pool (version 1.0.4)

poolCheckout: Check out and return object from the pool

Description

Use poolCheckout() to check out an object from the pool and poolReturn() to return it. You will receive a warning if all objects aren't returned before the pool is closed.

localCheckout() is a convenience function that can be used inside functions (and other function-scoped operations like shiny::reactive() and local()). It checks out an object and automatically returns it when the function exits

Note that validation is only performed when the object is checked out, so you generally want to keep the checked out around for as little time as possible.

When pooling DBI database connections, you normally would not use poolCheckout(). Instead, for single-shot queries, treat the pool object itself as the DBI connection object and it will perform checkout/return for you. And for transactions, use poolWithTransaction(). See dbPool() for an example.

Usage

poolCheckout(pool)
# S4 method for Pool
poolCheckout(pool)
poolReturn(object)
# S4 method for ANY
poolReturn(object)
localCheckout(pool, env = parent.frame())

Arguments

pool

The pool to get the object from.

object

Object to return

env

Environment corresponding to the execution frame. For expert use only.

Examples

pool <- dbPool(RSQLite::SQLite())
# For illustration only. You normally would not explicitly use
# poolCheckout with a DBI connection pool (see Description).
con <- poolCheckout(pool)
con
poolReturn(con)

f <- function() {
  con <- localCheckout(pool)
  # do something ...
}
f()

poolClose(pool)