gitlab-org--gitlab-foss/spec/lib/gitlab/metrics/method_call_spec.rb
Yorick Peterse be3b878443 Track method call times/counts as a single metric
Previously we'd create a separate Metric instance for every method call
that would exceed the method call threshold. This is problematic because
it doesn't provide us with information to accurately get the _total_
execution time of a particular method. For example, if the method
"Foo#bar" was called 4 times with a runtime of ~10 milliseconds we'd end
up with 4 different Metric instances. If we were to then get the
average/95th percentile/etc of the timings this would be roughly 10
milliseconds. However, the _actual_ total time spent in this method
would be around 40 milliseconds.

To solve this problem we now create a single Metric instance per method.
This Metric instance contains the _total_ real/CPU time and the call
count for every instrumented method.
2016-06-17 13:09:55 -04:00

91 lines
2.3 KiB
Ruby

require 'spec_helper'
describe Gitlab::Metrics::MethodCall do
let(:method_call) { described_class.new('Foo#bar', 'foo') }
describe '#measure' do
it 'measures the performance of the supplied block' do
method_call.measure { 'foo' }
expect(method_call.real_time).to be_a_kind_of(Numeric)
expect(method_call.cpu_time).to be_a_kind_of(Numeric)
expect(method_call.call_count).to eq(1)
end
end
describe '#to_metric' do
it 'returns a Metric instance' do
method_call.measure { 'foo' }
metric = method_call.to_metric
expect(metric).to be_an_instance_of(Gitlab::Metrics::Metric)
expect(metric.series).to eq('foo')
expect(metric.values[:duration]).to be_a_kind_of(Numeric)
expect(metric.values[:cpu_duration]).to be_a_kind_of(Numeric)
expect(metric.values[:call_count]).to an_instance_of(Fixnum)
expect(metric.tags).to eq({ method: 'Foo#bar' })
end
end
describe '#above_threshold?' do
it 'returns false when the total call time is not above the threshold' do
expect(method_call.above_threshold?).to eq(false)
end
it 'returns true when the total call time is above the threshold' do
expect(method_call).to receive(:real_time).and_return(9000)
expect(method_call.above_threshold?).to eq(true)
end
end
describe '#call_count' do
context 'without any method calls' do
it 'returns 0' do
expect(method_call.call_count).to eq(0)
end
end
context 'with method calls' do
it 'returns the number of method calls' do
method_call.measure { 'foo' }
expect(method_call.call_count).to eq(1)
end
end
end
describe '#cpu_time' do
context 'without timings' do
it 'returns 0.0' do
expect(method_call.cpu_time).to eq(0.0)
end
end
context 'with timings' do
it 'returns the total CPU time' do
method_call.measure { 'foo' }
expect(method_call.cpu_time >= 0.0).to be(true)
end
end
end
describe '#real_time' do
context 'without timings' do
it 'returns 0.0' do
expect(method_call.real_time).to eq(0.0)
end
end
context 'with timings' do
it 'returns the total real time' do
method_call.measure { 'foo' }
expect(method_call.real_time >= 0.0).to be(true)
end
end
end
end