Class: CallTracker

Inherits:
Object show all
Defined in:
lib/drumherum/call_tracker.rb

Overview

oreilly.com/catalog/9780596523695/ Ruby Cookbook, by Lucas Carlson and Leonard Richardson Copyright 2006 O’Reilly Media

Instance Method Summary collapse

Constructor Details

#initialize(show_stack_depth = 1) ⇒ CallTracker

Initialize and start the trace.



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# File 'lib/drumherum/call_tracker.rb', line 11

def initialize(show_stack_depth=1)
  @show_stack_depth = show_stack_depth
  @to_trace = Hash.new { |h,k| h[k] = {} }
  start
  at_exit { stop }
end

Instance Method Details

#register(klass, method_symbol) ⇒ Object

Register a class/method combination as being interesting. Subsequent calls to the method will be tallied by tally_calls.



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# File 'lib/drumherum/call_tracker.rb', line 20

def register(klass, method_symbol)  
  @to_trace[klass][method_symbol] = {}
end

#report(out = $stderr) ⇒ Object

Prints a report of the lines of code that called interesting methods, sorted so that the the most active lines of code show up first.



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# File 'lib/drumherum/call_tracker.rb', line 52

def report(out=$stderr)
  first = true
  @to_trace.each do |klass, symbols|
    symbols.each do |symbol, calls| 
      total = calls.inject(0) { |sum, ct| sum + ct[1] }        
      padding = total.to_s.size
      separator = (klass.is_a? Class) ? '#' : '.'
      plural = (total == 1) ? '' : 's'
      stack_join = "\n" + (' ' * (padding+2))
      first ? first = false : out.puts
      out.puts "#{total} call#{plural} to #{klass}#{separator}#{symbol}"
      (calls.sort_by { |caller, times| -times }).each do |caller, times|
        out.puts " %#{padding}.d #{caller.join(stack_join)}" % times
      end       
    end
  end
end

#start ⇒ Object

Tells the Ruby interpreter to call tally_calls whenever it’s about to do anything interesting.



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# File 'lib/drumherum/call_tracker.rb', line 26

def start
  set_trace_func method(:tally_calls).to_proc
end

#stop(out = $stderr) ⇒ Object

Stops the profiler, and prints a report of the interesting calls made while it was running.



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# File 'lib/drumherum/call_tracker.rb', line 32

def stop(out=$stderr)
  set_trace_func nil
  report(out)
end

#tally_calls(event, file, line, symbol, binding, klass) ⇒ Object

If the interpreter is about to call a method we find interesting, increment the count for that method.



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# File 'lib/drumherum/call_tracker.rb', line 39

def tally_calls(event, file, line, symbol, binding, klass)
  if @to_trace[klass] and @to_trace[klass][symbol] and 
  (event == 'call' or event =='c-call')
    stack = caller
    stack = stack[1..(@show_stack_depth ? @show_stack_depth : stack.size)]
    @to_trace[klass][symbol][stack] ||= 0
    @to_trace[klass][symbol][stack] += 1
  end    
end