前段时间 工作需要 生平第一次听到“无状态”一词 随后 了解了下 怕自己忘记 随手记录下来
/*
尚未创建过Session:
InitializeRequest -> CreateNewStoreData
InitializeRequest -> ResetItemTimeout -> InitializeRequest -> GetItemExclusive
(一种假象:http://localhost:29566和http://localhost:29566/Default.aspx)
已经创建过Session:
InitializeRequest -> GetItemExclusive
但如果没查到 会 CreateUninitializedItem -> GetItemExclusive(不管经过是什么,都会进入Page_Load)
--------------Page_load--------------
EndRequest(尚未创建过Session)
ReleaseItemExclusive -> EndRequest(已经创建过Session,此次无Update)
SetAndReleaseItemExclusive -> EndRequest (已经创建过Session,且此次有Update)
HttpModule -> RedisSession(InitializeRequest -> ResetItemTimeout只会在进入HttpHandle前调用这两个方法) -> HttpHandle
不要再HttpModule、HttpHandle中操作Session
HttpModel是因为调用顺序问题,HttpHandle是因为就算更新了,也不会进行被同步到Redis
好吧,其实这两个的context.Session 都是null
Media资源(图片、css、script)是不会进来的
*/
SessionStateStoreProviderBase类
定义一个数据存储会话状态所需的成员
Namespace: System.Web.SessionState
Assembly: System.Web (in System.Web.dll)
1.初始化每个请求对象
public abstract void InitializeRequest(HttpContext context)
Redis:
/// <summary> /// 在异步回发初始化期间提出 /// </summary> /// <param name="context"></param> public override void InitializeRequest(HttpContext context) { if (context != null && context.Request != null) { LogInfoFormat("InitializeRequest invoking: Cookie.ASP.NET_SessionId:{0},RequestRawUrl:{1}" , context.Request.Cookies != null && context.Request.Cookies["ASP.NET_SessionId"] != null ? context.Request.Cookies["ASP.NET_SessionId"].Value : "" , context.Request.RawUrl ); } }
2.创建一个新的对象用对当前的请求
public abstract SessionStateStoreData CreateNewStoreData(HttpContext context,int timeout)
Redis:
public override SessionStateStoreData CreateNewStoreData(HttpContext context, int timeout) { return new SessionStateStoreData(new SessionStateItemCollection(),staticObjectsGetter(context),timeout); }
3.更新此次会话的过期时间
public abstract void ResetItemTimeout(HttpContext context,string id)
Redis:
public override void ResetItemTimeout(HttpContext context, string id) { //throw new NotImplementedException(); }
4.从会话状态存储中返回只读会话状态
public abstract SessionStateStoreData GetItemExclusive(HttpContext context,string id,out bool locked,out TimeSpan lockAge,out object lockId,out SessionStateActions actions)
Redis:
public override SessionStateStoreData GetItemExclusive(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions) { LogInfoFormat("GetItemExclusive invoking: id:{0},RequestRawUrl:{1}" , id , context != null && context.Request != null ? context.Request.RawUrl : "" ); //读取redis,从redis获取session return GetItemFromSessionStore(true, context, id, out locked, out lockAge, out lockId, out actions); }/// <summary>/// 从Redis读取/// </summary>/// <param name="isWriteLockRequired"></param>/// <param name="context"></param>/// <param name="id"></param>/// <param name="locked"></param>/// <param name="lockAge"></param>/// <param name="lockId"></param>/// <param name="actions"></param>/// <returns></returns>private SessionStateStoreData GetItemFromSessionStore(bool isWriteLockRequired, HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions){ locked = false; lockAge = TimeSpan.Zero; lockId = null; actions = SessionStateActions.None; SessionStateStoreData result = null; var key = GetSessionIdKey(id); var stateRaw = RedisHelper.RedisDB.HashGetAll(key); RedisSessionState state; if (!RedisSessionState.TryParse(stateRaw, out state)) { locked = false; //如果在数据存储区中未找到会话项数据,GetItemExclusive 方法就会将 locked out 参数设置为 false 并返回 null return null; //CreateUninitializedItem -> GetItemExclusive } actions = state.Flags; if (state.Locked) { locked = true; //如果在数据存储区中找到会话项数据但是数据被锁定,GetItemExclusive 方法就会将 locked out 参数设置为 true,将 lockAge out 参数设置为当前日期和时间与项被锁定时的日期和时间(从数据存储区中检索)的差值,将 lockId out 参数设置为从数据存储区中检索的锁定标识符,并返回 null lockId = state.LockId; //lockAge = new TimeSpan((DateTime.UtcNow - state.LockDate).Ticks * 7);//ExecutionTimeout有点长,100s左右 lockAge = DateTime.UtcNow - state.LockDate; return null; } if (isWriteLockRequired) { locked = state.Locked = true; state.LockDate = DateTime.UtcNow; lockAge = TimeSpan.Zero; lockId = ++state.LockId; } state.Flags = SessionStateActions.None; UpdateSessionState(key, state); var items = actions == SessionStateActions.InitializeItem ? new SessionStateItemCollection() : state.Items; result = new SessionStateStoreData(items, staticObjectsGetter(context), state.Timeout); return result;}
5.添加一个新的会话状态项到会话存储里
public abstract void CreateUninitializedItem(HttpContext context,string id,int timeout)
Redis:
// GetItemExclusive如果没有查到,则会调用该方法(非因为Locked return null) public override void CreateUninitializedItem(HttpContext context, string id, int timeout) { var key = GetSessionIdKey(id); var state = new RedisSessionState() { Timeout = timeout, Flags = SessionStateActions.InitializeItem }; UpdateSessionState(key, state); } private void UpdateSessionState(string key, RedisSessionState state) { UseTransaction(transaction => { transaction.HashSetAsync(key, state.ToHashEntryArr()); transaction.KeyExpireAsync(key, TimeSpan.FromMinutes(state.Timeout)); }); }
6.一个请求结束后回传
public abstract void EndRequest(HttpContext context)
Redis:
public override void EndRequest(HttpContext context) { //throw new NotImplementedException(); }
7.释放会话状态存储中的锁定
public abstract void ReleaseItemExclusive(HttpContext context,string id,object lockId)
Redis:
///1、一次Http请求处理完之后(在Page_Load 及 aspx之后),如果没有发生了Session Update,则会调用此方法///2、Page_Load之前,如果反复执行GetItemExclusive始终是locked状态,一段时间之后系统会自行调用此方法来尝试释放./// 如果 SessionStateModule 对象在调用 GetItemExclusive 或 GetItem 方法期间遇到锁定的会话数据,它将以半秒为间隔重新请求会话数据,
/// 直到锁定被释放或者会话数据的锁定时间超过 ExecutionTimeout 属性的值。如果超过了执行超时时间,SessionStateModule 对象将调用 ReleaseItemExclusive 方法以释放会话存储区数据并随即请求会话存储区数据public override void ReleaseItemExclusive(HttpContext context, string id, object lockId) { UnlockSessionStateIfLocked(id, (int)lockId); } /// <summary> /// 释放会话存储区数据并随即请求会话存储区数据 /// </summary> /// <param name="id"></param> /// <param name="lockId"></param> private void UnlockSessionStateIfLocked(string id, int lockId) { var key = GetSessionIdKey(id); var stateRaw = RedisHelper.RedisDB.HashGetAll(key); RedisSessionState state; if (RedisSessionState.TryParse(stateRaw, out state) && state.Locked && state.LockId == lockId) { UnlockSessionState(key, state.Timeout); } } /// <summary> /// 不知道这样 对比 UpdateSessionState, 性能怎么样。这里虽然分成多项,但会作为一个transaction提交 /// </summary> /// <param name="client"></param> /// <param name="key"></param> /// <param name="state"></param> private void UnlockSessionState(string key, int timeout) { UseTransaction(transaction => { transaction.HashSetAsync(key, "locked", false); transaction.HashSetAsync(key, "lockId", 0); transaction.HashSetAsync(key, "lockDate", 0); //transaction.HashSetAsync(key, "timeout", timeout); //没必要 transaction.KeyExpireAsync(key, TimeSpan.FromMinutes(timeout)); }); } /// <summary> /// /// </summary> /// <param name="action"></param> private void UseTransaction(Action<ITransaction> action) { try { //Redis的更新 都会进这 var transaction = RedisHelper.RedisDB.CreateTransaction(); action(transaction); transaction.Execute(); } catch (Exception ex) { LogError(ex.Message, ex); } }
8.在更新会话状态数据存储与当前请求的值的会话项信息,并清除对数据的锁定
public abstract void SetAndReleaseItemExclusive(HttpContext context,string id,SessionStateStoreData item,object lockId,bool newItem)
Redis:
/// 一次Http请求处理完之后(在Page_Load 及 aspx之后),如果发生了Session Update,则会调用此方法public override void SetAndReleaseItemExclusive(HttpContext context, string id, SessionStateStoreData item, object lockId, bool newItem) { if (newItem) //true:定义一个新的状态 { var state = new RedisSessionState() { Items = (SessionStateItemCollection)item.Items, Timeout = item.Timeout, }; var key = GetSessionIdKey(id); UpdateSessionState(key, state); } else //false 已存在的状态 { UpdateSessionStateIfLocked(id, (int)lockId, state => { state.Items = (SessionStateItemCollection)item.Items; state.Locked = false; state.Timeout = item.Timeout; }); } } /// <summary> /// /// </summary> /// <param name="id"></param> /// <param name="lockId"></param> /// <param name="stateAction"></param> private void UpdateSessionStateIfLocked(string id, int lockId, Action<RedisSessionState> stateAction) { var key = GetSessionIdKey(id); var stateRaw = RedisHelper.RedisDB.HashGetAll(key); RedisSessionState state; if (RedisSessionState.TryParse(stateRaw, out state) && state.Locked && state.LockId == lockId) { stateAction(state); UpdateSessionState(key, state); } } /// <summary> /// /// </summary> /// <param name="client"></param> /// <param name="key"></param> /// <param name="state"></param> private void UpdateSessionState(string key, RedisSessionState state) { UseTransaction(transaction => { transaction.HashSetAsync(key, state.ToHashEntryArr()); transaction.KeyExpireAsync(key, TimeSpan.FromMinutes(state.Timeout)); }); } /// <summary> /// /// </summary> /// <param name="action"></param> private void UseTransaction(Action<ITransaction> action) { try { //Redis的更新 都会进这 var transaction = RedisHelper.RedisDB.CreateTransaction(); action(transaction); transaction.Execute(); } catch (Exception ex) { LogError(ex.Message, ex); } }
未完,待续...
原标题:说一说sateless的那些事~
关键词: