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 16 16: def initialize(db, opts = OPTS) 17: super 18: @available_connections = {} 19: @connections_to_remove = [] 20: @servers = opts.fetch(:servers_hash, Hash.new(:default)) 21: add_servers([:default]) 22: add_servers(opts[:servers].keys) if opts[:servers] 23: 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 28 28: def add_servers(servers) 29: sync do 30: servers.each do |server| 31: unless @servers.has_key?(server) 32: @servers[server] = server 33: @available_connections[server] = [] 34: @allocated[server] = {} 35: end 36: end 37: end 38: end
Yield all of the available connections, and the ones currently allocated to this thread. This will not yield connections currently allocated to other threads, as it is not safe to operate on them. This holds the mutex while it is yielding all of the connections, which means that until the method‘s block returns, the pool is locked.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 52 52: def all_connections 53: t = Thread.current 54: sync do 55: @allocated.values.each do |threads| 56: threads.each do |thread, conn| 57: yield conn if t == thread 58: end 59: end 60: @available_connections.values.each{|v| v.each{|c| yield c}} 61: end 62: 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 43 43: def allocated(server=:default) 44: @allocated[server] 45: 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 67 67: def available_connections(server=:default) 68: @available_connections[server] 69: 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 89 89: def disconnect(opts=OPTS) 90: sync do 91: (opts[:server] ? Array(opts[:server]) : @servers.keys).each do |s| 92: disconnect_server(s) 93: end 94: end 95: 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 111 111: def hold(server=:default) 112: server = pick_server(server) 113: t = Thread.current 114: if conn = owned_connection(t, server) 115: return yield(conn) 116: end 117: begin 118: unless conn = acquire(t, server) 119: time = Time.now 120: timeout = time + @timeout 121: sleep_time = @sleep_time 122: sleep sleep_time 123: until conn = acquire(t, server) 124: raise(::Sequel::PoolTimeout) if Time.now > timeout 125: sleep sleep_time 126: end 127: end 128: yield conn 129: rescue Sequel::DatabaseDisconnectError 130: sync{@connections_to_remove << conn} if conn 131: raise 132: ensure 133: sync{release(t, conn, server)} if conn 134: end 135: end
# File lib/sequel/connection_pool/sharded_threaded.rb, line 160 160: def pool_type 161: :sharded_threaded 162: 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 141 141: def remove_servers(servers) 142: sync do 143: raise(Sequel::Error, "cannot remove default server") if servers.include?(:default) 144: servers.each do |server| 145: if @servers.include?(server) 146: disconnect_server(server) 147: @available_connections.delete(server) 148: @allocated.delete(server) 149: @servers.delete(server) 150: end 151: end 152: end 153: 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 74 74: def size(server=:default) 75: server = @servers[server] 76: @allocated[server].length + @available_connections[server].length 77: end