Change scheduler list to be queue-like

The scheduler modifies the SchedulerData list mainly in two ways:
 1. Remove a finished item
 2. Append a new item

This optimizes the Append operation by keeping a last element
pointer, so we don't have to walk the whole list to find it. This
way this list is converted to a queue-like structure.

Change-Id: If7214e1f6016414551abbef11f26f332737f7893

1 files changed, 16 insertions, 13 deletions

diff --git a/vcl/source/app/scheduler.cxx b/vcl/source/app/scheduler.cxx
index dc6ff9fab5a9..9b954f4a1c3f 100644
--- a/vcl/source/app/scheduler.cxx
+++ b/vcl/source/app/scheduler.cxx
@@ -107,7 +107,8 @@ void Scheduler::ImplDeInitScheduler()
     }
 
     rSchedCtx.mpFirstSchedulerData = nullptr;
-    rSchedCtx.mnTimerPeriod = 0;
+    rSchedCtx.mpLastSchedulerData  = nullptr;
+    rSchedCtx.mnTimerPeriod        = 0;
 }
 
 /**
@@ -234,6 +235,8 @@ bool Scheduler::ProcessTaskScheduling( bool bIdle )
                 pPrevSchedulerData->mpNext = pSchedulerData->mpNext;
             else
                 rSchedCtx.mpFirstSchedulerData = pSchedulerData->mpNext;
+            if ( !pSchedulerData->mpNext )
+                rSchedCtx.mpLastSchedulerData = pPrevSchedulerData;
             if ( pSchedulerData->mpTask )
                 pSchedulerData->mpTask->mpSchedulerData = nullptr;
             ImplSchedulerData *pDeleteItem = pSchedulerData;
@@ -333,23 +336,23 @@ void Task::Start()
     if ( !mpSchedulerData )
     {
         // insert Task
-        mpSchedulerData                = new ImplSchedulerData;
-        mpSchedulerData->mpTask        = this;
-        mpSchedulerData->mbInScheduler = false;
+        ImplSchedulerData* pSchedulerData = new ImplSchedulerData;
+        pSchedulerData->mpTask            = this;
+        pSchedulerData->mbInScheduler     = false;
+        pSchedulerData->mpNext            = nullptr;
+        mpSchedulerData = pSchedulerData;
 
         // insert last due to SFX!
-        ImplSchedulerData* pPrev = nullptr;
-        ImplSchedulerData* pData = rSchedCtx.mpFirstSchedulerData;
-        while ( pData )
+        if ( !rSchedCtx.mpLastSchedulerData )
         {
-            pPrev = pData;
-            pData = pData->mpNext;
+            rSchedCtx.mpFirstSchedulerData = pSchedulerData;
+            rSchedCtx.mpLastSchedulerData = pSchedulerData;
         }
-        mpSchedulerData->mpNext = nullptr;
-        if ( pPrev )
-            pPrev->mpNext = mpSchedulerData;
         else
-            rSchedCtx.mpFirstSchedulerData = mpSchedulerData;
+        {
+            rSchedCtx.mpLastSchedulerData->mpNext = pSchedulerData;
+            rSchedCtx.mpLastSchedulerData = pSchedulerData;
+        }
         SAL_INFO( "vcl.schedule", tools::Time::GetSystemTicks()
                   << " " << mpSchedulerData << "  added      " << *this );
     }