[NTOSKRNL::CC] Implement CcOkToAddWriteBehindThread

NTOSKRNL/CC/cclazywriter.cpp

@@ -13,6 +13,95 @@
 
 extern "C"
 
+/* Move Typedef Later to cctypes.hpp */
+typedef struct _WRITE_BEHIND_THROUGHPUT
+{
+    ULONG PagesYetToWrite;
+    ULONG Throughput;
+} WRITE_BEHIND_THROUGHPUT, *PWRITE_BEHIND_THROUGHPUT;
+
+BOOLEAN
+CcOkToAddWriteBehindThread(VOID)
+{
+    ULONG ActiveExtraWriteBehindThreads = {0};
+    PWRITE_BEHIND_THROUGHPUT ThroughputStats = nullptr;
+    ULONG PagesYetToWrite = {0};
+    ULONG Throughput = {0};
+    ULONG PreviousThroughput = {0};
+    LONG ThroughputTrend = {0};
+    BOOLEAN Result = false;
+
+    ActiveExtraWriteBehindThreads = CcActiveExtraWriteBehindThreads;
+    ThroughputStats = CcThroughputStats;
+    PagesYetToWrite = CcPagesYetToWrite;
+
+    Throughput = ThroughputStats[ActiveExtraWriteBehindThreads].PagesYetToWrite;
+    PreviousThroughput = 0;
+
+    if (Throughput >= PagesYetToWrite)
+    {
+        Throughput -= PagesYetToWrite;
+    }
+    else
+    {
+        Throughput = 0;
+    }
+
+    ThroughputStats[ActiveExtraWriteBehindThreads].PagesYetToWrite = PagesYetToWrite;
+    Result = true;
+
+    if (ActiveExtraWriteBehindThreads > 0)
+    {
+        PreviousThroughput = ThroughputStats[ActiveExtraWriteBehindThreads - 1].Throughput;
+    }
+
+    ThroughputStats[ActiveExtraWriteBehindThreads].Throughput = Throughput;
+
+    if (Throughput > 0)
+    {
+        ThroughputTrend = CcThroughputTrend;
+
+        if (Throughput < PreviousThroughput)
+        {
+            if (ThroughputTrend > 0)
+                ThroughputTrend = 0;
+            ThroughputTrend--;
+        }
+        else
+        {
+            if (ThroughputTrend < 0)
+                ThroughputTrend = 0;
+            ThroughputTrend++;
+        }
+
+        CcThroughputTrend = ThroughputTrend;
+
+        if (ThroughputTrend == 3)
+        {
+            CcThroughputTrend = 0;
+            Result = true;
+
+            if (ActiveExtraWriteBehindThreads < CcMaxExtraWriteBehindThreads)
+            {
+                ThroughputStats[ActiveExtraWriteBehindThreads + 1].Throughput = 0;
+                ThroughputStats[ActiveExtraWriteBehindThreads + 1].PagesYetToWrite = PagesYetToWrite;
+            }
+        }
+        else if (ThroughputTrend == -3)
+        {
+            CcThroughputTrend = 0;
+            Result = true;
+
+            if (ActiveExtraWriteBehindThreads > 0)
+            {
+                ThroughputStats[ActiveExtraWriteBehindThreads - 1].Throughput = 0;
+                ThroughputStats[ActiveExtraWriteBehindThreads - 1].PagesYetToWrite = PagesYetToWrite;
+            }
+        }
+    }
+
+    return Result;
+}
 
 VOID
 NTAPI