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 13 13: def initialize(opts = {}, &block) 14: super 15: @available_connections = {} 16: @connections_to_remove = [] 17: @servers = Hash.new(:default) 18: add_servers([:default]) 19: add_servers(opts[:servers].keys) if opts[:servers] 20: 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 25 25: def add_servers(servers) 26: sync do 27: servers.each do |server| 28: unless @servers.has_key?(server) 29: @servers[server] = server 30: @available_connections[server] = [] 31: @allocated[server] = {} 32: end 33: end 34: end 35: 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 40 40: def allocated(server=:default) 41: @allocated[server] 42: 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 47 47: def available_connections(server=:default) 48: @available_connections[server] 49: end
Removes all connection 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 69 69: def disconnect(opts={}, &block) 70: block ||= @disconnection_proc 71: sync do 72: (opts[:server] ? Array(opts[:server]) : @servers.keys).each do |s| 73: disconnect_server(s, &block) 74: end 75: end 76: 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 92 92: def hold(server=:default) 93: sync{server = @servers[server]} 94: t = Thread.current 95: if conn = owned_connection(t, server) 96: return yield(conn) 97: end 98: begin 99: unless conn = acquire(t, server) 100: time = Time.now 101: timeout = time + @timeout 102: sleep_time = @sleep_time 103: sleep sleep_time 104: until conn = acquire(t, server) 105: raise(::Sequel::PoolTimeout) if Time.now > timeout 106: sleep sleep_time 107: end 108: end 109: yield conn 110: rescue Sequel::DatabaseDisconnectError 111: sync{@connections_to_remove << conn} if conn 112: raise 113: ensure 114: sync{release(t, conn, server)} if conn 115: end 116: 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 122 122: def remove_servers(servers) 123: sync do 124: raise(Sequel::Error, "cannot remove default server") if servers.include?(:default) 125: servers.each do |server| 126: if @servers.include?(server) 127: disconnect_server(server, &@disconnection_proc) 128: @available_connections.delete(server) 129: @allocated.delete(server) 130: @servers.delete(server) 131: end 132: end 133: end 134: 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 54 54: def size(server=:default) 55: server = @servers[server] 56: @allocated[server].length + @available_connections[server].length 57: end