nushell/crates/nu-command/src/conversions/into/filesize.rs
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

158 lines
4.7 KiB
Rust

use crate::input_handler::{operate, CellPathOnlyArgs};
use nu_engine::CallExt;
use nu_protocol::{
ast::{Call, CellPath},
engine::{Command, EngineState, Stack},
Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct SubCommand;
impl Command for SubCommand {
fn name(&self) -> &str {
"into filesize"
}
fn signature(&self) -> Signature {
Signature::build("into filesize")
.input_output_types(vec![
(Type::Int, Type::Filesize),
(Type::Number, Type::Filesize),
(Type::String, Type::Filesize),
(Type::Filesize, Type::Filesize),
])
.rest(
"rest",
SyntaxShape::CellPath,
"for a data structure input, convert data at the given cell paths",
)
.category(Category::Conversions)
}
fn usage(&self) -> &str {
"Convert value to filesize."
}
fn search_terms(&self) -> Vec<&str> {
vec!["convert", "number", "bytes"]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
let args = CellPathOnlyArgs::from(cell_paths);
operate(action, args, input, call.head, engine_state.ctrlc.clone())
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Convert string to filesize in table",
example: "[[bytes]; ['5'] [3.2] [4] [2kb]] | into filesize bytes",
result: None,
},
Example {
description: "Convert string to filesize",
example: "'2' | into filesize",
result: Some(Value::Filesize {
val: 2,
span: Span::test_data(),
}),
},
Example {
description: "Convert decimal to filesize",
example: "8.3 | into filesize",
result: Some(Value::Filesize {
val: 8,
span: Span::test_data(),
}),
},
Example {
description: "Convert int to filesize",
example: "5 | into filesize",
result: Some(Value::Filesize {
val: 5,
span: Span::test_data(),
}),
},
Example {
description: "Convert file size to filesize",
example: "4KB | into filesize",
result: Some(Value::Filesize {
val: 4000,
span: Span::test_data(),
}),
},
]
}
}
pub fn action(input: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
if let Ok(value_span) = input.span() {
match input {
Value::Filesize { .. } => input.clone(),
Value::Int { val, .. } => Value::Filesize {
val: *val,
span: value_span,
},
Value::Float { val, .. } => Value::Filesize {
val: *val as i64,
span: value_span,
},
Value::String { val, .. } => match int_from_string(val, value_span) {
Ok(val) => Value::Filesize {
val,
span: value_span,
},
Err(error) => Value::Error {
error: Box::new(error),
},
},
Value::Nothing { .. } => Value::Filesize {
val: 0,
span: value_span,
},
other => Value::Error {
error: Box::new(ShellError::OnlySupportsThisInputType {
exp_input_type: "string and integer".into(),
wrong_type: other.get_type().to_string(),
dst_span: span,
src_span: value_span,
}),
},
}
} else {
// Propagate existing errors
input.clone()
}
}
fn int_from_string(a_string: &str, span: Span) -> Result<i64, ShellError> {
match a_string.trim().parse::<bytesize::ByteSize>() {
Ok(n) => Ok(n.0 as i64),
Err(_) => Err(ShellError::CantConvert {
to_type: "int".into(),
from_type: "string".into(),
span,
help: None,
}),
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(SubCommand {})
}
}