2021-01-10 03:50:49 +01:00
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[package]
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2022-03-22 21:25:38 +01:00
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authors = ["The Nushell Project Developers"]
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2022-04-11 20:17:06 +02:00
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description = "Nushell's evaluation engine"
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2022-08-14 14:21:20 +02:00
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repository = "https://github.com/nushell/nushell/tree/main/crates/nu-engine"
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2022-03-22 21:25:38 +01:00
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edition = "2021"
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license = "MIT"
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2021-01-10 03:50:49 +01:00
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name = "nu-engine"
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2023-01-31 21:00:59 +01:00
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version = "0.75.0"
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2021-08-10 20:51:08 +02:00
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[dependencies]
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2023-01-31 21:00:59 +01:00
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nu-protocol = { path = "../nu-protocol", features = ["plugin"], version = "0.75.0" }
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nu-path = { path = "../nu-path", version = "0.75.0" }
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nu-glob = { path = "../nu-glob", version = "0.75.0" }
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nu-utils = { path = "../nu-utils", version = "0.75.0" }
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2022-03-13 19:30:27 +01:00
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2022-11-26 19:19:02 +01:00
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chrono = { version="0.4.23", features = ["std"], default-features = false }
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LazyRecord (#7619)
This is an attempt to implement a new `Value::LazyRecord` variant for
performance reasons.
`LazyRecord` is like a regular `Record`, but it's possible to access
individual columns without evaluating other columns. I've implemented
`LazyRecord` for the special `$nu` variable; accessing `$nu` is
relatively slow because of all the information in `scope`, and [`$nu`
accounts for about 2/3 of Nu's startup time on
Linux](https://github.com/nushell/nushell/issues/6677#issuecomment-1364618122).
### Benchmarks
I ran some benchmarks on my desktop (Linux, 12900K) and the results are
very pleasing.
Nu's time to start up and run a command (`cargo build --release;
hyperfine 'target/release/nu -c "echo \"Hello, world!\""' --shell=none
--warmup 10`) goes from **8.8ms to 3.2ms, about 2.8x faster**.
Tests are also much faster! Running `cargo nextest` (with our very slow
`proptest` tests disabled) goes from **7.2s to 4.4s (1.6x faster)**,
because most tests involve launching a new instance of Nu.
### Design (updated)
I've added a new `LazyRecord` trait and added a `Value` variant wrapping
those trait objects, much like `CustomValue`. `LazyRecord`
implementations must implement these 2 functions:
```rust
// All column names
fn column_names(&self) -> Vec<&'static str>;
// Get 1 specific column value
fn get_column_value(&self, column: &str) -> Result<Value, ShellError>;
```
### Serializability
`Value` variants must implement `Serializable` and `Deserializable`, which poses some problems because I want to use unserializable things like `EngineState` in `LazyRecord`s. To work around this, I basically lie to the type system:
1. Add `#[typetag::serde(tag = "type")]` to `LazyRecord` to make it serializable
2. Any unserializable fields in `LazyRecord` implementations get marked with `#[serde(skip)]`
3. At the point where a `LazyRecord` normally would get serialized and sent to a plugin, I instead collect it into a regular `Value::Record` (which can be serialized)
2023-01-19 04:27:26 +01:00
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serde = {version = "1.0.143", default-features = false }
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2023-01-23 04:09:15 +01:00
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sysinfo ="0.27.7"
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2021-12-02 07:35:32 +01:00
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[features]
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plugin = []
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