c# - Detect PowerModeChange and wait for execution -

i want run save routines when computer suspends. therefore use onpowerchange-event detect when suspends , resumes. unfortunately me save routine needs 3-5 seconds execute.

when receive suspend event computer shuts down within 1-2 seconds , routine isn't executed completely.

how can prevent suspend until routine finished?

systemevents.powermodechanged += onpowerchange;   private void onpowerchange(object s, powermodechangedeventargs e) {      switch (e.mode)     {         case powermodes.resume:             switchedifier(true);             break;         case powermodes.suspend:             switchedifier(false);             break;     } } 

there unmanaged apis can this, shutdownblockreasoncreate , shutdownblockreasondestroy.

its important note these 2 functions must paired, when call one, have make sure call other 1 (for example, in event of exception), otherwise shutdown may blocked indefinitely.

this cause dialog show telling user programs blocking shutdown, , reason it. important work done , out, because user has option of hitting "force shutdown" button, use.

here example using it:

[dllimport("user32.dll", setlasterror=true)] static extern bool shutdownblockreasoncreate(intptr hwnd, [marshalas(unmanagedtype.lpwstr)] string reason);  [dllimport("user32.dll", setlasterror=true)] static extern bool shutdownblockreasondestroy(intptr hwnd);  //the following needs go in form class, requires valid window handle public void blockshutdownandsave() {     //if calling event, may need invoke on main form     //because calling thread not owner of handle     //will cause "access denied" error.      try     {         shutdownblockreasoncreate(this.handle, "you need patient.");         //do saving here.     }         {         shutdownblockreasondestroy(this.handle);     } } 

short strings reason encouraged user typically won't read long messages. grabs attention, "saving data" or "flushing changes disk". mindful of "do anyway i'm impatient user" button.