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
getis called on an empty pool. Raises after timing out.Raises when
putis called on a full pool. That error is never expected in normal practice, as users should be callinggetfollowed byputwhenever 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. |
Methods
bind
bind(database)Associate the pool with a database.
| Parameter | |
|---|---|
| Name | Description |
database |
Database
database used by the pool: used to create sessions when needed. |
clear
clear()Delete all sessions in the pool.
get
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 |
`six.moves.queue.Empty | if the queue is empty. |
| Returns | |
|---|---|
| Type | Description |
Session | an existing session from the pool, or a newly-created session. |
ping
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
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 |
`six.moves.queue.Full | if the queue is full. |