File.open('somefile.txt', 'wb') do |fh| # Open the file
fh.write "hello world" # Do some work with the file
end # Close file when block returns
ActiveRecord::Base.establish_connection(
:adapter => "sqlite",
:database => "path/to/dbfile")
connection_handle = ActiveRecord::Base.connection
def retrieve_connection_pool(klass)
pool = @connection_pools[klass.name]
return pool if pool
return nil if ActiveRecord::Base == klass
retrieve_connection_pool klass.superclass
end
spec = ActiveRecord::Base.specificiation
ActiveRecord::ConnectionPool.open(spec) do |conn|
...
end
spec = database_a
ActiveRecord::ConnectionPool.open(spec) do |conn|
User.find_all
end
spec = database_b
ActiveRecord::ConnectionPool.open(spec) do |conn|
User.find_all
end
# Retrieve the connection associated with the current thread, or call
# #checkout to obtain one if necessary.
#
# #connection can be called any number of times; the connection is
# held in a hash keyed by the thread id.
def connection
@reserved_connections[current_connection_id] ||= checkout
end
def current_connection_id #:nodoc:
ActiveRecord::Base.connection_id ||= Thread.current.object_id
end
def connection_id
Thread.current['ActiveRecord::Base.connection_id']
end
def connection_id=(connection_id)
Thread.current['ActiveRecord::Base.connection_id'] = connection_id
end
# Returns any connections in use by the current thread back to the pool,
# and also returns connections to the pool cached by threads that are no
# longer alive.
def clear_active_connections!
@connection_pools.each_value {|pool| pool.release_connection }
end
# Signal that the thread is finished with the current connection.
# #release_connection releases the connection-thread association
# and returns the connection to the pool.
def release_connection(with_id = current_connection_id)
conn = @reserved_connections.delete(with_id)
checkin conn if conn
end
@queue.wait(@timeout)
if(@checked_out.size < @connections.size)
next
else
clear_stale_cached_connections!
if @size == @checked_out.size
raise ConnectionTimeoutError, "could not obtain a database connection#{" within #{@timeout} seconds" if @timeout}. The max pool size is currently #{@size}; consider increasing it."
end
end
def clear_stale_cached_connections!
keys = @reserved_connections.keys - Thread.list.find_all { |t|
t.alive?
}.map { |thread| thread.object_id }
keys.each do |key|
checkin @reserved_connections[key]
@reserved_connections.delete(key)
end
end
class ConnectionManagement
def call env
spec = ActiveRecord::Base.spec
connection = ActiveRecord::ConnectionPool.open spec
ActiveRecord::Base.connection = connection
@app.call env
connection.close
end
end
Thread.new do
spec = ActiveRecord::Base.spec
ActiveRecord::ConnectionPool.open(spec) do |connection|
ActiveRecord::Base.connection = connection
# do some stuff
end
end
