forked from extern/nushell
a52386e837
# 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
108 lines
2.9 KiB
Rust
108 lines
2.9 KiB
Rust
use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
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#[derive(Clone)]
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pub struct SubCommand;
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impl Command for SubCommand {
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fn name(&self) -> &str {
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"math sqrt"
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}
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fn signature(&self) -> Signature {
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Signature::build("math sqrt")
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.input_output_types(vec![(Type::Number, Type::Number)])
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.vectorizes_over_list(true)
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.category(Category::Math)
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}
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fn usage(&self) -> &str {
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"Returns the square root of the input number."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["square", "root"]
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}
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fn run(
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&self,
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engine_state: &EngineState,
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_stack: &mut Stack,
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call: &Call,
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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let head = call.head;
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// This doesn't match explicit nulls
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if matches!(input, PipelineData::Empty) {
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return Err(ShellError::PipelineEmpty { dst_span: head });
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}
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input.map(
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move |value| operate(value, head),
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engine_state.ctrlc.clone(),
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)
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}
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fn examples(&self) -> Vec<Example> {
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vec![Example {
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description: "Compute the square root of each number in a list",
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example: "[9 16] | math sqrt",
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result: Some(Value::List {
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vals: vec![Value::test_int(3), Value::test_int(4)],
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span: Span::test_data(),
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}),
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}]
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}
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}
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fn operate(value: Value, head: Span) -> Value {
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match value {
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Value::Int { val, span } => {
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let squared = (val as f64).sqrt();
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if squared.is_nan() {
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return error_negative_sqrt(head, span);
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}
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Value::Float { val: squared, span }
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}
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Value::Float { val, span } => {
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let squared = val.sqrt();
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if squared.is_nan() {
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return error_negative_sqrt(head, span);
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}
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Value::Float { val: squared, span }
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}
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Value::Error { .. } => value,
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other => Value::Error {
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error: Box::new(ShellError::OnlySupportsThisInputType {
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exp_input_type: "numeric".into(),
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wrong_type: other.get_type().to_string(),
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dst_span: head,
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src_span: other.expect_span(),
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}),
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},
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}
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}
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fn error_negative_sqrt(head: Span, span: Span) -> Value {
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Value::Error {
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error: Box::new(ShellError::UnsupportedInput(
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String::from("Can't square root a negative number"),
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"value originates from here".into(),
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head,
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span,
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)),
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_examples() {
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use crate::test_examples;
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test_examples(SubCommand {})
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}
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}
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