debian-mirror-gitlab/lib/gitlab/metrics/instrumentation.rb
2016-01-14 18:37:52 +05:30

148 lines
4.6 KiB
Ruby

module Gitlab
module Metrics
# Module for instrumenting methods.
#
# This module allows instrumenting of methods without having to actually
# alter the target code (e.g. by including modules).
#
# Example usage:
#
# Gitlab::Metrics::Instrumentation.instrument_method(User, :by_login)
module Instrumentation
SERIES = 'method_calls'
def self.configure
yield self
end
# Instruments a class method.
#
# mod - The module to instrument as a Module/Class.
# name - The name of the method to instrument.
def self.instrument_method(mod, name)
instrument(:class, mod, name)
end
# Instruments an instance method.
#
# mod - The module to instrument as a Module/Class.
# name - The name of the method to instrument.
def self.instrument_instance_method(mod, name)
instrument(:instance, mod, name)
end
# Recursively instruments all subclasses of the given root module.
#
# This can be used to for example instrument all ActiveRecord models (as
# these all inherit from ActiveRecord::Base).
#
# This method can optionally take a block to pass to `instrument_methods`
# and `instrument_instance_methods`.
#
# root - The root module for which to instrument subclasses. The root
# module itself is not instrumented.
def self.instrument_class_hierarchy(root, &block)
visit = root.subclasses
until visit.empty?
klass = visit.pop
instrument_methods(klass, &block)
instrument_instance_methods(klass, &block)
klass.subclasses.each { |c| visit << c }
end
end
# Instruments all public methods of a module.
#
# This method optionally takes a block that can be used to determine if a
# method should be instrumented or not. The block is passed the receiving
# module and an UnboundMethod. If the block returns a non truthy value the
# method is not instrumented.
#
# mod - The module to instrument.
def self.instrument_methods(mod)
mod.public_methods(false).each do |name|
method = mod.method(name)
if method.owner == mod.singleton_class
if !block_given? || block_given? && yield(mod, method)
instrument_method(mod, name)
end
end
end
end
# Instruments all public instance methods of a module.
#
# See `instrument_methods` for more information.
#
# mod - The module to instrument.
def self.instrument_instance_methods(mod)
mod.public_instance_methods(false).each do |name|
method = mod.instance_method(name)
if method.owner == mod
if !block_given? || block_given? && yield(mod, method)
instrument_instance_method(mod, name)
end
end
end
end
# Instruments a method.
#
# type - The type (:class or :instance) of method to instrument.
# mod - The module containing the method.
# name - The name of the method to instrument.
def self.instrument(type, mod, name)
return unless Metrics.enabled?
name = name.to_sym
alias_name = :"_original_#{name}"
target = type == :instance ? mod : mod.singleton_class
if type == :instance
target = mod
label = "#{mod.name}##{name}"
else
target = mod.singleton_class
label = "#{mod.name}.#{name}"
end
target.class_eval <<-EOF, __FILE__, __LINE__ + 1
alias_method #{alias_name.inspect}, #{name.inspect}
def #{name}(*args, &block)
trans = Gitlab::Metrics::Instrumentation.transaction
if trans
start = Time.now
retval = __send__(#{alias_name.inspect}, *args, &block)
duration = (Time.now - start) * 1000.0
if duration >= Gitlab::Metrics.method_call_threshold
trans.increment(:method_duration, duration)
trans.add_metric(Gitlab::Metrics::Instrumentation::SERIES,
{ duration: duration },
method: #{label.inspect})
end
retval
else
__send__(#{alias_name.inspect}, *args, &block)
end
end
EOF
end
# Small layer of indirection to make it easier to stub out the current
# transaction.
def self.transaction
Transaction.current
end
end
end
end