Commit c3f601e8 authored by Rémy Coutable's avatar Rémy Coutable 🔴

Merge branch 'fix-method-instrumentation' into 'master'

Use Module#prepend for method instrumentation

cc @pcarranza 

See merge request !3754
parents 6d899f46 7b6785b3
Pipeline #1942376 passed with stage
Please view this file on the master branch, on stable branches it's out of date.
v 8.7.0 (unreleased)
- Method instrumentation now uses Module#prepend instead of aliasing methods
- The Projects::HousekeepingService class has extra instrumentation
- All service classes (those residing in app/services) are now instrumented
- Developers can now add custom tags to transactions
......
......@@ -11,6 +11,8 @@ module Gitlab
module Instrumentation
SERIES = 'method_calls'
PROXY_IVAR = :@__gitlab_instrumentation_proxy
def self.configure
yield self
end
......@@ -91,6 +93,18 @@ module Gitlab
end
end
# Returns true if a module is instrumented.
#
# mod - The module to check
def self.instrumented?(mod)
mod.instance_variable_defined?(PROXY_IVAR)
end
# Returns the proxy module (if any) of `mod`.
def self.proxy_module(mod)
mod.instance_variable_get(PROXY_IVAR)
end
# Instruments a method.
#
# type - The type (:class or :instance) of method to instrument.
......@@ -99,9 +113,8 @@ module Gitlab
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
name = name.to_sym
target = type == :instance ? mod : mod.singleton_class
if type == :instance
target = mod
......@@ -113,6 +126,12 @@ module Gitlab
method = mod.method(name)
end
unless instrumented?(target)
target.instance_variable_set(PROXY_IVAR, Module.new)
end
proxy_module = self.proxy_module(target)
# Some code out there (e.g. the "state_machine" Gem) checks the arity of
# a method to make sure it only passes arguments when the method expects
# any. If we were to always overwrite a method to take an `*args`
......@@ -125,17 +144,13 @@ module Gitlab
args_signature = '*args, &block'
end
send_signature = "__send__(#{alias_name.inspect}, #{args_signature})"
target.class_eval <<-EOF, __FILE__, __LINE__ + 1
alias_method #{alias_name.inspect}, #{name.inspect}
proxy_module.class_eval <<-EOF, __FILE__, __LINE__ + 1
def #{name}(#{args_signature})
trans = Gitlab::Metrics::Instrumentation.transaction
if trans
start = Time.now
retval = #{send_signature}
retval = super
duration = (Time.now - start) * 1000.0
if duration >= Gitlab::Metrics.method_call_threshold
......@@ -148,10 +163,12 @@ module Gitlab
retval
else
#{send_signature}
super
end
end
EOF
target.prepend(proxy_module)
end
# Small layer of indirection to make it easier to stub out the current
......
......@@ -33,8 +33,16 @@ describe Gitlab::Metrics::Instrumentation do
described_class.instrument_method(@dummy, :foo)
end
it 'renames the original method' do
expect(@dummy).to respond_to(:_original_foo)
it 'instruments the Class' do
target = @dummy.singleton_class
expect(described_class.instrumented?(target)).to eq(true)
end
it 'defines a proxy method' do
mod = described_class.proxy_module(@dummy.singleton_class)
expect(mod.method_defined?(:foo)).to eq(true)
end
it 'calls the instrumented method with the correct arguments' do
......@@ -76,6 +84,14 @@ describe Gitlab::Metrics::Instrumentation do
expect(dummy.method(:test).arity).to eq(0)
end
describe 'when a module is instrumented multiple times' do
it 'calls the instrumented method with the correct arguments' do
described_class.instrument_method(@dummy, :foo)
expect(@dummy.foo).to eq('foo')
end
end
end
describe 'with metrics disabled' do
......@@ -86,7 +102,9 @@ describe Gitlab::Metrics::Instrumentation do
it 'does not instrument the method' do
described_class.instrument_method(@dummy, :foo)
expect(@dummy).to_not respond_to(:_original_foo)
target = @dummy.singleton_class
expect(described_class.instrumented?(target)).to eq(false)
end
end
end
......@@ -100,8 +118,14 @@ describe Gitlab::Metrics::Instrumentation do
instrument_instance_method(@dummy, :bar)
end
it 'renames the original method' do
expect(@dummy.method_defined?(:_original_bar)).to eq(true)
it 'instruments instances of the Class' do
expect(described_class.instrumented?(@dummy)).to eq(true)
end
it 'defines a proxy method' do
mod = described_class.proxy_module(@dummy)
expect(mod.method_defined?(:bar)).to eq(true)
end
it 'calls the instrumented method with the correct arguments' do
......@@ -144,7 +168,7 @@ describe Gitlab::Metrics::Instrumentation do
described_class.
instrument_instance_method(@dummy, :bar)
expect(@dummy.method_defined?(:_original_bar)).to eq(false)
expect(described_class.instrumented?(@dummy)).to eq(false)
end
end
end
......@@ -167,18 +191,17 @@ describe Gitlab::Metrics::Instrumentation do
it 'recursively instruments a class hierarchy' do
described_class.instrument_class_hierarchy(@dummy)
expect(@child1).to respond_to(:_original_child1_foo)
expect(@child2).to respond_to(:_original_child2_foo)
expect(described_class.instrumented?(@child1.singleton_class)).to eq(true)
expect(described_class.instrumented?(@child2.singleton_class)).to eq(true)
expect(@child1.method_defined?(:_original_child1_bar)).to eq(true)
expect(@child2.method_defined?(:_original_child2_bar)).to eq(true)
expect(described_class.instrumented?(@child1)).to eq(true)
expect(described_class.instrumented?(@child2)).to eq(true)
end
it 'does not instrument the root module' do
described_class.instrument_class_hierarchy(@dummy)
expect(@dummy).to_not respond_to(:_original_foo)
expect(@dummy.method_defined?(:_original_bar)).to eq(false)
expect(described_class.instrumented?(@dummy)).to eq(false)
end
end
......@@ -190,7 +213,7 @@ describe Gitlab::Metrics::Instrumentation do
it 'instruments all public class methods' do
described_class.instrument_methods(@dummy)
expect(@dummy).to respond_to(:_original_foo)
expect(described_class.instrumented?(@dummy.singleton_class)).to eq(true)
end
it 'only instruments methods directly defined in the module' do
......@@ -223,7 +246,7 @@ describe Gitlab::Metrics::Instrumentation do
it 'instruments all public instance methods' do
described_class.instrument_instance_methods(@dummy)
expect(@dummy.method_defined?(:_original_bar)).to eq(true)
expect(described_class.instrumented?(@dummy)).to eq(true)
end
it 'only instruments methods directly defined in the module' do
......
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