Add support to provide zero connection rate limit

libamqpprox/amqpprox_connectionlimitermanager.cpp

@@ -21,6 +21,7 @@
 #include <amqpprox_logging.h>
 
 #include <memory>
+#include <optional>
 #include <string>
 
 namespace Bloomberg {
@@ -29,15 +30,15 @@ namespace amqpprox {
 namespace {
 void maybePopulateDefaultLimiters(
     const std::string                            &vhostName,
-    uint32_t                                      defaultLimit,
+    std::optional<uint32_t>                       defaultLimit,
     ConnectionLimiterManager::ConnectionLimiters &limitersPerVhost)
 {
     if (limitersPerVhost.find(vhostName) == limitersPerVhost.end()) {
         if (defaultLimit) {
             limitersPerVhost[vhostName] = {
                 false,
                 std::make_shared<FixedWindowConnectionRateLimiter>(
-                    defaultLimit)};
+                    *defaultLimit)};
         }
     }
 }
@@ -46,8 +47,8 @@ void maybePopulateDefaultLimiters(
 ConnectionLimiterManager::ConnectionLimiterManager()
 : d_connectionRateLimitersPerVhost()
 , d_alarmOnlyConnectionRateLimitersPerVhost()
-, d_defaultConnectionRateLimit(0)
-, d_defaultAlarmOnlyConnectionRateLimit(0)
+, d_defaultConnectionRateLimit()
+, d_defaultAlarmOnlyConnectionRateLimit()
 , d_mutex()
 {
 }
@@ -95,7 +96,7 @@ void ConnectionLimiterManager::setDefaultConnectionRateLimit(
         if (!limiter.second.first) {
             limiter.second.second =
                 std::make_shared<FixedWindowConnectionRateLimiter>(
-                    d_defaultConnectionRateLimit);
+                    *d_defaultConnectionRateLimit);
         }
     }
 }
@@ -113,7 +114,7 @@ void ConnectionLimiterManager::setAlarmOnlyDefaultConnectionRateLimit(
         if (!limiter.second.first) {
             limiter.second.second =
                 std::make_shared<FixedWindowConnectionRateLimiter>(
-                    d_defaultAlarmOnlyConnectionRateLimit);
+                    *d_defaultAlarmOnlyConnectionRateLimit);
         }
     }
 }
@@ -127,7 +128,7 @@ void ConnectionLimiterManager::removeConnectionRateLimiter(
         d_connectionRateLimitersPerVhost[vhostName] = {
             false,
             std::make_shared<FixedWindowConnectionRateLimiter>(
-                d_defaultConnectionRateLimit)};
+                *d_defaultConnectionRateLimit)};
     }
     else {
         d_connectionRateLimitersPerVhost.erase(vhostName);
@@ -143,7 +144,7 @@ void ConnectionLimiterManager::removeAlarmOnlyConnectionRateLimiter(
         d_alarmOnlyConnectionRateLimitersPerVhost[vhostName] = {
             false,
             std::make_shared<FixedWindowConnectionRateLimiter>(
-                d_defaultAlarmOnlyConnectionRateLimit)};
+                *d_defaultAlarmOnlyConnectionRateLimit)};
     }
     else {
         d_alarmOnlyConnectionRateLimitersPerVhost.erase(vhostName);
@@ -154,7 +155,7 @@ void ConnectionLimiterManager::removeDefaultConnectionRateLimit()
 {
     std::lock_guard<std::mutex> lg(d_mutex);
 
-    d_defaultConnectionRateLimit = 0;
+    d_defaultConnectionRateLimit.reset();
     for (auto it = d_connectionRateLimitersPerVhost.cbegin();
          it != d_connectionRateLimitersPerVhost.cend();) {
         if (!it->second.first) {
@@ -170,7 +171,7 @@ void ConnectionLimiterManager::removeAlarmOnlyDefaultConnectionRateLimit()
 {
     std::lock_guard<std::mutex> lg(d_mutex);
 
-    d_defaultAlarmOnlyConnectionRateLimit = 0;
+    d_defaultAlarmOnlyConnectionRateLimit.reset();
     for (auto it = d_alarmOnlyConnectionRateLimitersPerVhost.cbegin();
          it != d_alarmOnlyConnectionRateLimitersPerVhost.cend();) {
         if (!it->second.first) {
@@ -263,12 +264,13 @@ ConnectionLimiterManager::getAlarmOnlyConnectionRateLimiter(
     return nullptr;
 }
 
-uint32_t ConnectionLimiterManager::getDefaultConnectionRateLimit() const
+std::optional<uint32_t>
+ConnectionLimiterManager::getDefaultConnectionRateLimit() const
 {
     return d_defaultConnectionRateLimit;
 }
 
-uint32_t
+std::optional<uint32_t>
 ConnectionLimiterManager::getAlarmOnlyDefaultConnectionRateLimit() const
 {
     return d_defaultAlarmOnlyConnectionRateLimit;

libamqpprox/amqpprox_connectionlimitermanager.h

@@ -18,9 +18,9 @@
 
 #include <amqpprox_connectionlimiterinterface.h>
 
-#include <iostream>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <unordered_map>
 #include <utility>
@@ -58,9 +58,9 @@ class ConnectionLimiterManager {
     ConnectionLimiters d_connectionRateLimitersPerVhost;
     ConnectionLimiters d_alarmOnlyConnectionRateLimitersPerVhost;
 
-    uint32_t           d_defaultConnectionRateLimit;
-    uint32_t           d_defaultAlarmOnlyConnectionRateLimit;
-    mutable std::mutex d_mutex;
+    std::optional<uint32_t> d_defaultConnectionRateLimit;
+    std::optional<uint32_t> d_defaultAlarmOnlyConnectionRateLimit;
+    mutable std::mutex      d_mutex;
 
   public:
     // CREATORS
@@ -142,6 +142,11 @@ class ConnectionLimiterManager {
      */
     bool allowNewConnectionForVhost(const std::string &vhostName);
 
+    /**
+     * \brief Called when a session is marked as disconnected.
+     */
+    void sessionClosedForVhost(const std::string &vhostName);
+
     // ACCESSORS
     /**
      * \brief Get particular connection rate limiter based on specified vhost
@@ -162,13 +167,13 @@ class ConnectionLimiterManager {
      * \brief Get default connection rate limit (allowed connections per
      * second) for all the connecting vhosts
      */
-    uint32_t getDefaultConnectionRateLimit() const;
+    std::optional<uint32_t> getDefaultConnectionRateLimit() const;
 
     /**
-     * \brief Get alarm onlt default connection rate limit (allowed connections
+     * \brief Get alarm only default connection rate limit (allowed connections
      * per second) for all the connecting vhosts
      */
-    uint32_t getAlarmOnlyDefaultConnectionRateLimit() const;
+    std::optional<uint32_t> getAlarmOnlyDefaultConnectionRateLimit() const;
 };
 
 }

libamqpprox/amqpprox_fixedwindowconnectionratelimiter.cpp

@@ -20,7 +20,6 @@
 
 #include <chrono>
 #include <memory>
-#include <mutex>
 #include <sstream>
 
 namespace Bloomberg {

libamqpprox/amqpprox_fixedwindowconnectionratelimiter.h

@@ -20,7 +20,6 @@
 
 #include <chrono>
 #include <memory>
-#include <mutex>
 #include <string>
 
 namespace Bloomberg {
@@ -47,8 +46,8 @@ struct LimiterClock {
  * provided connection limit and time window. The connection rate limit will be
  * connection limit/timeWindow (average allowed connections in the specified
  * time window). allowNewConnection member function will return true or false
- * based on the rate limit calculation. Implements the LimiterInterface
- * interface
+ * based on the rate limit calculation. Implements the
+ * ConnectionLimiterInterface interface
  */
 class FixedWindowConnectionRateLimiter : public ConnectionLimiterInterface {
   protected:
@@ -97,7 +96,7 @@ class FixedWindowConnectionRateLimiter : public ConnectionLimiterInterface {
 
     // ACCESSORS
     /**
-     * \return Information about limiter as a string
+     * \return Information about connection limiter as a string
      */
     virtual std::string toString() const override;
 

libamqpprox/amqpprox_limitcontrolcommand.cpp

@@ -67,6 +67,7 @@ void handleConnectionLimitAlarm(
             output << "Default connection rate limit is set to "
                    << connectionLimiterManager
                           ->getAlarmOnlyDefaultConnectionRateLimit()
+                          .value()
                    << " connections per second in alarm only mode.\n";
             output << "The limiter will only log at warning level with "
                       "AMQPPROX_CONNECTION_LIMIT as a substring and the "
@@ -122,6 +123,7 @@ void handleConnectionLimit(
                 numberOfConnections);
             output << "Default connection rate limit is set to "
                    << connectionLimiterManager->getDefaultConnectionRateLimit()
+                          .value()
                    << " connections per second.\n";
         }
         else {
@@ -155,19 +157,19 @@ void printVhostLimits(
     }
 
     if (!alarmLimiter && !limiter) {
-        uint32_t alarmOnlyConnectionRateLimit =
+        std::optional<uint32_t> alarmOnlyConnectionRateLimit =
             connectionLimiterManager->getAlarmOnlyDefaultConnectionRateLimit();
-        uint32_t connectionRateLimit =
+        std::optional<uint32_t> connectionRateLimit =
             connectionLimiterManager->getDefaultConnectionRateLimit();
         if (alarmOnlyConnectionRateLimit || connectionRateLimit) {
             if (alarmOnlyConnectionRateLimit) {
                 output << "Alarm only limit, for vhost " << vhostName
-                       << ", allow average " << alarmOnlyConnectionRateLimit
+                       << ", allow average " << *alarmOnlyConnectionRateLimit
                        << " number of connections per second.\n";
             }
             if (connectionRateLimit) {
                 output << "For vhost " << vhostName << ", allow average "
-                       << connectionRateLimit
+                       << *connectionRateLimit
                        << " number of connections per second.\n";
             }
         }
@@ -182,19 +184,19 @@ void printAllLimits(
     ConnectionLimiterManager *connectionLimiterManager,
     ControlCommandOutput<ControlCommand::OutputFunctor> &output)
 {
-    uint32_t alarmOnlyConnectionRateLimit =
+    std::optional<uint32_t> alarmOnlyConnectionRateLimit =
         connectionLimiterManager->getAlarmOnlyDefaultConnectionRateLimit();
-    uint32_t connectionRateLimit =
+    std::optional<uint32_t> connectionRateLimit =
         connectionLimiterManager->getDefaultConnectionRateLimit();
     if (alarmOnlyConnectionRateLimit || connectionRateLimit) {
         if (alarmOnlyConnectionRateLimit) {
             output << "Default limit for any vhost, allow average "
-                   << alarmOnlyConnectionRateLimit
+                   << *alarmOnlyConnectionRateLimit
                    << " connections per second in alarm only mode.\n";
         }
         if (connectionRateLimit) {
             output << "Default limit for any vhost, allow average "
-                   << connectionRateLimit << " connections per second.\n";
+                   << *connectionRateLimit << " connections per second.\n";
         }
     }
     else {