olegkovalenko · May 31, 2013 19:09 · May 31, 2013
diff --git a/allocation_map.rb b/allocation_map.rb
@@ -0,0 +1,47 @@
+#   Ruby has #source_location method that returns code location where a method was declared.
+# What Ruby lacks is alike functionality that could show where an object was created.
+# Below is a very rough solution that may help with tracing object allocations
+# by storing the first entry in the caller list during object initialization phase.
+# It doesn't work for built-in classes like Fixnum and for classes that don't invoke #initialize()
+# like the ones derived from ActiveRecord::Base, but can be potentially tailored to address
+# at least the latter case by overriding ActiveRecord::Base.new in addition to overriding #initialize()
+
+class BasicObject
+  attr_reader :allocated_at
+
+  def initialize_with_allocated_at(*options)
+    unless @allocated_at
+      @allocated_at = caller.first
+      return initialize_without_allocated_at(*options)
+    end
+  end
+
+  def self.enable_allocated_at
+    self.send :alias_method, :initialize_without_allocated_at, :initialize
+    self.send :alias_method, :initialize, :initialize_with_allocated_at
+  end
+end
+
+ObjectSpace.each_object(Class) do |klass|
+  klass.enable_allocated_at
+end
+
+class Object
+
+  # Call this method to get a hash where
+  # keys are strings representing locations in the source code
+  # and values are objects allocated at these locations
+  #
+  # Example:
+  #   allocation_map(Person) # only show places where Person.new was called
+  #         or
+  #   allocation_map() # beware, this may return A LOT of objects
+  #
+  def allocation_map(*each_object_options)
+    ObjectSpace.each_object(*each_object_options).reduce({}) { |hash, object|
+      hash[object.allocated_at] ||= []
+      hash[object.allocated_at] << object if object.respond_to?(:allocated_at)
+      hash
+    }
+  end
+end