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Diffstat (limited to 'activesupport/lib/active_support/vendor/memcache-client-1.5.0.5/memcache.rb')
| -rw-r--r-- | activesupport/lib/active_support/vendor/memcache-client-1.5.0.5/memcache.rb | 868 |
1 files changed, 868 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/vendor/memcache-client-1.5.0.5/memcache.rb b/activesupport/lib/active_support/vendor/memcache-client-1.5.0.5/memcache.rb new file mode 100644 index 0000000000..e90ddf3359 --- /dev/null +++ b/activesupport/lib/active_support/vendor/memcache-client-1.5.0.5/memcache.rb @@ -0,0 +1,868 @@ +# 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' + +## +# 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' + + ## + # Default options for the cache object. + + DEFAULT_OPTIONS = { + :namespace => nil, + :readonly => false, + :multithread => false, + :failover => true + } + + ## + # Default memcached port. + + DEFAULT_PORT = 11211 + + ## + # Default memcached server weight. + + 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 + + ## + # The multithread setting for this instance + + attr_reader :multithread + + ## + # The servers this client talks to. Play at your own peril. + + attr_reader :servers + + ## + # Whether this client should failover reads and writes to another server + + attr_accessor :failover + ## + # Accepts a list of +servers+ and a list of +opts+. +servers+ may be + # omitted. See +servers=+ for acceptable server list arguments. + # + # Valid options for +opts+ are: + # + # [: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. + # + # Other options are ignored. + + def initialize(*args) + servers = [] + opts = {} + + case args.length + when 0 then # NOP + when 1 then + arg = args.shift + case arg + when Hash then opts = arg + when Array then servers = arg + when String then servers = [arg] + else raise ArgumentError, 'first argument must be Array, Hash or String' + end + when 2 then + servers, opts = args + else + raise ArgumentError, "wrong number of arguments (#{args.length} for 2)" + end + + opts = DEFAULT_OPTIONS.merge opts + @namespace = opts[:namespace] + @readonly = opts[:readonly] + @multithread = opts[:multithread] + @failover = opts[:failover] + @mutex = Mutex.new if @multithread + @buckets = [] + self.servers = servers + end + + ## + # 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] + end + + ## + # Returns whether there is at least one active server for the object. + + def active? + not @servers.empty? + end + + ## + # Returns whether or not the cache object was created read only. + + def readonly? + @readonly + end + + ## + # 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| + case server + when String + host, port, weight = server.split ':', 3 + 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" + 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 + end + + ## + # Decrements the value for +key+ by +amount+ and returns the new value. + # +key+ must already exist. If +key+ is not an integer, it is assumed to be + # 0. +key+ can not be decremented below 0. + + def decr(key, amount = 1) + raise MemCacheError, "Update of readonly cache" if @readonly + with_server(key) do |server, cache_key| + cache_decr server, cache_key, amount + end + rescue TypeError => err + handle_error nil, err + end + + ## + # Retrieves +key+ from memcache. If +raw+ is false, the value will be + # unmarshalled. + + def get(key, raw = false) + with_server(key) do |server, cache_key| + value = cache_get server, cache_key + return nil if value.nil? + value = Marshal.load value unless raw + return value + end + rescue TypeError => err + handle_error nil, err + end + + ## + # Retrieves multiple values from memcached in parallel, if possible. + # + # The memcached protocol supports the ability to retrieve multiple + # keys in a single request. Pass in an array of keys to this method + # and it will: + # + # 1. map the key to the appropriate memcached server + # 2. send a single request to each server that has one or more key values + # + # Returns a hash of values. + # + # cache["a"] = 1 + # cache["b"] = 2 + # cache.get_multi "a", "b" # => { "a" => 1, "b" => 2 } + + def get_multi(*keys) + raise MemCacheError, 'No active servers' unless active? + + keys.flatten! + key_count = keys.length + cache_keys = {} + server_keys = Hash.new { |h,k| h[k] = [] } + + # map keys to servers + keys.each do |key| + server, cache_key = request_setup key + cache_keys[cache_key] = key + server_keys[server] << cache_key + end + + 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 + end + end + + return results + rescue TypeError, IndexError => err + handle_error nil, err + end + + ## + # Increments the value for +key+ by +amount+ and returns the new value. + # +key+ must already exist. If +key+ is not an integer, it is assumed to be + # 0. + + def incr(key, amount = 1) + raise MemCacheError, "Update of readonly cache" if @readonly + with_server(key) do |server, cache_key| + cache_incr server, cache_key, amount + end + rescue TypeError => err + handle_error nil, err + end + + ## + # Add +key+ to the cache with value +value+ that expires in +expiry+ + # seconds. If +raw+ is true, +value+ will not be Marshalled. + # + # Warning: Readers should not call this method in the event of a cache miss; + # see MemCache#add. + + 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" + + with_socket_management(server) do |socket| + socket.write command + result = socket.gets + raise_on_error_response! result + + if result.nil? + server.close + raise MemCacheError, "lost connection to #{server.host}:#{server.port}" + end + + result + end + end + end + + ## + # Add +key+ to the cache with value +value+ that expires in +expiry+ + # seconds, but only if +key+ does not already exist in the cache. + # If +raw+ is true, +value+ will not be Marshalled. + # + # Readers should call this method in the event of a cache miss, not + # MemCache#set or MemCache#[]=. + + def add(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 = "add #{cache_key} 0 #{expiry} #{value.size}\r\n#{value}\r\n" + + with_socket_management(server) do |socket| + socket.write command + result = socket.gets + raise_on_error_response! result + result + end + end + end + + ## + # Removes +key+ from the cache in +expiry+ seconds. + + def delete(key, expiry = 0) + raise MemCacheError, "Update of readonly cache" if @readonly + with_server(key) do |server, cache_key| + with_socket_management(server) do |socket| + socket.write "delete #{cache_key} #{expiry}\r\n" + result = socket.gets + raise_on_error_response! result + result + end + end + end + + ## + # Flush the cache from all memcache servers. + + def flush_all + raise MemCacheError, 'No active servers' unless active? + 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" + result = socket.gets + raise_on_error_response! result + result + end + end + rescue IndexError => err + handle_error nil, err + ensure + @mutex.unlock if @multithread + end + end + + ## + # Reset the connection to all memcache servers. This should be called if + # there is a problem with a cache lookup that might have left the connection + # in a corrupted state. + + def reset + @servers.each { |server| server.close } + end + + ## + # Returns statistics for each memcached server. An explanation of the + # statistics can be found in the memcached docs: + # + # http://code.sixapart.com/svn/memcached/trunk/server/doc/protocol.txt + # + # Example: + # + # >> pp CACHE.stats + # {"localhost:11211"=> + # {"bytes"=>4718, + # "pid"=>20188, + # "connection_structures"=>4, + # "time"=>1162278121, + # "pointer_size"=>32, + # "limit_maxbytes"=>67108864, + # "cmd_get"=>14532, + # "version"=>"1.2.0", + # "bytes_written"=>432583, + # "cmd_set"=>32, + # "get_misses"=>0, + # "total_connections"=>19, + # "curr_connections"=>3, + # "curr_items"=>4, + # "uptime"=>1557, + # "get_hits"=>14532, + # "total_items"=>32, + # "rusage_system"=>0.313952, + # "rusage_user"=>0.119981, + # "bytes_read"=>190619}} + # => nil + + def stats + raise MemCacheError, "No active servers" unless active? + server_stats = {} + + @servers.each do |server| + next unless server.alive? + + with_socket_management(server) do |socket| + value = nil + socket.write "stats\r\n" + stats = {} + while line = socket.gets do + raise_on_error_response! line + break if line == "END\r\n" + if line =~ /\ASTAT ([\w]+) ([\w\.\:]+)/ then + name, value = $1, $2 + stats[name] = case name + when 'version' + value + when 'rusage_user', 'rusage_system' then + seconds, microseconds = value.split(/:/, 2) + microseconds ||= 0 + Float(seconds) + (Float(microseconds) / 1_000_000) + else + if value =~ /\A\d+\Z/ then + value.to_i + else + value + end + end + end + end + server_stats["#{server.host}:#{server.port}"] = stats + end + end + + raise MemCacheError, "No active servers" if server_stats.empty? + server_stats + end + + ## + # Shortcut to get a value from the cache. + + alias [] get + + ## + # Shortcut to save a value in the cache. This method does not set an + # expiration on the entry. Use set to specify an explicit expiry. + + def []=(key, value) + set key, value + end + + protected unless $TESTING + + ## + # Create a key for the cache, incorporating the namespace qualifier if + # requested. + + def make_cache_key(key) + if namespace.nil? then + key + else + "#{@namespace}:#{key}" + end + end + + ## + # Pick a server to handle the request based on a hash of the key. + + def get_server_for_key(key, options = {}) + raise ArgumentError, "illegal character in key #{key.inspect}" if + key =~ /\s/ + raise ArgumentError, "key too long #{key.inspect}" if key.length > 250 + 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 + + ## + # Returns an interoperable hash value for +key+. (I think, docs are + # sketchy for down servers). + + def hash_for(key) + (Zlib.crc32(key) >> 16) & 0x7fff + end + + ## + # Performs a raw decr for +cache_key+ from +server+. Returns nil if not + # found. + + def cache_decr(server, cache_key, amount) + with_socket_management(server) do |socket| + socket.write "decr #{cache_key} #{amount}\r\n" + text = socket.gets + raise_on_error_response! text + return nil if text == "NOT_FOUND\r\n" + return text.to_i + end + end + + ## + # Fetches the raw data for +cache_key+ from +server+. Returns nil on cache + # miss. + + def cache_get(server, cache_key) + with_socket_management(server) do |socket| + socket.write "get #{cache_key}\r\n" + keyline = socket.gets # "VALUE <key> <flags> <bytes>\r\n" + + if keyline.nil? then + server.close + raise MemCacheError, "lost connection to #{server.host}:#{server.port}" + end + + raise_on_error_response! keyline + return nil if keyline == "END\r\n" + + unless keyline =~ /(\d+)\r/ then + server.close + raise MemCacheError, "unexpected response #{keyline.inspect}" + end + value = socket.read $1.to_i + socket.read 2 # "\r\n" + socket.gets # "END\r\n" + return value + end + end + + ## + # Fetches +cache_keys+ from +server+ using a multi-get. + + def cache_get_multi(server, cache_keys) + with_socket_management(server) do |socket| + values = {} + socket.write "get #{cache_keys}\r\n" + + while keyline = socket.gets do + return values if keyline == "END\r\n" + raise_on_error_response! keyline + + unless keyline =~ /\AVALUE (.+) (.+) (.+)/ then + server.close + raise MemCacheError, "unexpected response #{keyline.inspect}" + end + + key, data_length = $1, $3 + values[$1] = socket.read data_length.to_i + socket.read(2) # "\r\n" + end + + server.close + raise MemCacheError, "lost connection to #{server.host}:#{server.port}" # TODO: retry here too + end + end + + ## + # Performs a raw incr for +cache_key+ from +server+. Returns nil if not + # found. + + def cache_incr(server, cache_key, amount) + with_socket_management(server) do |socket| + socket.write "incr #{cache_key} #{amount}\r\n" + text = socket.gets + raise_on_error_response! text + return nil if text == "NOT_FOUND\r\n" + return text.to_i + end + end + + ## + # Gets or creates a socket connected to the given server, and yields it + # to the block, wrapped in a mutex synchronization if @multithread is true. + # + # If a socket error (SocketError, SystemCallError, IOError) or protocol error + # (MemCacheError) is raised by the block, closes the socket, attempts to + # connect again, and retries the block (once). If an error is again raised, + # reraises it as MemCacheError. + # + # If unable to connect to the server (or if in the reconnect wait period), + # raises MemCacheError. Note that the socket connect code marks a server + # dead for a timeout period, so retrying does not apply to connection attempt + # failures (but does still apply to unexpectedly lost connections etc.). + + def with_socket_management(server, &block) + @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) + handle_error(server, err) + + rescue MemCacheError, SocketError, SystemCallError, IOError => err + handle_error(server, err) if retried || socket.nil? + retried = true + retry + end + ensure + @mutex.unlock if @multithread + end + + def with_server(key) + retried = false + begin + server, cache_key = request_setup(key) + yield server, cache_key + rescue IndexError => e + if !retried && @servers.size > 1 + puts "Connection to server #{server.inspect} DIED! Retrying operation..." + retried = true + retry + end + handle_error(nil, e) + end + end + + ## + # Handles +error+ from +server+. + + def handle_error(server, error) + raise error if error.is_a?(MemCacheError) + server.close if server + new_error = MemCacheError.new error.message + new_error.set_backtrace error.backtrace + raise new_error + end + + ## + # Performs setup for making a request with +key+ from memcached. Returns + # the server to fetch the key from and the complete key to use. + + def request_setup(key) + raise MemCacheError, 'No active servers' unless active? + cache_key = make_cache_key key + server = get_server_for_key cache_key + return server, cache_key + end + + def raise_on_error_response!(response) + if response =~ /\A(?:CLIENT_|SERVER_)?ERROR(.*)/ + raise MemCacheError, $1.strip + end + end + + ## + # This class represents a memcached server instance. + + class Server + + ## + # The amount of time to wait to establish a connection with a memcached + # server. If a connection cannot be established within this time limit, + # the server will be marked as down. + + 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. + + RETRY_DELAY = 30.0 + + ## + # The host the memcached server is running on. + + attr_reader :host + + ## + # The port the memcached server is listening on. + + attr_reader :port + + ## + # The weight given to the server. + + attr_reader :weight + + ## + # The time of next retry if the connection is dead. + + attr_reader :retry + + ## + # A text status string describing the state of the server. + + attr_reader :status + + ## + # Create a new MemCache::Server object for the memcached instance + # listening on the given host and port, weighted by the given weight. + + def initialize(memcache, host, port = DEFAULT_PORT, weight = DEFAULT_WEIGHT) + 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' + end + + ## + # Return a string representation of the server object. + + def inspect + "<MemCache::Server: %s:%d [%d] (%s)>" % [@host, @port, @weight, @status] + end + + ## + # Check whether the server connection is alive. This will cause the + # socket to attempt to connect if it isn't already connected and or if + # the server was previously marked as down and the retry time has + # been exceeded. + + def alive? + !!socket + end + + ## + # Try to connect to the memcached server targeted by this object. + # 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 + + # If the host was dead, don't retry for a while. + return if @retry and @retry > Time.now + + # Attempt to connect if not already connected. + begin + + @sock = TCPTimeoutSocket.new @host, @port + + if Socket.constants.include? 'TCP_NODELAY' then + @sock.setsockopt Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1 + end + @retry = nil + @status = 'CONNECTED' + rescue SocketError, SystemCallError, IOError, Timeout::Error => err + mark_dead err.message + end + + return @sock + ensure + @mutex.unlock if @multithread + end + + ## + # Close the connection to the memcached server targeted by this + # 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") + @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 + end + + end + + ## + # Base MemCache exception class. + + class MemCacheError < RuntimeError; end + +end + +# TCPSocket facade class which implements timeouts. +class TCPTimeoutSocket + def initialize(*args) + Timeout::timeout(MemCache::Server::CONNECT_TIMEOUT, SocketError) do + @sock = TCPSocket.new(*args) + @len = MemCache::Server::SOCKET_TIMEOUT.to_f || 0.5 + 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
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