JLog
Ruby C-bindings for OmniTI Labs' Jlog. Founded upon work by Mark Bainter (@mbainter.)
JLog is short for "journaled log" and this package is really an API and implementation that is libjlog. What is libjlog? libjlog is a pure C, very simple durable message queue with multiple subscribers and publishers (both thread and multi-process safe). The basic concept is that publishers can open a log and write messages to it while subscribers open the log and consume messages from it. "That sounds easy." libjlog abstracts away the need to perform log rotation or maintenance by publishing into fixed size log buffers and eliminating old log buffers when there are no more consumers pending.
Installation
Add this line to your application's Gemfile:
gem 'jlog'
And then execute:
$ bundle
Or install it yourself as:
$ gem install jlog
Usage
log = Jlog.new('/var/log/logname')
log.add_subscriber 'LogSubscriber'
log.close
writer = Jlog::Writer.new('/var/log/logname')
writer.open
writer.write 'This is the first log message'
writer.write 'This is the second log message'
writer.write "This is the third log message, created at #{Time.now}"
writer.close
reader = Jlog::Reader.new '/var/log/logname'
reader.open 'LogSubscriber'
first = reader.read
second = reader.read
reader.rewind
if reader.read == second
puts "Rewind sets log position to last checkpoint."
end
reader.checkpoint
third = reader.read
reader.rewind
third_full = reader.
if third == third_msg[:message]
ts = third_msg[:timestamp]
puts "#{third} and logged #{Time.at(ts)} (or #{ts} seconds since epoch)"
end
reader.checkpoint
reader.close