# Logs timing of an operation:
#
# * Start a clock.
# * Calls the `operation`, passing in a `done` function that will:
#   * Stop the clock.
#   * Log the title of the operation with its elapsed duration and optional outcome.
#     If the operation calls the `done` function with no outcome, "completed" is used.
#
# Example:
#
# request = require("request")
#
# do_request = (url, title = "Request", callback) ->
#   log_duration title, (stop_clock) ->
#     request.get url, (error, response, body) ->
#       stop_clock(response?.statusCode or "500")
#       callback(error, body)
#
log_duration = (title, operation) ->
  start = Date.now()
  done = (outcome) ->
    outcome ||= "completed"
    end = Date.now()
    duration = (end - start) / 1000
    console.log "#{title} #{outcome} in #{duration} seconds"
  operation(done)