nushell/crates/nu-command/src/debug
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
..
ast.rs Shrink the size of Expr (#12610) 2024-04-24 15:46:35 +00:00
debug_.rs Add command_prelude module (#12291) 2024-03-26 21:17:30 +00:00
explain.rs ListStream touchup (#12524) 2024-05-05 16:00:59 +00:00
info.rs Remove lazy records (#12682) 2024-05-03 08:36:10 +08:00
inspect_table.rs Copy-on-write for record values (#12305) 2024-04-14 01:42:03 +00:00
inspect.rs Replace ExternalStream with new ByteStream type (#12774) 2024-05-16 07:11:18 -07:00
metadata_set.rs ListStream touchup (#12524) 2024-05-05 16:00:59 +00:00
metadata.rs Shrink the size of Expr (#12610) 2024-04-24 15:46:35 +00:00
mod.rs add ability to set metadata (#12564) 2024-04-19 09:03:59 +08:00
profile.rs Shrink the size of Expr (#12610) 2024-04-24 15:46:35 +00:00
timeit.rs Replace ExternalStream with new ByteStream type (#12774) 2024-05-16 07:11:18 -07:00
view_files.rs Shrink the size of Expr (#12610) 2024-04-24 15:46:35 +00:00
view_source.rs Remove the Value::Block case (#12582) 2024-04-21 07:03:33 +02:00
view_span.rs Add command_prelude module (#12291) 2024-03-26 21:17:30 +00:00
view.rs Add command_prelude module (#12291) 2024-03-26 21:17:30 +00:00