`class Cache`

Cache for storing and looking up allocation metadata. Caches gem names, file locations, class names, and string values to reduce memory overhead during profiling.

Definitions

`def initialize`

Initialize a new cache with empty lookup tables.

Implementation

def initialize
	@gem_guess_cache = Hash.new
	@location_cache = Hash.new {|h, k| h[k] = Hash.new.compare_by_identity}
	@class_name_cache = Hash.new.compare_by_identity
	@string_cache = Hash.new
end

`def guess_gem(path)`

Guess the gem or library name from a file path.

Signature

parameter　path　String: The file path to analyze.
returns　String: The guessed gem name, stdlib component, or "other".

Implementation

def guess_gem(path)
	@gem_guess_cache[path] ||=
		if /(\/gems\/.*)*\/gems\/(?<gemname>[^\/]+)/ =~ path
			gemname
		elsif /\/rubygems[\.\/]/ =~ path
			"rubygems"
		elsif /ruby\/2\.[^\/]+\/(?<stdlib>[^\/\.]+)/ =~ path
			stdlib
		elsif /(?<app>[^\/]+\/(bin|app|lib))/ =~ path
			app
		else
			"other"
		end
end

`def lookup_location(file, line)`

Look up and cache a file location string.

Signature

parameter　file　String: The source file path.
parameter　line　Integer: The line number.
returns　String: The formatted location string "file:line".

Implementation

def lookup_location(file, line)
	@location_cache[file][line] ||= "#{file}:#{line}"
end

`def lookup_class_name(klass)`

Look up and cache a class name.

Signature

parameter　klass　Class: The class object.
returns　String: The class name or unknown if unavailable.

Implementation

def lookup_class_name(klass)
	@class_name_cache[klass] ||= ((klass.is_a?(Class) && klass.name) || "unknown").to_s
end

`def lookup_string(obj)`

Look up and cache a string value. Strings are truncated to 64 characters to reduce memory usage.

Signature

parameter　obj　String: The string object to cache.
returns　String: A cached copy of the string (truncated to 64 characters).

Implementation

def lookup_string(obj)
	# This string is shortened to 200 characters which is what the string report shows
	# The string report can still list unique strings longer than 200 characters
	#   separately because the object_id of the shortened string will be different
	@string_cache[obj] ||= String.new << obj[0, 64]
end