基于MongoDB打造.Net的分布式Session子系统

基于MongoDB打造.Net的分布式Session子系统

Taobao有她自己的分布式session框架，.net阵营也不能落后了，在下做了个基于MongoDB的支持最多26台MongoDB的分布式Session框架。

先看看配置文件：

<?xml version="1.0" encoding="utf-8" ?>
<MongoDBSession>
  <DbName>SessionDB</DbName>
  <IdentityMap Identity="A">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="B">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="C">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="D">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="E">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="F">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="G">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="H">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="I">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="J">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="K">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="L">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="M">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="N">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="O">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="P">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="Q">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="R">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="S">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="T">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="U">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="V">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="W">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="X">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="Y">mongodb://localhost</IdentityMap>
  <IdentityMap Identity="Z">mongodb://localhost</IdentityMap>
</MongoDBSession>

从Identity A一直到Z，默认分成了26个Map，具体的C#应用代码：

protected void btnTest_Click(object sender, EventArgs e)
        {
            Session["A"] = DateTime.Now;
            Session["B"] = 1111111111111;
            Session["C"] = "fffffffffffffff";
        }
 
        protected void btnGetSession_Click(object sender, EventArgs e)
        {
            Response.Write(Session["A"].ToString());
            Response.Write("<br />");
            Response.Write(Session["B"].ToString());
            Response.Write("<br />");
            Response.Write(Session["C"].ToString());
        }
        protected void btnAbandon_Click(object sender, EventArgs e)
        {
            Session.Abandon();
        }

呵呵，就是普通的Session用法。

这个要配置web.config：

<system.web>
    <sessionState mode="Custom" customProvider="A2DSessionProvider" sessionIDManagerType="A2DFramework.SessionService.MongoDBSessionIDManager">
      <providers>
        <add name="A2DSessionProvider" type="A2DFramework.SessionService.MongoDBSessionStateStore"/>
      </providers>
    </sessionState>
  </system.web>

这里会牵扯出2个类：

1. A2DFramework.SessionService.MongoDBSessionIDManager
2. A2DFramework.SessionService.MongoDBSessionStateStore

MongoDBSessionIDManager

• 自定义生成的cookie值（也就是SessionID），在这个sample中，会生成如“E.asadfalkasdfjal”这样的SessionID，其中前缀E代表这个Session的信息会映射到哪台MongoDB上。
• 关键代码
• 

  public class MongoDBSessionIDManager : SessionIDManager
      {
          private Random rnd = new Random();
          private object oLock = new object();
   
          public override string CreateSessionID(System.Web.HttpContext context)
          {
              int index = 0;
              lock(this.oLock)
              {
                  index = rnd.Next(SessionConfiguration.SessionServerIdentities.Length);
              }
              string sessionId = string.Format("{0}.{1}", SessionConfiguration.SessionServerIdentities[index], base.CreateSessionID(context));
              return sessionId;
          }
   
          public override string Encode(string id)
          {
              return DESEncryptor.Encode(id, SessionConfiguration.DESKey);
          }
          public override string Decode(string id)
          {
              return DESEncryptor.Decode(id, SessionConfiguration.DESKey);
          }
   
          public override bool Validate(string id)
          {
              string prefix;
              string realId;
   
              if (!Helper.ParseSessionID(id, out prefix, out realId))
                  return false;
   
              return base.Validate(realId);
          }
      }

  

MongoDBSessionStateStore

• 自定义Session过程中最核心的一个类，代码如下（较多）：
• 

  public sealed class MongoDBSessionStateStore : SessionStateStoreProviderBase
      {
          private SessionStateSection pConfig;
          private string pApplicationName;
   
          public override void Initialize(string name, System.Collections.Specialized.NameValueCollection config)
          {
              base.Initialize(name, config);
   
              pApplicationName =System.Web.Hosting.HostingEnvironment.ApplicationVirtualPath;
              System.Configuration.Configuration cfg = WebConfigurationManager.OpenWebConfiguration(pApplicationName);
              pConfig =(SessionStateSection)cfg.GetSection("system.web/sessionState");
          }
   
          public override SessionStateStoreData CreateNewStoreData(System.Web.HttpContext context, int timeout)
          {
              return new SessionStateStoreData(new SessionStateItemCollection(), SessionStateUtility.GetSessionStaticObjects(context), timeout);
          }
   
          public override void CreateUninitializedItem(System.Web.HttpContext context, string id, int timeout)
          {
              //insert to db
              MongoDBSessionEntity session = new MongoDBSessionEntity();
              session.ApplicationName = this.pApplicationName;
              session.SessionId = id;
              session.Created = DateTime.Now;
              session.Expires = DateTime.Now.AddMinutes(pConfig.Timeout.Minutes);
              session.LockDate = DateTime.Now;
              session.LockId = 0;
              session.Timeout = timeout;
              session.Locked = false;
              session.Flags = (int)SessionStateActions.InitializeItem;
   
              MongoCollection<MongoDBSessionEntity> collection = Helper.GetMongoDBCollection(id);
              collection.Save(session);
          }
   
          public override void Dispose()
          {
          }
   
          public override void EndRequest(System.Web.HttpContext context)
          {
          }
   
          public override SessionStateStoreData GetItem(System.Web.HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions)
          {
              return GetSessionStoreItem(false, context, id, out locked, out lockAge, out lockId, out actions);
          }
   
          public override SessionStateStoreData GetItemExclusive(System.Web.HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions)
          {
              return GetSessionStoreItem(true, context, id, out locked, out lockAge, out lockId, out actions);
          }
   
          public override void InitializeRequest(System.Web.HttpContext context)
          {
          }
   
          public override void ReleaseItemExclusive(System.Web.HttpContext context, string id, object lockId)
          {
              //update locked=0, expired=, where lockId=?
              MongoCollection<MongoDBSessionEntity> collection = Helper.GetMongoDBCollection(id);
   
              var query = Query.And(  Query.EQ("LockId", int.Parse(lockId.ToString())),
                                      Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName));
              var update = Update.Set("Locked", false)
                                  .Set("Expires", DateTime.Now.AddMinutes(pConfig.Timeout.Minutes));
   
              collection.Update(query, update);
          }
   
          public override void RemoveItem(System.Web.HttpContext context, string id, object lockId, SessionStateStoreData item)
          {
              //delete where sessionId=? and lockId=? and applicationname=?
              MongoCollection<MongoDBSessionEntity> collection = Helper.GetMongoDBCollection(id);
   
              var query = Query.And(Query.EQ("LockId", int.Parse(lockId.ToString())),
                                      Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName));
              collection.Remove(query);
          }
   
          public override void ResetItemTimeout(System.Web.HttpContext context, string id)
          {
              //update expire date
              MongoCollection<MongoDBSessionEntity> collection = Helper.GetMongoDBCollection(id);
   
              var query = Query.And(Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName));
              var update = Update.Set("Expires", DateTime.Now.AddMinutes(pConfig.Timeout.Minutes));
              collection.Update(query, update);
          }
   
          public override void SetAndReleaseItemExclusive(System.Web.HttpContext context, string id, SessionStateStoreData item, object lockId, bool newItem)
          {
              MongoCollection<MongoDBSessionEntity> collection = Helper.GetMongoDBCollection(id);
              if (newItem)
              {
                  //delete expired items
                  var query = Query.And(Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName),
                                      Query.LT("Expires", DateTime.Now));
   
                  collection.Remove(query);
   
                  //insert new item
                  MongoDBSessionEntity session = new MongoDBSessionEntity();
                  session.ApplicationName = this.pApplicationName;
                  session.SessionId = id;
                  session.Created = DateTime.Now;
                  session.Expires = DateTime.Now.AddMinutes(pConfig.Timeout.Minutes);
                  session.LockDate = DateTime.Now;
                  session.LockId = 0;
                  session.Timeout = item.Timeout;
                  session.Locked = false;
                  session.Flags = (int)SessionStateActions.None;
                  session.SessionItems = Helper.Serialize((SessionStateItemCollection)item.Items);
   
                  collection.Save(session);
              }
              else
              {
                  //update item
                  var query = Query.And(Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName),
                                      Query.EQ("LockId", int.Parse(lockId.ToString())));
                  MongoDBSessionEntity entity= collection.FindOne(query);
                  entity.Expires = DateTime.Now.AddMinutes(item.Timeout);
                  entity.SessionItems = Helper.Serialize((SessionStateItemCollection)item.Items);
                  entity.Locked = false;
                  collection.Save(entity);
              }
          }
   
          public override bool SetItemExpireCallback(SessionStateItemExpireCallback expireCallback)
          {
              return false;
          }
   
          private SessionStateStoreData GetSessionStoreItem(bool lockRecord, System.Web.HttpContext context,
                                                              string id,
                                                              out bool locked,
                                                              out TimeSpan lockAge,
                                                              out object lockId,
                                                              out SessionStateActions actions)
          {
              SessionStateStoreData item = null;
              lockAge = TimeSpan.Zero;
              lockId = null;
              locked = false;
              actions = 0;
   
              bool foundRecord = false;
              bool deleteData = false;
   
              MongoCollection<MongoDBSessionEntity> collection = Helper.GetMongoDBCollection(id);
   
              if (lockRecord)
              {
                  //update db, set locked=1, lockdate=now
                  var query1 = Query.And(Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName),
                                      Query.EQ("Locked", MongoDB.Bson.BsonValue.Create(false)),
                                      Query.GT("Expires", DateTime.UtcNow));
   
                  long count = collection.Find(query1).Count();
                  if (count == 0)
                  {
                      locked = true;
                  }
                  else
                  {
                      var update = Update.Set("Locked", true).Set("LockDate", DateTime.Now);
                      collection.Update(query1, update);
                      locked = false;
                  }
              }
              //get item by id
              var query2 = Query.And(Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName));
              MongoDBSessionEntity entity=collection.FindOne(query2);
              if (entity != null)
              {
                  if (entity.Expires < DateTime.Now)
                  {
                      locked = false;
                      deleteData = true;
                  }
                  else
                  {
                      foundRecord = true;
                  }
              }
   
              //delete item if session expired
              if (deleteData)
              {
                  var query3 = Query.And(Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName));
                  collection.Remove(query3);
              }
   
              if (!foundRecord)
                  locked = false;
   
              if (foundRecord && !locked)
              {
                  if (lockId == null)
                      lockId = 0;
                  lockId = (int)lockId + 1;
   
                  var query4 = Query.And(Query.EQ("_id", id),
                                      Query.EQ("ApplicationName", pApplicationName));
                  var update4 = Update.Set("LockId", (int)lockId)
                                          .Set("Flags", (int)SessionStateActions.None);
                  collection.Update(query4, update4);
   
                  if (actions == SessionStateActions.InitializeItem)
                      item = CreateNewStoreData(context, pConfig.Timeout.Minutes);
                  else
                      item = Helper.Deserialize(context, entity.SessionItems, entity.Timeout);
              }
              return item;
          }
      }

  

由于很多方法会用到MongoCollection，因此写了个static公用函数，如下：

public static MongoCollection<MongoDBSessionEntity> GetMongoDBCollection(string sessionId)
        {
            IPartitionResolver resolver = new MongoDBSessionPartitionResolver();
            string mongoDbConnectionString = resolver.ResolvePartition(sessionId);
 
            MongoClient client = new MongoClient(mongoDbConnectionString);
            MongoServer srv = client.GetServer();
            MongoDatabase db = srv.GetDatabase(SessionConfiguration.MongoDBName);
            if (!db.CollectionExists(SessionConfiguration.MongoDBCollectionName))
                db.CreateCollection(SessionConfiguration.MongoDBCollectionName);
 
            MongoCollection<MongoDBSessionEntity> collection = db.GetCollection<MongoDBSessionEntity>(SessionConfiguration.MongoDBCollectionName);
 
            return collection;
        }

运行效果：

点击Set Session后：

点击Get Session后：

点击Abandon后：

源代码已经更新到A2D Framework中了。

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