Use ServiceLoaderUtil to create SPI ServiceLoader

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

sentinel-cluster/sentinel-cluster-server-default/src/main/java/com/alibaba/csp/sentinel/cluster/server/TokenServiceProvider.java

@@ -15,13 +15,10 @@
  */
 package com.alibaba.csp.sentinel.cluster.server;
 
-import java.util.ArrayList;
-import java.util.List;
-import java.util.ServiceLoader;
-
 import com.alibaba.csp.sentinel.cluster.TokenService;
 import com.alibaba.csp.sentinel.cluster.flow.DefaultTokenService;
 import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.util.SpiLoader;
 
 /**
  * @author Eric Zhao
@@ -31,8 +28,6 @@ public final class TokenServiceProvider {
 
     private static TokenService service = null;
 
-    private static final ServiceLoader<TokenService> LOADER = ServiceLoader.load(TokenService.class);
-
     static {
         resolveTokenServiceSpi();
     }
@@ -42,24 +37,12 @@ public final class TokenServiceProvider {
     }
 
     private static void resolveTokenServiceSpi() {
-        boolean hasOther = false;
-        List<TokenService> list = new ArrayList<TokenService>();
-        for (TokenService service : LOADER) {
-            if (service.getClass() != DefaultTokenService.class) {
-                hasOther = true;
-                list.add(service);
-            }
-        }
-
-        if (hasOther) {
-            // Pick the first.
-            service = list.get(0);
+        service = SpiLoader.loadFirstInstanceOrDefault(TokenService.class, DefaultTokenService.class);
+        if (service != null) {
+            RecordLog.info("[TokenServiceProvider] Global token service resolved: "
+                + service.getClass().getCanonicalName());
         } else {
-            // No custom token service, using default.
-            service = new DefaultTokenService();
+            RecordLog.warn("[TokenServiceProvider] Unable to resolve TokenService: no SPI found");
         }
-
-        RecordLog.info("[TokenServiceProvider] Global token service resolved: "
-            + service.getClass().getCanonicalName());
     }
 }

sentinel-cluster/sentinel-cluster-server-default/src/main/java/com/alibaba/csp/sentinel/cluster/server/processor/RequestProcessorProvider.java

@@ -20,6 +20,7 @@ import java.util.ServiceLoader;
 import java.util.concurrent.ConcurrentHashMap;
 
 import com.alibaba.csp.sentinel.cluster.annotation.RequestType;
+import com.alibaba.csp.sentinel.spi.ServiceLoaderUtil;
 import com.alibaba.csp.sentinel.util.AssertUtil;
 
 /**
@@ -30,7 +31,8 @@ public final class RequestProcessorProvider {
 
     private static final Map<Integer, RequestProcessor> PROCESSOR_MAP = new ConcurrentHashMap<>();
 
-    private static final ServiceLoader<RequestProcessor> SERVICE_LOADER = ServiceLoader.load(RequestProcessor.class);
+    private static final ServiceLoader<RequestProcessor> SERVICE_LOADER = ServiceLoaderUtil.getServiceLoader(
+        RequestProcessor.class);
 
     static {
         loadAndInit();
@@ -71,6 +73,5 @@ public final class RequestProcessorProvider {
         PROCESSOR_MAP.put(type, processor);
     }
 
-
     private RequestProcessorProvider() {}
 }

sentinel-core/src/main/java/com/alibaba/csp/sentinel/init/InitExecutor.java

@@ -21,6 +21,7 @@ import java.util.ServiceLoader;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.spi.ServiceLoaderUtil;
 
 /**
  * Load registered init functions and execute in order.
@@ -42,7 +43,7 @@ public final class InitExecutor {
             return;
         }
         try {
-            ServiceLoader<InitFunc> loader = ServiceLoader.load(InitFunc.class);
+            ServiceLoader<InitFunc> loader = ServiceLoaderUtil.getServiceLoader(InitFunc.class);
             List<OrderWrapper> initList = new ArrayList<OrderWrapper>();
             for (InitFunc initFunc : loader) {
                 RecordLog.info("[InitExecutor] Found init func: " + initFunc.getClass().getCanonicalName());

sentinel-core/src/main/java/com/alibaba/csp/sentinel/slotchain/SlotChainProvider.java

@@ -17,7 +17,7 @@ package com.alibaba.csp.sentinel.slotchain;
 
 import com.alibaba.csp.sentinel.log.RecordLog;
 import com.alibaba.csp.sentinel.slots.DefaultSlotChainBuilder;
-import java.util.ServiceLoader;
+import com.alibaba.csp.sentinel.util.SpiLoader;
 
 /**
  * A provider for creating slot chains via resolved slot chain builder SPI.
@@ -29,8 +29,6 @@ public final class SlotChainProvider {
 
     private static volatile SlotChainBuilder slotChainBuilder = null;
 
-    private static final ServiceLoader<SlotChainBuilder> LOADER = ServiceLoader.load(SlotChainBuilder.class);
-
     /**
      * The load and pick process is not thread-safe, but it's okay since the method should be only invoked
      * via {@code lookProcessChain} in {@link com.alibaba.csp.sentinel.CtSph} under lock.
@@ -42,30 +40,19 @@ public final class SlotChainProvider {
             return slotChainBuilder.build();
         }
 
-        resolveSlotChainBuilder();
+        // Resolve the slot chain builder SPI.
+        slotChainBuilder = SpiLoader.loadFirstInstanceOrDefault(SlotChainBuilder.class, DefaultSlotChainBuilder.class);
 
         if (slotChainBuilder == null) {
+            // Should not go through here.
             RecordLog.warn("[SlotChainProvider] Wrong state when resolving slot chain builder, using default");
             slotChainBuilder = new DefaultSlotChainBuilder();
+        } else {
+            RecordLog.info("[SlotChainProvider] Global slot chain builder resolved: "
+                + slotChainBuilder.getClass().getCanonicalName());
         }
         return slotChainBuilder.build();
     }
 
-    private static void resolveSlotChainBuilder() {
-        for (SlotChainBuilder builder : LOADER) {
-            if (builder.getClass() != DefaultSlotChainBuilder.class) {
-                slotChainBuilder = builder;
-                break;
-            }
-        }
-        if (slotChainBuilder == null){
-            // No custom builder, using default.
-            slotChainBuilder = new DefaultSlotChainBuilder();
-        }
-
-        RecordLog.info("[SlotChainProvider] Global slot chain builder resolved: "
-            + slotChainBuilder.getClass().getCanonicalName());
-    }
-
     private SlotChainProvider() {}
 }

sentinel-transport/sentinel-transport-common/src/main/java/com/alibaba/csp/sentinel/command/CommandHandlerProvider.java

@@ -21,6 +21,7 @@ import java.util.Map;
 import java.util.ServiceLoader;
 
 import com.alibaba.csp.sentinel.command.annotation.CommandMapping;
+import com.alibaba.csp.sentinel.spi.ServiceLoaderUtil;
 import com.alibaba.csp.sentinel.util.StringUtil;
 
 /**
@@ -30,7 +31,8 @@ import com.alibaba.csp.sentinel.util.StringUtil;
  */
 public class CommandHandlerProvider implements Iterable<CommandHandler> {
 
-    private final ServiceLoader<CommandHandler> serviceLoader = ServiceLoader.load(CommandHandler.class);
+    private final ServiceLoader<CommandHandler> serviceLoader = ServiceLoaderUtil.getServiceLoader(
+        CommandHandler.class);
 
     /**
      * Get all command handlers annotated with {@link CommandMapping} with command name.