tail_slow_log.rb

#!/usr/bin/env ruby

def parse_query(query)
  lines = query.split("\n")
  [lines.shift, lines.join("\n")]
end

require "shellwords"

path = ARGV[0] or abort "Usage: tail_slow_log.rb <path_to_slow_log>"

notifier = nil
if system("type terminal-notifier >/dev/null 2>&1")
  notifier = ->(header, query) {
    timestamp, query = parse_query(query)
    puts query

    escaped = Shellwords.escape(query)
    system(%Q{terminal-notifier -title "SLOW LOG" -message #{escaped} >/dev/null 2>&1})
  }
else
  notifier = ->(header, query) {
    timestamp, query = parse_query(query)
    puts query
  }

  warn <<-WARNING
terminal-notifier is not installed, So queries are only printed on this screen.
  WARNING
end

f = File.open(path)
f.seek(0, IO::SEEK_END)

header = String.new
query  = String.new

loop do
  begin
    line = f.readline

    if line.start_with?("#")
      if query.empty?
        header += line
      else
        notifier.call(header, query)
        header = String.new
        query  = String.new

        header += line
      end
    else
      if header.empty?
        # do nothing
      else
        query += line
      end
    end
  rescue EOFError
    if header.empty?
    else
      notifier.call(header, query)
      header = String.new
      query  = String.new
    end
  end
end