Update bundled memcache-client from 1.5.0.5 to 1.6.4.99.

See http://www.mikeperham.com/2009/02/15/memcache-client-performance/

2 files changed, 198 insertions, 131 deletions

diff --git a/activesupport/lib/active_support/vendor.rb b/activesupport/lib/active_support/vendor.rb
index cee45cfea1..39da70a9f3 100644
--- a/activesupport/lib/active_support/vendor.rb
+++ b/activesupport/lib/active_support/vendor.rb
@@ -9,9 +9,9 @@ end
 require 'builder'
 
 begin
-  gem 'memcache-client', '>= 1.5.0.5'
+  gem 'memcache-client', '>= 1.6.5'
 rescue Gem::LoadError
-  $:.unshift "#{File.dirname(__FILE__)}/vendor/memcache-client-1.5.0.5"
+  $:.unshift "#{File.dirname(__FILE__)}/vendor/memcache-client-1.6.5"
 end
 
 begin
diff --git a/activesupport/lib/active_support/vendor/memcache-client-1.5.0.5/memcache.rb b/activesupport/lib/active_support/vendor/memcache-client-1.6.5/memcache.rb
index e90ddf3359..4d594c2089 100644
--- a/activesupport/lib/active_support/vendor/memcache-client-1.5.0.5/memcache.rb
+++ b/activesupport/lib/active_support/vendor/memcache-client-1.6.5/memcache.rb
@@ -1,52 +1,21 @@
-# All original code copyright 2005, 2006, 2007 Bob Cottrell, Eric Hodel,
-# The Robot Co-op.  All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions
-# are met:
-#
-# 1. Redistributions of source code must retain the above copyright
-#    notice, this list of conditions and the following disclaimer.
-# 2. Redistributions in binary form must reproduce the above copyright
-#    notice, this list of conditions and the following disclaimer in the
-#    documentation and/or other materials provided with the distribution.
-# 3. Neither the names of the authors nor the names of their contributors
-#    may be used to endorse or promote products derived from this software
-#    without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS
-# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
-# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
-# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
-# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
-# BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
-# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
-# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
-# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
 $TESTING = defined?($TESTING) && $TESTING
 
 require 'socket'
 require 'thread'
 require 'timeout'
-require 'rubygems'
 require 'zlib'
+require 'digest/sha1'
 
 ##
 # A Ruby client library for memcached.
 #
-# This is intended to provide access to basic memcached functionality.  It
-# does not attempt to be complete implementation of the entire API, but it is
-# approaching a complete implementation.
 
 class MemCache
 
   ##
   # The version of MemCache you are using.
 
-  VERSION = '1.5.0.5'
+  VERSION = '1.6.4.99'
 
   ##
   # Default options for the cache object.
@@ -54,8 +23,10 @@ class MemCache
   DEFAULT_OPTIONS = {
     :namespace   => nil,
     :readonly    => false,
-    :multithread => false,
-    :failover    => true
+    :multithread => true,
+    :failover    => true,
+    :timeout     => 0.5,
+    :logger      => nil,
   }
 
   ##
@@ -69,13 +40,6 @@ class MemCache
   DEFAULT_WEIGHT = 1
 
   ##
-  # The amount of time to wait for a response from a memcached server.  If a
-  # response is not completed within this time, the connection to the server
-  # will be closed and an error will be raised.
-
-  attr_accessor :request_timeout
-
-  ##
   # The namespace for this instance
 
   attr_reader :namespace
@@ -91,9 +55,22 @@ class MemCache
   attr_reader :servers
 
   ##
-  # Whether this client should failover reads and writes to another server
+  # Socket timeout limit with this client, defaults to 0.5 sec.
+  # Set to nil to disable timeouts.
+
+  attr_reader :timeout
+
+  ##
+  # Should the client try to failover to another server if the
+  # first server is down?  Defaults to true.
+
+  attr_reader :failover
+
+  ##
+  # Log debug/info/warn/error to the given Logger, defaults to nil.
+
+  attr_reader :logger
 
-  attr_accessor :failover
   ##
   # Accepts a list of +servers+ and a list of +opts+.  +servers+ may be
   # omitted.  See +servers=+ for acceptable server list arguments.
@@ -103,7 +80,11 @@ class MemCache
   #   [:namespace]   Prepends this value to all keys added or retrieved.
   #   [:readonly]    Raises an exception on cache writes when true.
   #   [:multithread] Wraps cache access in a Mutex for thread safety.
-  #
+  #   [:failover]    Should the client try to failover to another server if the
+  #                  first server is down?  Defaults to true.
+  #   [:timeout]     Time to use as the socket read timeout.  Defaults to 0.5 sec,
+  #                  set to nil to disable timeouts (this is a major performance penalty in Ruby 1.8).
+  #   [:logger]      Logger to use for info/debug output, defaults to nil
   # Other options are ignored.
 
   def initialize(*args)
@@ -130,9 +111,15 @@ class MemCache
     @namespace   = opts[:namespace]
     @readonly    = opts[:readonly]
     @multithread = opts[:multithread]
-    @failover      = opts[:failover]
+    @timeout     = opts[:timeout]
+    @failover    = opts[:failover]
+    @logger      = opts[:logger]
     @mutex       = Mutex.new if @multithread
-    @buckets     = []
+
+    logger.info { "memcache-client #{VERSION} #{Array(servers).inspect}" } if logger
+
+    Thread.current[:memcache_client] = self.object_id if !@multithread
+
     self.servers = servers
   end
 
@@ -140,8 +127,8 @@ class MemCache
   # Returns a string representation of the cache object.
 
   def inspect
-    "<MemCache: %d servers, %d buckets, ns: %p, ro: %p>" %
-      [@servers.length, @buckets.length, @namespace, @readonly]
+    "<MemCache: %d servers, ns: %p, ro: %p>" %
+      [@servers.length, @namespace, @readonly]
   end
 
   ##
@@ -162,7 +149,7 @@ class MemCache
   # Set the servers that the requests will be distributed between.  Entries
   # can be either strings of the form "hostname:port" or
   # "hostname:port:weight" or MemCache::Server objects.
-
+  #
   def servers=(servers)
     # Create the server objects.
     @servers = Array(servers).collect do |server|
@@ -172,21 +159,17 @@ class MemCache
         port ||= DEFAULT_PORT
         weight ||= DEFAULT_WEIGHT
         Server.new self, host, port, weight
-      when Server
-        if server.memcache.multithread != @multithread then
-          raise ArgumentError, "can't mix threaded and non-threaded servers"
-        end
-        server
       else
-        raise TypeError, "cannot convert #{server.class} into MemCache::Server"
+        server
       end
     end
 
-    # Create an array of server buckets for weight selection of servers.
-    @buckets = []
-    @servers.each do |server|
-      server.weight.times { @buckets.push(server) }
-    end
+    logger.debug { "Servers now: #{@servers.inspect}" } if logger
+
+    # There's no point in doing this if there's only one server
+    @continuum = create_continuum_for(@servers) if @servers.size > 1
+
+    @servers
   end
 
   ##
@@ -210,6 +193,7 @@ class MemCache
   def get(key, raw = false)
     with_server(key) do |server, cache_key|
       value = cache_get server, cache_key
+      logger.debug { "GET #{key} from #{server.inspect}: #{value ? value.to_s.size : 'nil'}" } if logger
       return nil if value.nil?
       value = Marshal.load value unless raw
       return value
@@ -233,6 +217,8 @@ class MemCache
   #   cache["a"] = 1
   #   cache["b"] = 2
   #   cache.get_multi "a", "b" # => { "a" => 1, "b" => 2 }
+  #
+  # Note that get_multi assumes the values are marshalled.
 
   def get_multi(*keys)
     raise MemCacheError, 'No active servers' unless active?
@@ -252,15 +238,20 @@ class MemCache
     results = {}
 
     server_keys.each do |server, keys_for_server|
-      keys_for_server = keys_for_server.join ' '
-      values = cache_get_multi server, keys_for_server
-      values.each do |key, value|
-        results[cache_keys[key]] = Marshal.load value
+      keys_for_server_str = keys_for_server.join ' '
+      begin
+        values = cache_get_multi server, keys_for_server_str
+        values.each do |key, value|
+          results[cache_keys[key]] = Marshal.load value
+        end
+      rescue IndexError => e
+        # Ignore this server and try the others
+        logger.warn { "Unable to retrieve #{keys_for_server.size} elements from #{server.inspect}: #{e.message}"} if logger
       end
     end
 
     return results
-  rescue TypeError, IndexError => err
+  rescue TypeError => err
     handle_error nil, err
   end
 
@@ -285,12 +276,19 @@ class MemCache
   # Warning: Readers should not call this method in the event of a cache miss;
   # see MemCache#add.
 
+  ONE_MB = 1024 * 1024
+
   def set(key, value, expiry = 0, raw = false)
     raise MemCacheError, "Update of readonly cache" if @readonly
     with_server(key) do |server, cache_key|
 
       value = Marshal.dump value unless raw
-      command = "set #{cache_key} 0 #{expiry} #{value.to_s.size}\r\n#{value}\r\n"
+      logger.debug { "SET #{key} to #{server.inspect}: #{value ? value.to_s.size : 'nil'}" } if logger
+
+      data = value.to_s
+      raise MemCacheError, "Value too large, memcached can only store 1MB of data per key" if data.size > ONE_MB
+
+      command = "set #{cache_key} 0 #{expiry} #{data.size}\r\n#{data}\r\n"
 
       with_socket_management(server) do |socket|
         socket.write command
@@ -319,7 +317,8 @@ class MemCache
     raise MemCacheError, "Update of readonly cache" if @readonly
     with_server(key) do |server, cache_key|
       value = Marshal.dump value unless raw
-      command = "add #{cache_key} 0 #{expiry} #{value.size}\r\n#{value}\r\n"
+      logger.debug { "ADD #{key} to #{server}: #{value ? value.to_s.size : 'nil'}" } if logger
+      command = "add #{cache_key} 0 #{expiry} #{value.to_s.size}\r\n#{value}\r\n"
 
       with_socket_management(server) do |socket|
         socket.write command
@@ -353,7 +352,6 @@ class MemCache
     raise MemCacheError, "Update of readonly cache" if @readonly
 
     begin
-      @mutex.lock if @multithread
       @servers.each do |server|
         with_socket_management(server) do |socket|
           socket.write "flush_all\r\n"
@@ -364,8 +362,6 @@ class MemCache
       end
     rescue IndexError => err
       handle_error nil, err
-    ensure
-      @mutex.unlock if @multithread
     end
   end
 
@@ -424,7 +420,7 @@ class MemCache
         while line = socket.gets do
           raise_on_error_response! line
           break if line == "END\r\n"
-          if line =~ /\ASTAT ([\w]+) ([\w\.\:]+)/ then
+          if line =~ /\ASTAT ([\S]+) ([\w\.\:]+)/ then
             name, value = $1, $2
             stats[name] = case name
                           when 'version'
@@ -478,6 +474,14 @@ class MemCache
   end
 
   ##
+  # Returns an interoperable hash value for +key+.  (I think, docs are
+  # sketchy for down servers).
+
+  def hash_for(key)
+    Zlib.crc32(key)
+  end
+
+  ##
   # Pick a server to handle the request based on a hash of the key.
 
   def get_server_for_key(key, options = {})
@@ -487,27 +491,17 @@ class MemCache
     raise MemCacheError, "No servers available" if @servers.empty?
     return @servers.first if @servers.length == 1
 
-    hkey = hash_for key
-    
-    if @failover
-      20.times do |try|
-        server = @buckets[hkey % @buckets.compact.size]
-        return server if server.alive?
-        hkey += hash_for "#{try}#{key}"
-      end
-    else
-      return @buckets[hkey % @buckets.compact.size]
-    end
-    
-    raise MemCacheError, "No servers available"
-  end
+    hkey = hash_for(key)
 
-  ##
-  # Returns an interoperable hash value for +key+.  (I think, docs are
-  # sketchy for down servers).
+    20.times do |try|
+      entryidx = Continuum.binary_search(@continuum, hkey)
+      server = @continuum[entryidx].server
+      return server if server.alive?
+      break unless failover
+      hkey = hash_for "#{try}#{key}"
+    end
 
-  def hash_for(key)
-    (Zlib.crc32(key) >> 16) & 0x7fff
+    raise MemCacheError, "No servers available"
   end
 
   ##
@@ -608,24 +602,28 @@ class MemCache
   # failures (but does still apply to unexpectedly lost connections etc.).
 
   def with_socket_management(server, &block)
+    check_multithread_status!
+
     @mutex.lock if @multithread
     retried = false
-    
+
     begin
       socket = server.socket
 
       # Raise an IndexError to show this server is out of whack. If were inside
       # a with_server block, we'll catch it and attempt to restart the operation.
-      
+
       raise IndexError, "No connection to server (#{server.status})" if socket.nil?
-      
+
       block.call(socket)
-      
+
     rescue SocketError => err
-      server.mark_dead(err.message)
+      logger.warn { "Socket failure: #{err.message}" } if logger
+      server.mark_dead(err)
       handle_error(server, err)
 
-    rescue MemCacheError, SocketError, SystemCallError, IOError => err
+    rescue MemCacheError, SystemCallError, IOError => err
+      logger.warn { "Generic failure: #{err.class.name}: #{err.message}" } if logger
       handle_error(server, err) if retried || socket.nil?
       retried = true
       retry
@@ -640,8 +638,9 @@ class MemCache
       server, cache_key = request_setup(key)
       yield server, cache_key
     rescue IndexError => e
+      logger.warn { "Server failed: #{e.class.name}: #{e.message}" } if logger
       if !retried && @servers.size > 1
-        puts "Connection to server #{server.inspect} DIED! Retrying operation..."
+        logger.info { "Connection to server #{server.inspect} DIED! Retrying operation..." } if logger
         retried = true
         retry
       end
@@ -677,6 +676,37 @@ class MemCache
     end
   end
 
+  def create_continuum_for(servers)
+    total_weight = servers.inject(0) { |memo, srv| memo + srv.weight }
+    continuum = []
+
+    servers.each do |server|
+      entry_count_for(server, servers.size, total_weight).times do |idx|
+        hash = Digest::SHA1.hexdigest("#{server.host}:#{server.port}:#{idx}")
+        value = Integer("0x#{hash[0..7]}")
+        continuum << Continuum::Entry.new(value, server)
+      end
+    end
+
+    continuum.sort { |a, b| a.value <=> b.value }
+  end
+
+  def entry_count_for(server, total_servers, total_weight)
+    ((total_servers * Continuum::POINTS_PER_SERVER * server.weight) / Float(total_weight)).floor
+  end
+
+  def check_multithread_status!
+    return if @multithread
+
+    if Thread.current[:memcache_client] != self.object_id
+      raise MemCacheError, <<-EOM
+        You are accessing this memcache-client instance from multiple threads but have not enabled multithread support.
+        Normally:  MemCache.new(['localhost:11211'], :multithread => true)
+        In Rails:  config.cache_store = [:mem_cache_store, 'localhost:11211', { :multithread => true }]
+      EOM
+    end
+  end
+
   ##
   # This class represents a memcached server instance.
 
@@ -690,13 +720,6 @@ class MemCache
     CONNECT_TIMEOUT = 0.25
 
     ##
-    # The amount of time to wait for a response from a memcached server.
-    # If a response isn't received within this time limit,
-    # the server will be marked as down.
-
-    SOCKET_TIMEOUT = 0.5
-
-    ##
     # The amount of time to wait before attempting to re-establish a
     # connection with a server that is marked dead.
 
@@ -727,6 +750,8 @@ class MemCache
 
     attr_reader :status
 
+    attr_reader :logger
+
     ##
     # Create a new MemCache::Server object for the memcached instance
     # listening on the given host and port, weighted by the given weight.
@@ -735,17 +760,15 @@ class MemCache
       raise ArgumentError, "No host specified" if host.nil? or host.empty?
       raise ArgumentError, "No port specified" if port.nil? or port.to_i.zero?
 
-      @memcache = memcache
       @host   = host
       @port   = port.to_i
       @weight = weight.to_i
 
-      @multithread = @memcache.multithread
-      @mutex = Mutex.new
-
       @sock   = nil
       @retry  = nil
       @status = 'NOT CONNECTED'
+      @timeout = memcache.timeout
+      @logger = memcache.logger
     end
 
     ##
@@ -770,7 +793,6 @@ class MemCache
     # Returns the connected socket object on success or nil on failure.
 
     def socket
-      @mutex.lock if @multithread
       return @sock if @sock and not @sock.closed?
 
       @sock = nil
@@ -780,8 +802,7 @@ class MemCache
 
       # Attempt to connect if not already connected.
       begin
-
-        @sock = TCPTimeoutSocket.new @host, @port
+        @sock = @timeout ? TCPTimeoutSocket.new(@host, @port, @timeout) : TCPSocket.new(@host, @port)
 
         if Socket.constants.include? 'TCP_NODELAY' then
           @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1
@@ -789,12 +810,11 @@ class MemCache
         @retry  = nil
         @status = 'CONNECTED'
       rescue SocketError, SystemCallError, IOError, Timeout::Error => err
-        mark_dead err.message
+        logger.warn { "Unable to open socket: #{err.class.name}, #{err.message}" } if logger
+        mark_dead err
       end
 
       return @sock
-    ensure
-      @mutex.unlock if @multithread
     end
 
     ##
@@ -802,24 +822,23 @@ class MemCache
     # object.  The server is not considered dead.
 
     def close
-      @mutex.lock if @multithread
       @sock.close if @sock && !@sock.closed?
       @sock   = nil
       @retry  = nil
       @status = "NOT CONNECTED"
-    ensure
-      @mutex.unlock if @multithread
     end
 
     ##
     # Mark the server as dead and close its socket.
 
-    def mark_dead(reason = "Unknown error")
+    def mark_dead(error)
       @sock.close if @sock && !@sock.closed?
       @sock   = nil
       @retry  = Time.now + RETRY_DELAY
 
-      @status = sprintf "%s:%s DEAD: %s, will retry at %s", @host, @port, reason, @retry
+      reason = "#{error.class.name}: #{error.message}"
+      @status = sprintf "%s:%s DEAD (%s), will retry at %s", @host, @port, reason, @retry
+      @logger.info { @status } if @logger
     end
 
   end
@@ -833,36 +852,84 @@ end
 
 # TCPSocket facade class which implements timeouts.
 class TCPTimeoutSocket
-  def initialize(*args)
+
+  def initialize(host, port, timeout)
     Timeout::timeout(MemCache::Server::CONNECT_TIMEOUT, SocketError) do
-      @sock = TCPSocket.new(*args)
-      @len = MemCache::Server::SOCKET_TIMEOUT.to_f || 0.5
+      @sock = TCPSocket.new(host, port)
+      @len = timeout
     end
   end
-  
+
   def write(*args)
     Timeout::timeout(@len, SocketError) do
       @sock.write(*args)
     end
   end
-  
+
   def gets(*args)
     Timeout::timeout(@len, SocketError) do
       @sock.gets(*args)
     end
   end
-  
+
   def read(*args)
     Timeout::timeout(@len, SocketError) do
       @sock.read(*args)
     end
   end
-  
+
   def _socket
     @sock
   end
-  
+
   def method_missing(meth, *args)
     @sock.__send__(meth, *args)
   end
-end
\ No newline at end of file
+
+  def closed?
+    @sock.closed?
+  end
+
+  def close
+    @sock.close
+  end
+end
+
+module Continuum
+  POINTS_PER_SERVER = 160 # this is the default in libmemcached
+
+  # Find the closest index in Continuum with value <= the given value
+  def self.binary_search(ary, value, &block)
+    upper = ary.size - 1
+    lower = 0
+    idx = 0
+
+    while(lower <= upper) do
+      idx = (lower + upper) / 2
+      comp = ary[idx].value <=> value
+
+      if comp == 0
+        return idx
+      elsif comp > 0
+        upper = idx - 1
+      else
+        lower = idx + 1
+      end
+    end
+    return upper
+  end
+
+  class Entry
+    attr_reader :value
+    attr_reader :server
+
+    def initialize(val, srv)
+      @value = val
+      @server = srv
+    end
+
+    def inspect
+      "<#{value}, #{server.host}:#{server.port}>"
+    end
+  end
+end