nushell/crates/nu-cli/src/eval_cmds.rs
Ian Manske 6fd854ed9f
Replace ExternalStream with new ByteStream type (#12774)
# Description
This PR introduces a `ByteStream` type which is a `Read`-able stream of
bytes. Internally, it has an enum over three different byte stream
sources:
```rust
pub enum ByteStreamSource {
    Read(Box<dyn Read + Send + 'static>),
    File(File),
    Child(ChildProcess),
}
```

This is in comparison to the current `RawStream` type, which is an
`Iterator<Item = Vec<u8>>` and has to allocate for each read chunk.

Currently, `PipelineData::ExternalStream` serves a weird dual role where
it is either external command output or a wrapper around `RawStream`.
`ByteStream` makes this distinction more clear (via `ByteStreamSource`)
and replaces `PipelineData::ExternalStream` in this PR:
```rust
pub enum PipelineData {
    Empty,
    Value(Value, Option<PipelineMetadata>),
    ListStream(ListStream, Option<PipelineMetadata>),
    ByteStream(ByteStream, Option<PipelineMetadata>),
}
```

The PR is relatively large, but a decent amount of it is just repetitive
changes.

This PR fixes #7017, fixes #10763, and fixes #12369.

This PR also improves performance when piping external commands. Nushell
should, in most cases, have competitive pipeline throughput compared to,
e.g., bash.
| Command | Before (MB/s) | After (MB/s) | Bash (MB/s) |
| -------------------------------------------------- | -------------:|
------------:| -----------:|
| `throughput \| rg 'x'` | 3059 | 3744 | 3739 |
| `throughput \| nu --testbin relay o> /dev/null` | 3508 | 8087 | 8136 |

# User-Facing Changes
- This is a breaking change for the plugin communication protocol,
because the `ExternalStreamInfo` was replaced with `ByteStreamInfo`.
Plugins now only have to deal with a single input stream, as opposed to
the previous three streams: stdout, stderr, and exit code.
- The output of `describe` has been changed for external/byte streams.
- Temporary breaking change: `bytes starts-with` no longer works with
byte streams. This is to keep the PR smaller, and `bytes ends-with`
already does not work on byte streams.
- If a process core dumped, then instead of having a `Value::Error` in
the `exit_code` column of the output returned from `complete`, it now is
a `Value::Int` with the negation of the signal number.

# After Submitting
- Update docs and book as necessary
- Release notes (e.g., plugin protocol changes)
- Adapt/convert commands to work with byte streams (high priority is
`str length`, `bytes starts-with`, and maybe `bytes ends-with`).
- Refactor the `tee` code, Devyn has already done some work on this.

---------

Co-authored-by: Devyn Cairns <devyn.cairns@gmail.com>
2024-05-16 07:11:18 -07:00

71 lines
2.1 KiB
Rust

use log::info;
use nu_engine::{convert_env_values, eval_block};
use nu_parser::parse;
use nu_protocol::{
debugger::WithoutDebug,
engine::{EngineState, Stack, StateWorkingSet},
report_error, PipelineData, ShellError, Spanned, Value,
};
use std::sync::Arc;
/// Run a command (or commands) given to us by the user
pub fn evaluate_commands(
commands: &Spanned<String>,
engine_state: &mut EngineState,
stack: &mut Stack,
input: PipelineData,
table_mode: Option<Value>,
no_newline: bool,
) -> Result<(), ShellError> {
// Translate environment variables from Strings to Values
convert_env_values(engine_state, stack)?;
// Parse the source code
let (block, delta) = {
if let Some(ref t_mode) = table_mode {
let mut config = engine_state.get_config().clone();
config.table_mode = t_mode.coerce_str()?.parse().unwrap_or_default();
engine_state.set_config(config);
}
let mut working_set = StateWorkingSet::new(engine_state);
let output = parse(&mut working_set, None, commands.item.as_bytes(), false);
if let Some(warning) = working_set.parse_warnings.first() {
report_error(&working_set, warning);
}
if let Some(err) = working_set.parse_errors.first() {
report_error(&working_set, err);
std::process::exit(1);
}
(output, working_set.render())
};
// Update permanent state
engine_state.merge_delta(delta)?;
// Run the block
let pipeline = eval_block::<WithoutDebug>(engine_state, stack, &block, input)?;
if let PipelineData::Value(Value::Error { error, .. }, ..) = pipeline {
return Err(*error);
}
if let Some(t_mode) = table_mode {
Arc::make_mut(&mut engine_state.config).table_mode =
t_mode.coerce_str()?.parse().unwrap_or_default();
}
if let Some(status) = pipeline.print(engine_state, stack, no_newline, false)? {
if status.code() != 0 {
std::process::exit(status.code())
}
}
info!("evaluate {}:{}:{}", file!(), line!(), column!());
Ok(())
}