646 lines
17 KiB
C#
646 lines
17 KiB
C#
using System;
|
|
using System.Collections.Generic;
|
|
using System.Threading;
|
|
|
|
namespace Amib.Threading.Internal
|
|
{
|
|
#region WorkItemsQueue class
|
|
|
|
/// <summary>
|
|
/// WorkItemsQueue class.
|
|
/// </summary>
|
|
public class WorkItemsQueue : IDisposable
|
|
{
|
|
#region Member variables
|
|
|
|
/// <summary>
|
|
/// Waiters queue (implemented as stack).
|
|
/// </summary>
|
|
private readonly WaiterEntry _headWaiterEntry = new WaiterEntry();
|
|
|
|
/// <summary>
|
|
/// Waiters count
|
|
/// </summary>
|
|
private int _waitersCount = 0;
|
|
|
|
/// <summary>
|
|
/// Work items queue
|
|
/// </summary>
|
|
private readonly PriorityQueue _workItems = new PriorityQueue();
|
|
|
|
/// <summary>
|
|
/// Indicate that work items are allowed to be queued
|
|
/// </summary>
|
|
private bool _isWorkItemsQueueActive = true;
|
|
|
|
|
|
#if (WINDOWS_PHONE)
|
|
private static readonly Dictionary<int, WaiterEntry> _waiterEntries = new Dictionary<int, WaiterEntry>();
|
|
#elif (_WINDOWS_CE)
|
|
private static LocalDataStoreSlot _waiterEntrySlot = Thread.AllocateDataSlot();
|
|
#else
|
|
|
|
[ThreadStatic]
|
|
private static WaiterEntry _waiterEntry;
|
|
#endif
|
|
|
|
|
|
/// <summary>
|
|
/// Each thread in the thread pool keeps its own waiter entry.
|
|
/// </summary>
|
|
private static WaiterEntry CurrentWaiterEntry
|
|
{
|
|
#if (WINDOWS_PHONE)
|
|
get
|
|
{
|
|
lock (_waiterEntries)
|
|
{
|
|
WaiterEntry waiterEntry;
|
|
if (_waiterEntries.TryGetValue(Thread.CurrentThread.ManagedThreadId, out waiterEntry))
|
|
{
|
|
return waiterEntry;
|
|
}
|
|
}
|
|
return null;
|
|
}
|
|
set
|
|
{
|
|
lock (_waiterEntries)
|
|
{
|
|
_waiterEntries[Thread.CurrentThread.ManagedThreadId] = value;
|
|
}
|
|
}
|
|
#elif (_WINDOWS_CE)
|
|
get
|
|
{
|
|
return Thread.GetData(_waiterEntrySlot) as WaiterEntry;
|
|
}
|
|
set
|
|
{
|
|
Thread.SetData(_waiterEntrySlot, value);
|
|
}
|
|
#else
|
|
get
|
|
{
|
|
return _waiterEntry;
|
|
}
|
|
set
|
|
{
|
|
_waiterEntry = value;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/// <summary>
|
|
/// A flag that indicates if the WorkItemsQueue has been disposed.
|
|
/// </summary>
|
|
private bool _isDisposed = false;
|
|
|
|
#endregion
|
|
|
|
#region Public properties
|
|
|
|
/// <summary>
|
|
/// Returns the current number of work items in the queue
|
|
/// </summary>
|
|
public int Count
|
|
{
|
|
get
|
|
{
|
|
return _workItems.Count;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Returns the current number of waiters
|
|
/// </summary>
|
|
public int WaitersCount
|
|
{
|
|
get
|
|
{
|
|
return _waitersCount;
|
|
}
|
|
}
|
|
|
|
|
|
#endregion
|
|
|
|
#region Public methods
|
|
|
|
/// <summary>
|
|
/// Enqueue a work item to the queue.
|
|
/// </summary>
|
|
public bool EnqueueWorkItem(WorkItem workItem)
|
|
{
|
|
// A work item cannot be null, since null is used in the
|
|
// WaitForWorkItem() method to indicate timeout or cancel
|
|
if (null == workItem)
|
|
{
|
|
throw new ArgumentNullException("workItem" , "workItem cannot be null");
|
|
}
|
|
|
|
bool enqueue = true;
|
|
|
|
// First check if there is a waiter waiting for work item. During
|
|
// the check, timed out waiters are ignored. If there is no
|
|
// waiter then the work item is queued.
|
|
lock(this)
|
|
{
|
|
ValidateNotDisposed();
|
|
|
|
if (!_isWorkItemsQueueActive)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
while(_waitersCount > 0)
|
|
{
|
|
// Dequeue a waiter.
|
|
WaiterEntry waiterEntry = PopWaiter();
|
|
|
|
// Signal the waiter. On success break the loop
|
|
if (waiterEntry.Signal(workItem))
|
|
{
|
|
enqueue = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (enqueue)
|
|
{
|
|
// Enqueue the work item
|
|
_workItems.Enqueue(workItem);
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
|
|
/// <summary>
|
|
/// Waits for a work item or exits on timeout or cancel
|
|
/// </summary>
|
|
/// <param name="millisecondsTimeout">Timeout in milliseconds</param>
|
|
/// <param name="cancelEvent">Cancel wait handle</param>
|
|
/// <returns>Returns true if the resource was granted</returns>
|
|
public WorkItem DequeueWorkItem(
|
|
int millisecondsTimeout,
|
|
WaitHandle cancelEvent)
|
|
{
|
|
// This method cause the caller to wait for a work item.
|
|
// If there is at least one waiting work item then the
|
|
// method returns immidiately with it.
|
|
//
|
|
// If there are no waiting work items then the caller
|
|
// is queued between other waiters for a work item to arrive.
|
|
//
|
|
// If a work item didn't come within millisecondsTimeout or
|
|
// the user canceled the wait by signaling the cancelEvent
|
|
// then the method returns null to indicate that the caller
|
|
// didn't get a work item.
|
|
|
|
WaiterEntry waiterEntry;
|
|
WorkItem workItem = null;
|
|
lock (this)
|
|
{
|
|
ValidateNotDisposed();
|
|
|
|
// If there are waiting work items then take one and return.
|
|
if (_workItems.Count > 0)
|
|
{
|
|
workItem = _workItems.Dequeue() as WorkItem;
|
|
return workItem;
|
|
}
|
|
|
|
// No waiting work items ...
|
|
|
|
// Get the waiter entry for the waiters queue
|
|
waiterEntry = GetThreadWaiterEntry();
|
|
|
|
// Put the waiter with the other waiters
|
|
PushWaiter(waiterEntry);
|
|
}
|
|
|
|
// Prepare array of wait handle for the WaitHandle.WaitAny()
|
|
WaitHandle [] waitHandles = new WaitHandle[] {
|
|
waiterEntry.WaitHandle,
|
|
cancelEvent };
|
|
|
|
// Wait for an available resource, cancel event, or timeout.
|
|
|
|
// During the wait we are supposes to exit the synchronization
|
|
// domain. (Placing true as the third argument of the WaitAny())
|
|
// It just doesn't work, I don't know why, so I have two lock(this)
|
|
// statments instead of one.
|
|
|
|
int index = STPEventWaitHandle.WaitAny(
|
|
waitHandles,
|
|
millisecondsTimeout,
|
|
true);
|
|
|
|
lock(this)
|
|
{
|
|
// success is true if it got a work item.
|
|
bool success = (0 == index);
|
|
|
|
// The timeout variable is used only for readability.
|
|
// (We treat cancel as timeout)
|
|
bool timeout = !success;
|
|
|
|
// On timeout update the waiterEntry that it is timed out
|
|
if (timeout)
|
|
{
|
|
// The Timeout() fails if the waiter has already been signaled
|
|
timeout = waiterEntry.Timeout();
|
|
|
|
// On timeout remove the waiter from the queue.
|
|
// Note that the complexity is O(1).
|
|
if(timeout)
|
|
{
|
|
RemoveWaiter(waiterEntry, false);
|
|
}
|
|
|
|
// Again readability
|
|
success = !timeout;
|
|
}
|
|
|
|
// On success return the work item
|
|
if (success)
|
|
{
|
|
workItem = waiterEntry.WorkItem;
|
|
|
|
if (null == workItem)
|
|
{
|
|
workItem = _workItems.Dequeue() as WorkItem;
|
|
}
|
|
}
|
|
}
|
|
// On failure return null.
|
|
return workItem;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Cleanup the work items queue, hence no more work
|
|
/// items are allowed to be queue
|
|
/// </summary>
|
|
private void Cleanup()
|
|
{
|
|
lock(this)
|
|
{
|
|
// Deactivate only once
|
|
if (!_isWorkItemsQueueActive)
|
|
{
|
|
return;
|
|
}
|
|
|
|
// Don't queue more work items
|
|
_isWorkItemsQueueActive = false;
|
|
|
|
foreach(WorkItem workItem in _workItems)
|
|
{
|
|
workItem.DisposeOfState();
|
|
}
|
|
|
|
// Clear the work items that are already queued
|
|
_workItems.Clear();
|
|
|
|
// Note:
|
|
// I don't iterate over the queue and dispose of work items's states,
|
|
// since if a work item has a state object that is still in use in the
|
|
// application then I must not dispose it.
|
|
|
|
// Tell the waiters that they were timed out.
|
|
// It won't signal them to exit, but to ignore their
|
|
// next work item.
|
|
while(_waitersCount > 0)
|
|
{
|
|
WaiterEntry waiterEntry = PopWaiter();
|
|
waiterEntry.Timeout();
|
|
}
|
|
}
|
|
}
|
|
|
|
public object[] GetStates()
|
|
{
|
|
lock (this)
|
|
{
|
|
object[] states = new object[_workItems.Count];
|
|
int i = 0;
|
|
foreach (WorkItem workItem in _workItems)
|
|
{
|
|
states[i] = workItem.GetWorkItemResult().State;
|
|
++i;
|
|
}
|
|
return states;
|
|
}
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Private methods
|
|
|
|
/// <summary>
|
|
/// Returns the WaiterEntry of the current thread
|
|
/// </summary>
|
|
/// <returns></returns>
|
|
/// In order to avoid creation and destuction of WaiterEntry
|
|
/// objects each thread has its own WaiterEntry object.
|
|
private static WaiterEntry GetThreadWaiterEntry()
|
|
{
|
|
if (null == CurrentWaiterEntry)
|
|
{
|
|
CurrentWaiterEntry = new WaiterEntry();
|
|
}
|
|
CurrentWaiterEntry.Reset();
|
|
return CurrentWaiterEntry;
|
|
}
|
|
|
|
#region Waiters stack methods
|
|
|
|
/// <summary>
|
|
/// Push a new waiter into the waiter's stack
|
|
/// </summary>
|
|
/// <param name="newWaiterEntry">A waiter to put in the stack</param>
|
|
public void PushWaiter(WaiterEntry newWaiterEntry)
|
|
{
|
|
// Remove the waiter if it is already in the stack and
|
|
// update waiter's count as needed
|
|
RemoveWaiter(newWaiterEntry, false);
|
|
|
|
// If the stack is empty then newWaiterEntry is the new head of the stack
|
|
if (null == _headWaiterEntry._nextWaiterEntry)
|
|
{
|
|
_headWaiterEntry._nextWaiterEntry = newWaiterEntry;
|
|
newWaiterEntry._prevWaiterEntry = _headWaiterEntry;
|
|
|
|
}
|
|
// If the stack is not empty then put newWaiterEntry as the new head
|
|
// of the stack.
|
|
else
|
|
{
|
|
// Save the old first waiter entry
|
|
WaiterEntry oldFirstWaiterEntry = _headWaiterEntry._nextWaiterEntry;
|
|
|
|
// Update the links
|
|
_headWaiterEntry._nextWaiterEntry = newWaiterEntry;
|
|
newWaiterEntry._nextWaiterEntry = oldFirstWaiterEntry;
|
|
newWaiterEntry._prevWaiterEntry = _headWaiterEntry;
|
|
oldFirstWaiterEntry._prevWaiterEntry = newWaiterEntry;
|
|
}
|
|
|
|
// Increment the number of waiters
|
|
++_waitersCount;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Pop a waiter from the waiter's stack
|
|
/// </summary>
|
|
/// <returns>Returns the first waiter in the stack</returns>
|
|
private WaiterEntry PopWaiter()
|
|
{
|
|
// Store the current stack head
|
|
WaiterEntry oldFirstWaiterEntry = _headWaiterEntry._nextWaiterEntry;
|
|
|
|
// Store the new stack head
|
|
WaiterEntry newHeadWaiterEntry = oldFirstWaiterEntry._nextWaiterEntry;
|
|
|
|
// Update the old stack head list links and decrement the number
|
|
// waiters.
|
|
RemoveWaiter(oldFirstWaiterEntry, true);
|
|
|
|
// Update the new stack head
|
|
_headWaiterEntry._nextWaiterEntry = newHeadWaiterEntry;
|
|
if (null != newHeadWaiterEntry)
|
|
{
|
|
newHeadWaiterEntry._prevWaiterEntry = _headWaiterEntry;
|
|
}
|
|
|
|
// Return the old stack head
|
|
return oldFirstWaiterEntry;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Remove a waiter from the stack
|
|
/// </summary>
|
|
/// <param name="waiterEntry">A waiter entry to remove</param>
|
|
/// <param name="popDecrement">If true the waiter count is always decremented</param>
|
|
private void RemoveWaiter(WaiterEntry waiterEntry, bool popDecrement)
|
|
{
|
|
// Store the prev entry in the list
|
|
WaiterEntry prevWaiterEntry = waiterEntry._prevWaiterEntry;
|
|
|
|
// Store the next entry in the list
|
|
WaiterEntry nextWaiterEntry = waiterEntry._nextWaiterEntry;
|
|
|
|
// A flag to indicate if we need to decrement the waiters count.
|
|
// If we got here from PopWaiter then we must decrement.
|
|
// If we got here from PushWaiter then we decrement only if
|
|
// the waiter was already in the stack.
|
|
bool decrementCounter = popDecrement;
|
|
|
|
// Null the waiter's entry links
|
|
waiterEntry._prevWaiterEntry = null;
|
|
waiterEntry._nextWaiterEntry = null;
|
|
|
|
// If the waiter entry had a prev link then update it.
|
|
// It also means that the waiter is already in the list and we
|
|
// need to decrement the waiters count.
|
|
if (null != prevWaiterEntry)
|
|
{
|
|
prevWaiterEntry._nextWaiterEntry = nextWaiterEntry;
|
|
decrementCounter = true;
|
|
}
|
|
|
|
// If the waiter entry had a next link then update it.
|
|
// It also means that the waiter is already in the list and we
|
|
// need to decrement the waiters count.
|
|
if (null != nextWaiterEntry)
|
|
{
|
|
nextWaiterEntry._prevWaiterEntry = prevWaiterEntry;
|
|
decrementCounter = true;
|
|
}
|
|
|
|
// Decrement the waiters count if needed
|
|
if (decrementCounter)
|
|
{
|
|
--_waitersCount;
|
|
}
|
|
}
|
|
|
|
#endregion
|
|
|
|
#endregion
|
|
|
|
#region WaiterEntry class
|
|
|
|
// A waiter entry in the _waiters queue.
|
|
public sealed class WaiterEntry : IDisposable
|
|
{
|
|
#region Member variables
|
|
|
|
/// <summary>
|
|
/// Event to signal the waiter that it got the work item.
|
|
/// </summary>
|
|
//private AutoResetEvent _waitHandle = new AutoResetEvent(false);
|
|
private AutoResetEvent _waitHandle = EventWaitHandleFactory.CreateAutoResetEvent();
|
|
|
|
/// <summary>
|
|
/// Flag to know if this waiter already quited from the queue
|
|
/// because of a timeout.
|
|
/// </summary>
|
|
private bool _isTimedout = false;
|
|
|
|
/// <summary>
|
|
/// Flag to know if the waiter was signaled and got a work item.
|
|
/// </summary>
|
|
private bool _isSignaled = false;
|
|
|
|
/// <summary>
|
|
/// A work item that passed directly to the waiter withou going
|
|
/// through the queue
|
|
/// </summary>
|
|
private WorkItem _workItem = null;
|
|
|
|
private bool _isDisposed = false;
|
|
|
|
// Linked list members
|
|
internal WaiterEntry _nextWaiterEntry = null;
|
|
internal WaiterEntry _prevWaiterEntry = null;
|
|
|
|
#endregion
|
|
|
|
#region Construction
|
|
|
|
public WaiterEntry()
|
|
{
|
|
Reset();
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region Public methods
|
|
|
|
public WaitHandle WaitHandle
|
|
{
|
|
get { return _waitHandle; }
|
|
}
|
|
|
|
public WorkItem WorkItem
|
|
{
|
|
get
|
|
{
|
|
return _workItem;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Signal the waiter that it got a work item.
|
|
/// </summary>
|
|
/// <returns>Return true on success</returns>
|
|
/// The method fails if Timeout() preceded its call
|
|
public bool Signal(WorkItem workItem)
|
|
{
|
|
lock(this)
|
|
{
|
|
if (!_isTimedout)
|
|
{
|
|
_workItem = workItem;
|
|
_isSignaled = true;
|
|
_waitHandle.Set();
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Mark the wait entry that it has been timed out
|
|
/// </summary>
|
|
/// <returns>Return true on success</returns>
|
|
/// The method fails if Signal() preceded its call
|
|
public bool Timeout()
|
|
{
|
|
lock(this)
|
|
{
|
|
// Time out can happen only if the waiter wasn't marked as
|
|
// signaled
|
|
if (!_isSignaled)
|
|
{
|
|
// We don't remove the waiter from the queue, the DequeueWorkItem
|
|
// method skips _waiters that were timed out.
|
|
_isTimedout = true;
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reset the wait entry so it can be used again
|
|
/// </summary>
|
|
public void Reset()
|
|
{
|
|
_workItem = null;
|
|
_isTimedout = false;
|
|
_isSignaled = false;
|
|
_waitHandle.Reset();
|
|
}
|
|
|
|
/// <summary>
|
|
/// Free resources
|
|
/// </summary>
|
|
public void Close()
|
|
{
|
|
if (null != _waitHandle)
|
|
{
|
|
_waitHandle.Close();
|
|
_waitHandle = null;
|
|
}
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region IDisposable Members
|
|
|
|
public void Dispose()
|
|
{
|
|
lock (this)
|
|
{
|
|
if (!_isDisposed)
|
|
{
|
|
Close();
|
|
}
|
|
_isDisposed = true;
|
|
}
|
|
}
|
|
|
|
#endregion
|
|
}
|
|
|
|
#endregion
|
|
|
|
#region IDisposable Members
|
|
|
|
public void Dispose()
|
|
{
|
|
if (!_isDisposed)
|
|
{
|
|
Cleanup();
|
|
}
|
|
_isDisposed = true;
|
|
}
|
|
|
|
private void ValidateNotDisposed()
|
|
{
|
|
if(_isDisposed)
|
|
{
|
|
throw new ObjectDisposedException(GetType().ToString(), "The SmartThreadPool has been shutdown");
|
|
}
|
|
}
|
|
|
|
#endregion
|
|
}
|
|
|
|
#endregion
|
|
}
|
|
|