Class: Memcached

Inherits:
Object
  • Object
show all
Defined in:
lib/memcached/memcached.rb,
lib/memcached.rb,
lib/memcached/rails.rb,
lib/memcached/behaviors.rb,
lib/memcached/exceptions.rb,
lib/memcached/experimental.rb

Overview

The Memcached client class.

Direct Known Subclasses

Rails

Defined Under Namespace

Modules: Experimental Classes: Error, Rails

Constant Summary collapse

Lib = 
Rlibmemcached
VERSION = 
File.read("#{File.dirname(__FILE__)}/../CHANGELOG")[/v([\d\.]+)\./, 1]
FATAL = 
[
  ABadKeyWasProvidedOrCharactersOutOfRange,
  AKeyLengthOfZeroWasProvided,
  ConnectionBindFailure,
  ConnectionDataDoesNotExist,
  ConnectionFailure,
  ConnectionSocketCreateFailure,
  CouldNotOpenUnixSocket,
  NoServersDefined,
  TheHostTransportProtocolDoesNotMatchThatOfTheClient
]
NONFATAL = 
EXCEPTIONS - FATAL
BEHAVIORS = 
load_constants("MEMCACHED_BEHAVIOR_")
BEHAVIOR_VALUES = 
{
  false => 0,
  true => 1
}
HASH_VALUES = 
{}
DISTRIBUTION_VALUES = 
{}
DIRECT_VALUE_BEHAVIORS = 
[:retry_timeout, :connect_timeout, :rcv_timeout, :socket_recv_size, :poll_timeout, :socket_send_size, :server_failure_limit]
CONVERSION_FACTORS = 
{
  :rcv_timeout => 1_000_000,
  :poll_timeout => 1_000,
  :connect_timeout => 1_000
}
FLAGS = 
0x0
DEFAULTS = 
{
  :hash => :fnv1_32,
  :no_block => false,
  :noreply => false,
  :distribution => :consistent_ketama,
  :ketama_weighted => true,
  :buffer_requests => false,
  :cache_lookups => true,
  :support_cas => false,
  :tcp_nodelay => false,
  :show_backtraces => false,
  :retry_timeout => 30,
  :timeout => 0.25,
  :rcv_timeout => nil,
  :poll_timeout => nil,
  :connect_timeout => 4,
  :prefix_key => '',
  :prefix_delimiter => '',
  :hash_with_prefix_key => true,
  :default_ttl => 604800,
  :default_weight => 8,
  :sort_hosts => false,
  :auto_eject_hosts => true,
  :server_failure_limit => 2,
  :verify_key => true,
  :use_udp => false,
  :binary_protocol => false,
  :credentials => nil,
  :experimental_features => false,
  :exception_retry_limit => 5,
  :exceptions_to_retry => [
      Memcached::ServerIsMarkedDead,
      Memcached::ATimeoutOccurred,
      Memcached::ConnectionBindFailure,
      Memcached::ConnectionFailure,
      Memcached::ConnectionSocketCreateFailure,
      Memcached::Failure,
      Memcached::MemoryAllocationFailure,
      Memcached::ReadFailure,
      Memcached::ServerEnd,
      Memcached::ServerError,
      Memcached::SystemError,
      Memcached::UnknownReadFailure,
      Memcached::WriteFailure,
      Memcached::SomeErrorsWereReported]
}
IGNORED =

:stopdoc:

0
ERRNO_HASH = 

      
        
EXCEPTIONS =
          
        

        
[]

      
    

  




  
Instance Attribute Summary collapse

  




  
    

      Class Method Summary
      collapse
    


    
  
    

      Instance Method Summary
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Constructor Details

  
    

  

  
    #initialize(servers = nil, opts = {})  ⇒ Memcached 
  

  

  




  

    

Create a new Memcached instance. Accepts string or array of server strings, as well an an optional configuration hash.



Memcached.new('localhost', ...) # A single server
Memcached.new(['web001:11212', 'web002:11212'], ...) # Two servers with custom ports
Memcached.new(['web001:11211:2', 'web002:11211:8'], ...) # Two servers with default ports and explicit weights




Weights only affect Ketama hashing.  If you use Ketama hashing and don’t specify a weight, the client will poll each server’s stats and use its size as the weight.



Valid option parameters are:


:prefix_key



A string to prepend to every key, for namespacing. Max length is 127. Defaults to the empty string.


:prefix_delimiter



A character to append to the prefix key. Defaults to the empty string.


:hash



The name of a hash function to use. Possible values are: :crc, :default, :fnv1_32, :fnv1_64, :fnv1a_32, :fnv1a_64, :hsieh, :md5, :murmur, and :none. :fnv1_32 is fast and well known, and is the default. Use :md5 for compatibility with other ketama clients. :none is for use when there is a single server, and performs no actual hashing.


:distribution



Either :modula, :consistent_ketama, :consistent_wheel, or :ketama. Defaults to :ketama.


:server_failure_limit



How many consecutive failures to allow before marking a host as dead. Has no effect unless :retry_timeout is also set.


:retry_timeout



How long to wait until retrying a dead server. Has no effect unless :server_failure_limit is non-zero. Defaults to 30.


:auto_eject_hosts



Whether to temporarily eject dead hosts from the pool. Defaults to true. Note that in the event of an ejection, :auto_eject_hosts will remap the entire pool unless :distribution is set to :consistent.


:exception_retry_limit



How many times to retry before raising exceptions in :exceptions_to_retry. Defaults to 5.


:exceptions_to_retry



Which exceptions to retry. Defaults to ServerIsMarkedDead, ATimeoutOccurred, ConnectionBindFailure, ConnectionFailure, ConnectionSocketCreateFailure, Failure, MemoryAllocationFailure, ReadFailure, ServerError, SystemError, UnknownReadFailure, and WriteFailure.


:cache_lookups



Whether to cache hostname lookups for the life of the instance. Defaults to true.


:support_cas



Flag CAS support in the client. Accepts true or false. Defaults to false because it imposes a slight performance penalty. Note that your server must also support CAS or you will trigger ProtocolError exceptions.


:tcp_nodelay



Turns on the no-delay feature for connecting sockets. Accepts true or false. Performance may or may not change, depending on your system.


:no_block



Whether to use pipelining for writes. Defaults to false.


:buffer_requests



Whether to use an internal write buffer. Accepts true or false. Calling get or closing the connection will force the buffer to flush. Client behavior is undefined unless :no_block is enabled. Defaults to false.


:noreply



Ask server not to reply for storage commands. Client behavior is undefined unless :no_block and :buffer_requests are enabled. Defaults to false.


:show_backtraces



Whether NotFound and NotStored exceptions should include backtraces. Generating backtraces is slow, so this is off by default. Turn it on to ease debugging.


:connect_timeout



How long to wait for a connection to a server. Defaults to 2 seconds. Set to 0 if you want to wait forever.


:timeout



How long to wait for a response from the server. Defaults to 0.25 seconds. Set to 0 if you want to wait forever.


:default_ttl



The ttl to use on set if no ttl is specified, in seconds. Defaults to one week. Set to 0 if you want things to never expire.


:default_weight



The weight to use if :ketama_weighted is true, but no weight is specified for a server.


:hash_with_prefix_key



Whether to include the prefix when calculating which server a key falls on. Defaults to true.


:use_udp



Use the UDP protocol to reduce connection overhead. Defaults to false.


:binary_protocol



Use the binary protocol. Defaults to false. Please note that using the binary protocol is usually slower than the ASCII protocol.


:sort_hosts



Whether to force the server list to stay sorted. This defeats consistent hashing and is rarely useful.


:verify_key



Validate keys before accepting them. Never disable this.





Please note that when :no_block => true, update methods do not raise on errors. For example, if you try to set an invalid key, it will appear to succeed. The actual setting of the key occurs after libmemcached has returned control to your program, so there is no way to backtrack and raise the exception.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 103

def initialize(servers = nil, opts = {})
  @struct = Lib.memcached_create(nil)

  # Merge option defaults and discard meaningless keys
  @options = DEFAULTS.merge(opts)
  @options.delete_if { |k,v| not DEFAULTS.keys.include? k }
  @default_ttl = options[:default_ttl]

  if servers == nil || servers == []
    if ENV.key?("MEMCACHE_SERVERS")
      servers = ENV["MEMCACHE_SERVERS"].split(",").map do | s | s.strip end
    else
      servers = "127.0.0.1:11211"
    end
  end

  if !options[:credentials] and ENV["MEMCACHE_USERNAME"] and ENV["MEMCACHE_PASSWORD"]
    options[:credentials] = [ENV["MEMCACHE_USERNAME"], ENV["MEMCACHE_PASSWORD"]]
  end

  instance_eval { send(:extend, Experimental) } if options[:experimental_features]

  # SASL requires binary protocol
  options[:binary_protocol] = true if options[:credentials]

  # UDP requires noreply
  options[:noreply] = true if options[:use_udp]

  # Buffering requires non-blocking
  # FIXME This should all be wrapped up in a single :pipeline option.
  options[:no_block] = true if options[:buffer_requests]

  # Disallow weights without ketama
  options.delete(:ketama_weighted) if options[:distribution] != :consistent_ketama

  # Disallow :sort_hosts with consistent hashing
  if options[:sort_hosts] and options[:distribution] == :consistent
    raise ArgumentError, ":sort_hosts defeats :consistent hashing"
  end

  # Read timeouts
  options[:rcv_timeout] ||= options[:timeout]
  options[:poll_timeout] ||= options[:timeout]

  # Set the prefix key. Support the legacy name.
  set_prefix_key(options[:prefix_key] || options[:namespace])

  # Set the behaviors and credentials on the struct
  set_behaviors
  set_credentials

  # Freeze the hash
  options.freeze

  # Set the servers on the struct
  set_servers(servers)

  # Not found exceptions
  if options[:show_backtraces]
    # Raise classes for full context
    @not_found = NotFound
    @not_stored = NotStored
  else
    # Raise fast context-free exception instances
    @not_found = NotFound.new
    @not_found.no_backtrace = true
    @not_stored = NotStored.new
    @not_stored.no_backtrace = true
  end
end

    		
  





  



  

    
Instance Attribute Details

    
      
      
      

  

  
    #options  ⇒ Object  (readonly)
  

  

  




  

    

:startdoc:



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 58

def options
  @options
end

    		
  





    
  



  

    
Class Method Details


    
      

  

  
    .load_constants(prefix, hash = {})  ⇒ Object 
  

  

  




  

    

:stopdoc:



  





  



  

    
      


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# File 'lib/memcached/behaviors.rb', line 6

def self.load_constants(prefix, hash = {})
  Lib.constants.grep(/^#{prefix}/).each do |const_name|
    hash[const_name[prefix.length..-1].downcase.to_sym] = Lib.const_get(const_name)
  end
  hash
end

    		
  





    
  


  

    
Instance Method Details


    
      

  

  
    #add(key, value, ttl = @default_ttl, marshal = true, flags = FLAGS)  ⇒ Object 
  

  

  




  

    

Add a key/value pair. Raises Memcached::NotStored if the key already exists on the server. The parameters are the same as set.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 319

def add(key, value, ttl=@default_ttl, marshal=true, flags=FLAGS)
  value = marshal ? Marshal.dump(value) : value
  begin
    check_return_code(
      Lib.memcached_add(@struct, key, value, ttl, flags),
      key
    )
  rescue => e
    tries ||= 0
    raise unless tries < options[:exception_retry_limit] && should_retry(e)
    tries += 1
    retry
  end
end

    		
  





    
      

  

  
    #append(key, value)  ⇒ Object 
  

  

  




  

    

Appends a string to a key’s value. Accepts a String key and a String value. Raises Memcached::NotFound if the key does not exist on the server.



Note that the key must be initialized to an unmarshalled string first, via set, add, or replace with marshal set to false.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 386

def append(key, value)
  # Requires memcached 1.2.4
  check_return_code(
    Lib.memcached_append(@struct, key, value.to_s, IGNORED, IGNORED),
    key
  )
rescue => e
  tries ||= 0
  raise unless tries < options[:exception_retry_limit] && should_retry(e)
  tries += 1
  retry
end

    		
  





    
      

  

  
    #cas(key, ttl = @default_ttl, marshal = true, flags = FLAGS)  ⇒ Object 
  

  
    Also known as:
    compare_and_swap
    
  

  




  

    

Reads a key’s value from the server and yields it to a block. Replaces the key’s value with the result of the block as long as the key hasn’t been updated in the meantime, otherwise raises Memcached::NotStored. Accepts a String key and a block.



Also accepts an optional ttl value.



CAS stands for “compare and swap”, and avoids the need for manual key mutexing. CAS support must be enabled in Memcached.new or a Memcached::ClientError will be raised. Note that CAS may be buggy in memcached itself. :retry_on_exceptions does not apply to this method



  





  

Raises:


    
  
    
  • 
      
      
        (ClientError)
      
      
      
    
    • 
  





  

    
      


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# File 'lib/memcached/memcached.rb', line 419

def cas(key, ttl=@default_ttl, marshal=true, flags=FLAGS)
  raise ClientError, "CAS not enabled for this Memcached instance" unless options[:support_cas]

  begin
    value, flags, ret = Lib.memcached_get_rvalue(@struct, key)
    check_return_code(ret, key)
  rescue => e
    tries_for_get ||= 0
    raise unless tries_for_get < options[:exception_retry_limit] && should_retry(e)
    tries_for_get += 1
    retry
  end

  cas = @struct.result.cas

  value = Marshal.load(value) if marshal
  value = yield value
  value = Marshal.dump(value) if marshal

  begin
    check_return_code(
      Lib.memcached_cas(@struct, key, value, ttl, flags, cas),
      key
    )
  rescue => e
    tries_for_cas ||= 0
    raise unless tries_for_cas < options[:exception_retry_limit] && should_retry(e)
    tries_for_cas += 1
    retry
  end
end

    		
  





    
      

  

  
    #clone  ⇒ Object 
  

  
    Also known as:
    dup
    
  

  




  

    

Safely copy this instance. Returns a Memcached instance.



clone is useful for threading, since each thread must have its own unshared Memcached object.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 236

def clone
  memcached = super
  struct = Lib.memcached_clone(nil, @struct)
  memcached.instance_variable_set('@struct', struct)
  memcached
end

    		
  





    
      

  

  
    #decrement(key, offset = 1)  ⇒ Object 
  

  
    Also known as:
    decr
    
  

  




  

    

Decrement a key’s value. The parameters and exception behavior are the same as increment.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 351

def decrement(key, offset=1)
  ret, value = Lib.memcached_decrement(@struct, key, offset)
  check_return_code(ret, key)
  value
rescue => e
  tries ||= 0
  raise unless tries < options[:exception_retry_limit] && should_retry(e)
  tries += 1
  retry
end

    		
  





    
      

  

  
    #delete(key)  ⇒ Object 
  

  

  




  

    

Deletes a key/value pair from the server. Accepts a String key. Raises Memcached::NotFound if the key does not exist.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 456

def delete(key)
  check_return_code(
    Lib.memcached_delete(@struct, key, IGNORED),
    key
  )
rescue => e
  tries ||= 0
  raise unless tries < options[:exception_retry_limit] && should_retry(e)
  tries += 1
  retry
end

    		
  





    
      

  

  
    #exist(key)  ⇒ Object 
  

  

  




  

    

Check if a key exists on the server. It will return nil if the value is found, or raise Memcached::NotFound if the key does not exist.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 529

def exist(key)
  check_return_code(
    Lib.memcached_exist(@struct, key),
    key
  )
end

    		
  





    
      

  

  
    #flush  ⇒ Object 
  

  

  




  

    

Flushes all key/value pairs from all the servers.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 469

def flush
  check_return_code(
    Lib.memcached_flush(@struct, IGNORED)
  )
rescue => e
  tries ||= 0
  raise unless tries < options[:exception_retry_limit] && should_retry(e)
  tries += 1
  retry
end

    		
  





    
      

  

  
    #get(keys, marshal = true)  ⇒ Object 
  

  

  




  

    

Gets a key’s value from the server. Accepts a String key or array of String keys.



Also accepts a marshal value, which defaults to true. Set marshal to false if you want the value to be returned directly as a String. Otherwise it will be assumed to be a marshalled Ruby object and unmarshalled.



If you pass a String key, and the key does not exist on the server, Memcached::NotFound will be raised. If you pass an array of keys, memcached’s multiget mode will be used, and a hash of key/value pairs will be returned. The hash will contain only the keys that were found.



The multiget behavior is subject to change in the future; however, for multiple lookups, it is much faster than normal mode.



Note that when you rescue Memcached::NotFound exceptions, you should use a the block rescue syntax instead of the inline syntax. Block rescues are very fast, but inline rescues are very slow.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 492

def get(keys, marshal=true)
  if keys.is_a? Array
    # Multi get
    ret = Lib.memcached_mget(@struct, keys);
    check_return_code(ret, keys)

    hash = {}
    value, key, flags, ret = Lib.memcached_fetch_rvalue(@struct)
    while ret != 21 do # Lib::MEMCACHED_END
      if ret == 0 # Lib::MEMCACHED_SUCCESS
        hash[key] = value
      elsif ret != 16 # Lib::MEMCACHED_NOTFOUND
        check_return_code(ret, key)
      end
      value, key, flags, ret = Lib.memcached_fetch_rvalue(@struct)
    end
    if marshal
      hash.each do |key, value|
        hash[key] = Marshal.load(value)
      end
    end
    hash
  else
    # Single get
    value, flags, ret = Lib.memcached_get_rvalue(@struct, keys)
    check_return_code(ret, keys)
    marshal ? Marshal.load(value) : value
  end
rescue => e
  tries ||= 0
  raise unless tries < options[:exception_retry_limit] && should_retry(e)
  tries += 1
  retry
end

    		
  





    
      

  

  
    #get_from_last(key, marshal = true)  ⇒ Object 
  

  

  




  

    

Gets a key’s value from the previous server. Only useful with random distribution.



  





  

Raises:


    
  
    
  • 
      
      
        (ArgumentError)
      
      
      
    
    • 
  





  

    
      


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# File 'lib/memcached/memcached.rb', line 537

def get_from_last(key, marshal=true)
  raise ArgumentError, "get_from_last() is not useful unless :random distribution is enabled." unless options[:distribution] == :random
  value, flags, ret = Lib.memcached_get_from_last_rvalue(@struct, key)
  check_return_code(ret, key)
  marshal ? Marshal.load(value) : value
end

    		
  





    
      

  

  
    #increment(key, offset = 1)  ⇒ Object 
  

  
    Also known as:
    incr
    
  

  




  

    

Increment a key’s value. Accepts a String key. Raises Memcached::NotFound if the key does not exist.



Also accepts an optional offset paramater, which defaults to 1. offset must be an integer.



Note that the key must be initialized to an unmarshalled integer first, via set, add, or replace with marshal set to false.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 339

def increment(key, offset=1)
  ret, value = Lib.memcached_increment(@struct, key, offset)
  check_return_code(ret, key)
  value
rescue => e
  tries ||= 0
  raise unless tries < options[:exception_retry_limit] && should_retry(e)
  tries += 1
  retry
end

    		
  





    
      

  

  
    #prefix_key  ⇒ Object 
  

  
    Also known as:
    namespace
    
  

  




  

    

Return the current prefix key.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 222

def prefix_key
  if @struct.prefix_key.size > 0
    @struct.prefix_key[0..-1 - options[:prefix_delimiter].size]
  else
    ""
  end
end

    		
  





    
      

  

  
    #prepend(key, value)  ⇒ Object 
  

  

  




  

    

Prepends a string to a key’s value. The parameters and exception behavior are the same as append.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 400

def prepend(key, value)
  # Requires memcached 1.2.4
  check_return_code(
    Lib.memcached_prepend(@struct, key, value.to_s, IGNORED, IGNORED),
    key
  )
rescue => e
  tries ||= 0
  raise unless tries < options[:exception_retry_limit] && should_retry(e)
  tries += 1
  retry
end

    		
  





    
      

  

  
    #quit  ⇒ Object 
  

  

  




  

    

Disconnect from all currently connected servers



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 260

def quit
  Lib.memcached_quit(@struct)
  self
end

    		
  





    
      

  

  
    #replace(key, value, ttl = @default_ttl, marshal = true, flags = FLAGS)  ⇒ Object 
  

  

  




  

    

Replace a key/value pair. Raises Memcached::NotFound if the key does not exist on the server. The parameters are the same as set.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 368

def replace(key, value, ttl=@default_ttl, marshal=true, flags=FLAGS)
  value = marshal ? Marshal.dump(value) : value
  begin
    check_return_code(
       Lib.memcached_replace(@struct, key, value, ttl, flags),
      key
    )
  rescue => e
    tries ||= 0
    raise unless tries < options[:exception_retry_limit] && should_retry(e)
    tries += 1
    retry
  end
end

    		
  





    
      

  

  
    #reset(current_servers = nil)  ⇒ Object 
  

  

  




  

    

Reset the state of the libmemcached struct. This is useful for changing the server list at runtime.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 244

def reset(current_servers = nil)
  # Store state and teardown
  current_servers ||= servers
  prev_prefix_key = prefix_key
  quit

  # Create
  # FIXME Duplicates logic with initialize()
  @struct = Lib.memcached_create(nil)
  set_prefix_key(prev_prefix_key)
  set_behaviors
  set_credentials
  set_servers(current_servers)
end

    		
  





    
      

  

  
    #server_by_key(key)  ⇒ Object 
  

  

  




  

    

Return the server used by a particular key.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 547

def server_by_key(key)
  ret = Lib.memcached_server_by_key(@struct, key)
  if ret.is_a?(Array)
    check_return_code(ret.last)
    inspect_server(ret.first)
  else
    check_return_code(ret)
  end
rescue ABadKeyWasProvidedOrCharactersOutOfRange
end

    		
  





    
      

  

  
    #servers  ⇒ Object 
  

  

  




  

    

Return the array of server strings used to configure this instance.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 200

def servers
  server_structs.map do |server|
    inspect_server(server)
  end
end

    		
  





    
      

  

  
    #set(key, value, ttl = @default_ttl, marshal = true, flags = FLAGS)  ⇒ Object 
  

  

  




  

    

Set a key/value pair. Accepts a String key and an arbitrary Ruby object. Overwrites any existing value on the server.



Accepts an optional ttl value to specify the maximum lifetime of the key on the server, in seconds. ttl must be a FixNum. 0 means no ttl. Note that there is no guarantee that the key will persist as long as the ttl, but it will not persist longer.



Also accepts a marshal value, which defaults to true. Set marshal to false, and pass a String as the value, if you want to set a raw byte array.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 302

def set(key, value, ttl=@default_ttl, marshal=true, flags=FLAGS)
  value = marshal ? Marshal.dump(value) : value
  begin
    check_return_code(
      Lib.memcached_set(@struct, key, value, ttl, flags),
      key
    )
  rescue => e
    tries ||= 0
    retry if e.instance_of?(ClientError) && !tries
    raise unless tries < options[:exception_retry_limit] && should_retry(e)
    tries += 1
    retry
  end
end

    		
  





    
      

  

  
    #set_prefix_key(key)  ⇒ Object 
  

  
    Also known as:
    set_namespace
    
  

  




  

    

Set the prefix key.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 207

def set_prefix_key(key)
  check_return_code(
    if key
      key += options[:prefix_delimiter]
      raise ArgumentError, "Max prefix key + prefix delimiter size is #{Lib::MEMCACHED_PREFIX_KEY_MAX_SIZE - 1}" unless
        key.size < Lib::MEMCACHED_PREFIX_KEY_MAX_SIZE
      Lib.memcached_callback_set(@struct, Lib::MEMCACHED_CALLBACK_PREFIX_KEY, key)
    else
      Lib.memcached_callback_set(@struct, Lib::MEMCACHED_CALLBACK_PREFIX_KEY, "")
    end
  )
end

    		
  





    
      

  

  
    #set_servers(servers)  ⇒ Object 
  

  

  




  

    

Set the server list. FIXME Does not necessarily free any existing server structs.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 176

def set_servers(servers)
  Array(servers).each_with_index do |server, index|
    # Socket
    check_return_code(
      if server.is_a?(String) and File.socket?(server)
        args = [@struct, server, options[:default_weight].to_i]
        Lib.memcached_server_add_unix_socket_with_weight(*args)
      # Network
      elsif server.is_a?(String) and server =~ /^[\w\d\.-]+(:\d{1,5}){0,2}$/
        host, port, weight = server.split(":")
        args = [@struct, host, port.to_i, (weight || options[:default_weight]).to_i]
        if options[:use_udp]
          Lib.memcached_server_add_udp_with_weight(*args)
        else
          Lib.memcached_server_add_with_weight(*args)
        end
      else
        raise ArgumentError, "Servers must be either in the format 'host:port[:weight]' (e.g., 'localhost:11211' or  'localhost:11211:10') for a network server, or a valid path to a Unix domain socket (e.g., /var/run/memcached)."
      end
    )
  end
end

    		
  





    
      

  

  
    #should_retry(e)  ⇒ Object 
  

  

  




  

    

Should retry the exception



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 266

def should_retry(e)
  options[:exceptions_to_retry].each {|ex_class| return true if e.instance_of?(ex_class)}
  false
end

    		
  





    
      

  

  
    #stats(subcommand = nil)  ⇒ Object 
  

  

  




  

    

Return a Hash of statistics responses from the set of servers. Each value is an array with one entry for each server, in the same order the servers were defined.



  





  



  

    
      


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# File 'lib/memcached/memcached.rb', line 559

def stats(subcommand = nil)
  stats = Hash.new([])

  stat_struct, ret = Lib.memcached_stat(@struct, subcommand)
  check_return_code(ret)

  keys, ret = Lib.memcached_stat_get_keys(@struct, stat_struct)
  check_return_code(ret)

  keys.each do |key|
     server_structs.size.times do |index|

       value, ret = Lib.memcached_stat_get_value(
         @struct,
         Lib.memcached_select_stat_at(@struct, stat_struct, index),
         key)
       check_return_code(ret, key)

       value = case value
         when /^\d+\.\d+$/ then value.to_f
         when /^\d+$/ then value.to_i
         else value
       end

       stats[key.to_sym] += [value]
     end
  end

  Lib.memcached_stat_free(@struct, stat_struct)
  stats
rescue Memcached::SomeErrorsWereReported => _
  e = _.class.new("Error getting stats")
  e.set_backtrace(_.backtrace)
  raise e
end