Panic quick-round-tripping parquet file

[NotTheDr01ds]

Describe the bug

polars save panics while attempting to open and save a parquet file in the same pipeline.

How to reproduce

[ 1 2 3 ] | polars into-df | polars save simple.parquet
polars open simple.parquet | polars save simple.parquet
# => thread 'polars-0' panicked at /home/ntd/.local/share/rust/cargo/registry/src/index.crates.io-6f17d22bba15001f/polars-io-# => 0.46.0/src/parquet/read/mmap.rs:49:23:
# => range end index 106 out of range for slice of length 0
# => note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
# => Rayon: detected unexpected panic; aborting
# => thread 'plugin runner (primary)' panicked at /home/ntd/.local/share/rust/cargo/registry/src/index.crates.io-6f17d22bba15001f/polars-io-0.46.0/src/pl_async.rs:362:22:
# => called `Result::unwrap()` on an `Err` value: RecvError(())
# => Error:   × Failed to receive response to plugin call from `polars`
# =>    ╭─[entry #13:1:30]
# =>  1 │ polars open simple.parquet | polars save simple.parquet
# =>    ·                              ─────┬─────
# =>    ·                                   ╰── while waiting for this operation to complete
# =>    ╰────
# =>   help: try restarting the plugin with `plugin use 'polars'`

Expected behavior

This might be expected to fail given the way polars works (I'm not sure), but it probably shouldn't panic.

Configuration

key	value
version	0.103.1
major	0
minor	103
patch	1
branch	main
commit_hash	c8c0184
build_os	linux-x86_64
build_target	x86_64-unknown-linux-gnu
rust_version	rustc 1.84.1 (e71f9a9a9 2025-01-27)
rust_channel	1.84.1-x86_64-unknown-linux-gnu
cargo_version	cargo 1.84.1 (66221abde 2024-11-19)
build_time	2025-04-11 14:54:23 -04:00
build_rust_channel	release
allocator	standard
features	default, sqlite, trash
installed_plugins	formats 0.101.0, gstat 0.101.1, polars 0.102.1, query 0.102.1

[sholderbach]

Apparently we don't have the same DataSource::FilePath protection we use for the mainline open and save that protect you from writing to the same file while it is being read.

If I understand the plugin protocol corrrectly, PipelineMetadata should be passed to plugins

nushell/crates/nu-plugin-protocol/src/lib.rs

Lines 74 to 91 in 0e9927e

	/// The initial (and perhaps only) part of any [`nu_protocol::PipelineData`] sent over the wire.
	///
	/// This may contain a single value, or may initiate a stream with a [`StreamId`].
	#[derive(Serialize, Deserialize, Debug, PartialEq, Clone)]
	pub enum PipelineDataHeader {
	/// No input
	Empty,
	/// A single value
	Value(Value, Option<PipelineMetadata>),
	/// Initiate [`nu_protocol::PipelineData::ListStream`].
	///
	/// Items are sent via [`StreamData`]
	ListStream(ListStreamInfo),
	/// Initiate [`nu_protocol::PipelineData::ByteStream`].
	///
	/// Items are sent via [`StreamData`]
	ByteStream(ByteStreamInfo),
	}

so implementing the protection using that should be possible in theory. (Even though maybe another scheme other than metadata would be more appropriate.)

[jjflash95]

I'll try to tackle this one

[jjflash95]

Attempted to fix at #15601