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  24 
  25 #ifndef SHARE_VM_UTILITIES_INTHISTO_HPP
  26 #define SHARE_VM_UTILITIES_INTHISTO_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "utilities/growableArray.hpp"
  30 
  31 // This class implements a simple histogram.
  32 
  33 // A histogram summarizes a series of "measurements", each of which is
  34 // assumed (required in this implementation) to have an outcome that is a
  35 // non-negative integer.  The histogram efficiently maps measurement outcomes
  36 // to the number of measurements had that outcome.
  37 
  38 // To print the results, invoke print() on your Histogram*.
  39 
  40 // Note: there is already an existing "Histogram" class, in file
  41 // histogram.{hpp,cpp}, but to my mind that's not a histogram, it's a table
  42 // mapping strings to counts.  To be a histogram (IMHO) it needs to map
  43 // numbers (in fact, integers) to number of occurrences of that number.
  44 
  45 // ysr: (i am not sure i agree with the above note.) i suspect we want to have a
  46 // histogram template that will map an arbitrary type (with a defined order
  47 // relation) to a count.
  48 
  49 
  50 class IntHistogram : public CHeapObj {
  51  protected:
  52   int _max;
  53   int _tot;
  54   GrowableArray<int>* _elements;
  55 
  56 public:
  57   // Create a new, empty table.  "est" is an estimate of the maximum outcome
  58   // that will be added, and "max" is an outcome such that all outcomes at
  59   // least that large will be bundled with it.
  60   IntHistogram(int est, int max);
  61   // Add a measurement with the given outcome to the sequence.
  62   void add_entry(int outcome);
  63   // Return the number of entries recorded so far with the given outcome.
  64   int  entries_for_outcome(int outcome);
  65   // Return the total number of entries recorded so far.
  66   int  total_entries() { return _tot; }
  67   // Return the number of entries recorded so far with the given outcome as
  68   // a fraction of the total number recorded so far.
  69   double fraction_for_outcome(int outcome) {
  70     return
  71       (double)entries_for_outcome(outcome)/
  72       (double)total_entries();
  73   }
  74   // Print the histogram on the given output stream.
  75   void print_on(outputStream* st) const;
  76 };
  77 
  78 #endif // SHARE_VM_UTILITIES_INTHISTO_HPP