Metrics in a key-value store.
Accepts, summarizes, and stores continuous metrics updates to a key-value store. Answers queries in constant time.
We assume that the backing key-value store is fast, durable, and supports TTL. Initial implementation will use Couchbase.
Follow the instructions at https://github.com/couchbase/couchbase-ruby-client to install the couchbase gem.
Add this line to your application's Gemfile:
gem 'metricstore'
And then execute:
$ bundle
Or install it yourself as:
$ gem install metricstore
m = Metricstore.couchbase(:hostname => "localhost")
# Configure...
m.ttl_of_hours = 31_556_926 # 1 year, default
m.max_ttl_of_dimension[:session_id] = 7200 # 2 hours
m.list_threshold = 1000 # default
# Open the connection
m.open
# (Suppose that the current time is 17:05 UTC on April 13, 2012.)
m.counter(:when => Time.now, :what => "logins", :where =>
{:user => 'joe', :ip => '10.20.30.40'})
m.counter(:when => Time.now, :what => "logins", :where =>
{:user => 'bob', :ip => '10.20.30.40'})
m.counter(:when => Time.now, :what => "logins", :where =>
{:user => 'joe', :ip => '10.20.30.50'})
m.measure(:when => Time.now, :what => "load_time", :value => 340, :where =>
{:page => '/welcome/', :session_id => "h0zhmb1c-u1xfgw305e"})
m.measure(:when => Time.now, :what => "load_time", :value => 501, :where =>
{:page => '/welcome/', :session_id => "h0zhmb2q-643dotlcgd"})
m.measure(:when => Time.now, :what => "load_time", :value => 212, :where =>
{:page => '/welcome/', :session_id => "h0zhmb1c-u1xfgw305e"})
m.measure(:when => Time.now, :what => "load_time", :value => 343, :where =>
{:page => '/welcome/', :session_id => "h0zhmb2q-643dotlcgd"})
# Now we can query...
m.count(:hour => "2012-04-13-17", :what => "logins")
=> 3
m.list(:hour => "2012-04-13-17", :what => "logins", :list => :user)
=> ['joe', 'bob']
m.count(:hour => "2012-04-13-17", :what => "logins", :where => {:user => 'joe'})
=> 2
m.count(:hour => "2012-04-13-17", :what => "logins", :where => {:user => 'bob'})
=> 1
m.list(:hour => "2012-04-13-17", :what => "logins", :where => {:user => 'joe'}, :list => :ip)
=> ['10.20.30.40', '10.20.30.50']
m.list(:hour => "2012-04-13-17", :what => "logins", :where => {:user => 'bob'}, :list => :ip)
=> ['10.20.30.40']
m.count(:hour => "2012-04-13-17", :what => "logins", :where => {:user => 'joe', :ip => '10.20.30.40'})
=> 1
m.count(:hour => "2012-04-13-17", :what => "load_time")
=> 4
m.sum(:hour => "2012-04-13-17", :what => "load_time")
=> 1396
m.average(:hour => "2012-04-13-17", :what => "load_time")
=> 349.0
m.maximum(:hour => "2012-04-13-17", :what => "load_time")
=> 501
m.minimum(:hour => "2012-04-13-17", :what => "load_time")
=> 212
m.stddev(:hour => "2012-04-13-17", :what => "load_time")
=> 102.45730818248154
m.list(:hour => "2012-04-13-17", :what => "load_time", :list => :page)
=> ['/welcome/']
# We can do queries related to groups as well, with some limitations.
# We only guarantee the accuracy of a particular group summary if for every
# member in the group, all the metrics related to that member were loaded
# from start-to-finish before the preceeding such metric expired its TTL.
#
# Note: a range is the difference between the minimum and maximum metric,
# for an individual group.
m.count_of_groups(:hour => "2012-04-13-17", :what => "load_time", :group => :session_id)
=> 2
m.sum_of_ranges(:hour => "2012-04-13-17", :what => "load_time", :group => :session_id)
=> 286
m.average_range(:hour => "2012-04-13-17", :what => "load_time", :group => :session_id)
=> 143
m.maximum_range(:hour => "2012-04-13-17", :what => "load_time", :group => :session_id)
=> 158
m.minimum_range(:hour => "2012-04-13-17", :what => "load_time", :group => :session_id)
=> 128
m.stddev_of_ranges(:hour => "2012-04-13-17", :what => "load_time", :group => :session_id)
=> 15.0
# Supposing there were instead millions of counter and measure operations,
# metricstore may reach its list_threshold. Some queries will fail.
m.list(:hour => "2012-04-13-17", :what => "load_time", :list => :page)
=> ['/welcome/', '/projects/']
m.list(:hour => "2012-04-13-17", :what => "load_time", :list => :session_id)
Metricstore::DataLossError: Too many session_id for "2012-04-13-17", "load_time".
m.estimated_list_size(:hour => "2012-04-13-17", :what => "load_time", :list => :session_id)
=> 3560831
m.close
The Metricstore client's write methods (counter, measure) are designed to run within an EventMachine reactor. This allows writes to be batched up together (only when there's a backlog), and to re-try in the case of intermittent connection problems or other non-fatal errors. You will want to design your app to leave the reactor running.
If it does not make sense to leave a reactor running in your app, you can make your updates within a temporary reactor using the client's "run" method. Be aware though, that the "run" method itself will block until the write backlog is clear again.
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Added some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request