Class: Sequel::TimedQueueConnectionPool

Inherits:
ConnectionPool show all
Defined in:
lib/sequel/connection_pool/timed_queue.rb

Overview

A connection pool allowing multi-threaded access to a pool of connections, using a timed queue (only available in Ruby 3.2+).

Constant Summary

Constants inherited from ConnectionPool

ConnectionPool::OPTS, ConnectionPool::POOL_CLASS_MAP

Instance Attribute Summary collapse

Attributes inherited from ConnectionPool

#after_connect, #connect_sqls, #db

Instance Method Summary collapse

Methods inherited from ConnectionPool

#servers

Methods included from ConnectionPool::ClassMethods

#get_pool

Constructor Details

#initialize(db, opts = OPTS) ⇒ TimedQueueConnectionPool

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 PoolTimeout (default 5)

Raises:



18
19
20
21
22
23
24
25
26
27
28
29
 
# File 'lib/sequel/connection_pool/timed_queue.rb', line 18

def initialize(db, opts = OPTS)
  super
  @max_size = Integer(opts[:max_connections] || 4)
  raise(Sequel::Error, ':max_connections must be positive') if @max_size < 1
  @mutex = Mutex.new  
  # Size inside array so this still works while the pool is frozen.
  @size = [0]
  @allocated = {}
  @allocated.compare_by_identity
  @timeout = Float(opts[:pool_timeout] || 5)
  @queue = Queue.new
end

Instance Attribute Details

#max_size ⇒ Object (readonly)

The maximum number of connections this pool will create.



11
12
13
 
# File 'lib/sequel/connection_pool/timed_queue.rb', line 11

def max_size
  @max_size
end

Instance Method Details

#all_connections ⇒ Object

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.



34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
 
# File 'lib/sequel/connection_pool/timed_queue.rb', line 34

def all_connections
  hold do |conn|
    yield conn

    # Use a hash to record all connections already seen.  As soon as we
    # come across a connection we've already seen, we stop the loop.
    conns = {}
    conns.compare_by_identity
    while true
      conn = nil
      begin
        break unless (conn = @queue.pop(timeout: 0)) && !conns[conn]
        conns[conn] = true
        yield conn
      ensure
        @queue.push(conn) if conn
      end
    end
  end
end

#disconnect(opts = OPTS) ⇒ Object

Removes all connections currently in the pool’s queue. This method has the effect of disconnecting from the database, assuming that no connections are currently being used.

Once a connection is requested using #hold, the connection pool creates new connections to the database.



61
62
63
64
65
66
67
 
# File 'lib/sequel/connection_pool/timed_queue.rb', line 61

def disconnect(opts=OPTS)
  while conn = @queue.pop(timeout: 0)
    disconnect_connection(conn)
  end
  fill_queue
  nil
end

#hold(server = nil) ⇒ Object

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.



82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
 
# File 'lib/sequel/connection_pool/timed_queue.rb', line 82

def hold(server=nil)
  t = Sequel.current
  if conn = owned_connection(t)
    return yield(conn)
  end

  begin
    conn = acquire(t)
    yield conn
  rescue Sequel::DatabaseDisconnectError, *@error_classes => e
    if disconnect_error?(e)
      oconn = conn
      conn = nil
      disconnect_connection(oconn) if oconn
      sync{@allocated.delete(t)}
      fill_queue
    end
    raise
  ensure
    release(t) if conn
  end
end

#pool_type ⇒ Object 



105
106
107
 
# File 'lib/sequel/connection_pool/timed_queue.rb', line 105

def pool_type
  :timed_queue
end

#size ⇒ Object

The total number of connections in the pool.



110
111
112
 
# File 'lib/sequel/connection_pool/timed_queue.rb', line 110

def size
  sync{@size[0]}
end