Add library API for pure Ruby tracer

README.md

@@ -22,7 +22,8 @@ gem install codetracer_pure_ruby_recorder
 After installing, load the tracer:
 
 ```ruby
-require 'codetracer_ruby_recorder'
+require 'codetracer_ruby_recorder' # native implementation
+# require 'codetracer_pure_ruby_recorder' # pure Ruby implementation
 
 recorder = RubyRecorder.new
 recorder.enable_tracing

examples/selective_tracing_pure.rb

@@ -0,0 +1,18 @@
+#!/usr/bin/env ruby
+
+# Load the pure Ruby tracer library if RubyRecorder is not already defined
+unless defined?(RubyRecorder)
+  lib_base = File.expand_path('../gems/pure-ruby-tracer/lib/codetracer_pure_ruby_recorder', __dir__)
+  require lib_base
+end
+
+recorder = RubyRecorder.new
+
+puts 'start trace'
+recorder.disable_tracing
+puts 'this will not be traced'
+recorder.enable_tracing
+puts 'this will be traced'
+recorder.disable_tracing
+puts 'tracing disabled'
+recorder.flush_trace(Dir.pwd)

gems/pure-ruby-tracer/lib/codetracer_pure_ruby_recorder.rb

@@ -0,0 +1,43 @@
+require_relative 'trace'
+
+# Ruby implementation of the RubyRecorder API used by the native tracer.
+# Provides basic tracing controls and serialization using the pure Ruby tracer.
+class RubyRecorder
+  def initialize(debug: ENV['CODETRACER_RUBY_RECORDER_DEBUG'] == '1')
+    @record = $codetracer_record
+    @tracer = Tracer.new(@record, debug: debug)
+    setup_defaults
+  end
+
+  # Enable tracing of Ruby code execution.
+  def enable_tracing
+    @tracer.activate
+  end
+
+  # Disable tracing without discarding collected data.
+  def disable_tracing
+    @tracer.deactivate
+  end
+
+  # Serialize the trace to +out_dir+.
+  def flush_trace(out_dir)
+    @tracer.stop_tracing
+    @record.serialize('', out_dir)
+  end
+
+  # Record a custom event at +path+ and +line+ with +content+.
+  def record_event(path, line, content)
+    @tracer.record_event(["#{path}:#{line}"], content)
+  end
+
+  private
+
+  def setup_defaults
+    @record.register_call('', 1, '<top-level>', [])
+    @tracer.ignore('lib/ruby')
+    @tracer.ignore('trace.rb')
+    @tracer.ignore('recorder.rb')
+    @tracer.ignore('<internal:')
+    @tracer.ignore('gems/')
+  end
+end

gems/pure-ruby-tracer/lib/trace.rb

@@ -18,39 +18,44 @@
 # however this seems as a risky solution, as it clears global gem state!
 # BE CAREFUL if you have other ruby projects/data there!
 
-# override some of the IO methods to record them for event log
-module Kernel
-  alias :old_p :p
-  alias :old_puts :puts
-  alias :old_print :print
-
-  def p(*args)
-    if $tracer.tracing
-      $tracer.deactivate
-      $tracer.record_event(caller, args.join("\n"))
-      $tracer.activate
-    end
-    old_p(*args)
-  end
+# instrumentation helpers for recording IO calls
+module CodetracerKernelPatches
+  def self.install(tracer)
+    Kernel.module_eval do
+      unless method_defined?(:old_p)
+        alias :old_p :p
+        alias :old_puts :puts
+        alias :old_print :print
+      end
 
-  def puts(*args)
-    if $tracer.tracing
-      $tracer.deactivate
-      $tracer.record_event(caller, args.join("\n"))
-      $tracer.activate
-    end
-    old_puts(*args)
-  end
+      define_method(:p) do |*args|
+        if tracer.tracing
+          tracer.deactivate
+          tracer.record_event(caller, args.join("\n"))
+          tracer.activate
+        end
+        old_p(*args)
+      end
 
-  def print(*args)
-    if $tracer.tracing
-      $tracer.deactivate
-      $tracer.record_event(caller, args.join("\n"))
-      $tracer.activate
+      define_method(:puts) do |*args|
+        if tracer.tracing
+          tracer.deactivate
+          tracer.record_event(caller, args.join("\n"))
+          tracer.activate
+        end
+        old_puts(*args)
+      end
+
+      define_method(:print) do |*args|
+        if tracer.tracing
+          tracer.deactivate
+          tracer.record_event(caller, args.join("\n"))
+          tracer.activate
+        end
+        old_print(*args)
+      end
     end
-    old_print(*args)
   end
-
 end
 
 # class IO
@@ -252,6 +257,7 @@ def load_variables(binding)
 
 if __FILE__ == $PROGRAM_NAME
   $tracer = Tracer.new($codetracer_record, debug: ENV['CODETRACER_RUBY_RECORDER_DEBUG'] == '1')
+  CodetracerKernelPatches.install($tracer)
 
   options = {}
   parser = OptionParser.new do |opts|