Use monotonic clock for keep alive mechanism

Wiebe Cazemier
1 parent de87724a
Showing 4 changed files with 21 additions and 11 deletions
client.cpp
client.h
session.cpp
session.h
@@ -21,6 +21,7 @@ License along with FlashMQ. If not, see &lt;https://www.gnu.org/licenses/&gt;.
 #include <sstream>
 #include <iostream>
 #include <cassert>
+#include <chrono>
  
 #include "logger.h"
  
@@ -136,7 +137,7 @@ bool Client::readFdIntoBuffer()
         return false;
     }
  
-    lastActivity = time(NULL);
+    lastActivity = std::chrono::steady_clock::now();
     if (session)
         session->touch(lastActivity);
  
@@ -273,17 +274,22 @@ bool Client::keepAliveExpired()
     if (keepalive == 0)
         return false;
  
+    const std::chrono::time_point<std::chrono::steady_clock> now = std::chrono::steady_clock::now();
+
     if (!authenticated)
-        return lastActivity + 20 < time(NULL);
+        return lastActivity + std::chrono::seconds(20) < now;
  
-    bool result = (lastActivity + (keepalive*10/5)) < time(NULL);
+    std::chrono::seconds x(keepalive*10/5);
+    bool result = (lastActivity + x) < now;
     return result;
 }
  
 std::string Client::getKeepAliveInfoString() const
 {
-    std::string s = "authenticated: " + std::to_string(authenticated) + ", keep-alive: " + std::to_string(keepalive) + "s, last activity "
-            + std::to_string(time(NULL) - lastActivity) + " seconds ago.";
+    std::chrono::seconds secondsSinceLastActivity = std::chrono::duration_cast<std::chrono::seconds>(std::chrono::steady_clock::now() - lastActivity);
+
+    std::string s = formatString("authenticated=%s, keep-alive=%ss, last activity=%s seconds ago.", std::to_string(authenticated).c_str(), std::to_string(keepalive).c_str(),
+                                  std::to_string(secondsSinceLastActivity.count()).c_str());
     return s;
 }
  
@@ -65,7 +65,7 @@ class Client
     bool disconnectWhenBytesWritten = false;
     bool disconnecting = false;
     std::string disconnectReason;
-    time_t lastActivity = time(NULL);
+    std::chrono::time_point<std::chrono::steady_clock> lastActivity;
  
     std::string clientid;
     std::string username;
@@ -164,15 +164,19 @@ uint64_t Session::sendPendingQosMessages()
     return count;
 }
  
-void Session::touch(time_t val)
+std::chrono::time_point<std::chrono::steady_clock> zeroTime;
+std::chrono::seconds expireAfter(EXPIRE_SESSION_AFTER);
+
+void Session::touch(std::chrono::time_point<std::chrono::steady_clock> val)
 {
-    time_t newval = val > 0 ? val : time(NULL);
+    std::chrono::time_point<std::chrono::steady_clock> newval = val > zeroTime ? val : std::chrono::steady_clock::now();
     lastTouched = newval;
 }
  
 bool Session::hasExpired()
 {
-    return clientDisconnected() && (lastTouched + EXPIRE_SESSION_AFTER) < time(NULL);
+    std::chrono::time_point<std::chrono::steady_clock> now = std::chrono::steady_clock::now();
+    return clientDisconnected() && (lastTouched + expireAfter) < now;
 }
  
 void Session::addIncomingQoS2MessageId(uint16_t packet_id)
@@ -51,7 +51,7 @@ class Session
     std::mutex qosQueueMutex;
     uint16_t nextPacketId = 0;
     ssize_t qosQueueBytes = 0;
-    time_t lastTouched = time(NULL);
+    std::chrono::time_point<std::chrono::steady_clock> lastTouched;
     Logger *logger = Logger::getInstance();
  
 public:
@@ -67,7 +67,7 @@ public:
     void writePacket(const MqttPacket &packet, char max_qos, uint64_t &count);
     void clearQosMessage(uint16_t packet_id);
     uint64_t sendPendingQosMessages();
-    void touch(time_t val = 0);
+    void touch(std::chrono::time_point<std::chrono::steady_clock> val = std::chrono::time_point<std::chrono::steady_clock>());
     bool hasExpired();
  
     void addIncomingQoS2MessageId(uint16_t packet_id);