Make executor an instance property (flutter#3633)

Author: Emmanuel Garcia

.gitignore

@@ -46,3 +46,6 @@ build/
 .project
 .classpath
 .settings
+
+# Downloaded by the plugin tools.
+google-java-format-1.3-all-deps.jar

packages/shared_preferences/shared_preferences/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.0.2
+
+* Don't create additional thread pools when method channel is called.
+
 ## 2.0.1
 
 * Removed deprecated [AsyncTask](https://developer.android.com/reference/android/os/AsyncTask) was deprecated in API level 30 ([#3481](https://github.com/flutter/plugins/pull/3481))

packages/shared_preferences/shared_preferences/android/src/main/java/io/flutter/plugins/sharedpreferences/MethodCallHandlerImpl.java

@@ -43,12 +43,16 @@ class MethodCallHandlerImpl implements MethodChannel.MethodCallHandler {
 
   private final android.content.SharedPreferences preferences;
 
+  private final ExecutorService executor;
+
   /**
    * Constructs a {@link MethodCallHandlerImpl} instance. Creates a {@link
    * android.content.SharedPreferences} based on the {@code context}.
    */
   MethodCallHandlerImpl(Context context) {
     preferences = context.getSharedPreferences(SHARED_PREFERENCES_NAME, Context.MODE_PRIVATE);
+    executor =
+        new ThreadPoolExecutor(0, 1, 30L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>());
   }
 
   @Override
@@ -123,8 +127,6 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
 
   private void commitAsync(
       final SharedPreferences.Editor editor, final MethodChannel.Result result) {
-    final ExecutorService executor =
-        new ThreadPoolExecutor(0, 1, 30L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>());
     final Handler handler = new Handler(Looper.getMainLooper());
 
     executor.execute(

packages/shared_preferences/shared_preferences/pubspec.yaml

@@ -2,7 +2,7 @@ name: shared_preferences
 description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 homepage: https://github.com/flutter/plugins/tree/master/packages/shared_preferences/shared_preferences
-version: 2.0.1
+version: 2.0.2
 
 flutter:
   plugin: