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
3.0 KiB
Rust
108 lines
3.0 KiB
Rust
use crate::input_handler::{operate, CellPathOnlyArgs};
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use nu_engine::CallExt;
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use nu_protocol::ast::Call;
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use nu_protocol::ast::CellPath;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::Category;
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use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value};
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#[derive(Clone)]
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pub struct BytesReverse;
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impl Command for BytesReverse {
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fn name(&self) -> &str {
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"bytes reverse"
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}
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fn signature(&self) -> Signature {
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Signature::build("bytes reverse")
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.input_output_types(vec![(Type::Binary, Type::Binary)])
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.rest(
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"rest",
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SyntaxShape::CellPath,
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"for a data structure input, reverse data at the given cell paths",
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)
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.category(Category::Bytes)
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}
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fn usage(&self) -> &str {
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"Reverse the bytes in the pipeline."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["convert", "inverse", "flip"]
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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 cell_paths: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
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let arg = CellPathOnlyArgs::from(cell_paths);
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operate(reverse, arg, input, call.head, engine_state.ctrlc.clone())
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Reverse bytes `0x[1F FF AA AA]`",
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example: "0x[1F FF AA AA] | bytes reverse",
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result: Some(Value::Binary {
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val: vec![0xAA, 0xAA, 0xFF, 0x1F],
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span: Span::test_data(),
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}),
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},
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Example {
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description: "Reverse bytes `0x[FF AA AA]`",
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example: "0x[FF AA AA] | bytes reverse",
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result: Some(Value::Binary {
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val: vec![0xAA, 0xAA, 0xFF],
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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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}
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fn reverse(val: &Value, _args: &CellPathOnlyArgs, span: Span) -> Value {
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match val {
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Value::Binary {
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val,
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span: val_span,
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} => {
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let mut reversed_input = val.to_vec();
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reversed_input.reverse();
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Value::Binary {
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val: reversed_input,
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span: *val_span,
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}
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}
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// Propagate errors by explicitly matching them before the final case.
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Value::Error { .. } => val.clone(),
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other => Value::Error {
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error: Box::new(ShellError::OnlySupportsThisInputType {
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exp_input_type: "binary".into(),
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wrong_type: other.get_type().to_string(),
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dst_span: span,
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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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#[cfg(test)]
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mod tests {
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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(BytesReverse {})
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}
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}
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