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/*
* Copyright (c) 2017-2019 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 messenger_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 missive_Release} on it.
*
*/
#include <parc/algol/parc_ArrayList.h>
#include <parc/algol/parc_Event.h>
#include <parc/algol/parc_EventScheduler.h>
#include <parc/algol/parc_Memory.h>
#include <parc/assert/parc_Assert.h>
#include <src/config.h>
#include <stdio.h>
#include <src/messenger/messenger.h>
#include <src/messenger/missiveDeque.h>
struct messenger {
PARCArrayList *callbacklist;
Dispatcher *dispatcher;
MissiveDeque *eventQueue;
PARCEventTimer *timerEvent;
};
static void messenger_Dequeue(int fd, PARCEventType which_event,
void *messengerVoidPtr);
// =========================================
// Public API
Messenger *messenger_Create(Dispatcher *dispatcher) {
Messenger *messenger = parcMemory_AllocateAndClear(sizeof(Messenger));
parcAssertNotNull(messenger, "parcMemory_AllocateAndClear(%zu) returned NULL",
sizeof(Messenger));
// NULL destroyer because we're storing structures owned by the caller
messenger->dispatcher = dispatcher;
messenger->callbacklist = parcArrayList_Create(NULL);
messenger->eventQueue = missiveDeque_Create();
// creates the timer, but does not start it
messenger->timerEvent =
dispatcher_CreateTimer(dispatcher, false, messenger_Dequeue, messenger);
return messenger;
}
void messenger_Destroy(Messenger **messengerPtr) {
parcAssertNotNull(messengerPtr, "Parameter must be non-null double pointer");
parcAssertNotNull(*messengerPtr,
"Parameter must dereference to non-null pointer");
Messenger *messenger = *messengerPtr;
parcArrayList_Destroy(&messenger->callbacklist);
missiveDeque_Release(&messenger->eventQueue);
dispatcher_DestroyTimerEvent(messenger->dispatcher, &messenger->timerEvent);
parcMemory_Deallocate((void **)&messenger);
*messengerPtr = NULL;
}
void messenger_Send(Messenger *messenger, Missive *missive) {
parcAssertNotNull(messenger, "Parameter messenger must be non-null");
parcAssertNotNull(missive, "Parameter event must be non-null");
missiveDeque_Append(messenger->eventQueue, missive);
if (missiveDeque_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};
dispatcher_StartTimer(messenger->dispatcher, messenger->timerEvent,
&immediateTimeout);
}
}
static void removeRecipient(Messenger *messenger,
const MessengerRecipient *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 eventMessenger_Register
* @abstract Receive all event messages
*/
void messenger_Register(Messenger *messenger,
const MessengerRecipient *recipient) {
parcAssertNotNull(messenger, "Parameter messenger must be non-null");
parcAssertNotNull(recipient, "Parameter recipient must be non-null");
// do not allow duplicates
removeRecipient(messenger, recipient);
parcArrayList_Add(messenger->callbacklist, recipient);
}
/**
* @function eventMessenger_Unregister
* @abstract Stop receiving event messages
*/
void messenger_Unregister(Messenger *messenger,
const MessengerRecipient *recipient) {
parcAssertNotNull(messenger, "Parameter messenger must be non-null");
parcAssertNotNull(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 Messenger
*/
static void messenger_Dequeue(int fd, PARCEventType which_event,
void *messengerVoidPtr) {
Messenger *messenger = (Messenger *)messengerVoidPtr;
parcAssertNotNull(messenger, "Called with null messenger pointer");
Missive *missive;
while ((missive = missiveDeque_RemoveFirst(messenger->eventQueue)) != NULL) {
for (size_t i = 0; i < parcArrayList_Size(messenger->callbacklist); i++) {
MessengerRecipient *recipient =
parcArrayList_Get(messenger->callbacklist, i);
parcAssertTrue(recipient, "Recipient is null at index %zu", i);
messengerRecipient_Deliver(recipient, missive_Acquire(missive));
}
// now let go of our reference to the missive
missive_Release(&missive);
}
}
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