| /* |
| * Copyright (C) 2014 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.tools.idea.npw; |
| |
| import com.android.annotations.concurrency.GuardedBy; |
| import com.intellij.openapi.application.Application; |
| import org.jetbrains.annotations.NotNull; |
| |
| /** |
| * Simple utility that reruns task in another thread and reports the result back. |
| * <p/> |
| * The goal is to run validation in a non-UI thread. Some validation results |
| * may be dropped as user input may change before validation completes. |
| * <p/> |
| * Some threading information: |
| * invalidate() is called by client from any thread to signal that |
| * user input had changed and needs to be invalidated. |
| * This will mark this validator as dirty and schedule |
| * a runnable in the background thread if there is none |
| * pending/running. |
| * |
| * validate() will be called on a background thread to obtain |
| * the validation result. This call can be repeated |
| * if the data is marked dirty before a call to |
| * validate() completes. |
| * |
| * showValidationResult() will be called on the UI thread with the data |
| * returned by validate() called on a background thread. |
| * Note that that data may be dropped if invalidate() |
| * was called at some point while the UI thread task |
| * was pending. |
| */ |
| public abstract class AsyncValidator<V> { |
| @NotNull private final Application myApplication; |
| private final ResultReporter myResultReporter = new ResultReporter(); |
| @GuardedBy("this") |
| private boolean myIsDirty = false; |
| @GuardedBy("this") |
| private boolean myIsScheduled = false; |
| |
| public AsyncValidator(@NotNull Application application) { |
| myApplication = application; |
| } |
| |
| /** |
| * Informs the validator that data had updated and validation status needs to be recomputed. |
| * <p/> |
| * Can be called on any thread. |
| */ |
| public synchronized final void invalidate() { |
| myIsDirty = true; |
| myResultReporter.setDirty(); |
| if (!myIsScheduled) { |
| myIsScheduled = true; |
| myApplication.executeOnPooledThread(new Runnable() { |
| @Override |
| public void run() { |
| revalidateUntilClean(); |
| } |
| }); |
| } |
| } |
| |
| /** |
| * Runs validation on the background thread, repeating it if it was reported |
| * that data was updated. |
| */ |
| private void revalidateUntilClean() { |
| V result; |
| do { |
| markClean(); |
| result = validate(); |
| } |
| while (!submit(result)); |
| } |
| |
| /** |
| * Submit will be canceled if the validator was marked dirty since we cleared the flag. |
| */ |
| private synchronized boolean submit(@NotNull V result) { |
| myIsScheduled = myIsDirty; |
| if (!myIsScheduled) { |
| myResultReporter.report(result); |
| return true; |
| } |
| else { |
| return false; |
| } |
| } |
| |
| /** |
| * Marks validator status clean, meaning the validation result is in sync |
| * with user input. |
| */ |
| private synchronized void markClean() { |
| myIsDirty = false; |
| } |
| |
| /** |
| * Invoked on UI thread to show "stable" validation result in the UI. |
| */ |
| protected abstract void showValidationResult(V result); |
| |
| /** |
| * Invoked on a validation thread to perform long-running operation. |
| */ |
| @NotNull |
| protected abstract V validate(); |
| |
| /** |
| * Sent to main thread to report result of the background operation. |
| */ |
| private final class ResultReporter implements Runnable { |
| @GuardedBy("this") |
| private V myResult = null; |
| @GuardedBy("this") |
| private boolean myIsPending = false; |
| |
| public synchronized void report(@NotNull V value) { |
| myResult = value; |
| if (!myIsPending) { |
| myIsPending = true; |
| myApplication.invokeLater(this, myApplication.getAnyModalityState()); |
| } |
| } |
| |
| @Override |
| public synchronized void run() { |
| V result = myResult; |
| myResult = null; |
| try { |
| if (result != null) { |
| showValidationResult(result); |
| } |
| } finally { |
| myIsPending = false; |
| } |
| } |
| |
| public synchronized void setDirty() { |
| myResult = null; |
| } |
| } |
| } |