nushell/crates/nu-command/src/conversions
Stefan Holderbach a52386e837
Box ShellError in Value::Error (#8375)
# Description

Our `ShellError` at the moment has a `std::mem::size_of<ShellError>` of
136 bytes (on AMD64). As a result `Value` directly storing the struct
also required 136 bytes (thanks to alignment requirements).

This change stores the `Value::Error` `ShellError` on the heap.

Pro:
- Value now needs just 80 bytes
- Should be 1 cacheline less (still at least 2 cachelines)

Con:
- More small heap allocations when dealing with `Value::Error`
  - More heap fragmentation
  - Potential for additional required memcopies

# Further code changes

Includes a small refactor of `try` due to a type mismatch in its large
match.

# User-Facing Changes

None for regular users.

Plugin authors may have to update their matches on `Value` if they use
`nu-protocol`

Needs benchmarking to see if there is a benefit in real world workloads.
**Update** small improvements in runtime for workloads with high volume
of values. Significant reduction in maximum resident set size, when many
values are held in memory.

# Tests + Formatting
2023-03-12 09:57:27 +01:00
..
into Box ShellError in Value::Error (#8375) 2023-03-12 09:57:27 +01:00
fill.rs Box ShellError in Value::Error (#8375) 2023-03-12 09:57:27 +01:00
fmt.rs Box ShellError in Value::Error (#8375) 2023-03-12 09:57:27 +01:00
mod.rs A fill command to replace str lpad and str rpad (#7846) 2023-02-09 14:56:52 -06:00