GeoDistanceApp: updated code to load max mind database only once.

Apps/GeoDistanceApp/Address.cs

@@ -18,13 +18,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 using DnsApplicationCommon;
-using MaxMind.GeoIP2;
 using MaxMind.GeoIP2.Model;
 using MaxMind.GeoIP2.Responses;
 using Newtonsoft.Json;
 using System;
 using System.Collections.Generic;
-using System.IO;
 using System.Net;
 using System.Net.Sockets;
 using System.Threading.Tasks;
@@ -38,7 +36,7 @@ namespace GeoDistance
     {
         #region variables
 
-        DatabaseReader _mmCityReader;
+        MaxMind _maxMind;
 
         #endregion
 
@@ -53,8 +51,8 @@ namespace GeoDistance
 
             if (disposing)
             {
-                if (_mmCityReader != null)
+                if (_maxMind is not null)
-                    _mmCityReader.Dispose();
+                    _maxMind.Dispose();
             }
 
             _disposed = true;
@@ -86,18 +84,7 @@ namespace GeoDistance
 
         public Task InitializeAsync(IDnsServer dnsServer, string config)
         {
-            if (_mmCityReader == null)
+            _maxMind = MaxMind.Create(dnsServer);
-            {
-                string mmFile = Path.Combine(dnsServer.ApplicationFolder, "GeoIP2-City.mmdb");
-
-                if (!File.Exists(mmFile))
-                    mmFile = Path.Combine(dnsServer.ApplicationFolder, "GeoLite2-City.mmdb");
-
-                if (!File.Exists(mmFile))
-                    throw new FileNotFoundException("MaxMind City file is missing!");
-
-                _mmCityReader = new DatabaseReader(mmFile);
-            }
 
             return Task.CompletedTask;
         }
@@ -111,7 +98,7 @@ namespace GeoDistance
                 case DnsResourceRecordType.AAAA:
                     Location location = null;
 
-                    if (_mmCityReader.TryCity(remoteEP.Address, out CityResponse response))
+                    if (_maxMind.DatabaseReader.TryCity(remoteEP.Address, out CityResponse response))
                         location = response.Location;
 
                     dynamic jsonAppRecordData = JsonConvert.DeserializeObject(appRecordData);

Apps/GeoDistanceApp/CNAME.cs

@@ -18,13 +18,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 using DnsApplicationCommon;
-using MaxMind.GeoIP2;
 using MaxMind.GeoIP2.Model;
 using MaxMind.GeoIP2.Responses;
 using Newtonsoft.Json;
 using System;
 using System.Collections.Generic;
-using System.IO;
 using System.Net;
 using System.Threading.Tasks;
 using TechnitiumLibrary.Net.Dns;
@@ -36,7 +34,7 @@ namespace GeoDistance
     {
         #region variables
 
-        DatabaseReader _mmCityReader;
+        MaxMind _maxMind;
 
         #endregion
 
@@ -51,8 +49,8 @@ namespace GeoDistance
 
             if (disposing)
             {
-                if (_mmCityReader != null)
+                if (_maxMind is not null)
-                    _mmCityReader.Dispose();
+                    _maxMind.Dispose();
             }
 
             _disposed = true;
@@ -84,18 +82,7 @@ namespace GeoDistance
 
         public Task InitializeAsync(IDnsServer dnsServer, string config)
         {
-            if (_mmCityReader == null)
+            _maxMind = MaxMind.Create(dnsServer);
-            {
-                string mmFile = Path.Combine(dnsServer.ApplicationFolder, "GeoIP2-City.mmdb");
-
-                if (!File.Exists(mmFile))
-                    mmFile = Path.Combine(dnsServer.ApplicationFolder, "GeoLite2-City.mmdb");
-
-                if (!File.Exists(mmFile))
-                    throw new FileNotFoundException("MaxMind City file is missing!");
-
-                _mmCityReader = new DatabaseReader(mmFile);
-            }
 
             return Task.CompletedTask;
         }
@@ -104,7 +91,7 @@ namespace GeoDistance
         {
             Location location = null;
 
-            if (_mmCityReader.TryCity(remoteEP.Address, out CityResponse response))
+            if (_maxMind.DatabaseReader.TryCity(remoteEP.Address, out CityResponse response))
                 location = response.Location;
 
             dynamic jsonAppRecordData = JsonConvert.DeserializeObject(appRecordData);

Apps/GeoDistanceApp/MaxMind.cs

@@ -0,0 +1,99 @@
+/*
+Technitium DNS Server
+Copyright (C) 2021  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using DnsApplicationCommon;
+using MaxMind.GeoIP2;
+using System;
+using System.IO;
+
+namespace GeoDistance
+{
+    class MaxMind : IDisposable
+    {
+        #region variables
+
+        static MaxMind _maxMind;
+
+        readonly DatabaseReader _mmCityReader;
+
+        #endregion
+
+        #region constructor
+
+        private MaxMind(IDnsServer dnsServer)
+        {
+            string mmFile = Path.Combine(dnsServer.ApplicationFolder, "GeoIP2-City.mmdb");
+
+            if (!File.Exists(mmFile))
+                mmFile = Path.Combine(dnsServer.ApplicationFolder, "GeoLite2-City.mmdb");
+
+            if (!File.Exists(mmFile))
+                throw new FileNotFoundException("MaxMind City file is missing!");
+
+            _mmCityReader = new DatabaseReader(mmFile);
+        }
+
+        #endregion
+
+        #region IDisposable
+
+        bool _disposed;
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (_disposed)
+                return;
+
+            if (disposing)
+            {
+                if (_mmCityReader is not null)
+                    _mmCityReader.Dispose();
+            }
+
+            _disposed = true;
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        #endregion
+
+        #region public
+
+        public static MaxMind Create(IDnsServer dnsServer)
+        {
+            if (_maxMind is null)
+                _maxMind = new MaxMind(dnsServer);
+
+            return _maxMind;
+        }
+
+        #endregion
+
+        #region properties
+
+        public DatabaseReader DatabaseReader
+        { get { return _mmCityReader; } }
+
+        #endregion
+    }
+}