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ReaderWriterLockSlim to lock #2553

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ReaderWriterLockSlim to lock #2553

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93 changes: 27 additions & 66 deletions LiteDB/Engine/Services/LockService.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
using System;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
Expand All @@ -18,7 +18,7 @@ public class LockService
private IDiskService _disk;
private CacheService _cache;
private Logger _log;
private ReaderWriterLockSlim _thread = new ReaderWriterLockSlim(LockRecursionPolicy.NoRecursion);
private readonly object thisLock = new object();

internal LockService(IDiskService disk, CacheService cache, TimeSpan timeout, Logger log)
{
Expand All @@ -28,18 +28,6 @@ internal LockService(IDiskService disk, CacheService cache, TimeSpan timeout, Lo
_timeout = timeout;
}

/// <summary>
/// Get current datafile lock state defined by thread only (do not check if datafile is locked)
/// </summary>
public LockState ThreadState
{
get
{
return _thread.IsWriteLockHeld ? LockState.Write :
_thread.CurrentReadCount > 0 ? LockState.Read : LockState.Unlocked;
}
}

/// <summary>
/// Get current thread id
/// </summary>
Expand All @@ -64,75 +52,48 @@ public int ThreadId
/// </summary>
public LockControl Read()
{
// if read or write
if (_thread.IsReadLockHeld || _thread.IsWriteLockHeld)
{
return new LockControl(false, () => { });
}

// try enter in read mode
if (!_thread.TryEnterReadLock(_timeout))
lock (thisLock)
{
throw LiteException.LockTimeout(_timeout);
}
_log.Write(Logger.LOCK, "entered in read lock mode in thread #{0}", this.ThreadId);

_log.Write(Logger.LOCK, "entered in read lock mode in thread #{0}", this.ThreadId);
// lock disk in shared mode
var position = _disk.Lock(LockState.Read, _timeout);

// lock disk in shared mode
var position = _disk.Lock(LockState.Read, _timeout);
var changed = this.DetectDatabaseChanges();

var changed = this.DetectDatabaseChanges();
return new LockControl(changed, () =>
{
// exit disk lock mode
_disk.Unlock(LockState.Read, position);

return new LockControl(changed, () =>
{
// exit disk lock mode
_disk.Unlock(LockState.Read, position);

// exit thread lock mode
_thread.ExitReadLock();

_log.Write(Logger.LOCK, "exited read lock mode in thread #{0}", this.ThreadId);
});
_log.Write(Logger.LOCK, "exited read lock mode in thread #{0}", this.ThreadId);
});
}
}

/// <summary>
/// Enter in Exclusive lock mode
/// </summary>
public LockControl Write()
{
// if already in exclusive, do nothing
if (_thread.IsWriteLockHeld)
{
return new LockControl(false, () => { });
}

// let's test if is not in read lock
if (_thread.IsReadLockHeld) throw new NotSupportedException("Not support Write lock inside a Read lock");

// try enter in write mode (thread)
if (!_thread.TryEnterWriteLock(_timeout))
lock (thisLock)
{
throw LiteException.LockTimeout(_timeout);
}

_log.Write(Logger.LOCK, "entered in write lock mode in thread #{0}", this.ThreadId);
_log.Write(Logger.LOCK, "entered in write lock mode in thread #{0}", this.ThreadId);

// try enter in exclusive mode in disk
var position = _disk.Lock(LockState.Write, _timeout);
// try enter in exclusive mode in disk
var position = _disk.Lock(LockState.Write, _timeout);

// call avoid dirty only if not came from a shared mode
var changed = this.DetectDatabaseChanges();
// call avoid dirty only if not came from a shared mode
var changed = this.DetectDatabaseChanges();

return new LockControl(changed, () =>
{
// release disk write
_disk.Unlock(LockState.Write, position);

// release thread write
_thread.ExitWriteLock();
return new LockControl(changed, () =>
{
// release disk write
_disk.Unlock(LockState.Write, position);

_log.Write(Logger.LOCK, "exited write lock mode in thread #{0}", this.ThreadId);
});
_log.Write(Logger.LOCK, "exited write lock mode in thread #{0}", this.ThreadId);
});
}
}

#endregion
Expand Down