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Fixed chaining of promises with 'Then' method
Fixed chaining of promises with 'Then' method
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r130:671f60cd0250 v2
r135:656815cb7147 v2
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SharedLock.cs
76 lines | 2.0 KiB | text/x-csharp | CSharpLexer
/ Implab / Parallels / SharedLock.cs
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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;
return true;
}
}
public void LockExclusive() {
LockExclusive(-1);
}
public bool LockShared(int timeout) {
lock (m_lock) {
if (!m_exclusive) {
m_locks++;
return true;
}
if (m_locks == 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);
}
}
}
}