Peter M. Groen / FlashMQ

Commit 96c1dd91cf5580d83d80d6903067e4b24765ef7b

Authored by Wiebe Cazemier
1 parent 4cd9300c

Queue session removals 

This replaces the old style checking of expired sessions once every 10
minutes or so.
Inline Side-by-side
Showing 5 changed files with 94 additions and 52 deletions
client.cpp
  View file @96c1dd9
... ... @@ -69,10 +69,13 @@ Client::~Client()
69 69 close(fd);
70 70 }
71 71  
72   - // MQTT-3.1.2-6
73 72 if (session->getDestroyOnDisconnect())
74 73 {
75   - store->removeSession(clientid);
  74 + store->removeSession(session);
  75 + }
  76 + else
  77 + {
  78 + store->queueSessionRemoval(session);
76 79 }
77 80 }
78 81  
... ...
subscriptionstore.cpp
  View file @96c1dd9
... ... @@ -269,24 +269,9 @@ bool SubscriptionStore::sessionPresent(const std::string &clientid)
269 269 return result;
270 270 }
271 271  
272   -/**
273   - * @brief SubscriptionStore::purgeEmptyWills doesn't lock a mutex, because it's a helper for elsewhere.
274   - */
275   -void SubscriptionStore::purgeEmptyWills()
276   -{
277   - auto it = pendingWillMessages.begin();
278   - while (it != pendingWillMessages.end())
279   - {
280   - std::shared_ptr<Publish> p = (*it).lock();
281   - if (!p)
282   - {
283   - it = pendingWillMessages.erase(it);
284   - }
285   - }
286   -}
287   -
288 272 void SubscriptionStore::sendQueuedWillMessages()
289 273 {
  274 + const auto now = std::chrono::steady_clock::now();
290 275 std::lock_guard<std::mutex>(this->pendingWillsMutex);
291 276  
292 277 auto it = pendingWillMessages.begin();
... ... @@ -295,7 +280,7 @@ void SubscriptionStore::sendQueuedWillMessages()
295 280 std::shared_ptr<Publish> p = (*it).lock();
296 281 if (p)
297 282 {
298   - if (p->createdAt + std::chrono::seconds(p->will_delay) > std::chrono::steady_clock::now())
  283 + if (p->createdAt + std::chrono::seconds(p->will_delay) > now)
299 284 break;
300 285  
301 286 logger->logf(LOG_DEBUG, "Sending delayed will on topic '%s'.", p->topic.c_str() );
... ... @@ -306,14 +291,15 @@ void SubscriptionStore::sendQueuedWillMessages()
306 291 }
307 292 }
308 293  
309   -void SubscriptionStore::queueWillMessage(std::shared_ptr<Publish> &willMessage)
  294 +void SubscriptionStore::queueWillMessage(std::shared_ptr<Publish> &willMessage, bool forceNow)
310 295 {
311 296 if (!willMessage)
312 297 return;
313 298  
314   - logger->logf(LOG_DEBUG, "Queueing will on topic '%s', with delay %d seconds.", willMessage->topic.c_str(), willMessage->will_delay );
  299 + const int delay = forceNow ? 0 : willMessage->will_delay;
  300 + logger->logf(LOG_DEBUG, "Queueing will on topic '%s', with delay %d seconds.", willMessage->topic.c_str(), delay );
315 301  
316   - if (willMessage->will_delay == 0)
  302 + if (delay == 0)
317 303 {
318 304 PublishCopyFactory factory(willMessage.get());
319 305 queuePacketAtSubscribers(factory);
... ... @@ -577,13 +563,20 @@ int SubscriptionNode::cleanSubscriptions()
577 563 return subscribers.size() + subscribersLeftInChildren;
578 564 }
579 565  
580   -void SubscriptionStore::removeSession(const std::string &clientid)
  566 +void SubscriptionStore::removeSession(const std::shared_ptr<Session> &session)
581 567 {
  568 + const std::string &clientid = session->getClientId();
  569 + logger->logf(LOG_DEBUG, "Removing session of client '%s'.", clientid.c_str());
  570 +
  571 + std::shared_ptr<Publish> &will = session->getWill();
  572 + if (will)
  573 + {
  574 + queueWillMessage(will, true);
  575 + }
  576 +
582 577 RWLockGuard lock_guard(&subscriptionsRwlock);
583 578 lock_guard.wrlock();
584 579  
585   - logger->logf(LOG_DEBUG, "Removing session of client '%s'.", clientid.c_str());
586   -
587 580 auto session_it = sessionsById.find(clientid);
588 581 if (session_it != sessionsById.end())
589 582 {
... ... @@ -600,37 +593,59 @@ void SubscriptionStore::removeExpiredSessionsClients()
600 593 {
601 594 logger->logf(LOG_DEBUG, "Cleaning out old sessions");
602 595  
603   - RWLockGuard lock_guard(&subscriptionsRwlock);
604   - lock_guard.wrlock();
  596 + const std::chrono::time_point<std::chrono::steady_clock> now = std::chrono::steady_clock::now();
605 597  
606   - auto session_it = sessionsById.begin();
607   - while (session_it != sessionsById.end())
608 598 {
609   - std::shared_ptr<Session> &session = session_it->second;
  599 + std::lock_guard<std::mutex>(this->queuedSessionRemovalsMutex);
610 600  
611   - if (session->hasExpired())
  601 + auto it = queuedSessionRemovals.begin();
  602 + while (it != queuedSessionRemovals.end())
612 603 {
613   - logger->logf(LOG_DEBUG, "Removing expired session from store %s", session->getClientId().c_str());
614   - std::shared_ptr<Publish> &will = session->getWill();
615   - if (will)
  604 + QueuedSessionRemoval &qsr = *it;
  605 + std::shared_ptr<Session> session = (*it).getSession();
  606 + if (session)
616 607 {
617   - will->will_delay = 0;
618   - queueWillMessage(will);
  608 + if (qsr.getExpiresAt() > now)
  609 + {
  610 + logger->logf(LOG_DEBUG, "Breaking from sorted list of queued session removals. %d left in the future.", queuedSessionRemovals.size());
  611 + break;
  612 + }
  613 +
  614 + // A session could have been picked up again, so we have to verify its expiration status.
  615 + if (session->hasExpired())
  616 + {
  617 + removeSession(session);
  618 + }
619 619 }
620   - session_it = sessionsById.erase(session_it);
  620 + it = queuedSessionRemovals.erase(it);
621 621 }
622   - else
623   - session_it++;
624 622 }
625 623  
626   - if (lastTreeCleanup + std::chrono::minutes(30) < std::chrono::steady_clock::now())
  624 + if (lastTreeCleanup + std::chrono::minutes(30) < now)
627 625 {
  626 + RWLockGuard lock_guard(&subscriptionsRwlock);
  627 + lock_guard.wrlock();
  628 +
628 629 logger->logf(LOG_NOTICE, "Rebuilding subscription tree");
629 630 root.cleanSubscriptions();
630   - lastTreeCleanup = std::chrono::steady_clock::now();
  631 + lastTreeCleanup = now;
631 632 }
632 633 }
633 634  
  635 +void SubscriptionStore::queueSessionRemoval(const std::shared_ptr<Session> &session)
  636 +{
  637 + QueuedSessionRemoval qsr(session);
  638 +
  639 + auto comp = [](const QueuedSessionRemoval &a, const QueuedSessionRemoval &b)
  640 + {
  641 + return a.getExpiresAt() < b.getExpiresAt();
  642 + };
  643 +
  644 + std::lock_guard<std::mutex>(this->queuedSessionRemovalsMutex);
  645 + auto pos = std::upper_bound(this->queuedSessionRemovals.begin(), this->queuedSessionRemovals.end(), qsr, comp);
  646 + this->queuedSessionRemovals.insert(pos, qsr);
  647 +}
  648 +
634 649 int64_t SubscriptionStore::getRetainedMessageCount() const
635 650 {
636 651 return retainedMessageCount;
... ... @@ -927,3 +942,20 @@ RetainedMessageNode *RetainedMessageNode::getChildren(const std::string &amp;subtopi
927 942 return it->second.get();
928 943 return nullptr;
929 944 }
  945 +
  946 +QueuedSessionRemoval::QueuedSessionRemoval(const std::shared_ptr<Session> &session) :
  947 + session(session),
  948 + expiresAt(std::chrono::steady_clock::now() + std::chrono::seconds(session->getSessionExpiryInterval()))
  949 +{
  950 +
  951 +}
  952 +
  953 +std::chrono::time_point<std::chrono::steady_clock> QueuedSessionRemoval::getExpiresAt() const
  954 +{
  955 + return this->expiresAt;
  956 +}
  957 +
  958 +std::shared_ptr<Session> QueuedSessionRemoval::getSession() const
  959 +{
  960 + return session.lock();
  961 +}
... ...
subscriptionstore.h
  View file @96c1dd9
... ... @@ -84,6 +84,17 @@ class RetainedMessageNode
84 84 RetainedMessageNode *getChildren(const std::string &subtopic) const;
85 85 };
86 86  
  87 +class QueuedSessionRemoval
  88 +{
  89 + std::weak_ptr<Session> session;
  90 + std::chrono::time_point<std::chrono::steady_clock> expiresAt;
  91 +
  92 +public:
  93 + QueuedSessionRemoval(const std::shared_ptr<Session> &session);
  94 + std::chrono::time_point<std::chrono::steady_clock> getExpiresAt() const;
  95 + std::shared_ptr<Session> getSession() const;
  96 +};
  97 +
87 98 class SubscriptionStore
88 99 {
89 100 #ifdef TESTING
... ... @@ -96,6 +107,9 @@ class SubscriptionStore
96 107 std::unordered_map<std::string, std::shared_ptr<Session>> sessionsById;
97 108 const std::unordered_map<std::string, std::shared_ptr<Session>> &sessionsByIdConst;
98 109  
  110 + std::mutex queuedSessionRemovalsMutex;
  111 + std::list<QueuedSessionRemoval> queuedSessionRemovals;
  112 +
99 113 pthread_rwlock_t retainedMessagesRwlock = PTHREAD_RWLOCK_INITIALIZER;
100 114 RetainedMessageNode retainedMessagesRoot;
101 115 RetainedMessageNode retainedMessagesRootDollar;
... ... @@ -121,8 +135,6 @@ class SubscriptionStore
121 135 void countSubscriptions(SubscriptionNode *this_node, int64_t &count) const;
122 136  
123 137 SubscriptionNode *getDeepestNode(const std::string &topic, const std::vector<std::string> &subtopics);
124   -
125   - void purgeEmptyWills();
126 138 public:
127 139 SubscriptionStore();
128 140  
... ... @@ -133,14 +145,14 @@ public:
133 145 bool sessionPresent(const std::string &clientid);
134 146  
135 147 void sendQueuedWillMessages();
136   - void queueWillMessage(std::shared_ptr<Publish> &willMessage);
  148 + void queueWillMessage(std::shared_ptr<Publish> &willMessage, bool forceNow = false);
137 149 void queuePacketAtSubscribers(PublishCopyFactory &copyFactory, bool dollar = false);
138 150 uint64_t giveClientRetainedMessages(const std::shared_ptr<Client> &client, const std::shared_ptr<Session> &ses,
139 151 const std::vector<std::string> &subscribeSubtopics, char max_qos);
140 152  
141 153 void setRetainedMessage(const std::string &topic, const std::vector<std::string> &subtopics, const std::string &payload, char qos);
142 154  
143   - void removeSession(const std::string &clientid);
  155 + void removeSession(const std::shared_ptr<Session> &session);
144 156 void removeExpiredSessionsClients();
145 157  
146 158 int64_t getRetainedMessageCount() const;
... ... @@ -152,6 +164,8 @@ public:
152 164  
153 165 void saveSessionsAndSubscriptions(const std::string &filePath);
154 166 void loadSessionsAndSubscriptions(const std::string &filePath);
  167 +
  168 + void queueSessionRemoval(const std::shared_ptr<Session> &session);
155 169 };
156 170  
157 171 #endif // SUBSCRIPTIONSTORE_H
... ...
types.cpp
  View file @96c1dd9
... ... @@ -134,12 +134,6 @@ void PublishBase::setClientSpecificProperties()
134 134 propertyBuilder->writeMessageExpiryInterval(newExpiresAfter.count());
135 135 }
136 136  
137   -bool PublishBase::hasExpired() const
138   -{
139   - auto now = std::chrono::steady_clock::now();
140   - return (createdAt + expiresAfter) > now;
141   -}
142   -
143 137 Publish::Publish(const Publish &other) :
144 138 PublishBase(other)
145 139 {
... ...
... ... @@ -209,7 +209,6 @@ public:
209 209 PublishBase(const std::string &topic, const std::string &payload, char qos);
210 210 size_t getLengthWithoutFixedHeader() const;
211 211 void setClientSpecificProperties();
212   - bool hasExpired() const;
213 212 };
214 213  
215 214 class Publish : public PublishBase
... ...