spi 优化

Author: beston123

src/main/java/code/spi/extension/ExtensionLoader.java

@@ -164,21 +164,26 @@ private void init(){
             }
         }
 
-        public synchronized S find(String name){
+        public S find(String name){
             //if exist in cache
             if(providers.containsKey(name)){
                 return providers.get(name);
             }
 
-            //lookup
-            if (acc == null) {
-                return findService(name);
-            } else {
-                PrivilegedAction<S> action = new PrivilegedAction<S>() {
-                    @Override
-                    public S run() { return findService(name); }
-                };
-                return AccessController.doPrivileged(action, acc);
+            synchronized(this){
+                if(providers.containsKey(name)){
+                    return providers.get(name);
+                }
+                //lookup
+                if (acc == null) {
+                    return findService(name);
+                } else {
+                    PrivilegedAction<S> action = new PrivilegedAction<S>() {
+                        @Override
+                        public S run() { return findService(name); }
+                    };
+                    return AccessController.doPrivileged(action, acc);
+                }
             }
         }
 

src/main/java/code/spi/extension/ExtensionTest.java

@@ -3,10 +3,14 @@
 import code.serialize.ISerializer;
 import code.serialize.ProtostuffSerializer;
 import code.spi.Words;
-
 import org.junit.Test;
 import org.springframework.util.Assert;
 
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
 /**
  * 〈一句话功能简述〉<p>
  * 〈功能详细描述〉
@@ -33,4 +37,26 @@ public void testFind(){
         System.out.println(serializer.deserialize(bytes, Words.class));
     }
 
+    @Test
+    public void test() throws InterruptedException {
+        int threads = 20;
+        CountDownLatch latch = new CountDownLatch(threads);
+        ExecutorService executorService = Executors.newFixedThreadPool(threads);
+        for (int i=0; i<threads; i++){
+            executorService.execute(() -> {
+                latch.countDown();
+                try {
+                    latch.await();
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+                System.out.println(System.nanoTime());
+                ISerializer serializer = extensionLoader.find("json");
+                byte[] bytes = serializer.serialize(Words.HELLO);
+                System.out.println(serializer.deserialize(bytes, Words.class));
+            });
+        }
+        executorService.shutdown();
+        executorService.awaitTermination(5, TimeUnit.SECONDS);
+    }
 }