| java.lang.Object
 org.jgroups.blocks.RequestCorrelator
| RequestCorrelator | | public class RequestCorrelator (Code) | | Framework to send requests and receive matching responses (matching on
request ID).
Multiple requests can be sent at a time. Whenever a response is received,
the correct RspCollector is looked up (key = id) and its
method receiveResponse() invoked. A caller may use
done() to signal that no more responses are expected, and that
the corresponding entry may be removed.
RequestCorrelator can be installed at both client and server
sides, it can also switch roles dynamically; i.e., send a request and at
the same time process an incoming request (when local delivery is enabled,
this is actually the default).
author:
Bela Ban |
| Constructor Summary | |
| public | RequestCorrelator(String name, Object transport, RequestHandler handler)
Constructor. | | public | RequestCorrelator(String name, Object transport, RequestHandler handler, Address local_addr)
| | public | RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection)
Constructor. | | public | RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection, boolean concurrent_processing)
| | public | RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection, Address local_addr)
| | public | RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection, Address local_addr, boolean concurrent_processing)
|
| Method Summary | |
| public void | done(long id)
Used to signal that a certain request may be garbage collected as
all responses have been received. | | public Address | getLocalAddress()
| | public RpcDispatcher.Marshaller | getMarshaller()
| | public void | receive(Event evt)
Callback.
Called by the protocol below when a message has been received. | | public boolean | receiveMessage(Message msg)
| | public void | receiveSuspect(Address mbr)
Event.SUSPECT event received from a layer below. | | public void | receiveView(View new_view)
Event.VIEW_CHANGE event received from a layer below. | | public void | sendRequest(long id, Message msg, RspCollector coll)
Helper method for
RequestCorrelator.sendRequest(long,List,Message,RspCollector) . | | public void | sendRequest(long id, List dest_mbrs, Message msg, RspCollector coll)
| | public void | sendRequest(long id, List dest_mbrs, Message msg, RspCollector coll, boolean use_anycasting)
Send a request to a group. | | public void | setConcurrentProcessing(boolean flag)
| | public void | setDeadlockDetection(boolean flag)
| | public void | setLocalAddress(Address local_addr)
| | public void | setMarshaller(RpcDispatcher.Marshaller marshaller)
| | public void | setRequestHandler(RequestHandler handler)
| | final public void | start()
| | void | startScheduler()
| | public void | stop()
| | void | stopScheduler()
|
| call_stack | | protected ThreadLocal call_stack(Code) | | This field is used only if deadlock detection is enabled.
In case of nested synchronous requests, it holds a list of the
addreses of the senders with the address at the bottom being the
address of the first caller
|
| concurrent_processing | | protected boolean concurrent_processing(Code) | | Process items on the queue concurrently (Scheduler). The default is to wait until the processing of an item
has completed before fetching the next item from the queue. Note that setting this to true
may destroy the properties of a protocol stack, e.g total or causal order may not be
guaranteed. Set this to true only if you know what you're doing !
|
| deadlock_detection | | protected boolean deadlock_detection(Code) | | Whether or not to perform deadlock detection for synchronous (potentially recursive) group method invocations.
If on, we use a scheduler (handling a priority queue), otherwise we don't and call handleRequest() directly.
|
| local_addr | | protected Address local_addr(Code) | | The address of this group member
|
| log | | final protected static Log log(Code) | | |
| name | | protected String name(Code) | | makes the instance unique (together with IDs)
|
| request_handler | | protected RequestHandler request_handler(Code) | | The handler for the incoming requests. It is called from inside the dispatcher thread
|
| requests | | final protected Map requests(Code) | | The table of pending requests (keys=Long (request IDs), values=RequestEntry)
|
| started | | protected boolean started(Code) | | |
| transport | | protected Object transport(Code) | | The protocol layer to use to pass up/down messages. Can be either a Protocol or a Transport
|
| RequestCorrelator | | public RequestCorrelator(String name, Object transport, RequestHandler handler)(Code) | | Constructor. Uses transport to send messages. If handler
is not null, all incoming requests will be dispatched to it (via
handle(Message)).
Parameters:
name - Used to differentiate between different RequestCorrelators(e.g. in different protocol layers). Has to be unique if multiplerequest correlators are used.
Parameters:
transport - Used to send/pass up requests. Can be either a Transport (only send() will beused then), or a Protocol (passUp()/passDown() will be used)
Parameters:
handler - Request handler. Method handle(Message)will be called when a request is received. |
| RequestCorrelator | | public RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection)(Code) | | Constructor. Uses transport to send messages. If handler
is not null, all incoming requests will be dispatched to it (via
handle(Message)).
Parameters:
name - Used to differentiate between different RequestCorrelators(e.g. in different protocol layers). Has to be unique if multiplerequest correlators are used.
Parameters:
transport - Used to send/pass up requests. Can be either a Transport (only send() will beused then), or a Protocol (passUp()/passDown() will be used)
Parameters:
handler - Request handler. Method handle(Message)will be called when a request is received.
Parameters:
deadlock_detection - When enabled (true) recursive synchronousmessage calls will be detected and processed with higher priority inorder to solve deadlocks. Slows down processing a little bit whenenabled due to runtime checks involved. |
| RequestCorrelator | | public RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection, boolean concurrent_processing)(Code) | | |
| done | | public void done(long id)(Code) | | Used to signal that a certain request may be garbage collected as
all responses have been received.
|
| receive | | public void receive(Event evt)(Code) | | Callback.
Called by the protocol below when a message has been received. The
algorithm should test whether the message is destined for us and,
if not, pass it up to the next layer. Otherwise, it should remove
the header and check whether the message is a request or response.
In the first case, the message will be delivered to the request
handler registered (calling its handle() method), in the
second case, the corresponding response collector is looked up and
the message delivered.
|
| receiveMessage | | public boolean receiveMessage(Message msg)(Code) | | Handles a message coming from a layer below
true if the event should be forwarded further up, otherwise false (message was consumed) |
| receiveSuspect | | public void receiveSuspect(Address mbr)(Code) | | Event.SUSPECT event received from a layer below.
All response collectors currently registered will
be notified that mbr may have crashed, so they won't
wait for its response.
|
| receiveView | | public void receiveView(View new_view)(Code) | | Event.VIEW_CHANGE event received from a layer below.
Mark all responses from members that are not in new_view as
NOT_RECEIVED.
|
| sendRequest | | public void sendRequest(long id, List dest_mbrs, Message msg, RspCollector coll, boolean use_anycasting) throws Exception(Code) | | Send a request to a group. If no response collector is given, no
responses are expected (making the call asynchronous).
Parameters:
id - The request ID. Must be unique for this JVM (e.g. currenttime in millisecs)
Parameters:
dest_mbrs - The list of members who should receive the call. Usually a group RPCis sent via multicast, but a receiver drops the request if its own addressis not in this list. Will not be used if it is null.
Parameters:
msg - The request to be sent. The body of the message carriesthe request data
Parameters:
coll - A response collector (usually the object that invokesthis method). Its methods receiveResponse() andsuspect() will be invoked when a message has been receivedor a member is suspected, respectively. |
| setConcurrentProcessing | | public void setConcurrentProcessing(boolean flag)(Code) | | |
| setDeadlockDetection | | public void setDeadlockDetection(boolean flag)(Code) | | Switch the deadlock detection mechanism on/off
Parameters:
flag - the deadlock detection flag |
| setLocalAddress | | public void setLocalAddress(Address local_addr)(Code) | | |
| start | | final public void start()(Code) | | |
| startScheduler | | void startScheduler()(Code) | | |
| stopScheduler | | void stopScheduler()(Code) | | |
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