Disable search for ScheduledExecutorService.setRemoveOnCancelPolicy()…

… on Android API < 21
ReactiveX · Jul 29, 2015 · 85d2e83 · 85d2e83
1 parent 3494c00
commit 85d2e83
Show file tree

Hide file tree

Showing 2 changed files with 40 additions and 29 deletions.
diff --git a/src/main/java/rx/internal/schedulers/NewThreadWorker.java b/src/main/java/rx/internal/schedulers/NewThreadWorker.java
@@ -43,13 +43,25 @@ public class NewThreadWorker extends Scheduler.Worker implements Subscription {
     private static final boolean PURGE_FORCE;
     /** The purge frequency in milliseconds. */
     public static final int PURGE_FREQUENCY;
+    private static final boolean IS_ANDROID;
+    /** Android supports setRemoveOnCancelPolicy since Android API 21 */
+    private static final boolean IS_ANDROID_AND_SUPPORTS_SET_REMOVE_ON_CANCEL_POLICY;
     private static final ConcurrentHashMap<ScheduledThreadPoolExecutor, ScheduledThreadPoolExecutor> EXECUTORS;
     private static final AtomicReference<ScheduledExecutorService> PURGE;
     static {
         EXECUTORS = new ConcurrentHashMap<ScheduledThreadPoolExecutor, ScheduledThreadPoolExecutor>();
         PURGE = new AtomicReference<ScheduledExecutorService>();
         PURGE_FORCE = Boolean.getBoolean(PURGE_FORCE_KEY);
         PURGE_FREQUENCY = Integer.getInteger(FREQUENCY_KEY, 1000);
+
+        // Cached to prevent method call
+        IS_ANDROID = PlatformDependent.isAndroid();
+
+        final Integer androidApiVersion = PlatformDependent.getAndroidApiVersion();
+
+        // According to http://developer.android.com/reference/java/util/concurrent/ScheduledThreadPoolExecutor.html#setRemoveOnCancelPolicy(boolean)
+        // setRemoveOnCancelPolicy available since Android API 21
+        IS_ANDROID_AND_SUPPORTS_SET_REMOVE_ON_CANCEL_POLICY = androidApiVersion != null && androidApiVersion >= 21;
     }
     /** 
      * Registers the given executor service and starts the purge thread if not already started. 
@@ -112,7 +124,7 @@ static void purgeExecutors() {
      * @return true if the policy was successfully enabled 
      */
     public static boolean tryEnableCancelPolicy(ScheduledExecutorService exec) {
-        if (!PURGE_FORCE) {
+        if (!PURGE_FORCE && (!IS_ANDROID || IS_ANDROID_AND_SUPPORTS_SET_REMOVE_ON_CANCEL_POLICY)) {
             for (Method m : exec.getClass().getMethods()) {
                 if (m.getName().equals("setRemoveOnCancelPolicy")
                         && m.getParameterTypes().length == 1

diff --git a/src/main/java/rx/internal/util/PlatformDependent.java b/src/main/java/rx/internal/util/PlatformDependent.java
@@ -15,51 +15,50 @@
  */
 package rx.internal.util;
 
-import java.security.AccessController;
-import java.security.PrivilegedAction;
-
 /**
  * Allow platform dependent logic such as checks for Android.
- * 
+ *
  * Modeled after Netty with some code copy/pasted from: https://github.com/netty/netty/blob/master/common/src/main/java/io/netty/util/internal/PlatformDependent.java
  */
 public final class PlatformDependent {
 
-    private static final boolean IS_ANDROID = isAndroid0();
+    // Will be null if current platform is not Android
+    // Or if Android API Version can not be resolved.
+    private static final Integer ANDROID_API_VERSION = resolveAndroidApiVersion();
+
+    private static final boolean IS_ANDROID = ANDROID_API_VERSION != null;
 
     /**
-     * Returns {@code true} if and only if the current platform is Android
+     * Returns {@code true} if and only if the current platform is Android.
      */
     public static boolean isAndroid() {
         return IS_ANDROID;
     }
 
-    private static boolean isAndroid0() {
-        boolean android;
-        try {
-            Class.forName("android.app.Application", false, getSystemClassLoader());
-            android = true;
-        } catch (Exception e) {
-            // Failed to load the class uniquely available in Android.
-            android = false;
-        }
-
-        return android;
+    /**
+     * Returns version of Android API.
+     *
+     * @return version of Android API or {@code null} if version can not be resolved or current platform is not Android.
+     */
+    public static Integer getAndroidApiVersion() {
+        return ANDROID_API_VERSION;
     }
 
     /**
-     * Return the system {@link ClassLoader}.
+     * Resolves version of Android API.
+     *
+     * @return version of Android API or {@code null} if version can not be resolved.
+     * @see <a href="http://developer.android.com/reference/android/os/Build.VERSION.html#SDK_INT">Documentation</a>
      */
-    static ClassLoader getSystemClassLoader() {
-        if (System.getSecurityManager() == null) {
-            return ClassLoader.getSystemClassLoader();
-        } else {
-            return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
-                @Override
-                public ClassLoader run() {
-                    return ClassLoader.getSystemClassLoader();
-                }
-            });
+    private static Integer resolveAndroidApiVersion() {
+        try {
+            return (Integer) Class
+                    .forName("android.os.Build$VERSION")
+                    .getField("SDK_INT")
+                    .get(null);
+        } catch (Exception e) {
+            // Can not resolve version of Android API :(
+            return null;
         }
     }
 }