313 lines
8.0 KiB
Ruby
313 lines
8.0 KiB
Ruby
# frozen_string_literal: true
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#
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# A wrapper around redis that namespaces keys with the current site id
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#
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class DiscourseRedis
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class FallbackHandler
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include Singleton
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MASTER_ROLE_STATUS = "role:master"
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MASTER_LOADING_STATUS = "loading:1"
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MASTER_LOADED_STATUS = "loading:0"
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CONNECTION_TYPES = %w{normal pubsub}
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def initialize
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@master = true
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@running = false
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@mutex = Mutex.new
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@slave_config = DiscourseRedis.slave_config
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@message_bus_keepalive_interval = MessageBus.keepalive_interval
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end
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def verify_master
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synchronize do
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return if @thread && @thread.alive?
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@thread = Thread.new do
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loop do
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begin
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thread = Thread.new { initiate_fallback_to_master }
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thread.join
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break if synchronize { @master }
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sleep 5
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ensure
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thread.kill
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end
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end
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end
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end
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end
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def initiate_fallback_to_master
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success = false
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begin
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redis_config = DiscourseRedis.config.dup
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redis_config.delete(:connector)
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master_client = ::Redis::Client.new(redis_config)
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logger.warn "#{log_prefix}: Checking connection to master server..."
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info = master_client.call([:info])
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if info.include?(MASTER_LOADED_STATUS) && info.include?(MASTER_ROLE_STATUS)
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begin
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logger.warn "#{log_prefix}: Master server is active, killing all connections to slave..."
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self.master = true
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slave_client = ::Redis::Client.new(@slave_config)
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CONNECTION_TYPES.each do |connection_type|
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slave_client.call([:client, [:kill, 'type', connection_type]])
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end
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MessageBus.keepalive_interval = @message_bus_keepalive_interval
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Discourse.clear_readonly!
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Discourse.request_refresh!
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success = true
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ensure
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slave_client&.disconnect
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end
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end
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rescue => e
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logger.warn "#{log_prefix}: Connection to Master server failed with '#{e.message}'"
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ensure
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master_client&.disconnect
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end
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success
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end
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def master
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synchronize { @master }
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end
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def master=(args)
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synchronize do
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@master = args
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# Disables MessageBus keepalive when Redis is in readonly mode
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MessageBus.keepalive_interval = 0 if !@master
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end
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end
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private
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def synchronize
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@mutex.synchronize { yield }
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end
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def logger
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Rails.logger
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end
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def log_prefix
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"#{self.class}"
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end
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end
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class Connector < Redis::Client::Connector
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def initialize(options)
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super(options)
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@slave_options = DiscourseRedis.slave_config(options)
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@fallback_handler = DiscourseRedis::FallbackHandler.instance
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end
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def resolve(client = nil)
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if !@fallback_handler.master
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@fallback_handler.verify_master
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return @slave_options
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end
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begin
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options = @options.dup
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options.delete(:connector)
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client ||= Redis::Client.new(options)
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loading = client.call([:info, :persistence]).include?(
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DiscourseRedis::FallbackHandler::MASTER_LOADING_STATUS
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)
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loading ? @slave_options : @options
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rescue Redis::ConnectionError, Redis::CannotConnectError, RuntimeError => ex
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raise ex if ex.class == RuntimeError && ex.message != "Name or service not known"
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@fallback_handler.master = false
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@fallback_handler.verify_master
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raise ex
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ensure
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client.disconnect
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end
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end
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end
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def self.raw_connection(config = nil)
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config ||= self.config
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Redis.new(config)
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end
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def self.config
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GlobalSetting.redis_config
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end
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def self.slave_config(options = config)
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options.dup.merge!(host: options[:slave_host], port: options[:slave_port])
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end
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def initialize(config = nil, namespace: true)
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@config = config || DiscourseRedis.config
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@redis = DiscourseRedis.raw_connection(@config.dup)
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@namespace = namespace
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end
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def self.fallback_handler
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@fallback_handler ||= DiscourseRedis::FallbackHandler.instance
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end
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def without_namespace
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# Only use this if you want to store and fetch data that's shared between sites
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@redis
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end
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def self.ignore_readonly
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yield
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rescue Redis::CommandError => ex
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if ex.message =~ /READONLY/
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if !ENV["REDIS_RAILS_FAILOVER"]
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fallback_handler.verify_master if !fallback_handler.master
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end
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Discourse.received_redis_readonly!
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nil
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else
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raise ex
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end
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end
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# prefix the key with the namespace
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def method_missing(meth, *args, &block)
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if @redis.respond_to?(meth)
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DiscourseRedis.ignore_readonly { @redis.public_send(meth, *args, &block) }
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else
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super
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end
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end
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# Proxy key methods through, but prefix the keys with the namespace
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[:append, :blpop, :brpop, :brpoplpush, :decr, :decrby, :expire, :expireat, :get, :getbit, :getrange, :getset,
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:hdel, :hexists, :hget, :hgetall, :hincrby, :hincrbyfloat, :hkeys, :hlen, :hmget, :hmset, :hset, :hsetnx, :hvals, :incr,
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:incrby, :incrbyfloat, :lindex, :linsert, :llen, :lpop, :lpush, :lpushx, :lrange, :lrem, :lset, :ltrim,
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:mapped_hmset, :mapped_hmget, :mapped_mget, :mapped_mset, :mapped_msetnx, :move, :mset,
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:msetnx, :persist, :pexpire, :pexpireat, :psetex, :pttl, :rename, :renamenx, :rpop, :rpoplpush, :rpush, :rpushx, :sadd, :scard,
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:sdiff, :set, :setbit, :setex, :setnx, :setrange, :sinter, :sismember, :smembers, :sort, :spop, :srandmember, :srem, :strlen,
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:sunion, :ttl, :type, :watch, :zadd, :zcard, :zcount, :zincrby, :zrange, :zrangebyscore, :zrank, :zrem, :zremrangebyrank,
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:zremrangebyscore, :zrevrange, :zrevrangebyscore, :zrevrank, :zrangebyscore ].each do |m|
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define_method m do |*args|
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args[0] = "#{namespace}:#{args[0]}" if @namespace
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DiscourseRedis.ignore_readonly { @redis.public_send(m, *args) }
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end
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end
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# Implement our own because https://github.com/redis/redis-rb/issues/698 has stalled
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def exists(*keys)
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keys.map! { |a| "#{namespace}:#{a}" } if @namespace
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DiscourseRedis.ignore_readonly do
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@redis.synchronize do |client|
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client.call([:exists, *keys]) do |value|
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value > 0
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end
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end
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end
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end
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def mget(*args)
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args.map! { |a| "#{namespace}:#{a}" } if @namespace
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DiscourseRedis.ignore_readonly { @redis.mget(*args) }
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end
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def del(k)
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DiscourseRedis.ignore_readonly do
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k = "#{namespace}:#{k}" if @namespace
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@redis.del k
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end
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end
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def scan_each(options = {}, &block)
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DiscourseRedis.ignore_readonly do
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match = options[:match].presence || '*'
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options[:match] =
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if @namespace
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"#{namespace}:#{match}"
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else
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match
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end
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if block
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@redis.scan_each(options) do |key|
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key = remove_namespace(key) if @namespace
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block.call(key)
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end
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else
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@redis.scan_each(options).map do |key|
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key = remove_namespace(key) if @namespace
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key
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end
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end
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end
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end
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def keys(pattern = nil)
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DiscourseRedis.ignore_readonly do
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pattern = pattern || '*'
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pattern = "#{namespace}:#{pattern}" if @namespace
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keys = @redis.keys(pattern)
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if @namespace
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len = namespace.length + 1
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keys.map! { |k| k[len..-1] }
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end
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keys
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end
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end
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def delete_prefixed(prefix)
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DiscourseRedis.ignore_readonly do
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keys("#{prefix}*").each { |k| Discourse.redis.del(k) }
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end
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end
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def reconnect
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@redis._client.reconnect
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end
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def namespace_key(key)
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if @namespace
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"#{namespace}:#{key}"
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else
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key
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end
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end
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def namespace
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RailsMultisite::ConnectionManagement.current_db
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end
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def self.namespace
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Rails.logger.warn("DiscourseRedis.namespace is going to be deprecated, do not use it!")
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RailsMultisite::ConnectionManagement.current_db
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end
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def self.new_redis_store
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Cache.new
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end
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private
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def remove_namespace(key)
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key[(namespace.length + 1)..-1]
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end
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end
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