SharedLock.cs
75 lines
| 2.0 KiB
| text/x-csharp
|
CSharpLexer
cin
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r129 | using System; | ||
| using System.Threading; | ||||
| using System.Diagnostics; | ||||
| namespace Implab.Parallels { | ||||
| /// <summary> | ||||
| /// Implements a lightweight mechanism to aquire a shared or an exclusive lock. | ||||
| /// </summary> | ||||
| public class SharedLock { | ||||
| readonly object m_lock = new object(); | ||||
| int m_locks; | ||||
| bool m_exclusive; | ||||
| public bool LockExclusive(int timeout) { | ||||
| lock (m_lock) { | ||||
| if (m_locks > 0 && !Monitor.Wait(m_lock, timeout)) | ||||
| return false; | ||||
| m_exclusive = true; | ||||
| m_locks = 1; | ||||
| } | ||||
| } | ||||
| public void LockExclusive() { | ||||
| LockExclusive(-1); | ||||
| } | ||||
| public bool LockShared(int timeout) { | ||||
| lock (m_lock) { | ||||
| if (!m_exclusive) { | ||||
| m_locks++; | ||||
| return true; | ||||
| } | ||||
| if (m_lock == 0) { | ||||
| m_exclusive = false; | ||||
| m_locks = 1; | ||||
| return true; | ||||
| } | ||||
| if (Monitor.Wait(m_lock, timeout)) { | ||||
| Debug.Assert(m_locks == 0); | ||||
| m_locks = 1; | ||||
| m_exclusive = false; | ||||
| return true; | ||||
| } | ||||
| return false; | ||||
| } | ||||
| } | ||||
| public void LockShared() { | ||||
| LockShared(-1); | ||||
| } | ||||
| public void ReleaseShared() { | ||||
| lock (m_lock) { | ||||
| if (m_exclusive || m_locks <= 0) | ||||
| throw new InvalidOperationException(); | ||||
| m_locks--; | ||||
| if (m_locks == 0) | ||||
| Monitor.PulseAll(m_lock); | ||||
| } | ||||
| } | ||||
| public void ReleaseExclusive() { | ||||
| lock (m_lock) { | ||||
| if (!m_exclusive && m_locks != 1) | ||||
| throw new InvalidOperationException(); | ||||
| m_locks = 0; | ||||
| Monitor.PulseAll(m_lock); | ||||
| } | ||||
| } | ||||
| } | ||||
| } | ||||