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
109 lines
3.5 KiB
Rust
109 lines
3.5 KiB
Rust
use nu_engine::CallExt;
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use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::{
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Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, Span, Spanned,
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SyntaxShape, Type, Value,
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};
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#[derive(Clone)]
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pub struct Decode;
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impl Command for Decode {
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fn name(&self) -> &str {
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"decode"
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}
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fn usage(&self) -> &str {
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"Decode bytes into a string."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["text", "encoding", "decoding"]
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}
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fn signature(&self) -> nu_protocol::Signature {
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Signature::build("decode")
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.input_output_types(vec![(Type::Binary, Type::String)])
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.required("encoding", SyntaxShape::String, "the text encoding to use")
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.category(Category::Strings)
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}
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fn extra_usage(&self) -> &str {
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r#"Multiple encodings are supported; here are a few:
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big5, euc-jp, euc-kr, gbk, iso-8859-1, utf-16, cp1252, latin5
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For a more complete list of encodings please refer to the encoding_rs
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documentation link at https://docs.rs/encoding_rs/latest/encoding_rs/#statics"#
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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: "Decode the output of an external command",
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example: "^cat myfile.q | decode utf-8",
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result: None,
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},
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Example {
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description: "Decode an UTF-16 string into nushell UTF-8 string",
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example: r#"0x[00 53 00 6F 00 6D 00 65 00 20 00 44 00 61 00 74 00 61] | decode utf-16be"#,
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result: Some(Value::String {
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val: "Some Data".to_owned(),
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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 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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let encoding: Spanned<String> = call.req(engine_state, stack, 0)?;
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match input {
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PipelineData::ExternalStream { stdout: None, .. } => Ok(PipelineData::empty()),
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PipelineData::ExternalStream {
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stdout: Some(stream),
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..
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} => {
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let bytes: Vec<u8> = stream.into_bytes()?.item;
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super::encoding::decode(head, encoding, &bytes).map(|val| val.into_pipeline_data())
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}
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PipelineData::Value(v, ..) => match v {
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Value::Binary { val: bytes, .. } => super::encoding::decode(head, encoding, &bytes)
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.map(|val| val.into_pipeline_data()),
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Value::Error { error } => Err(*error),
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_ => Err(ShellError::OnlySupportsThisInputType {
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exp_input_type: "binary".into(),
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wrong_type: v.get_type().to_string(),
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dst_span: head,
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src_span: v.expect_span(),
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}),
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},
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// This should be more precise, but due to difficulties in getting spans
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// from PipelineData::ListData, this is as it is.
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_ => Err(ShellError::UnsupportedInput(
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"non-binary input".into(),
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"value originates from here".into(),
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head,
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input.span().unwrap_or(head),
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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 test {
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use super::*;
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#[test]
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fn test_examples() {
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crate::test_examples(Decode)
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}
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}
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