Speed up tight loop benchmarks (#8609)

# Description

This does a few speedups for tight loops:
* Caches the DeclId for `table` so we don't look it up. This means users
can't easily replace the default one, we might want to talk about this
tradeoff. The lookup for finding `table` in a tight loop is currently
pretty heavy. Might be another way to speed this up.
* `table` no longer pre-calculates the width. Instead, it only
calculates the width when printing a table or record.
* Use more efficient way of collecting the block of each loop
* When printing output, only get the config when needed

Combined, this drops the runtime from a million loop tight iteration
from 1sec 8ms to 236ms.

# User-Facing Changes

_(List of all changes that impact the user experience here. This helps
us keep track of breaking changes.)_

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-cmd-lang/src/core_commands/for_.rs

@@ -162,7 +162,8 @@ impl Command for For {
                             return Err(err);
                         }
                         Ok(pipeline) => {
-                            let exit_code = pipeline.print(&engine_state, stack, false, false)?;
+                            let exit_code =
+                                pipeline.print_not_formatted(&engine_state, false, false)?;
                             if exit_code != 0 {
                                 break;
                             }

crates/nu-cmd-lang/src/core_commands/while_.rs

@@ -78,7 +78,7 @@ impl Command for While {
                             }
                             Ok(pipeline) => {
                                 let exit_code =
-                                    pipeline.print(engine_state, stack, false, false)?;
+                                    pipeline.print_not_formatted(engine_state, false, false)?;
                                 if exit_code != 0 {
                                     break;
                                 }

crates/nu-command/src/default_context.rs

@@ -462,5 +462,9 @@ pub fn create_default_context() -> EngineState {
         eprintln!("Error creating default context: {err:?}");
     }
 
+    // Cache the table decl id so we don't have to look it up later
+    let table_decl_id = engine_state.find_decl("table".as_bytes(), &[]);
+    engine_state.table_decl_id = table_decl_id;
+
     engine_state
 }

crates/nu-command/src/viewers/table.rs

@@ -110,7 +110,6 @@ impl Command for Table {
         let list: bool = call.has_flag("list");
 
         let width_param: Option<i64> = call.get_flag(engine_state, stack, "width")?;
-        let term_width = get_width_param(width_param);
 
         let expand: bool = call.has_flag("expand");
         let expand_limit: Option<usize> = call.get_flag(engine_state, stack, "expand-deep")?;
@@ -152,7 +151,7 @@ impl Command for Table {
             input,
             row_offset,
             table_view,
-            term_width,
+            width_param,
         )
     }
 
@@ -232,7 +231,7 @@ fn handle_table_command(
     input: PipelineData,
     row_offset: usize,
     table_view: TableView,
-    term_width: usize,
+    term_width: Option<i64>,
 ) -> Result<PipelineData, ShellError> {
     let ctrlc = engine_state.ctrlc.clone();
     let config = engine_state.get_config();
@@ -278,7 +277,10 @@ fn handle_table_command(
             ctrlc,
             metadata,
         ),
-        PipelineData::Value(Value::Record { cols, vals, span }, ..) => handle_record(
+        PipelineData::Value(Value::Record { cols, vals, span }, ..) => {
+            let term_width = get_width_param(term_width);
+
+            handle_record(
                 cols,
                 vals,
                 span,
@@ -289,7 +291,8 @@ fn handle_table_command(
                 term_width,
                 ctrlc,
                 config,
-        ),
+            )
+        }
         PipelineData::Value(Value::LazyRecord { val, .. }, ..) => {
             let collected = val.collect()?.into_pipeline_data();
             handle_table_command(

crates/nu-protocol/src/engine/engine_state.rs

@@ -126,6 +126,7 @@ pub struct EngineState {
     pub config: Config,
     pub pipeline_externals_state: Arc<(AtomicU32, AtomicU32)>,
     pub repl_buffer_state: Arc<Mutex<String>>,
+    pub table_decl_id: Option<usize>,
     // A byte position, as `EditCommand::MoveToPosition` is also a byte position
     pub repl_cursor_pos: Arc<Mutex<usize>>,
     #[cfg(feature = "plugin")]
@@ -180,6 +181,7 @@ impl EngineState {
             pipeline_externals_state: Arc::new((AtomicU32::new(0), AtomicU32::new(0))),
             repl_buffer_state: Arc::new(Mutex::new("".to_string())),
             repl_cursor_pos: Arc::new(Mutex::new(0)),
+            table_decl_id: None,
             #[cfg(feature = "plugin")]
             plugin_signatures: None,
             #[cfg(not(windows))]

crates/nu-protocol/src/pipeline_data.rs

@@ -704,7 +704,7 @@ impl PipelineData {
             return print_if_stream(stream, stderr_stream, to_stderr, exit_code);
         }
 
-        if let Some(decl_id) = engine_state.find_decl("table".as_bytes(), &[]) {
+        if let Some(decl_id) = engine_state.table_decl_id {
             let command = engine_state.get_decl(decl_id);
             if command.get_block_id().is_some() {
                 return self.write_all_and_flush(engine_state, config, no_newline, to_stderr);
@@ -734,8 +734,6 @@ impl PipelineData {
         no_newline: bool,
         to_stderr: bool,
     ) -> Result<i64, ShellError> {
-        let config = engine_state.get_config();
-
         if let PipelineData::ExternalStream {
             stdout: stream,
             stderr: stderr_stream,
@@ -745,6 +743,7 @@ impl PipelineData {
         {
             print_if_stream(stream, stderr_stream, to_stderr, exit_code)
         } else {
+            let config = engine_state.get_config();
             self.write_all_and_flush(engine_state, config, no_newline, to_stderr)
         }
     }
@@ -835,6 +834,7 @@ pub fn print_if_stream(
 ) -> Result<i64, ShellError> {
     // NOTE: currently we don't need anything from stderr
     // so we just consume and throw away `stderr_stream` to make sure the pipe doesn't fill up
+
     thread::Builder::new()
         .name("stderr consumer".to_string())
         .spawn(move || stderr_stream.map(|x| x.into_bytes()))