Custom Memprof Tracer and a Controller/View pair to browse traces

custom_tracer.rb

require 'memprof/tracer'

class CustomTracer
  def initialize(app, opts = {})
    @app = app
    @options = opts
    @options[:except] = %r{^/(?:memprof|admin)\b}
  end

  def call(env)
    if memprof_request?(env)
      ret = trace(env)
      GC.start if @options[:force_gc]
      ret
    else
      @app.call(env)
    end
  end

private

  def memprof_request?(env)
    env['REQUEST_URI'] !~ @options[:except]
  end

  def trace(env)
    ::Memprof.trace_filename ||= @options[:tracer_file] || "/tmp/memprof_tracer-#{Process.pid}.json"
    ::Memprof.trace_request(env) { @app.call(env) }
  end

end

index.html.haml

!!! 5
%html
  %head
    %meta(charset="utf-8")
    %title Memprof Traces

    = javascript_include_tag "http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js"

    = stylesheet_link_tag "http://jquery.bassistance.de/treeview/demo/screen.css"
    = stylesheet_link_tag "http://jquery.bassistance.de/treeview/jquery.treeview.css"
    = javascript_include_tag "http://jquery.bassistance.de/treeview/jquery.treeview.js"
    :javascript
      $(function() {
        $('#traces > ul').treeview({ collapsed: true });
        $('#diff-traces > ul').treeview({ collapsed: true });

        $('input.filter').change(function(e) {
          var traces = $(this).next().find('> li');
          var expr = $(this).val().split(/\s*,\s*/);
          traces.each(function() {
            var trace = $(this), match = true;
            $.each(expr, function(i, ex) {
              var m;
              if (m = ex.match(/(.*)\s*(?:<|<=|==|>=|>)\s*(?:[\d\.]+)/)) {
                var selector = m[1].split(".").map(function(v,i) { return ".key:iseq("+v+")"; }).join(" + ul "), key;
                if ((key = $(selector, trace).first()).length == 0) {
                  return match = false;
                }
                var value = key.next();
                if (!value.is('span') || !eval(ex.replace(m[1], value.text()))) {
                  return match = false;
                }
              } else {
                var re = new RegExp(ex.trim());
                if (!re.test(trace.find('.key:first').text())) {
                  return match = false;
                }
              }
            });
            match ? trace.show() : trace.hide();
          });
        });
      });

      $.expr[":"].iseq = function(obj, index, meta, stack) {
        return (obj.textContent || obj.innerText || $(obj).text() || "").toLowerCase().trim() == meta[3].toLowerCase();
      }

    :css
      #traces h3, #diff-traces h3 {
        margin-bottom: 0.5em;
      }
      #traces {
        float: left;
        width: 50%;
      }
      #diff-traces {
        float: right;
        width: 49%;
        border-left: 1px solid #ccc;
        padding-left: 0.9%;
      }
      .key { font-weight: bold; }

  %body
    .container
      #content
        #traces
          - unless @pid == Process.pid.to_s
            = link_to "current process", url_for(:pid => nil, :diff_with => params[:diff_with]), :style => "float: right; margin-right: 1em"
          %h3== Traces for process ##{@pid}
          - if @traces.present?
            %input.filter
            %ul
              - @traces.each do |trace|
                %li
                  %span.key= trace['request']['PATH_INFO']
                  %span== (#{trace['time']}s)
                  = hash_to_tree(trace)
          - else
            %p No traces yet.
        - if @diff_pid
          #diff-traces
            = link_to "go back", url_for(:diff_with => nil, :pid => params[:pid]), :style => "float: right; margin-right: 1em"
            %h3== Traces for process ##{@diff_pid}
            - if @diff_with.is_a?(String)
              %p= @diff_with
            - elsif @diff_with.present?
              %input.filter
              %ul
                - @diff_with.each do |trace|
                  %li
                    %span.key= trace['request']['PATH_INFO']
                    %span== (#{trace['time']}s)
                    = hash_to_tree(trace)
            - else
              %p No traces for this process.
        - elsif @old_traces.present?
          #diff-traces
            %h3 Compare with...
            %ul
              - @old_traces.each do |pid, mtime|
                %li
                  %span.key= link_to "##{pid}", url_for(:diff_with => pid, :pid => params[:pid])
                  %span== (#{time_ago_in_words(mtime)} old)

      %footer
        Copyright &copy; 2010, Secret Sauce Partners, Inc.

memprof_traces_controller.rb

class MemprofTracesController < ActionController::Base

  def index
    @pid = params[:pid] || Process.pid.to_s
    traces_file = "/tmp/memprof_tracer-#{@pid}.json"
    if File.exists?(traces_file)
      @traces = File.readlines(traces_file)
      @traces.map! {|json| JSON.parse(json)}
    end
    if @diff_pid = params[:diff_with]
      diff_file = "/tmp/memprof_tracer-#{@diff_pid}.json"
      @diff_with =
        if File.exists?(diff_file)
          File.readlines(diff_file).map! {|json| JSON.parse(json)}
        else
          "Diff file #{diff_file} doesn't exist"
        end
    end
    @old_traces =
      Dir["/tmp/memprof_tracer-*.json"].
        map     { |f| [f[/-(\d+)\.json$/, 1], File.mtime(f)] }.
        sort_by { |_,m| -m.to_i }.
        reject  { |f,_| f.blank? or f == @pid }
  end

end

memprof_traces_helper.rb

module MemprofTracesHelper

  def hash_to_tree(hash)
    case hash
    when Hash
      items = hash.map do |key, value|
        item = content_tag(:span, key, :class => "key") + ": " + hash_to_tree(value)
        content_tag(:li, item)
      end
      content_tag(:ul, items.join.html_safe)
    else
      content_tag(:span, hash.inspect)
    end.html_safe
  end

end