Class | Sequel::ShardedThreadedConnectionPool |
In: |
lib/sequel/connection_pool/sharded_threaded.rb
|
Parent: | Sequel::ThreadedConnectionPool |
The slowest and most advanced connection, dealing with both multi-threaded access and configurations with multiple shards/servers.
In addition, this pool subclass also handles scheduling in-use connections to be removed from the pool when they are returned to it.
The following additional options are respected:
# File lib/sequel/connection_pool/sharded_threaded.rb, line 17 17: def initialize(opts = {}, &block) 18: super 19: @available_connections = {} 20: @connections_to_remove = [] 21: @servers = opts.fetch(:servers_hash, Hash.new(:default)) 22: add_servers([:default]) 23: add_servers(opts[:servers].keys) if opts[:servers] 24: end
Adds new servers to the connection pool. Primarily used in conjunction with master/slave or shard configurations. Allows for dynamic expansion of the potential slaves/shards at runtime. servers argument should be an array of symbols.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 29 29: def add_servers(servers) 30: sync do 31: servers.each do |server| 32: unless @servers.has_key?(server) 33: @servers[server] = server 34: @available_connections[server] = [] 35: @allocated[server] = {} 36: end 37: end 38: end 39: end
A hash of connections currently being used for the given server, key is the Thread, value is the connection. Nonexistent servers will return nil. Treat this as read only, do not modify the resulting object.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 44 44: def allocated(server=:default) 45: @allocated[server] 46: end
An array of connections opened but not currently used, for the given server. Nonexistent servers will return nil. Treat this as read only, do not modify the resulting object.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 51 51: def available_connections(server=:default) 52: @available_connections[server] 53: end
Removes all connections currently available on all servers, optionally yielding each connection to the given block. This method has the effect of disconnecting from the database, assuming that no connections are currently being used. If connections are being used, they are scheduled to be disconnected as soon as they are returned to the pool.
Once a connection is requested using hold, the connection pool creates new connections to the database. Options:
# File lib/sequel/connection_pool/sharded_threaded.rb, line 73 73: def disconnect(opts={}, &block) 74: block ||= @disconnection_proc 75: sync do 76: (opts[:server] ? Array(opts[:server]) : @servers.keys).each do |s| 77: disconnect_server(s, &block) 78: end 79: end 80: end
Chooses the first available connection to the given server, or if none are available, creates a new connection. Passes the connection to the supplied block:
pool.hold {|conn| conn.execute('DROP TABLE posts')}
Pool#hold is re-entrant, meaning it can be called recursively in the same thread without blocking.
If no connection is immediately available and the pool is already using the maximum number of connections, Pool#hold will block until a connection is available or the timeout expires. If the timeout expires before a connection can be acquired, a Sequel::PoolTimeout is raised.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 96 96: def hold(server=:default) 97: sync{server = @servers[server]} 98: t = Thread.current 99: if conn = owned_connection(t, server) 100: return yield(conn) 101: end 102: begin 103: unless conn = acquire(t, server) 104: time = Time.now 105: timeout = time + @timeout 106: sleep_time = @sleep_time 107: sleep sleep_time 108: until conn = acquire(t, server) 109: raise(::Sequel::PoolTimeout) if Time.now > timeout 110: sleep sleep_time 111: end 112: end 113: yield conn 114: rescue Sequel::DatabaseDisconnectError 115: sync{@connections_to_remove << conn} if conn 116: raise 117: ensure 118: sync{release(t, conn, server)} if conn 119: end 120: end
Remove servers from the connection pool. Primarily used in conjunction with master/slave or shard configurations. Similar to disconnecting from all given servers, except that after it is used, future requests for the server will use the :default server instead.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 126 126: def remove_servers(servers) 127: sync do 128: raise(Sequel::Error, "cannot remove default server") if servers.include?(:default) 129: servers.each do |server| 130: if @servers.include?(server) 131: disconnect_server(server, &@disconnection_proc) 132: @available_connections.delete(server) 133: @allocated.delete(server) 134: @servers.delete(server) 135: end 136: end 137: end 138: end
The total number of connections opened for the given server, should be equal to available_connections.length + allocated.length. Nonexistent servers will return the created count of the default server.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 58 58: def size(server=:default) 59: server = @servers[server] 60: @allocated[server].length + @available_connections[server].length 61: end