How to measure moped insert runtime in a ruby mongoid app? - ruby

Question

I'm currently writing a moped log parser in order to monitor moped queries runtime.
It's work great for QUERY command using the runtime parameter, but INSERT and UPDATE have no runtime parameter. All INSERT and UPDATE are followed by a getLastError COMMAND which contains a runtime.
Here are some samples of moped logs:
QUERY with runtime
MOPED: 127.0.0.1:27017 QUERY database=X collection=X selector=X
flags=[] limit=-1 skip=0 batch_size=nil fields=nil runtime: 0.6950ms
INSERT without runtime but with COMMAND
MOPED: 127.0.0.1:27017 INSERT database=X collection=X documents=X flags=[]
COMMAND database=X command={:getlasterror=>1, :w=>1}
runtime: 0.4750ms
I'm pretty sure that COMMAND runtime is for the getlasterror call and not for my INSERT one.
So is there a way to get this runtime info for an INSERT query?

Answer 1

Instead of using a log parser, I use something like this and it works great:
ActiveSupport::Notifications.subscribe('query.moped') do |name, start, finish, id, payload|
runtime = (finish - start)*1000
moped_ops = payload[:ops]
moped_ops.each do |op|
unless op.collection == '$cmd'
query = op.class.name.split('::').last.downcase
query = op.selector.first[0].to_s.gsub(/\$/, '') if query == 'command'
DO SOMETHING WITH #{op.database}.#{op.collection}.#{query}
end
end
end