; |
| |
| import static com.android.documentsui.base.Shared.VERBOSE; |
| |
| import android.annotation.MainThread; |
| import android.annotation.Nullable; |
| import android.util.Log; |
| |
| import com.android.documentsui.base.Shared; |
| import com.android.documentsui.selection.BandController; |
| |
| /** |
| * A lock used by {@link DirectoryLoader} and {@link BandController} to ensure refresh is blocked |
| * while Band Selection is active. |
| */ |
| public final class DirectoryReloadLock { |
| private static final String TAG = "DirectoryReloadLock"; |
| |
| private int mPauseCount = 0; |
| private @Nullable Runnable mCallback; |
| |
| /** |
| * Increment the block count by 1 |
| */ |
| @MainThread |
| public void block() { |
| Shared.checkMainLoop(); |
| mPauseCount++; |
| if (VERBOSE) Log.v(TAG, "Block count increments to " + mPauseCount + "."); |
| } |
| |
| /** |
| * Decrement the block count by 1; If no other object is trying to block and there exists some |
| * callback, that callback will be run |
| */ |
| @MainThread |
| public void unblock() { |
| Shared.checkMainLoop(); |
| assert(mPauseCount > 0); |
| mPauseCount--; |
| if (VERBOSE) Log.v(TAG, "Block count decrements to " + mPauseCount + "."); |
| if (mPauseCount == 0 && mCallback != null) { |
| mCallback.run(); |
| mCallback = null; |
| } |
| } |
| |
| /** |
| * Attempts to run the given Runnable if not-blocked, or else the Runnable is set to be ran next |
| * (replacing any previous set Runnables). |
| */ |
| public void tryUpdate(Runnable update) { |
| if (mPauseCount == 0) { |
| update.run(); |
| } else { |
| mCallback = update; |
| } |
| } |
| } |