Added breakpoints to stand-alone Active Record, so we can use them in tests for AR

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@218 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/support/binding_of_caller.rb

@@ -0,0 +1,81 @@
+begin
+  require 'simplecc'
+rescue LoadError
+  def Continuation.create(*args, &block)
+    cc = nil; result = callcc {|c| cc = c; block.call(cc) if block and args.empty?}
+    result ||= args
+    return *[cc, *result]
+  end
+end
+
+# This method returns the binding of the method that called your
+# method. It will raise an Exception when you're not inside a method.
+#
+# It's used like this:
+#   def inc_counter(amount = 1)
+#     Binding.of_caller do |binding|
+#       # Create a lambda that will increase the variable 'counter'
+#       # in the caller of this method when called.
+#       inc = eval("lambda { |arg| counter += arg }", binding)
+#       # We can refer to amount from inside this block safely.
+#       inc.call(amount)
+#     end
+#     # No other statements can go here. Put them inside the block.
+#   end
+#   counter = 0
+#   2.times { inc_counter }
+#   counter # => 2
+#
+# Binding.of_caller must be the last statement in the method.
+# This means that you will have to put everything you want to
+# do after the call to Binding.of_caller into the block of it.
+# This should be no problem however, because Ruby has closures.
+# If you don't do this an Exception will be raised. Because of
+# the way that Binding.of_caller is implemented it has to be
+# done this way.
+def Binding.of_caller(&block)
+  old_critical = Thread.critical
+  Thread.critical = true
+  count = 0
+  cc, result, error, extra_data = Continuation.create(nil, nil)
+  error.call if error
+
+  tracer = lambda do |*args|
+    type, context, extra_data = args[0], args[4], args
+    if type == "return"
+      count += 1
+      # First this method and then calling one will return --
+      # the trace event of the second event gets the context
+      # of the method which called the method that called this
+      # method.
+      if count == 2
+        # It would be nice if we could restore the trace_func
+        # that was set before we swapped in our own one, but
+        # this is impossible without overloading set_trace_func
+        # in current Ruby.
+        set_trace_func(nil)
+        cc.call(eval("binding", context), nil, extra_data)
+      end
+    elsif type == "line" then
+      nil
+    elsif type == "c-return" and extra_data[3] == :set_trace_func then
+      nil
+    else
+      set_trace_func(nil)
+      error_msg = "Binding.of_caller used in non-method context or " +
+        "trailing statements of method using it aren't in the block."
+      cc.call(nil, lambda { raise(ArgumentError, error_msg) }, nil)
+    end
+  end
+
+  unless result
+    set_trace_func(tracer)
+    return nil
+  else
+    Thread.critical = old_critical
+    case block.arity
+      when 1 then yield(result)
+      else yield(result, extra_data)        
+    end
+  end
+end

activerecord/lib/active_record/support/breakpoint.rb

@@ -0,0 +1,525 @@
+# The Breakpoint library provides the convenience of
+# being able to inspect and modify state, diagnose
+# bugs all via IRB by simply setting breakpoints in
+# your applications by the call of a method.
+#
+# This library was written and is supported by me,
+# Florian Gross. I can be reached at flgr@ccan.de
+# and enjoy getting feedback about my libraries.
+#
+# The whole library (including breakpoint_client.rb
+# and binding_of_caller.rb) is licensed under the
+# same license that Ruby uses. (Which is currently
+# either the GNU General Public License or a custom
+# one that allows for commercial usage.) If you for
+# some good reason need to use this under another
+# license please contact me.
+
+require 'irb'
+# require 'binding_of_caller' <- Needs this
+require 'drb'
+require 'drb/acl'
+
+module Breakpoint
+  extend self
+
+  # This will pop up an interactive ruby session at a
+  # pre-defined break point in a Ruby application. In
+  # this session you can examine the environment of
+  # the break point.
+  #
+  # You can get a list of variables in the context using
+  # local_variables via +local_variables+. You can then
+  # examine their values by typing their names.
+  #
+  # You can have a look at the call stack via +caller+.
+  #
+  # The source code around the location where the breakpoint
+  # was executed can be examined via +source_lines+. Its
+  # argument specifies how much lines of context to display.
+  # The default amount of context is 5 lines. Note that
+  # the call to +source_lines+ can raise an exception when
+  # it isn't able to read in the source code.
+  #
+  # breakpoints can also return a value. They will execute
+  # a supplied block for getting a default return value.
+  # A custom value can be returned from the session by doing
+  # +throw(:debug_return, value)+.
+  #
+  # You can also give names to break points which will be
+  # used in the message that is displayed upon execution 
+  # of them.
+  #
+  # Here's a sample of how breakpoints should be placed:
+  #
+  #   class Person
+  #     def initialize(name, age)
+  #       @name, @age = name, age
+  #       breakpoint("Person#initialize")
+  #     end
+  #
+  #     attr_reader :age
+  #     def name
+  #       breakpoint("Person#name") { @name }
+  #     end
+  #   end
+  #
+  #   person = Person.new("Random Person", 23)
+  #   puts "Name: #{person.name}"
+  #
+  # And here is a sample debug session:
+  #
+  #   Executing break point "Person#initialize" at file.rb:4 in `initialize'
+  #   irb(#<Person:0x292fbe8>):001:0> local_variables
+  #   => ["name", "age", "_", "__"]
+  #   irb(#<Person:0x292fbe8>):002:0> [name, age]
+  #   => ["Random Person", 23]
+  #   irb(#<Person:0x292fbe8>):003:0> [@name, @age]
+  #   => ["Random Person", 23]
+  #   irb(#<Person:0x292fbe8>):004:0> self
+  #   => #<Person:0x292fbe8 @age=23, @name="Random Person">
+  #   irb(#<Person:0x292fbe8>):005:0> @age += 1; self
+  #   => #<Person:0x292fbe8 @age=24, @name="Random Person">
+  #   irb(#<Person:0x292fbe8>):006:0> exit
+  #   Executing break point "Person#name" at file.rb:9 in `name'
+  #   irb(#<Person:0x292fbe8>):001:0> throw(:debug_return, "Overriden name")
+  #   Name: Overriden name
+  #
+  # Breakpoint sessions will automatically have a few
+  # convenience methods available. See Breakpoint::CommandBundle
+  # for a list of them.
+  #
+  # Breakpoints can also be used remotely over sockets.
+  # This is implemented by running part of the IRB session
+  # in the application and part of it in a special client.
+  # You have to call Breakpoint.activate_drb to enable
+  # support for remote breakpoints and then run
+  # breakpoint_client.rb which is distributed with this
+  # library. See the documentation of Breakpoint.activate_drb
+  # for details.
+  def breakpoint(id = nil, context = nil, &block)
+    callstack = caller
+    callstack.slice!(0, 3) if callstack.first["breakpoint"]
+    file, line, method = *callstack.first.match(/^(.+?):(\d+)(?::in `(.*?)')?/).captures
+
+    message = "Executing break point " + (id ? "#{id.inspect} " : "") +
+              "at #{file}:#{line}" + (method ? " in `#{method}'" : "")
+
+    if context then
+      return handle_breakpoint(context, message, file, line, &block)
+    end
+
+    Binding.of_caller do |binding_context|
+      handle_breakpoint(binding_context, message, file, line, &block)
+    end
+  end
+
+  module CommandBundle #:nodoc:
+    # Proxy to a Breakpoint client. Lets you directly execute code
+    # in the context of the client.
+    class Client#:nodoc:
+      def initialize(eval_handler) # :nodoc:
+        @eval_handler = eval_handler
+      end
+
+      instance_methods.each do |method|
+        next if method[/^__.+__$/]
+        undef_method method
+      end
+
+      # Executes the specified code at the client.
+      def eval(code)
+        @eval_handler.call(code)
+      end
+
+      # Will execute the specified statement at the client.
+      def method_missing(method, *args)
+        if args.empty?
+          result = eval("#{method}")
+        else
+          result = eval("#{method}(*Marshal.load(#{Marshal.dump(args).inspect}))")
+        end
+
+        unless [true, false, nil].include?(result)
+          result.extend(DRbUndumped) if result
+        end
+
+        return result
+      end
+    end
+
+    # Returns the source code surrounding the location where the
+    # breakpoint was issued.
+    def source_lines(context = 5, return_line_numbers = false)
+      lines = File.readlines(@__bp_file).map { |line| line.chomp }
+
+      break_line = @__bp_line
+      start_line = [break_line - context, 1].max
+      end_line = break_line + context
+
+      result = lines[(start_line - 1) .. (end_line - 1)]
+
+      if return_line_numbers then
+        return [start_line, break_line, result]
+      else
+        return result
+      end
+    end
+
+    # Lets an object that will forward method calls to the breakpoint
+    # client. This is useful for outputting longer things at the client
+    # and so on. You can for example do these things:
+    #
+    #   client.puts "Hello" # outputs "Hello" at client console
+    #   # outputs "Hello" into the file temp.txt at the client
+    #   client.File.open("temp.txt", "w") { |f| f.puts "Hello" } 
+    def client()
+      if Breakpoint.use_drb? then
+        Client.new(Breakpoint.drb_service.eval_handler)
+      else
+        Client.new(lambda { |code| eval(code, TOPLEVEL_BINDING) })
+      end
+    end
+  end
+
+  def handle_breakpoint(context, message, file = "", line = "", &block) # :nodoc:
+    catch(:debug_return) do |value|
+      eval(%{
+        @__bp_file = #{file.inspect}
+        @__bp_line = #{line}
+        extend Breakpoint::CommandBundle
+        extend DRbUndumped if self
+      }, context) rescue nil
+
+      if not use_drb? then
+        puts message
+        IRB.start(nil, IRB::WorkSpace.new(context))
+      else
+        @drb_service.add_breakpoint(context, message)
+      end
+
+      block.call if block
+    end
+  end
+
+  # These exceptions will be raised on failed asserts
+  # if Breakpoint.asserts_cause_exceptions is set to
+  # true.
+  class FailedAssertError < RuntimeError#:nodoc:
+  end
+
+  # This asserts that the block evaluates to true.
+  # If it doesn't evaluate to true a breakpoint will
+  # automatically be created at that execution point.
+  #
+  # You can disable assert checking in production
+  # code by setting Breakpoint.optimize_asserts to
+  # true. (It will still be enabled when Ruby is run
+  # via the -d argument.)
+  #
+  # Example:
+  #   person_name = "Foobar"
+  #   assert { not person_name.nil? }
+  #
+  # Note: If you want to use this method from an
+  # unit test, you will have to call it by its full
+  # name, Breakpoint.assert.
+  def assert(context = nil, &condition)
+    return if Breakpoint.optimize_asserts and not $DEBUG
+    return if yield
+
+    callstack = caller
+    callstack.slice!(0, 3) if callstack.first["assert"]
+    file, line, method = *callstack.first.match(/^(.+?):(\d+)(?::in `(.*?)')?/).captures
+
+    message = "Assert failed at #{file}:#{line}#{" in `#{method}'" if method}."
+
+    if Breakpoint.asserts_cause_exceptions and not $DEBUG then
+      raise(Breakpoint::FailedAssertError, message)
+    end
+
+    message += " Executing implicit breakpoint."
+
+    if context then
+      return handle_breakpoint(context, message, file, line)
+    end
+
+    Binding.of_caller do |context|
+      handle_breakpoint(context, message, file, line)
+    end
+  end
+
+  # Whether asserts should be ignored if not in debug mode.
+  # Debug mode can be enabled by running ruby with the -d
+  # switch or by setting $DEBUG to true.
+  attr_accessor :optimize_asserts
+  self.optimize_asserts = false
+
+  # Whether an Exception should be raised on failed asserts
+  # in non-$DEBUG code or not. By default this is disabled.
+  attr_accessor :asserts_cause_exceptions
+  self.asserts_cause_exceptions = false
+  @use_drb = false
+
+  attr_reader :drb_service # :nodoc:
+
+  class DRbService # :nodoc:
+    include DRbUndumped
+
+    def initialize
+      @handler = @eval_handler = @collision_handler = nil
+
+      IRB.instance_eval { @CONF[:RC] = true }
+      IRB.run_config
+    end
+
+    def collision
+      sleep(0.5) until @collision_handler
+
+      @collision_handler.call
+    end
+
+    def ping; end
+
+    def add_breakpoint(context, message)
+      workspace = IRB::WorkSpace.new(context)
+      workspace.extend(DRbUndumped)
+
+      sleep(0.5) until @handler
+
+      @handler.call(workspace, message)
+    end
+
+    def register_handler(&block)
+      @handler = block
+    end
+
+    def unregister_handler
+      @handler = nil
+    end
+
+    attr_reader :eval_handler
+
+    def register_eval_handler(&block)
+      @eval_handler = block
+    end
+
+    def unregister_eval_handler
+      @eval_handler = lambda { }
+    end
+
+    def register_collision_handler(&block)
+      @collision_handler = block
+    end
+
+    def unregister_collision_handler
+      @collision_handler = lambda { }
+    end
+  end
+
+  # Will run Breakpoint in DRb mode. This will spawn a server
+  # that can be attached to via the breakpoint-client command
+  # whenever a breakpoint is executed. This is useful when you
+  # are debugging CGI applications or other applications where
+  # you can't access debug sessions via the standard input and
+  # output of your application.
+  #
+  # You can specify an URI where the DRb server will run at.
+  # This way you can specify the port the server runs on. The
+  # default URI is druby://localhost:42531.
+  #
+  # Please note that breakpoints will be skipped silently in
+  # case the DRb server can not spawned. (This can happen if
+  # the port is already used by another instance of your
+  # application on CGI or another application.)
+  #
+  # Also note that by default this will only allow access
+  # from localhost. You can however specify a list of
+  # allowed hosts or nil (to allow access from everywhere).
+  # But that will still not protect you from somebody
+  # reading the data as it goes through the net.
+  #
+  # A good approach for getting security and remote access
+  # is setting up an SSH tunnel between the DRb service
+  # and the client. This is usually done like this:
+  #
+  # $ ssh -L20000:127.0.0.1:20000 -R10000:127.0.0.1:10000 example.com
+  # (This will connect port 20000 at the client side to port
+  # 20000 at the server side, and port 10000 at the server
+  # side to port 10000 at the client side.)
+  #
+  # After that do this on the server side: (the code being debugged)
+  # Breakpoint.activate_drb("druby://127.0.0.1:20000", "localhost")
+  #
+  # And at the client side:
+  # ruby breakpoint_client.rb -c druby://127.0.0.1:10000 -s druby://127.0.0.1:20000
+  #
+  # Running through such a SSH proxy will also let you use 
+  # breakpoint.rb in case you are behind a firewall.
+  #
+  # Detailed information about running DRb through firewalls is
+  # available at http://www.rubygarden.org/ruby?DrbTutorial
+  def activate_drb(uri = nil, allowed_hosts = ['localhost', '127.0.0.1', '::1'], ignore_collisions = false) #:nodoc:
+
+    return false if @use_drb
+
+    uri ||= 'druby://localhost:42531'
+
+    if allowed_hosts then
+      acl = ["deny", "all"]
+
+      Array(allowed_hosts).each do |host|
+        acl += ["allow", host]
+      end
+
+      DRb.install_acl(ACL.new(acl))
+    end
+
+    @use_drb = true
+    @drb_service = DRbService.new
+    did_collision = false
+    begin
+      @service = DRb.start_service(uri, @drb_service)
+    rescue Errno::EADDRINUSE
+      if ignore_collisions then
+        nil
+      else
+        # The port is already occupied by another
+        # Breakpoint service. We will try to tell
+        # the old service that we want its port.
+        # It will then forward that request to the
+        # user and retry.
+        unless did_collision then
+          DRbObject.new(nil, uri).collision
+          did_collision = true
+        end
+        sleep(10)
+        retry
+      end
+    end
+
+    return true
+  end
+
+  # Deactivates a running Breakpoint service.
+  def deactivate_drb #:nodoc:
+    @service.stop_service unless @service.nil?
+    @service = nil
+    @use_drb = false
+    @drb_service = nil
+  end
+
+  # Returns true when Breakpoints are used over DRb.
+  # Breakpoint.activate_drb causes this to be true.
+  def use_drb? #:nodoc:
+    @use_drb == true
+  end
+end
+
+module IRB # :nodoc:
+  class << self; remove_method :start; end
+  def self.start(ap_path = nil, main_context = nil, workspace = nil)
+    $0 = File::basename(ap_path, ".rb") if ap_path
+
+    # suppress some warnings about redefined constants
+    old_verbose, $VERBOSE = $VERBOSE, nil
+    IRB.setup(ap_path)
+    $VERBOSE = old_verbose
+
+    if @CONF[:SCRIPT] then
+      irb = Irb.new(main_context, @CONF[:SCRIPT])
+    else
+      irb = Irb.new(main_context)
+    end
+
+    if workspace then
+      irb.context.workspace = workspace
+    end
+
+    @CONF[:IRB_RC].call(irb.context) if @CONF[:IRB_RC]
+    @CONF[:MAIN_CONTEXT] = irb.context
+
+    old_sigint = trap("SIGINT") do
+      irb.signal_handle
+    end
+    
+    catch(:IRB_EXIT) do
+      irb.eval_input
+    end
+  ensure
+    trap("SIGINT", old_sigint)
+  end
+
+  class << self
+    alias :old_CurrentContext :CurrentContext
+    remove_method :CurrentContext
+  end
+  def IRB.CurrentContext
+    if old_CurrentContext.nil? and Breakpoint.use_drb? then
+      result = Object.new
+      def result.last_value; end
+      return result
+    else
+      old_CurrentContext
+    end
+  end
+
+  class Context#:nodoc:
+    alias :old_evaluate :evaluate
+    def evaluate(line, line_no)
+      if line.chomp == "exit" then
+        exit
+      else
+        old_evaluate(line, line_no)
+      end
+    end
+  end
+
+  class WorkSpace#:nodoc:
+    alias :old_evaluate :evaluate
+
+    def evaluate(*args)
+      if Breakpoint.use_drb? then
+        result = old_evaluate(*args)
+        if args[0] != :no_proxy and
+          not [true, false, nil].include?(result)
+        then
+          result.extend(DRbUndumped) rescue nil
+        end
+        return result
+      else
+        old_evaluate(*args)
+      end
+    end
+  end
+
+  module InputCompletor#:nodoc:
+    def self.eval(code, context, *more)
+      # Big hack, this assumes that InputCompletor
+      # will only call eval() when it wants code
+      # to be executed in the IRB context.
+      IRB.conf[:MAIN_CONTEXT].workspace.evaluate(:no_proxy, code, *more)
+    end
+  end
+end
+
+module DRb # :nodoc:
+  class DRbObject#:nodoc:
+    undef :inspect
+    undef :clone
+  end
+end
+
+# See Breakpoint.breakpoint
+def breakpoint(id = nil, &block)
+  Binding.of_caller do |context|
+    Breakpoint.breakpoint(id, context, &block)
+  end
+end
+
+# See Breakpoint.assert
+def assert(&block)
+  Binding.of_caller do |context|
+    Breakpoint.assert(context, &block)
+  end
+end