I implemented Task synchronization using Monitor in C#. However, I have read Monitor should not be used in asynchronous operation.
In the below code, how do I implement Monitor methods Wait and PulseAll with a construct that works with Task (asynchronous operations).
I have read that SemaphoreSlim.WaitAsync and Release methods can help. But how do they fit in the below sample where multiple tasks need to wait on a lock object, and releasing the lock wakes up all waiting tasks ?
private bool m_condition = false;
private readonly Object m_lock = new Object();
private async Task<bool> SyncInteralWithPoolingAsync(
SyncDatabase db,
List<EntryUpdateInfo> updateList)
{
List<Task> activeTasks = new List<Task>();
int addedTasks = 0;
int removedTasks = 0;
foreach (EntryUpdateInfo entryUpdateInfo in updateList)
{
Monitor.Enter(m_lock);
//If 5 tasks are waiting in ProcessEntryAsync method
if(m_count >= 5)
{
//Do some batch processing to obtian values to set for adapterEntry.AdapterEntryId in ProcessEntryAsync
//.......
//.......
m_condition = true;
Monitor.PulseAll(m_lock); // Wakes all waiters AFTER lock is released
}
Monitor.Exit(m_lock);
removedTasks += activeTasks.RemoveAll(t => t.IsCompleted);
Task processingTask = Task.Run(
async () =>
{
await this.ProcessEntryAsync(
entryUpdateInfo,
db)
.ContinueWith(this.ProcessEntryCompleteAsync)
.ConfigureAwait(false);
});
activeTasks.Add(processingTask);
addedTasks++;
}
}
private async Task<bool> ProcessEntryAsync(SyncDatabase db, EntryUpdateInfo entryUpdateInfo)
{
SyncEntryAdapterData adapterEntry =
updateInfo.Entry.AdapterEntries.FirstOrDefault(e => e.AdapterId == this.Config.Id);
if (adapterEntry == null)
{
adapterEntry = new SyncEntryAdapterData()
{
SyncEntry = updateInfo.Entry,
AdapterId = this.Config.Id
};
updateInfo.Entry.AdapterEntries.Add(adapterEntry);
}
m_condition = false;
Monitor.Enter(m_lock);
while (!m_condition)
{
m_count++;
Monitor.Wait(m_lock);
}
m_count--;
adapterEntry.AdapterEntryId = .... //Set Value obtained form batch processing
Monitor.Exit(m_lock);
}
private void ProcessEntryCompleteAsync(Task<bool> task, object context)
{
EntryProcessingContext ctx = (EntryProcessingContext)context;
try
{
string message;
if (task.IsCanceled)
{
Logger.Warning("Processing was cancelled");
message = "The change was cancelled during processing";
}
else if (task.Exception != null)
{
Exception ex = task.Exception;
Logger.Warning("Processing failed with {0}: {1}", ex.GetType().FullName, ex.Message);
message = "An error occurred while synchronzing the changed.";
}
else
{
message = "The change was successfully synchronized";
if (task.Result)
{
//Processing
//...
//...
}
}
}
catch (Exception e)
{
Logger.Info(
"Caught an exception while completing entry processing. " + e);
}
finally
{
}
}
Thanks