Class: Tina4::CacheBackends::MemcachedBackend

Inherits:
BaseBackend
  • Object
show all
Defined in:
lib/tina4/cache_backends/memcached_backend.rb

Overview

Memcached backend using the zero-dependency text protocol over TCP (parity with Python _MemcachedBackend). Keys are SHA-256 hashed to stay within memcached’s 250-char / no-space key constraints. Memcached has no auth, so credentials are ignored.

Constant Summary collapse

PREFIX = 
"tina4:cache:"

Instance Method Summary collapse

Constructor Details

#initialize(url: "memcached://localhost:11211", max_entries: 1000) ⇒ MemcachedBackend

Returns a new instance of MemcachedBackend.



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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 17

def initialize(url: "memcached://localhost:11211", max_entries: 1000)
  cleaned = url.sub(%r{^memcached://}, "").sub(%r{^memcache://}, "")
  parts = cleaned.split("/").first.to_s.split(":")
  @host = parts[0].nil? || parts[0].empty? ? "localhost" : parts[0]
  @port = parts[1] && !parts[1].empty? ? parts[1].to_i : 11_211
  @max_entries = max_entries
  @hits = 0
  @misses = 0
  @available = command("version\r\n", "\r\n").start_with?("VERSION")
end

Instance Method Details

#available? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 28

def available?
  @available
end

#clear ⇒ Object 



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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 58

def clear
  @hits = 0
  @misses = 0
  command("flush_all\r\n", "\r\n")
end

#delete(key) ⇒ Object 



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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 54

def delete(key)
  command("delete #{mc_key(key)}\r\n", "\r\n").start_with?("DELETED")
end

#get(key) ⇒ Object 



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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 32

def get(key)
  resp = command("get #{mc_key(key)}\r\n", "END\r\n")
  if resp.start_with?("VALUE")
    begin
      header, rest = resp.split("\r\n", 2)
      nbytes = header.split[3].to_i
      @hits += 1
      return JSON.parse(rest[0, nbytes])
    rescue StandardError
    end
  end
  @misses += 1
  nil
end

#name ⇒ Object 



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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 75

def name
  "memcached"
end

#set(key, value, ttl) ⇒ Object 



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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 47

def set(key, value, ttl)
  data = JSON.generate(value)
  exptime = ttl > 0 ? ttl : 0
  payload = "set #{mc_key(key)} 0 #{exptime} #{data.bytesize}\r\n#{data}\r\n"
  command(payload, "\r\n")
end

#stats ⇒ Object 



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# File 'lib/tina4/cache_backends/memcached_backend.rb', line 64

def stats
  size = 0
  resp = command("stats\r\n", "END\r\n")
  resp.split("\r\n").each do |line|
    if line.start_with?("STAT curr_items ")
      size = line.split[2].to_i
    end
  end
  { hits: @hits, misses: @misses, size: size, backend: "memcached" }
end