[incubator-dubbo] branch 2.7.0-release updated: [Dubbo-3169]Check future status before get(), return default value if not completed yet. (#3185)

[iluo]

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iluo pushed a commit to branch 2.7.0-release
in repository https://gitbox.apache.org/repos/asf/incubator-dubbo.git


The following commit(s) were added to refs/heads/2.7.0-release by this push:
     new 031c011  [Dubbo-3169]Check future status before get(), return default 
value if not completed yet. (#3185)
031c011 is described below

commit 031c01199bba324f0a1acb80f7660403a8686122
Author: ken.lj <ken.lj...@gmail.com>
AuthorDate: Fri Jan 11 15:41:28 2019 +0800

    [Dubbo-3169]Check future status before get(), return default value if not 
completed yet. (#3185)
    
    * Announce AsyncRpcResult internally use only;
    Check future status before get().
    
    * Code review: simplify code
---
 .../java/org/apache/dubbo/rpc/AsyncRpcResult.java  | 38 +++++++++++++++++++---
 .../org/apache/dubbo/rpc/SimpleAsyncRpcResult.java | 11 +++++++
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git 
a/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/AsyncRpcResult.java
 
b/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/AsyncRpcResult.java
index 76675bc..b631dff 100644
--- 
a/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/AsyncRpcResult.java
+++ 
b/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/AsyncRpcResult.java
@@ -25,6 +25,34 @@ import java.util.concurrent.CompletionException;
 import java.util.function.Function;
 
 /**
+ * <b>NOTICE!!</b>
+ *
+ * <p>
+ * You should never rely on this class directly when using or extending Dubbo, 
the implementation of {@link AsyncRpcResult}
+ * is only a workaround for compatibility purpose. It may be changed or even 
get removed from the next major version.
+ * Please only use {@link Result} or {@link RpcResult}.
+ *
+ * Extending the {@link Filter} is one typical use case:
+ * <pre>
+ * {@code
+ * public class YourFilter implements Filter {
+ *     @Override
+ *     public Result onResponse(Result result, Invoker<?> invoker, Invocation 
invocation) {
+ *         System.out.println("Filter get the return value: " + 
result.getValue());
+ *         // Don't do this
+ *         // AsyncRpcResult asyncRpcResult = ((AsyncRpcResult)result;
+ *         // System.out.println("Filter get the return value: " + 
asyncRpcResult.getValue());
+ *         return result;
+ *     }
+ *
+ *     @Override
+ *     public Result invoke(Invoker<?> invoker, Invocation invocation) throws 
RpcException {
+ *         return invoker.invoke(invocation);
+ *     }
+ * }
+ * }
+ * </pre>
+ * </p>
  * TODO RpcResult can be an instance of {@link 
java.util.concurrent.CompletionStage} instead of composing CompletionStage 
inside.
  */
 public class AsyncRpcResult extends AbstractResult {
@@ -119,15 +147,15 @@ public class AsyncRpcResult extends AbstractResult {
     }
 
     public Result getRpcResult() {
-        Result result;
         try {
-            result = resultFuture.get();
+            if (resultFuture.isDone()) {
+                return resultFuture.get();
+            }
         } catch (Exception e) {
             // This should never happen;
-            logger.error("", e);
-            result = new RpcResult();
+            logger.error("Got exception when trying to fetch the underlying 
result from AsyncRpcResult.", e);
         }
-        return result;
+        return new RpcResult();
     }
 
     @Override
diff --git 
a/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/SimpleAsyncRpcResult.java
 
b/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/SimpleAsyncRpcResult.java
index 49a492b..98e42d9 100644
--- 
a/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/SimpleAsyncRpcResult.java
+++ 
b/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/SimpleAsyncRpcResult.java
@@ -20,6 +20,17 @@ import java.util.concurrent.CompletableFuture;
 
 /**
  * A sub class used for normal async invoke.
+ *
+ * <b>NOTICE!!</b>
+ *
+ * <p>
+ * You should never rely on this class directly when using or extending Dubbo, 
the implementation of {@link SimpleAsyncRpcResult}
+ * is only a workaround for compatibility purpose. It may be changed or even 
get removed from the next major version.
+ * Please only use {@link Result} or {@link RpcResult}.
+ * </p>
+ *
+ * Check {@link AsyncRpcResult} for more details.
+ *
  * TODO AsyncRpcResult, AsyncNormalRpcResult should not be a parent-child 
hierarchy.
  */
 public class SimpleAsyncRpcResult extends AsyncRpcResult {