Managed Connections

This module provides the capability to from an abstract Paypal name, such as “paymentserv”, or “occ-conf” to an open connection.

The main entry point is the ConnectionManager.get_connection(). This function will promptly either:

1- raise an Exception which is a subclass of socket.error 2- return a socket

ConnectionManagers provide the following services:

1- name resolution (“paymentserv” to actual ip/port from topos) 2- transient markdown (keeping track of connection failures) 3- socket throttling (keeping track of total open sockets) 4- timeouts (connection and read timeouts from opscfg) 5- protecteds

In addition, by routing all connections through ConnectionManager, future refactorings/modifications will be easier. For example, fallbacks or IP multi-plexing.

class support.connection_mgr.Address(ip, port)

ip

Alias for field number 0

port

Alias for field number 1

class support.connection_mgr.AddressGroup(tiers)

An address group represents the set of addresses known by a specific name to a client at runtime. That is, in a specific environment (stage, live, etc), an address group represents the set of <ip, port> pairs to try.

An address group consists of tiers. Each tier should be fully exhausted before moving on to the next; tiers are “fallbacks”. A tier consists of prioritized addresses. Within a tier, the addresses should be tried in a priority weighted random order.

The simplest way to use an address group is just to iterate over it, and try each address in the order returned.

tiers: [ [(weight, (ip, port)), (weight, (ip, port)) ... ] ... ]

connect_ordering()

class support.connection_mgr.AddressGroupMap

For dev mode, will lazily pull in additional addresses.

class support.connection_mgr.ConnectInfo(connect_timeout_ms, response_timeout_ms, max_connect_retry, transient_markdown_enabled, markdown)

connect_timeout_ms

Alias for field number 0

markdown

Alias for field number 4

max_connect_retry

Alias for field number 2

response_timeout_ms

Alias for field number 1

transient_markdown_enabled

Alias for field number 3

class support.connection_mgr.ConnectionManager(address_groups=None, address_aliases=None, ssl_context=None)

cull_loop()

get_addr(name)

returns the first address which the logical name would resolve to, equivalent to get_all_addrs(name)[0]

get_all_addrs(name)

returns the all addresses which the logical name would resolve to, or raises NameNotFound if there is no known address for the given name

get_connection(name_or_addr, ssl=False, sock_type=None, read_timeout=None)

name_or_addr - the logical name to connect to, e.g. “db-r” ssl - if set to True, wrap socket with context.protected;

if set to an SSL context, wrap socket with that

sock_type - a type to wrap the socket in; the intention here is for protocols

that want to run asynchronous keep-alives, or higher level handshaking (strictly speaking, this is just a callable which accepts socket and

returns the thing that should be pooled, but for must uses it will probably be a class)

release_connection(sock)

exception support.connection_mgr.MarkedDownError

class support.connection_mgr.MonitoredSocket(sock, registry, protected, name=None, type=None, state=None)

A socket proxy which allows socket lifetime to be monitored.

close()

recv(bufsize, flags=0)

send(data, flags=0)

sendall(data, flags=0)

shutdown(how)

exception support.connection_mgr.MultiConnectFailure

exception support.connection_mgr.NameNotFound

exception support.connection_mgr.OutOfSockets

class support.connection_mgr.ServerModel(address)

This class represents an estimate of the state of a given “server”. “Server” is defined here by whatever accepts the socket connections, which in practice may be an entire pool of server machines/VMS, each of which has multiple worker thread/procs.

For example, estimate how many connections are currently open (note: only an estimate, since the exact server-side state of the sockets is unknown)

sock_in_use(sock)

class support.connection_mgr.ServerModelDirectory