public IEnumerator GetEnumerator()
{
// we are going to return the default enumerator implementation of ConcurrentDictionary, but
// there is one snafu. The keys that have not been read yet are of type
// NotYetDeserializedPlaceholderValue, we need to deserialize them now.
lock (this.enumLock)
{
foreach (KeyValuePair <string, object> itm in this.Items)
{
if (itm.Value is NotYetDeserializedPlaceholderValue)
{
this.MemoizedDeserializeGet(itm.Key); // deserialize the value
}
}
try
{
return(this.Items.GetEnumerator());
}
catch (Exception exc)
{
RedisSessionConfig.LogSessionException(exc);
}
}
return(new ConcurrentDictionary <string, object>().GetEnumerator());
}
/// <summary>
/// Gets a Session from Redis, indicating a non-exclusive lock on the Session. Note that GetItemExclusive
/// calls this method internally, meaning we do not support locks at all retrieving the Session.
/// </summary>
/// <param name="context">The HttpContext of the current request</param>
/// <param name="id">The Session Id, which is the key name in Redis</param>
/// <param name="locked">Whether or not the Session is locked to exclusive access for a single request
/// thread</param>
/// <param name="lockAge">The age of the lock</param>
/// <param name="lockId">The object used to lock the Session</param>
/// <param name="actions">Whether or not to initialize the Session (never)</param>
/// <returns>The Session objects wrapped in a SessionStateStoreData object</returns>
public override SessionStateStoreData GetItem(HttpContext context, string id, out bool locked, out TimeSpan lockAge, out object lockId, out SessionStateActions actions)
{
locked = false;
lockAge = new TimeSpan(0);
lockId = null;
actions = SessionStateActions.None;
try
{
return(new SessionStateStoreData(GetSessionItems(context, id), SessionStateUtility.GetSessionStaticObjects(context), Convert.ToInt32(RedisSessionConfig.SessionTimeout.TotalMinutes)));
}
catch (Exception e)
{
RedisSessionConfig.LogSessionException(e);
}
return(CreateNewStoreData(context, Convert.ToInt32(RedisSessionConfig.SessionTimeout.TotalMinutes)));
}
/// <summary>
/// Returns a class that allows iteration over the objects in the Session collection that have changed
/// since being pulled from Redis. Each key is checked for being all of the following: key was
/// accessed, key was not removed or set to null, if the key holds the same object reference as it
/// did when pulled from redis, then the current object at the reference address is serialized and
/// the serialized string is compared with the serialized string that was originally pulled from
/// Redis. The last condition is to ensure Dirty checking is correct, i.e.
/// ((List<string>)Session["a"]).Add("a");
/// does not change what Session["a"] refers to, but it does change the object and we need to write
/// that back to Redis at the end.
/// </summary>
/// <returns>an IEnumerator that allows iteration over the changed elements of the Session.</returns>
public IEnumerable <KeyValuePair <string, string> > GetChangedObjectsEnumerator()
{
var changedObjs = new List <KeyValuePair <string, string> >();
lock (enumLock)
{
try
{
// for items that have definitely changed (ints, strings, value types and
// reference types whose refs have changed), add to the resulting list
// and reset their serialized raw data
foreach (KeyValuePair <string, ActionAndValue> changeData in ChangedKeysDict)
{
if (changeData.Value is SetValue)
{
UpdateSerializedDataForChanges(changedObjs, changeData);
}
else if (changeData.Value is DeleteValue)
{
UpdateSerializedDataForDeletes(changedObjs, changeData);
}
}
// check each key that was accessed for changes
foreach (KeyValuePair <string, object> itm in this.Items)
{
try
{
UpdateChangedObjectList(changedObjs, itm);
}
catch (Exception) { }
}
}
catch (Exception enumExc)
{
RedisSessionConfig.LogSessionException(enumExc);
}
}
return(changedObjs);
}
/// <summary>
/// Gets a hash from Redis and passes it to the constructor of RedisSessionStateItemCollection
/// </summary>
/// <param name="redisKey">The key of the Redis hash</param>
/// <param name="context">The HttpContext of the current web request</param>
/// <returns>An instance of RedisSessionStateItemCollection, may be empty if Redis call fails</returns>
public static RedisSessionStateItemCollection GetItemFromRedis(string redisKey, HttpContextBase context, TimeSpan expirationTimeout)
{
RedisConnectionWrapper rConnWrap = RedisSessionStateStoreProvider.RedisConnWrapperFromContext(context);
IDatabase redisConn = rConnWrap.GetConnection(redisKey);
try
{
HashEntry[] redisData = redisConn.HashGetAll(redisKey);
redisConn.KeyExpire(redisKey, expirationTimeout, CommandFlags.FireAndForget);
return(new RedisSessionStateItemCollection(redisData, redisKey));
}
catch (Exception e)
{
RedisSessionConfig.LogSessionException(e);
}
return(new RedisSessionStateItemCollection());
}
static void EnsureLocalCacheFreshness(object sender, ElapsedEventArgs e)
{
try
{
rwlock.EnterWriteLock();
cacheFreshnessTimer.Stop();
LocalSessionInfo removed;
foreach (string expKey in GetPurgableKeys())
{
localCache.TryRemove(expKey, out removed);
}
}
catch (Exception sharedDictExc)
{
RedisSessionConfig.LogSessionException(sharedDictExc);
}
finally
{
rwlock.ExitWriteLock();
cacheFreshnessTimer.Start();
}
}
/// <summary>
/// Checks if any items have changed in the Session, and stores the results to Redis
/// </summary>
/// <param name="context">The HttpContext of the current web request</param>
/// <param name="id">The Session Id and Redis key name</param>
/// <param name="item">The Session properties</param>
/// <param name="lockId">The object used to exclusively lock the Session (there shouldn't be one)</param>
/// <param name="newItem">Whether or not the Session was created in this HttpContext</param>
public override void SetAndReleaseItemExclusive(HttpContext context, string id, SessionStateStoreData item, object lockId, bool newItem)
{
try
{
string currentRedisHashId = RedisHashIdFromSessionId(new HttpContextWrapper(context), id);
LocalSharedSessionDictionary sharedSessDict = new LocalSharedSessionDictionary();
// we were unable to pull it from shared cache, meaning either this is the first request or
// something went wrong with the local cache. We still have all the parts needed to write
// to redis, however, by looking at SessionStateStoreData passed in from the Session module
// and the current hash key provided by the id parameter.
var redisItems = sharedSessDict.GetSessionForEndRequest(currentRedisHashId) ?? (RedisSessionStateItemCollection)item.Items;
if (redisItems != null)
{
SerializeToRedis(new HttpContextWrapper(context), redisItems, currentRedisHashId, RedisSessionConfig.SessionTimeout);
}
}
catch (Exception e)
{
RedisSessionConfig.LogSessionException(e);
}
}
