diff options
Diffstat (limited to 'activesupport/lib/active_support/notifications.rb')
| -rw-r--r-- | activesupport/lib/active_support/notifications.rb | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/notifications.rb b/activesupport/lib/active_support/notifications.rb index 89afe7b982..719f074948 100644 --- a/activesupport/lib/active_support/notifications.rb +++ b/activesupport/lib/active_support/notifications.rb @@ -63,6 +63,40 @@ module ActiveSupport # and even pass no argument to +subscribe+, in which case you are subscribing # to all events. # + # == Temporary Subscriptions + # + # Sometimes you do not want to subscribe to an event for the entire life of + # the application. There are two ways two unsubscribe. + # + # === Subscribe While a Block Runs + # + # You can subscribe to some event temporarily while some block runs. For + # example, in + # + # callback = lambda {|*args| ... } + # ActiveSupport::Notifications.subscribed(callback, "sql.active_record") do + # ... + # end + # + # the callback will be called for all "sql.active_record" events instrumented + # during the execution of the block. The callback is unsubscribed automatically + # after that. + # + # === Manual Unsubscription + # + # The +subscribe+ method returns a subscriber object: + # + # subscriber = ActiveSupport::Notifications.subscribe("render") do |*args| + # ... + # end + # + # To prevent that block from being called anymore, just unsubscribe passing + # that reference: + # + # ActiveSupport::Notifications.unsubscribe(subscriber) + # + # == Default Queue + # # Notifications ships with a queue implementation that consumes and publish events # to log subscribers in a thread. You can use any queue implementation you want. # @@ -94,6 +128,13 @@ module ActiveSupport end end + def subscribed(callback, *args, &block) + subscriber = subscribe(*args, &callback) + yield + ensure + unsubscribe(subscriber) + end + def unsubscribe(args) notifier.unsubscribe(args) @instrumenters.clear |