Class | Sequel::ThreadedConnectionPool |
In: |
lib/sequel/connection_pool/threaded.rb
|
Parent: | Sequel::ConnectionPool |
A connection pool allowing multi-threaded access to a pool of connections. This is the default connection pool used by Sequel.
USE_WAITER | = | true |
allocated | [R] | A hash with thread keys and connection values for currently allocated connections. |
available_connections | [R] | An array of connections that are available for use by the pool. |
max_size | [R] | The maximum number of connections this pool will create (per shard/server if sharding). |
The following additional options are respected:
:max_connections : | The maximum number of connections the connection pool will open (default 4) |
:pool_timeout : | The amount of seconds to wait to acquire a connection before raising a PoolTimeoutError (default 5) |
# File lib/sequel/connection_pool/threaded.rb, line 25 25: def initialize(db, opts = OPTS) 26: super 27: @max_size = Integer(opts[:max_connections] || 4) 28: raise(Sequel::Error, ':max_connections must be positive') if @max_size < 1 29: @mutex = Mutex.new 30: @connection_handling = opts[:connection_handling] 31: @available_connections = [] 32: @allocated = {} 33: @timeout = Float(opts[:pool_timeout] || 5) 34: @waiter = ConditionVariable.new 35: end
Yield all of the available connections, and the one 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 available connections, which means that until the method‘s block returns, the pool is locked.
# File lib/sequel/connection_pool/threaded.rb, line 42 42: def all_connections 43: hold do |c| 44: sync do 45: yield c 46: @available_connections.each{|conn| yield conn} 47: end 48: end 49: end
Removes all connections currently available, 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 you want to be able to disconnect connections that are currently in use, use the ShardedThreadedConnectionPool, which can do that. This connection pool does not, for performance reasons. To use the sharded pool, pass the servers: {} option when connecting to the database.
Once a connection is requested using hold, the connection pool creates new connections to the database.
# File lib/sequel/connection_pool/threaded.rb, line 61 61: def disconnect(opts=OPTS) 62: conns = nil 63: sync do 64: conns = @available_connections.dup 65: @available_connections.clear 66: @waiter.signal 67: end 68: conns.each{|conn| disconnect_connection(conn)} 69: end
Chooses the first available connection, 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/threaded.rb, line 84 84: def hold(server=nil) 85: t = Thread.current 86: if conn = owned_connection(t) 87: return yield(conn) 88: end 89: begin 90: conn = acquire(t) 91: yield conn 92: rescue Sequel::DatabaseDisconnectError, *@error_classes => e 93: if disconnect_error?(e) 94: oconn = conn 95: conn = nil 96: disconnect_connection(oconn) if oconn 97: sync do 98: @allocated.delete(t) 99: @waiter.signal 100: end 101: end 102: raise 103: ensure 104: if conn 105: sync{release(t)} 106: if @connection_handling == :disconnect 107: disconnect_connection(conn) 108: end 109: end 110: end 111: end