Package org.apache.dubbo.rpc

Class AsyncRpcResult

java.lang.Object

org.apache.dubbo.rpc.AsyncRpcResult

All Implemented Interfaces:

Serializable, Result

public class AsyncRpcResult
extends Object
implements Result

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

Constructor Summary

Constructors

Constructor	Description
AsyncRpcResult(CompletableFuture<AppResponse> future, Invocation invocation)

Method Summary

Modifier and Type	Method	Description
void	addAttachments(Map<String,String> map)	Deprecated.
void	addObjectAttachments(Map<String,Object> map)	Add the specified map to existing attachments in this instance.
Result	get()	This method will always return after a maximum 'timeout' waiting: 1. if value returns before timeout, return normally. 2. if no value returns after timeout, throw TimeoutException.
Result	get(long timeout, TimeUnit unit)
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()	Deprecated.
Throwable	getException()	Get exception.
Executor	getExecutor()
Object	getObjectAttachment(String key)	get attachment by key.
Object	getObjectAttachment(String key, Object defaultValue)	get attachment by key with default value.
Map<String,Object>	getObjectAttachments()	get attachments.
CompletableFuture<AppResponse>	getResponseFuture()
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(Object value, Throwable t, Invocation invocation)
static AsyncRpcResult	newDefaultAsyncResult(Object value, Invocation invocation)
static AsyncRpcResult	newDefaultAsyncResult(Throwable t, Invocation invocation)
static AsyncRpcResult	newDefaultAsyncResult(AppResponse appResponse, Invocation invocation)	Some utility methods used to quickly generate default AsyncRpcResult instance.
static AsyncRpcResult	newDefaultAsyncResult(Invocation invocation)
Object	recreate()	Recreate.
void	setAttachment(String key, Object value)
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	setExecutor(Executor executor)
void	setObjectAttachment(String key, Object value)
void	setObjectAttachments(Map<String,Object> map)	Replace the existing attachments with the specified param.
void	setResponseFuture(CompletableFuture<AppResponse> responseFuture)
void	setValue(Object value)	CompletableFuture can only be completed once, so try to update the result of one completed CompletableFuture will have no effect.
<U> CompletableFuture<U>	thenApply(Function<Result,? extends U> fn)
Result	whenCompleteWithContext(BiConsumer<Result,Throwable> fn)	Add a callback which can be triggered when the RPC call finishes.

Methods inherited from class java.lang.Object

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

Constructor Details

AsyncRpcResult

public AsyncRpcResult(CompletableFuture<AppResponse> future,
 Invocation invocation)

Method Details

getValue

public Object getValue()

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

Specified by:

getValue in interface Result

Returns:

setValue

public void setValue(Object value)

CompletableFuture can only be completed once, so try to update the result of one completed CompletableFuture will have no effect. To avoid this problem, we check the complete status of this future before update its 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.

Specified by:

setValue in interface Result

Parameters:

value -

getException

public Throwable getException()

Description copied from interface: Result

Get exception.

Specified by:

getException in interface Result

Returns:

exception. if no exception return null.

setException

public void setException(Throwable t)

Specified by:

setException in interface Result

hasException

public boolean hasException()

Description copied from interface: Result

Has exception.

Specified by:

hasException in interface Result

Returns:

has exception.

getResponseFuture

public CompletableFuture<AppResponse> getResponseFuture()

setResponseFuture

public void setResponseFuture(CompletableFuture<AppResponse> responseFuture)

getAppResponse

public Result getAppResponse()

get

public Result get()
           throws InterruptedException,
ExecutionException

This method will always return after a maximum 'timeout' waiting: 1. if value returns before timeout, return normally. 2. if no value returns after timeout, throw TimeoutException.

Specified by:

get in interface Result

Returns:

Throws:

InterruptedException

ExecutionException

get

public Result get(long timeout,
 TimeUnit unit)
           throws InterruptedException,
ExecutionException,
TimeoutException

Specified by:

get in interface Result

Throws:

InterruptedException

ExecutionException

TimeoutException

recreate

public Object recreate()
                throws Throwable

Description copied from interface: Result

Recreate.

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

Specified by:

recreate in interface Result

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)

Specified by:

whenCompleteWithContext in interface Result

Parameters:

fn -

Returns:

thenApply

public <U> CompletableFuture<U> thenApply(Function<Result,? extends U> fn)

Specified by:

thenApply in interface Result

getAttachments

@Deprecated
public Map<String,String> getAttachments()

Deprecated.

Description copied from interface: Result

get attachments.

Specified by:

getAttachments in interface Result

Returns:

attachments.

getObjectAttachments

public Map<String,Object> getObjectAttachments()

Description copied from interface: Result

get attachments.

Specified by:

getObjectAttachments in interface Result

Returns:

attachments.

setAttachments

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

Description copied from interface: Result

Replace the existing attachments with the specified param.

Specified by:

setAttachments in interface Result

Parameters:

map -

setObjectAttachments

public void setObjectAttachments(Map<String,Object> map)

Description copied from interface: Result

Replace the existing attachments with the specified param.

Specified by:

setObjectAttachments in interface Result

Parameters:

map -

addAttachments

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

Deprecated.

Description copied from interface: Result

Add the specified map to existing attachments in this instance.

Specified by:

addAttachments in interface Result

Parameters:

map -

addObjectAttachments

public void addObjectAttachments(Map<String,Object> map)

Description copied from interface: Result

Add the specified map to existing attachments in this instance.

Specified by:

addObjectAttachments in interface Result

Parameters:

map -

getAttachment

public String getAttachment(String key)

Description copied from interface: Result

get attachment by key.

Specified by:

getAttachment in interface Result

Returns:

attachment value.

getObjectAttachment

public Object getObjectAttachment(String key)

Description copied from interface: Result

get attachment by key.

Specified by:

getObjectAttachment in interface Result

Returns:

attachment value.

getAttachment

public String getAttachment(String key,
 String defaultValue)

Description copied from interface: Result

get attachment by key with default value.

Specified by:

getAttachment in interface Result

Returns:

attachment value.

getObjectAttachment

public Object getObjectAttachment(String key,
 Object defaultValue)

Description copied from interface: Result

get attachment by key with default value.

Specified by:

getObjectAttachment in interface Result

Returns:

attachment value.

setAttachment

public void setAttachment(String key,
 String value)

Specified by:

setAttachment in interface Result

setAttachment

public void setAttachment(String key,
 Object value)

Specified by:

setAttachment in interface Result

setObjectAttachment

public void setObjectAttachment(String key,
 Object value)

Specified by:

setObjectAttachment in interface Result

getExecutor

public Executor getExecutor()

setExecutor

public void setExecutor(Executor executor)

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)