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:
:servers - A hash of servers to use. Keys should be symbols. If not present, will use a single :default server. The server name symbol will be passed to the connection_proc.
:servers_hash - The base hash to use for the servers. By default, Sequel uses Hash.new(:default). You can use a hash with a default proc that raises an error if you want to catch all cases where a nonexistent server is used.
# 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
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 53 53: def all_connections 54: t = Thread.current 55: sync do 56: @allocated.values.each do |threads| 57: threads.each do |thread, conn| 58: yield conn if t == thread 59: end 60: end 61: @available_connections.values.each{|v| v.each{|c| yield c}} 62: end 63: 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 68 68: def available_connections(server=:default) 69: @available_connections[server] 70: 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 #, the connection pool creates new connections to the database. Options:
:server - Should be a symbol specifing the server to disconnect from, or an array of symbols to specify multiple servers.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 90 90: def disconnect(opts={}, &block) 91: block ||= @disconnection_proc 92: sync do 93: (opts[:server] ? Array(opts[:server]) : @servers.keys).each do |s| 94: disconnect_server(s, &block) 95: end 96: end 97: 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 113 113: def hold(server=:default) 114: server = pick_server(server) 115: t = Thread.current 116: if conn = owned_connection(t, server) 117: return yield(conn) 118: end 119: begin 120: unless conn = acquire(t, server) 121: time = Time.now 122: timeout = time + @timeout 123: sleep_time = @sleep_time 124: sleep sleep_time 125: until conn = acquire(t, server) 126: raise(::Sequel::PoolTimeout) if Time.now > timeout 127: sleep sleep_time 128: end 129: end 130: yield conn 131: rescue Sequel::DatabaseDisconnectError 132: sync{@connections_to_remove << conn} if conn 133: raise 134: ensure 135: sync{release(t, conn, server)} if conn 136: end 137: 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 143 143: def remove_servers(servers) 144: sync do 145: raise(Sequel::Error, "cannot remove default server") if servers.include?(:default) 146: servers.each do |server| 147: if @servers.include?(server) 148: disconnect_server(server, &@disconnection_proc) 149: @available_connections.delete(server) 150: @allocated.delete(server) 151: @servers.delete(server) 152: end 153: end 154: end 155: end
Return an array of symbols for servers in the connection pool.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 158 158: def servers 159: sync{@servers.keys} 160: 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 75 75: def size(server=:default) 76: server = @servers[server] 77: @allocated[server].length + @available_connections[server].length 78: end
Assigns a connection to the supplied thread for the given server, if one is available. The calling code should NOT already have the mutex when calling this.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 167 167: def acquire(thread, server) 168: sync do 169: if conn = available(server) 170: allocated(server)[thread] = conn 171: end 172: end 173: end
Returns an available connection to the given server. If no connection is available, tries to create a new connection. The calling code should already have the mutex before calling this.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 178 178: def available(server) 179: available_connections(server).pop || make_new(server) 180: end
Disconnect from the given server. Disconnects available connections immediately, and schedules currently allocated connections for disconnection as soon as they are returned to the pool. The calling code should already have the mutex before calling this.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 186 186: def disconnect_server(server, &block) 187: if conns = available_connections(server) 188: conns.each{|conn| block.call(conn)} if block 189: conns.clear 190: end 191: @connections_to_remove.concat(allocated(server).values) 192: end
Creates a new connection to the given server if the size of the pool for the server is less than the maximum size of the pool. The calling code should already have the mutex before calling this.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 197 197: def make_new(server) 198: if (n = size(server)) >= @max_size 199: allocated(server).to_a.each{|t, c| release(t, c, server) unless t.alive?} 200: n = nil 201: end 202: default_make_new(server) if (n || size(server)) < @max_size 203: end
Returns the connection owned by the supplied thread for the given server, if any. The calling code should NOT already have the mutex before calling this.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 207 207: def owned_connection(thread, server) 208: sync{@allocated[server][thread]} 209: end
If the server given is in the hash, return it, otherwise, return the default server.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 212 212: def pick_server(server) 213: sync{@servers[server]} 214: end
Releases the connection assigned to the supplied thread and server. If the server or connection given is scheduled for disconnection, remove the connection instead of releasing it back to the pool. The calling code should already have the mutex before calling this.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 220 220: def release(thread, conn, server) 221: if @connections_to_remove.include?(conn) 222: remove(thread, conn, server) 223: else 224: if @queue 225: available_connections(server).unshift(allocated(server).delete(thread)) 226: else 227: available_connections(server) << allocated(server).delete(thread) 228: end 229: end 230: end
Removes the currently allocated connection from the connection pool. The calling code should already have the mutex before calling this.
# File lib/sequel/connection_pool/sharded_threaded.rb, line 234 234: def remove(thread, conn, server) 235: @connections_to_remove.delete(conn) 236: allocated(server).delete(thread) if @servers.include?(server) 237: @disconnection_proc.call(conn) if @disconnection_proc 238: end
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