implab/ImplabNet Files · Implab/Parallels/SharedLock.cs

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             SharedLock.cs
        
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             / 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);

                  }

              }

          }

      }

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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);
				}
				}

				}
				}