Dumping and restoring the memcache key values using telnet & dalli gem

dump_memcache.rb

#!/usr/bin/env ruby

# List all keys stored in memcache. 
# Credit to Graham King at http://www.darkcoding.net/software/memcached-list-all-keys/ for the original article on how to get the data from memcache in the first place.

require 'net/telnet'
require 'csv'

headings = %w(id expires bytes key)
rows = []

host = ENV['MEMCACHE_DB_HOST'] || "localhost"
port = ENV['MEMCACHE_DB_PORT'] || 11211
dump_file = ENV['MEMCACHE_DB_DUMP_FILE'] || "memcache_dump.csv"

connection = Net::Telnet::new("Host" => host, "Port" => port, "Timeout" => 3)
matches   = connection.cmd("String" => "stats items", "Match" => /^END/).scan(/STAT items:(\d+):number (\d+)/)

slabs = matches.inject([]) { |items, item| items << Hash[*['id','items'].zip(item).flatten]; items }
longest_key_len = 0

CSV.open(dump_file, "w") do |csv|
  csv << headings
  slabs.each do |slab|
    connection.cmd("String" => "stats cachedump #{slab['id']} #{slab['items']}", "Match" => /^END/) do |c|                                                                                         
      matches = c.scan(/^ITEM (.+?) \[(\d+) b; (\d+) s\]$/).each do |key_data|
        cache_key, bytes, expires_time = key_data
        csv << [slab['id'], Time.at(expires_time.to_i), bytes, cache_key]
        rows << [slab['id'], Time.at(expires_time.to_i), bytes, cache_key]
        longest_key_len = [longest_key_len,cache_key.length].max
      end
    end
  end

end

row_format = %Q(|%8s | %28s | %12s | %-#{longest_key_len}s |)
puts row_format%headings
rows.each{|row| puts row_format%row}

puts "\n############# successfully dumped in #{dump_file} ##############"
connection.close

memcache_copy.rb

#!/usr/bin/env ruby

# List all keys stored in memcache. 
# Credit to Graham King at http://www.darkcoding.net/software/memcached-list-all-keys/ for the original article on how to get the data from memcache in the first place.
require 'dalli'
require 'net/telnet'

destination = ENV['MEMCACHE_DESTINATION_HOST'] || "localhost"
source = ENV['MEMCACHE_SOURCE_HOST'] || "localhost"
port = ENV['MEMCACHE_DB_PORT'] || 11211
expires_in = ENV['MEMCACHE_DB_EXPIRE_TIME'] || 604800 # 1.week in seconds
options = {:expires_in => expires_in }

dc_source = Dalli::Client.new("#{source}:#{port}")
dc_destination = Dalli::Client.new("#{destination}:#{port}", options)

connection = Net::Telnet::new("Host" => source, "Port" => port, "Timeout" => 3)
matches   = connection.cmd("String" => "stats items", "Match" => /^END/).scan(/STAT items:(\d+):number (\d+)/)
slabs = matches.inject([]) { |items, item| items << Hash[*['id','items'].zip(item).flatten]; items }

slabs.each do |slab|
  connection.cmd("String" => "stats cachedump #{slab['id']} #{slab['items']}", "Match" => /^END/) do |c|
    matches = c.scan(/^ITEM (.+?) \[(\d+) b; (\d+) s\]$/).each do |key_data|
      cache_key, bytes, expires_time = key_data
      value = dc_source.get cache_key
      p key_data
      dc_destination.set cache_key, value
    end
  end
end

puts "\nsuccessfully copied from #{source} to #{destination}"
connection.close