Class PingingPool (3.15.0)

PingingPool(size=10, default_timeout=10, ping_interval=3000, labels=None)

Concrete session pool implementation:

Pre-allocates / creates a fixed number of sessions.
Sessions are used in "round-robin" order (LRU first).
"Pings" existing sessions in the background after a specified interval via an API call (session.ping()).
Blocks, with a timeout, when get is called on an empty pool. Raises after timing out.
Raises when put is called on a full pool. That error is never expected in normal practice, as users should be calling get followed by put whenever in need of a session.

The application is responsible for calling ping at appropriate times, e.g. from a background thread.

Parameters

Name	Description
size	`int` fixed pool size
default_timeout	`int` default timeout, in seconds, to wait for a returned session.
ping_interval	`int` interval at which to ping sessions.
labels	`dict (str -> str) or None` (Optional) user-assigned labels for sessions created by the pool.

builtins.object > AbstractSessionPool > PingingPool

bind(database)

Associate the pool with a database.

Parameter

Name	Description
database	`Database` database used by the pool to create sessions when needed.

clear()

Delete all sessions in the pool.

get(timeout=None)

Check a session out from the pool.

Parameter

Name	Description
timeout	`int` seconds to block waiting for an available session

Exceptions

Type	Description
`queue.Empty	if the queue is empty.

Returns

Type	Description
Session	an existing session from the pool, or a newly-created session.

ping()

Refresh maybe-expired sessions in the pool.

This method is designed to be called from a background thread, or during the "idle" phase of an event loop.

put(session)

Return a session to the pool.

Never blocks: if the pool is full, raises.

Parameter

Name	Description
session	`Session` the session being returned.

Exceptions

Type	Description
`queue.Full	if the queue is full.