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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
*
* The messenger is contructued with a reference to the forwarder's dispatcher so it can
* schedule future events. When someone calls metisMessenger_Send(...), it will put the
* message on a queue. If the queue was empty, it will scheudle itself to be run.
* By running the queue in a future dispatcher slice, it guarantees that there will be
* no re-entrant behavior between callers and message listeners.
*
* A recipient will receive a reference counted copy of the missive, so it must call
* {@link metisMissive_Release} on it.
*
*/
#include <config.h>
#include <stdio.h>
#include <LongBow/runtime.h>
#include <parc/algol/parc_Memory.h>
#include <parc/algol/parc_ArrayList.h>
#include <parc/algol/parc_EventScheduler.h>
#include <parc/algol/parc_Event.h>
#include <ccnx/forwarder/metis/messenger/metis_Messenger.h>
#include <ccnx/forwarder/metis/messenger/metis_MissiveDeque.h>
struct metis_messenger {
PARCArrayList *callbacklist;
MetisDispatcher *dispatcher;
MetisMissiveDeque *eventQueue;
PARCEventTimer *timerEvent;
};
static void metisMessenger_Dequeue(int fd, PARCEventType which_event, void *messengerVoidPtr);
// =========================================
// Public API
MetisMessenger *
metisMessenger_Create(MetisDispatcher *dispatcher)
{
MetisMessenger *messenger = parcMemory_AllocateAndClear(sizeof(MetisMessenger));
assertNotNull(messenger, "parcMemory_AllocateAndClear(%zu) returned NULL", sizeof(MetisMessenger));
// NULL destroyer because we're storing structures owned by the caller
messenger->dispatcher = dispatcher;
messenger->callbacklist = parcArrayList_Create(NULL);
messenger->eventQueue = metisMissiveDeque_Create();
// creates the timer, but does not start it
messenger->timerEvent = metisDispatcher_CreateTimer(dispatcher, false, metisMessenger_Dequeue, messenger);
return messenger;
}
void
metisMessenger_Destroy(MetisMessenger **messengerPtr)
{
assertNotNull(messengerPtr, "Parameter must be non-null double pointer");
assertNotNull(*messengerPtr, "Parameter must dereference to non-null pointer");
MetisMessenger *messenger = *messengerPtr;
parcArrayList_Destroy(&messenger->callbacklist);
metisMissiveDeque_Release(&messenger->eventQueue);
metisDispatcher_DestroyTimerEvent(messenger->dispatcher, &messenger->timerEvent);
parcMemory_Deallocate((void **) &messenger);
*messengerPtr = NULL;
}
void
metisMessenger_Send(MetisMessenger *messenger, MetisMissive *missive)
{
assertNotNull(messenger, "Parameter messenger must be non-null");
assertNotNull(missive, "Parameter event must be non-null");
metisMissiveDeque_Append(messenger->eventQueue, missive);
if (metisMissiveDeque_Size(messenger->eventQueue) == 1) {
// We need to scheudle ourself when an event is added to an empty queue
// precondition: timer should not be running.
struct timeval immediateTimeout = { 0, 0 };
metisDispatcher_StartTimer(messenger->dispatcher, messenger->timerEvent, &immediateTimeout);
}
}
static void
removeRecipient(MetisMessenger *messenger, const MetisMessengerRecipient *recipient)
{
// don't increment i in the loop
for (size_t i = 0; i < parcArrayList_Size(messenger->callbacklist); ) {
const void *p = parcArrayList_Get(messenger->callbacklist, i);
if (p == recipient) {
// removing will compact the list, so next element will also be at i.
parcArrayList_RemoveAndDestroyAtIndex(messenger->callbacklist, i);
} else {
i++;
}
}
}
/**
* @function metisEventMessenger_Register
* @abstract Receive all event messages
* @discussion
* <#Discussion#>
*
* @param <#param1#>
* @return <#return#>
*/
void
metisMessenger_Register(MetisMessenger *messenger, const MetisMessengerRecipient *recipient)
{
assertNotNull(messenger, "Parameter messenger must be non-null");
assertNotNull(recipient, "Parameter recipient must be non-null");
// do not allow duplicates
removeRecipient(messenger, recipient);
parcArrayList_Add(messenger->callbacklist, recipient);
}
/**
* @function metisEventMessenger_Unregister
* @abstract Stop receiving event messages
* @discussion
* <#Discussion#>
*
* @param <#param1#>
* @return <#return#>
*/
void
metisMessenger_Unregister(MetisMessenger *messenger, const MetisMessengerRecipient *recipient)
{
assertNotNull(messenger, "Parameter messenger must be non-null");
assertNotNull(recipient, "Parameter recipient must be non-null");
removeRecipient(messenger, recipient);
}
/**
* Called by event scheduler to give us a slice in which to dequeue events
*
* Called inside an event callback, so we now have exclusive access to the system.
* Dequeues all pending events and calls all the listeners for each one.
*
* @param [in] fd unused, required for compliance with function prototype
* @param [in] which_event unused, required for compliance with function prototype
* @param [in] messengerVoidPtr A void* to MetisMessenger
*
* @return <#value#> <#explanation#>
*
* Example:
* @code
* <#example#>
* @endcode
*/
static void
metisMessenger_Dequeue(int fd, PARCEventType which_event, void *messengerVoidPtr)
{
MetisMessenger *messenger = (MetisMessenger *) messengerVoidPtr;
assertNotNull(messenger, "Called with null messenger pointer");
MetisMissive *missive;
while ((missive = metisMissiveDeque_RemoveFirst(messenger->eventQueue)) != NULL) {
for (size_t i = 0; i < parcArrayList_Size(messenger->callbacklist); i++) {
MetisMessengerRecipient *recipient = parcArrayList_Get(messenger->callbacklist, i);
assertTrue(recipient, "Recipient is null at index %zu", i);
metisMessengerRecipient_Deliver(recipient, metisMissive_Acquire(missive));
}
// now let go of our reference to the missive
metisMissive_Release(&missive);
}
}
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