;+  
;
; Laboratory for Atmospheric and Space Physics
; University of Colorado, Boulder, Colorado, USA
;
; AUTHOR:
;   Lon Riesberg
;
; DATE:   March 26. 2007
;
; PURPOSE:
;    Keeps track of memory usage and garbage collects if
;    memory waste is 50 MB+.  Expects that calling code
;    is actively managing its resources and memory is 
;    checked after releasing unused resources.  This
;    uses common blocks so it can be quickly added 
;    anywhere but the usefulness of check_memory will
;    quickly deteriorate if multiple procedures are 
;    using it simulataneously.  Use the reset keyword 
;    to allow a new procedure to use check_memory.
; 
; NOTESa;
; 
; USAGE EXAMPLE:
;    check_memory
;-
pro check_memory, reset=reset

   COMMON MEMORY_MONITOR, mem_history
   
   if keyword_set(reset) and (n_elements(mem_history) gt 0) then begin
      mem_history = temporary(mem_history)
      return
   endif

   if n_elements(mem_history) eq 0 then begin
      mem_history = ptr_new()
      if get_debug_level() gt 9 then device, decomposed=0
   endif
   
   curr_mem = memory(/current) / 1E6
   print, 'memory currently in use: ', curr_mem, ' MB'
   
   if ~ptr_valid(mem_history) then begin
      mem_history = ptr_new(curr_mem)
   endif else begin
      *mem_history = [*mem_history, curr_mem]
      
      if get_debug_level() gt 9 then begin
         plot, *mem_history, title='CIPS Processing Memory Use', xtitle='iteration', ytitle='MB', $
                xticks=1, min_value=0
      endif
      n_history = n_elements(*mem_history)
       
      mem_leak = (*mem_history)[n_history-1] - (*mem_history)[0]
      if mem_leak gt 50 then begin
         heap_gc
         print, 'memory released: ', curr_mem-(memory(/current)/1E6), ' MB'
      endif   
   endelse
   return
end