org.jgroups.blocks
public class RequestCorrelator extends Object
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).
Nested Class Summary | |
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static class | RequestCorrelator.Header
The header for RequestCorrelator messages |
Field Summary | |
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protected Stack | call_stack
This field is used only if deadlock detection is enabled.
|
protected boolean | concurrent_processing Process items on the queue concurrently (Scheduler). |
protected boolean | deadlock_detection Whether or not to perform deadlock detection for synchronous (potentially recursive) group method invocations.
|
protected Address | local_addr The address of this group member |
protected static Log | log |
protected String | name makes the instance unique (together with IDs) |
protected Map | requests The table of pending requests (keys=Long (request IDs), values=RequestEntry) |
protected RequestHandler | request_handler The handler for the incoming requests. |
protected Scheduler | scheduler The dispatching thread pool |
protected boolean | started |
protected Object | transport The protocol layer to use to pass up/down messages. |
Constructor Summary | |
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RequestCorrelator(String name, Object transport, RequestHandler handler)
Constructor. | |
RequestCorrelator(String name, Object transport, RequestHandler handler, Address local_addr) | |
RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection)
Constructor. | |
RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection, boolean concurrent_processing) | |
RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection, Address local_addr) | |
RequestCorrelator(String name, Object transport, RequestHandler handler, boolean deadlock_detection, Address local_addr, boolean concurrent_processing) |
Method Summary | |
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void | done(long id)
Used to signal that a certain request may be garbage collected as
all responses have been received. |
Address | getLocalAddress() |
void | receive(Event evt)
Callback.
|
boolean | receiveMessage(Message msg)
Handles a message coming from a layer below
|
void | receiveSuspect(Address mbr)
Event.SUSPECT event received from a layer below.
|
void | receiveView(View new_view)
Event.VIEW_CHANGE event received from a layer below.
|
void | sendRequest(long id, Message msg, RspCollector coll)
Helper method for RequestCorrelator. |
void | sendRequest(long id, List dest_mbrs, Message msg, RspCollector coll)
Send a request to a group. |
void | setConcurrentProcessing(boolean concurrent_processing) |
void | setDeadlockDetection(boolean flag)
Switch the deadlock detection mechanism on/off |
void | setLocalAddress(Address local_addr) |
void | setRequestHandler(RequestHandler handler) |
void | start() |
void | stop() |
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 multiple
request correlators are used.
transport Used to send/pass up requests. Can be either a Transport (only send() will be
used then), or a Protocol (passUp()/passDown() will be used)
handler Request handler. Method handle(Message)
will be called when a request is received.
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 multiple
request correlators are used.
transport Used to send/pass up requests. Can be either a Transport (only send() will be
used then), or a Protocol (passUp()/passDown() will be used)
handler Request handler. Method handle(Message)
will be called when a request is received.
deadlock_detection When enabled (true) recursive synchronous
message calls will be detected and processed with higher priority in
order to solve deadlocks. Slows down processing a little bit when
enabled due to runtime checks involved.
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.
Returns: true if the event should be forwarded further up, otherwise false (message was consumed)
All response collectors currently registered will
be notified that mbr
may have crashed, so they won't
wait for its response.
Mark all responses from members that are not in new_view as NOT_RECEIVED.
Parameters: id The request ID. Must be unique for this JVM (e.g. current
time in millisecs) dest_mbrs The list of members who should receive the call. Usually a group RPC
is sent via multicast, but a receiver drops the request if its own address
is not in this list. Will not be used if it is null. msg The request to be sent. The body of the message carries
the request data
coll A response collector (usually the object that invokes
this method). Its methods receiveResponse()
and
suspect()
will be invoked when a message has been received
or a member is suspected, respectively.
Parameters: flag the deadlock detection flag