1 files changed, 59 insertions, 0 deletions
diff --git a/zen/process_priority.h b/zen/process_priority.h
new file mode 100644
index 00000000..15266b28
--- /dev/null
+++ b/zen/process_priority.h
@@ -0,0 +1,59 @@
+#ifndef PREVENTSTANDBY_H_INCLUDED
+#define PREVENTSTANDBY_H_INCLUDED
+
+#ifdef FFS_WIN
+#include "win.h" //includes "windows.h"
+
+#elif defined FFS_LINUX
+#endif
+
+namespace zen
+{
+struct PreventStandby //signal a "busy" state to the operating system
+{
+#ifdef FFS_WIN
+    PreventStandby() { ::SetThreadExecutionState(ES_CONTINUOUS | ES_SYSTEM_REQUIRED /* | ES_AWAYMODE_REQUIRED*/ ); }
+    ~PreventStandby() { ::SetThreadExecutionState(ES_CONTINUOUS); }
+#endif
+};
+
+
+struct ScheduleForBackgroundProcessing //lower CPU and file I/O priorities
+{
+#ifdef FFS_WIN
+#ifndef PROCESS_MODE_BACKGROUND_BEGIN
+#define PROCESS_MODE_BACKGROUND_BEGIN     0x00100000 // Windows Server 2003 and Windows XP/2000:  This value is not supported!
+#define PROCESS_MODE_BACKGROUND_END       0x00200000 //
+#endif
+
+    ScheduleForBackgroundProcessing() { ::SetPriorityClass(::GetCurrentProcess(), PROCESS_MODE_BACKGROUND_BEGIN); } //this call lowers CPU priority, too!!
+    ~ScheduleForBackgroundProcessing() { ::SetPriorityClass(::GetCurrentProcess(), PROCESS_MODE_BACKGROUND_END); }
+
+#elif defined FFS_LINUX
+    /*
+    CPU prio:
+    int getpriority(PRIO_PROCESS, 0); - errno caveat!
+    int ::setpriority(PRIO_PROCESS, 0, int prio); //a zero value for "who" denotes the calling process
+
+    priority can be decreased, but NOT increased :(
+
+    file I/O prio:
+        ScheduleForBackgroundProcessing() : oldIoPrio(::ioprio_get(IOPRIO_WHO_PROCESS, ::getpid()))
+        {
+            if (oldIoPrio != -1)
+                ::ioprio_set(IOPRIO_WHO_PROCESS, ::getpid(), IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
+        }
+        ~ScheduleForBackgroundProcessing()
+        {
+            if (oldIoPrio != -1)
+                ::ioprio_set(IOPRIO_WHO_PROCESS, ::getpid(), oldIoPrio);
+          }
+
+    private:
+            const int oldIoPrio;
+    */
+#endif
+};
+}
+
+#endif // PREVENTSTANDBY_H_INCLUDED