[3798] Changes after review:

 - {update,remove}Statistics moved from CfgMgr to SrvConfig,CfgSubnets4

src/lib/dhcpsrv/cfg_subnets4.cc

@@ -17,6 +17,7 @@
 #include <dhcpsrv/cfg_subnets4.h>
 #include <dhcpsrv/dhcpsrv_log.h>
 #include <dhcpsrv/subnet_id.h>
+#include <stats/stats_mgr.h>
 
 using namespace isc::asiolink;
 
@@ -109,7 +110,7 @@ CfgSubnets4::selectSubnet(const SubnetSelector& selector) const {
     }
 
     // We have identified an address in the client's packet that can be
-    // used for subnet selection. Match this packet with the subnets. 
+    // used for subnet selection. Match this packet with the subnets.
     return (selectSubnet(address, selector.client_classes_));
 }
 
@@ -145,8 +146,40 @@ CfgSubnets4::isDuplicate(const Subnet4& subnet) const {
     return (false);
 }
 
+void
+CfgSubnets4::removeStatistics() {
+    using namespace isc::stats;
+
+    // For each v4 subnet currently configured, remove the statistic.
+    /// @todo: May move this to CfgSubnets4 class if there will be more
+    /// statistics here.
+    for (Subnet4Collection::const_iterator subnet4 = subnets_.begin();
+         subnet4 != subnets_.end(); ++subnet4) {
+
+        StatsMgr::instance().del(StatsMgr::generateName("subnet",
+                                                        (*subnet4)->getID(),
+                                                        "total-addresses"));
+
+        StatsMgr::instance().del(StatsMgr::generateName("subnet",
+                                                        (*subnet4)->getID(),
+                                                        "assigned-addresses"));
+    }
+}
 
+void
+CfgSubnets4::updateStatistics() {
+    using namespace isc::stats;
 
+    /// @todo: May move this to CfgSubnets4 class if there will be more
+    /// statistics here.
+    for (Subnet4Collection::const_iterator subnet = subnets_.begin();
+         subnet != subnets_.end(); ++subnet) {
+
+        StatsMgr::instance().setValue(
+            StatsMgr::generateName("subnet", (*subnet)->getID(), "total-addresses"),
+            static_cast<int64_t>((*subnet)->getPoolCapacity(Lease::TYPE_V4)));
+    }
+}
 
 } // end of namespace isc::dhcp
 } // end of namespace isc

src/lib/dhcpsrv/cfg_subnets4.h

@@ -125,6 +125,23 @@ public:
                             const ClientClasses& client_classes
                             = ClientClasses()) const;
 
+    /// @brief Updates statistics.
+    ///
+    /// This method updates statistics that are affected by the newly committed
+    /// configuration. In particular, it updates the number of available addresses
+    /// in each subnet. Other statistics may be added in the future. In general,
+    /// these are statistics that are dependant only on configuration, so they are
+    /// not expected to change until the next reconfiguration event.
+    void updateStatistics();
+
+    /// @brief Removes statistics.
+    ///
+    /// During commitment of a new configuration, we need to get rid of the old
+    /// statistics for the old configuration. In particular, we need to remove
+    /// anything related to subnets, as there may be fewer subnets in the new
+    /// configuration and also subnet-ids may change.
+    void removeStatistics();
+
 private:
 
     /// @brief Checks that the IPv4 subnet with the given id already exists.

src/lib/dhcpsrv/cfgmgr.cc

@@ -120,12 +120,14 @@ CfgMgr::clear() {
 void
 CfgMgr::commit() {
 
+
+    ensureCurrentAllocated();
+
     // First we need to remove statistics. The new configuration can have fewer
     // subnets. Also, it may change subnet-ids. So we need to remove them all
     // and add it back.
-    removeStatistics();
+    configuration_->removeStatistics();
 
-    ensureCurrentAllocated();
     if (!configs_.back()->sequenceEquals(*configuration_)) {
         configuration_ = configs_.back();
         // Keep track of the maximum size of the configs history. Before adding
@@ -138,7 +140,7 @@ CfgMgr::commit() {
     }
 
     // Now we need to set the statistics back.
-    updateStatistics();
+    configuration_->updateStatistics();
 }
 
 void
@@ -198,40 +200,6 @@ CfgMgr::getStagingCfg() {
     return (configs_.back());
 }
 
-void
-CfgMgr::removeStatistics() {
-    const Subnet4Collection* subnets = getCurrentCfg()->getCfgSubnets4()->getAll();
-
-    // For each subnet currently configured, remove the statistic
-    for (Subnet4Collection::const_iterator subnet = subnets->begin();
-         subnet != subnets->end(); ++subnet) {
-
-        /// @todo: Once stat contexts are implemented, we'll need to remove all
-        /// statistics from the subnet[subnet-id] context.
-        std::stringstream stat1;
-        stat1 << "subnet[" << (*subnet)->getID() << "].total-addresses";
-        StatsMgr::instance().del(stat1.str());
-
-        std::stringstream stat2;
-        stat2 << "subnet[" << (*subnet)->getID() << "].assigned-addresses";
-        isc::stats::StatsMgr::instance().del(stat2.str());
-    }
-}
-
-void
-CfgMgr::updateStatistics() {
-    const Subnet4Collection* subnets = getCurrentCfg()->getCfgSubnets4()->getAll();
-
-    for (Subnet4Collection::const_iterator subnet = subnets->begin();
-         subnet != subnets->end(); ++subnet) {
-        std::stringstream name;
-        name << "subnet[" << (*subnet)->getID() << "].total-addresses";
-
-        StatsMgr::instance().setValue(name.str(),
-            static_cast<int64_t>((*subnet)->getPoolCapacity(Lease::TYPE_V4)));
-    }
-}
-
 CfgMgr::CfgMgr()
     : datadir_(DHCP_DATA_DIR), echo_v4_client_id_(true),
       d2_client_mgr_(), verbose_mode_(false) {

src/lib/dhcpsrv/cfgmgr.h

@@ -339,23 +339,6 @@ private:
     /// @return true if the duplicate subnet exists.
     bool isDuplicate(const Subnet6& subnet) const;
 
-    /// @brief Updates statistics.
-    ///
-    /// This method updates statistics that are affected by the newly committed
-    /// configuration. In particular, it updates the number of available addresses
-    /// in each subnet. Other statistics may be added in the future. In general,
-    /// these are statistics that are dependant only on configuration, so they are
-    /// not expected to change until the next reconfiguration event.
-    void updateStatistics();
-
-    /// @brief Removes statistics.
-    ///
-    /// During commitment of a new configuration, we need to get rid of the old
-    /// statistics for the old configuration. In particular, we need to remove
-    /// anything related to subnets, as there may be fewer subnets in the new
-    /// configuration and also subnet-ids may change.
-    void removeStatistics();
-
     /// @brief Container for defined DHCPv6 option spaces.
     OptionSpaceCollection spaces6_;
 

src/lib/dhcpsrv/srv_config.cc

@@ -145,5 +145,20 @@ SrvConfig::equals(const SrvConfig& other) const {
             (*cfg_option_ == *other.cfg_option_));
 }
 
+void
+SrvConfig::removeStatistics() {
+
+    // For now, this method only removes statistics for v4 subnets, but in the
+    // near future, we'll also get statistics for v6 subnets.
+    getCfgSubnets4()->removeStatistics();
+}
+
+void
+SrvConfig::updateStatistics() {
+    // For now, this method only updates statistics for v4 subnets, but in the
+    // near future, we'll also get statistics for v6 subnets.
+    getCfgSubnets4()->updateStatistics();
+}
+
 }
 }

src/lib/dhcpsrv/srv_config.h

@@ -349,6 +349,17 @@ public:
 
     //@}
 
+    /// @brief Updates statistics.
+    ///
+    /// This method calls appropriate methods in child objects that update
+    /// related statistics. See @ref CfgSubnets4::updateStatistics for details.
+    void updateStatistics();
+
+    /// @brief Removes statistics.
+    ///
+    /// This method calls appropriate methods in child objects that remove
+    /// related statistics. See @ref CfgSubnets4::removeStatistics for details.
+    void removeStatistics();
 
 private: