Use a BlockingCollection to avoid busy loop in REST API threads

doc/100-General/10-Changelog.md

@@ -19,6 +19,7 @@ Released closed milestones can be found on [GitHub](https://github.com/Icinga/ic
 * [#480](https://github.com/Icinga/icinga-powershell-framework/pull/480) Fixes service locking during Icinga Agent upgrade and ensures errors on service management are caught and printed with internal error handling
 * [#483](https://github.com/Icinga/icinga-powershell-framework/issues/483) Fixes REST-Api SSL certificate lookup from the Icinga Agent, in case a custom hostname was used or in certain domain environments were domain is not matching DNS domain
 * [#490](https://github.com/Icinga/icinga-powershell-framework/pull/490) Fixes the command `Uninstall-IcingaComponent` for the `service` component which is not doing anything
+* [#497](https://github.com/Icinga/icinga-powershell-framework/pull/497) Fixes loop sleep for idle REST-Api threads by replacing them with [BlockingCollection](https://docs.microsoft.com/en-us/dotnet/api/system.collections.concurrent.blockingcollection-1?view=net-6.0) [ConcurrentQueue](https://docs.microsoft.com/en-us/dotnet/api/system.collections.concurrent.concurrentqueue-1?view=net-6.0)
 
 ### Enhancements
 

lib/daemons/RestAPI/daemon/New-IcingaForWindowsRESTApi.psm1

@@ -108,7 +108,7 @@ function New-IcingaForWindowsRESTApi()
                 continue;
             }
 
-            $Global:Icinga.Public.Daemons.RESTApi.ApiRequests.$NextRESTApiThreadId.Enqueue($Connection);
+            $Global:Icinga.Public.Daemons.RESTApi.ApiRequests.$NextRESTApiThreadId.Add($Connection);
         } catch {
             Write-IcingaEventMessage -Namespace 'RESTApi' -EvenId 2050 -ExceptionObject $_;
         }

lib/daemons/RestAPI/daemon/Start-IcingaWindowsRESTApi.psm1

@@ -75,8 +75,9 @@ function Start-IcingaWindowsRESTApi()
 
     while ($ConcurrentThreads -gt 0) {
         $ConcurrentThreads                         = $ConcurrentThreads - 1;
-        [System.Collections.Queue]$RESTThreadQueue = @();
-        $Global:Icinga.Public.Daemons.RESTApi.ApiRequests.Add($ThreadId, [System.Collections.Queue]::Synchronized($RESTThreadQueue));
+        $RESTThreadQueue = New-Object System.Collections.Concurrent.BlockingCollection[PSObject] `
+            -ArgumentList (New-Object System.Collections.Concurrent.ConcurrentQueue[PSObject]);
+        $Global:Icinga.Public.Daemons.RESTApi.ApiRequests.Add($ThreadId, $RESTThreadQueue);
         Start-IcingaForWindowsRESTThread -ThreadId $ThreadId -RequireAuth:$RequireAuth;
         $ThreadId += 1;
 

lib/daemons/RestAPI/threads/New-IcingaForWindowsRESTThread.psm1

@@ -16,17 +16,8 @@ function New-IcingaForWindowsRESTThread()
                 continue;
             }
 
-            if ($Global:Icinga.Public.Daemons.RESTApi.ApiRequests.$ThreadId.Count -eq 0) {
-                Start-Sleep -Milliseconds 10;
-                continue;
-            }
-
-            $Connection = $Global:Icinga.Public.Daemons.RESTApi.ApiRequests.$ThreadId.Dequeue();
-
-            if ($null -eq $Connection) {
-                Start-Sleep -Milliseconds 10;
-                continue;
-            }
+            # block sleeping until content available
+            $Connection = $Global:Icinga.Public.Daemons.RESTApi.ApiRequests.$ThreadId.Take();
 
             # Read the received message from the stream by using our smart functions
             [string]$RestMessage = Read-IcingaTCPStream -Client $Connection.Client -Stream $Connection.Stream;
@@ -107,9 +98,7 @@ function New-IcingaForWindowsRESTThread()
 
         # Finally close the clients connection as we are done here and
         # ensure this thread will close by simply leaving the function
-        if ($null -ne $Connection) {
-            Close-IcingaTCPConnection -Client $Connection.Client;
-        }
+        Close-IcingaTCPConnection -Client $Connection.Client;
 
         # Force Icinga for Windows Garbage Collection
         Optimize-IcingaForWindowsMemory -ClearErrorStack;