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Use Monitor.TryEnter/Exit in the Scan loop (#189) 

- Avoids overlapping Scans
- Noops if dispose is being called at the same time
This commit is contained in:
David Fowler 2017-02-10 16:34:31 -08:00 committed by GitHub
parent 633c572a22
commit fc93c47789
1 changed files with 37 additions and 28 deletions
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65
src/Microsoft.AspNetCore.Sockets/ConnectionManager.cs
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@ -87,7 +87,16 @@ namespace Microsoft.AspNetCore.Sockets
private void Scan()
{
lock (_executionLock)
// If we couldn't get the lock it means one of 2 things is true:
// - We're about to dispose so we don't care to run the scan callback anyways.
// - The previous Scan took long enough that the next scan tried to run in parallel
// In either case just do nothing and end the timer callback as soon as possible
if (!Monitor.TryEnter(_executionLock))
{
return;
}
try
{
if (_disposed)
{
@ -97,40 +106,40 @@ namespace Microsoft.AspNetCore.Sockets
// Pause the timer while we're running
_timer.Change(Timeout.Infinite, Timeout.Infinite);
try
// Scan the registered connections looking for ones that have timed out
foreach (var c in _connections)
{
// Scan the registered connections looking for ones that have timed out
foreach (var c in _connections)
var status = ConnectionState.ConnectionStatus.Inactive;
var lastSeenUtc = DateTimeOffset.UtcNow;
try
{
var status = ConnectionState.ConnectionStatus.Inactive;
var lastSeenUtc = DateTimeOffset.UtcNow;
c.Value.Lock.Wait();
try
{
c.Value.Lock.Wait();
// Capture the connection state
status = c.Value.Status;
// Capture the connection state
status = c.Value.Status;
lastSeenUtc = c.Value.LastSeenUtc;
}
finally
{
c.Value.Lock.Release();
}
lastSeenUtc = c.Value.LastSeenUtc;
}
finally
{
c.Value.Lock.Release();
}
// Once the decision has been made to to dispose we don't check the status again
if (status == ConnectionState.ConnectionStatus.Inactive && (DateTimeOffset.UtcNow - lastSeenUtc).TotalSeconds > 5)
{
var ignore = DisposeAndRemoveAsync(c.Value);
}
// Once the decision has been made to to dispose we don't check the status again
if (status == ConnectionState.ConnectionStatus.Inactive && (DateTimeOffset.UtcNow - lastSeenUtc).TotalSeconds > 5)
{
var ignore = DisposeAndRemoveAsync(c.Value);
}
}
finally
{
// Resume once we finished processing all connections
_timer.Change(TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(1));
}
}
finally
{
// Resume once we finished processing all connections
_timer.Change(TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(1));
// Exit the lock now
Monitor.Exit(_executionLock);
}
}