org.apache.dubbo.rpc

Class AsyncRpcResult

java.lang.Object

java.util.concurrent.CompletableFuture<Result>

org.apache.dubbo.rpc.AbstractResult

org.apache.dubbo.rpc.AsyncRpcResult

All Implemented Interfaces:

Serializable, CompletionStage<Result>, Future<Result>, Result

public class AsyncRpcResult
extends AbstractResult

This class represents an unfinished RPC call, it will hold some context information for this call, for example RpcContext and Invocation, so that when the call finishes and the result returns, it can guarantee all the contexts being recovered as the same as when the call was made before any callback is invoked.

TODO if it's reasonable or even right to keep a reference to Invocation?

As Result implements CompletionStage, AsyncRpcResult allows you to easily build a async filter chain whose status will be driven entirely by the state of the underlying RPC call.

AsyncRpcResult does not contain any concrete value (except the underlying value bring by CompletableFuture), consider it as a status transfer node. getValue() and getException() are all inherited from Result interface, implementing them are mainly for compatibility consideration. Because many legacy Filter implementation are most possibly to call getValue directly.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.concurrent.CompletableFuture

CompletableFuture.AsynchronousCompletionTask

Constructor Summary

Constructors

Constructor and Description
AsyncRpcResult(AsyncRpcResult asyncRpcResult)
AsyncRpcResult(Invocation invocation)

Method Summary

Modifier and Type	Method and Description
void	addAttachments(Map<String,String> map) Add the specified map to existing attachments in this instance.
Result	getAppResponse()
String	getAttachment(String key) get attachment by key.
String	getAttachment(String key, String defaultValue) get attachment by key with default value.
Map<String,String>	getAttachments() get attachments.
Throwable	getException() Get exception.
Invocation	getInvocation()
RpcContext	getStoredContext()
RpcContext	getStoredServerContext()
Object	getValue() Notice the return type of getValue() is the actual type of the RPC method, not AppResponse
boolean	hasException() Has exception.
static AsyncRpcResult	newDefaultAsyncResult(AppResponse appResponse, Invocation invocation) Some utility methods used to quickly generate default AsyncRpcResult instance.
static AsyncRpcResult	newDefaultAsyncResult(Invocation invocation)
static AsyncRpcResult	newDefaultAsyncResult(Object value, Invocation invocation)
static AsyncRpcResult	newDefaultAsyncResult(Object value, Throwable t, Invocation invocation)
static AsyncRpcResult	newDefaultAsyncResult(Throwable t, Invocation invocation)
Object	recreate() Recreate.
void	setAttachment(String key, String value)
void	setAttachments(Map<String,String> map) Replace the existing attachments with the specified param.
void	setException(Throwable t)
void	setValue(Object value) CompletableFuture can only be completed once, so try to update the result of one completed CompletableFuture will has no effect.
void	subscribeTo(CompletableFuture<?> future)
Result	whenCompleteWithContext(BiConsumer<Result,Throwable> fn) Add a callback which can be triggered when the RPC call finishes.

Methods inherited from class java.util.concurrent.CompletableFuture

acceptEither, acceptEitherAsync, acceptEitherAsync, allOf, anyOf, applyToEither, applyToEitherAsync, applyToEitherAsync, cancel, complete, completedFuture, completeExceptionally, exceptionally, get, get, getNow, getNumberOfDependents, handle, handleAsync, handleAsync, isCancelled, isCompletedExceptionally, isDone, join, obtrudeException, obtrudeValue, runAfterBoth, runAfterBothAsync, runAfterBothAsync, runAfterEither, runAfterEitherAsync, runAfterEitherAsync, runAsync, runAsync, supplyAsync, supplyAsync, thenAccept, thenAcceptAsync, thenAcceptAsync, thenAcceptBoth, thenAcceptBothAsync, thenAcceptBothAsync, thenApply, thenApplyAsync, thenApplyAsync, thenCombine, thenCombineAsync, thenCombineAsync, thenCompose, thenComposeAsync, thenComposeAsync, thenRun, thenRunAsync, thenRunAsync, toCompletableFuture, toString, whenComplete, whenCompleteAsync, whenCompleteAsync

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.dubbo.rpc.Result

completionFuture, getNow

Methods inherited from interface java.util.concurrent.CompletionStage

acceptEither, acceptEitherAsync, acceptEitherAsync, applyToEither, applyToEitherAsync, applyToEitherAsync, exceptionally, handle, handleAsync, handleAsync, runAfterBoth, runAfterBothAsync, runAfterBothAsync, runAfterEither, runAfterEitherAsync, runAfterEitherAsync, thenAccept, thenAcceptAsync, thenAcceptAsync, thenAcceptBoth, thenAcceptBothAsync, thenAcceptBothAsync, thenApply, thenApplyAsync, thenApplyAsync, thenCombine, thenCombineAsync, thenCombineAsync, thenCompose, thenComposeAsync, thenComposeAsync, thenRun, thenRunAsync, thenRunAsync, toCompletableFuture, whenComplete, whenCompleteAsync, whenCompleteAsync

Methods inherited from interface java.util.concurrent.Future

cancel, get, get, isCancelled, isDone

Constructor Detail

AsyncRpcResult

public AsyncRpcResult(Invocation invocation)

AsyncRpcResult

public AsyncRpcResult(AsyncRpcResult asyncRpcResult)

Method Detail

getValue

public Object getValue()

Notice the return type of getValue() is the actual type of the RPC method, not AppResponse

Returns:

setValue

public void setValue(Object value)

CompletableFuture can only be completed once, so try to update the result of one completed CompletableFuture will has no effect. To avoid this problem, we check the complete status of this future before update it's value. But notice that trying to give an uncompleted CompletableFuture a new specified value may face a race condition, because the background thread watching the real result will also change the status of this CompletableFuture. The result is you may lose the value you expected to set.

Parameters:

value -

getException

public Throwable getException()

Description copied from interface: Result

Get exception.

Returns:

exception. if no exception return null.

setException

public void setException(Throwable t)

hasException

public boolean hasException()

Description copied from interface: Result

Has exception.

Returns:

has exception.

getAppResponse

public Result getAppResponse()

recreate

public Object recreate()
                throws Throwable

Description copied from interface: Result

Recreate.

if (hasException()) { throw getException(); } else { return getValue(); }

Returns:

result.

Throws:

Throwable

whenCompleteWithContext

public Result whenCompleteWithContext(BiConsumer<Result,Throwable> fn)

Description copied from interface: Result

Add a callback which can be triggered when the RPC call finishes.

Just as the method name implies, this method will guarantee the callback being triggered under the same context as when the call was started, see implementation in Result.whenCompleteWithContext(BiConsumer)

Returns:

subscribeTo

public void subscribeTo(CompletableFuture<?> future)

getAttachments

public Map<String,String> getAttachments()

Description copied from interface: Result

get attachments.

Returns:

attachments.

setAttachments

public void setAttachments(Map<String,String> map)

Description copied from interface: Result

Replace the existing attachments with the specified param.

addAttachments

public void addAttachments(Map<String,String> map)

Description copied from interface: Result

Add the specified map to existing attachments in this instance.

getAttachment

public String getAttachment(String key)

Description copied from interface: Result

get attachment by key.

Returns:

attachment value.

getAttachment

public String getAttachment(String key,
                            String defaultValue)

Description copied from interface: Result

get attachment by key with default value.

Returns:

attachment value.

setAttachment

public void setAttachment(String key,
                          String value)

getStoredContext

public RpcContext getStoredContext()

getStoredServerContext

public RpcContext getStoredServerContext()

getInvocation

public Invocation getInvocation()

newDefaultAsyncResult

public static AsyncRpcResult newDefaultAsyncResult(AppResponse appResponse,
                                                   Invocation invocation)

Some utility methods used to quickly generate default AsyncRpcResult instance.

newDefaultAsyncResult

public static AsyncRpcResult newDefaultAsyncResult(Invocation invocation)

newDefaultAsyncResult

public static AsyncRpcResult newDefaultAsyncResult(Object value,
                                                   Invocation invocation)

newDefaultAsyncResult

public static AsyncRpcResult newDefaultAsyncResult(Throwable t,
                                                   Invocation invocation)

newDefaultAsyncResult

public static AsyncRpcResult newDefaultAsyncResult(Object value,
                                                   Throwable t,
                                                   Invocation invocation)