A concurrent data structure that exposes a linear sequence of R
resources as a single
cats.effect.kernel.Resource in F
without accumulation.
A Hotswap is allocated within a cats.effect.kernel.Resource that dictates the scope
of its lifetime. After creation, a Resource[F, R]
can be swapped in by calling swap.
The newly acquired resource is returned and is released either when the Hotswap is
finalized or upon the next call to swap, whichever occurs first.
The following diagram illustrates the linear allocation and release of three resources r1
,
r2
, and r3
cycled through Hotswap:
>----- swap(r1) ---- swap(r2) ---- swap(r3) ----X
| | | | |
Creation | | | |
r1 acquired | | |
r2 acquired | |
r1 released r3 acquired |
r2 released |
r3 released
Hotswap is particularly useful when working with effects that cycle through resources, like writing bytes to files or rotating files every N bytes or M seconds. Without Hotswap, such effects leak resources: on each file rotation, a file handle or some internal resource handle accumulates. With Hotswap, the only registered resource is the Hotswap itself, and each file is swapped in only after swapping the previous one out.
Ported from https://github.com/typelevel/fs2.
- Companion:
- object
Value members
Abstract methods
Allocates a new resource, closes the previous one if it exists, and returns the newly
allocated R
.
Allocates a new resource, closes the previous one if it exists, and returns the newly
allocated R
.
When the lifetime of the Hotswap is completed, the resource allocated by the most recent swap will be finalized.
swap finalizes the previous resource immediately, so users must ensure that the old R
is not used thereafter. Failure to do so may result in an error on the consumer side. In
any case, no resources will be leaked.
If swap is called after the lifetime of the Hotswap is over, it will raise an error, but will ensure that all resources are finalized before returning.