Commit 755edd80 authored by Robert Speicher's avatar Robert Speicher

Merge branch 'metrics-measure-block' into 'master'

Support for measuring Ruby blocks using GitLab performance monitoring

This adds support for measuring timings of arbitrary Ruby blocks.

Fixes #14710 

See merge request !3515
parents 801e870d 352bc7d2
Pipeline #1502696 passed with stage
...@@ -4,6 +4,7 @@ ...@@ -4,6 +4,7 @@
- [CI setup](ci_setup.md) for testing GitLab - [CI setup](ci_setup.md) for testing GitLab
- [Gotchas](gotchas.md) to avoid - [Gotchas](gotchas.md) to avoid
- [How to dump production data to staging](db_dump.md) - [How to dump production data to staging](db_dump.md)
- [Instrumentation](instrumentation.md)
- [Migration Style Guide](migration_style_guide.md) for creating safe migrations - [Migration Style Guide](migration_style_guide.md) for creating safe migrations
- [Rake tasks](rake_tasks.md) for development - [Rake tasks](rake_tasks.md) for development
- [Shell commands](shell_commands.md) in the GitLab codebase - [Shell commands](shell_commands.md) in the GitLab codebase
......
# Instrumenting Ruby Code
GitLab Performance Monitoring allows instrumenting of custom blocks of Ruby
code. This can be used to measure the time spent in a specific part of a larger
chunk of code. The resulting data is written to a separate series.
To start measuring a block of Ruby code you should use
`Gitlab::Metrics.measure` and give it a name for the series to store the data
in:
```ruby
Gitlab::Metrics.measure(:user_logins) do
...
end
```
The first argument of this method is the series name and should be plural. This
name will be prefixed with `rails_` or `sidekiq_` depending on whether the code
was run in the Rails application or one of the Sidekiq workers. In the
above example the final series names would be as follows:
- rails_user_logins
- sidekiq_user_logins
Series names should be plural as this keeps the naming style in line with the
other series names.
By default metrics measured using a block contain a single value, "duration",
which contains the number of milliseconds it took to execute the block. Custom
values can be added by passing a Hash as the 2nd argument. Custom tags can be
added by passing a Hash as the 3rd argument. A simple example is as follows:
```ruby
Gitlab::Metrics.measure(:example_series, { number: 10 }, { class: self.class.to_s }) do
...
end
```
...@@ -70,6 +70,32 @@ module Gitlab ...@@ -70,6 +70,32 @@ module Gitlab
value.to_s.gsub('=', '\\=') value.to_s.gsub('=', '\\=')
end end
# Measures the execution time of a block.
#
# Example:
#
# Gitlab::Metrics.measure(:find_by_username_timings) do
# User.find_by_username(some_username)
# end
#
# series - The name of the series to store the data in.
# values - A Hash containing extra values to add to the metric.
# tags - A Hash containing extra tags to add to the metric.
#
# Returns the value yielded by the supplied block.
def self.measure(series, values = {}, tags = {})
return yield unless Transaction.current
start = Time.now.to_f
retval = yield
duration = (Time.now.to_f - start) * 1000.0
values = values.merge(duration: duration)
Transaction.current.add_metric(series, values, tags)
retval
end
# When enabled this should be set before being used as the usual pattern # When enabled this should be set before being used as the usual pattern
# "@foo ||= bar" is _not_ thread-safe. # "@foo ||= bar" is _not_ thread-safe.
if enabled? if enabled?
......
...@@ -13,7 +13,7 @@ describe Gitlab::Metrics do ...@@ -13,7 +13,7 @@ describe Gitlab::Metrics do
end end
end end
describe '#submit_metrics' do describe '.submit_metrics' do
it 'prepares and writes the metrics to InfluxDB' do it 'prepares and writes the metrics to InfluxDB' do
connection = double(:connection) connection = double(:connection)
pool = double(:pool) pool = double(:pool)
...@@ -26,7 +26,7 @@ describe Gitlab::Metrics do ...@@ -26,7 +26,7 @@ describe Gitlab::Metrics do
end end
end end
describe '#prepare_metrics' do describe '.prepare_metrics' do
it 'returns a Hash with the keys as Symbols' do it 'returns a Hash with the keys as Symbols' do
metrics = described_class. metrics = described_class.
prepare_metrics([{ 'values' => {}, 'tags' => {} }]) prepare_metrics([{ 'values' => {}, 'tags' => {} }])
...@@ -51,7 +51,7 @@ describe Gitlab::Metrics do ...@@ -51,7 +51,7 @@ describe Gitlab::Metrics do
end end
end end
describe '#escape_value' do describe '.escape_value' do
it 'escapes an equals sign' do it 'escapes an equals sign' do
expect(described_class.escape_value('foo=')).to eq('foo\\=') expect(described_class.escape_value('foo=')).to eq('foo\\=')
end end
...@@ -60,4 +60,45 @@ describe Gitlab::Metrics do ...@@ -60,4 +60,45 @@ describe Gitlab::Metrics do
expect(described_class.escape_value(10)).to eq('10') expect(described_class.escape_value(10)).to eq('10')
end end
end end
describe '.measure' do
context 'without a transaction' do
it 'returns the return value of the block' do
val = Gitlab::Metrics.measure(:foo) { 10 }
expect(val).to eq(10)
end
end
context 'with a transaction' do
let(:transaction) { Gitlab::Metrics::Transaction.new }
before do
allow(Gitlab::Metrics::Transaction).to receive(:current).
and_return(transaction)
end
it 'adds a metric to the current transaction' do
expect(transaction).to receive(:add_metric).
with(:foo, { duration: a_kind_of(Numeric) }, { tag: 'value' })
Gitlab::Metrics.measure(:foo, {}, tag: 'value') { 10 }
end
it 'supports adding of custom values' do
values = { duration: a_kind_of(Numeric), number: 10 }
expect(transaction).to receive(:add_metric).
with(:foo, values, { tag: 'value' })
Gitlab::Metrics.measure(:foo, { number: 10 }, tag: 'value') { 10 }
end
it 'returns the return value of the block' do
val = Gitlab::Metrics.measure(:foo) { 10 }
expect(val).to eq(10)
end
end
end
end end
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