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//
// System.Web.SessionState.RemoteStateServer
//
// Author(s):
// Jackson Harper (jackson@ximian.com)
// Gonzalo Paniagua (gonzalo@ximian.com)
// Marek Habersack (grendello@gmail.com)
//
// (C) 2003-2006 Novell, Inc (http://www.novell.com)
//
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Threading;
using System.Web.Caching;
namespace System.Web.SessionState {
class LockableStateServerItem
{
public StateServerItem item;
public ReaderWriterLock rwlock;
public LockableStateServerItem (StateServerItem item)
{
this.item = item;
this.rwlock = new ReaderWriterLock ();
}
}
internal class RemoteStateServer : MarshalByRefObject {
const Int32 lockAcquireTimeout = 30000;
Cache cache;
internal RemoteStateServer ()
{
cache = new Cache ();
}
void Insert (string id, LockableStateServerItem item)
{
cache.Insert (id, item, null, Cache.NoAbsoluteExpiration, new TimeSpan (0, item.item.Timeout, 0));
}
LockableStateServerItem Retrieve (string id)
{
return cache [id] as LockableStateServerItem;
}
internal void CreateUninitializedItem (string id, int timeout)
{
StateServerItem item = new StateServerItem (timeout);
item.Action = SessionStateActions.InitializeItem;
LockableStateServerItem cacheItem = new LockableStateServerItem (item);
Insert (id, cacheItem);
}
internal StateServerItem GetItem (string id,
out bool locked,
out TimeSpan lockAge,
out object lockId,
out SessionStateActions actions,
bool exclusive)
{
locked = false;
lockAge = TimeSpan.MinValue;
lockId = Int32.MinValue;
actions = SessionStateActions.None;
LockableStateServerItem item = Retrieve (id);
if (item == null || item.item.IsAbandoned ())
return null;
try {
item.rwlock.AcquireReaderLock (lockAcquireTimeout);
if (item.item.Locked) {
locked = true;
lockAge = DateTime.UtcNow.Subtract (item.item.LockedTime);
lockId = item.item.LockId;
return null;
}
item.rwlock.ReleaseReaderLock ();
if (exclusive) {
item.rwlock.AcquireWriterLock (lockAcquireTimeout);
item.item.Locked = true;
item.item.LockedTime = DateTime.UtcNow;
item.item.LockId++;
lockId = item.item.LockId;
}
} catch {
throw;
} finally {
if (item.rwlock.IsReaderLockHeld)
item.rwlock.ReleaseReaderLock ();
if (item.rwlock.IsWriterLockHeld)
item.rwlock.ReleaseWriterLock ();
}
actions = item.item.Action;
return item.item;
}
internal void Remove (string id, object lockid)
{
cache.Remove (id);
}
internal void ResetItemTimeout (string id)
{
LockableStateServerItem item = Retrieve (id);
if (item == null)
return;
item.item.Touch ();
}
internal void ReleaseItemExclusive (string id, object lockId)
{
LockableStateServerItem item = Retrieve (id);
if (item == null || item.item.LockId != (Int32)lockId)
return;
try {
item.rwlock.AcquireWriterLock (lockAcquireTimeout);
item.item.Locked = false;
} catch {
throw;
} finally {
if (item.rwlock.IsWriterLockHeld)
item.rwlock.ReleaseWriterLock ();
}
}
internal void SetAndReleaseItemExclusive (string id, byte [] collection_data, byte [] sobjs_data,
object lockId, int timeout, bool newItem)
{
LockableStateServerItem item = Retrieve (id);
bool fresh = false;
if (newItem || item == null) {
item = new LockableStateServerItem (new StateServerItem (collection_data, sobjs_data, timeout));
item.item.LockId = (Int32)lockId;
fresh = true;
} else {
if (item.item.LockId != (Int32)lockId)
return;
Remove (id, lockId);
}
try {
item.rwlock.AcquireWriterLock (lockAcquireTimeout);
item.item.Locked = false;
if (!fresh) {
item.item.CollectionData = collection_data;
item.item.StaticObjectsData = sobjs_data;
}
Insert (id, item);
} catch {
throw;
} finally {
if (item.rwlock.IsWriterLockHeld)
item.rwlock.ReleaseWriterLock ();
}
}
public override object InitializeLifetimeService ()
{
return null; // just in case...
}
}
}
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