From 22c50185b5bbc051b0d457fc3e230d5835b30512 Mon Sep 17 00:00:00 2001
From: Reilly Wood <26268125+rgwood@users.noreply.github.com>
Date: Wed, 21 Dec 2022 14:28:27 -0800
Subject: [PATCH] `table`: Check stream timeout on every item (#7509)

`table` handles slow `ListStream`s in a special way: every 100 items, it
checks whether 1 second has elapsed since the last table page, and if so
it outputs a new page with all the items in its buffer.

**I would like to remove the "every 100 items" condition and always
output whatever we have if a second has elapsed.** I think this will be
a better user experience for very slow streams.

As a motivating example, imagine tailing a log file and doing some
string parsing/projection on each line. The user will be really annoyed
if they have to wait for 100 lines to be written to the log before
seeing new results!

I did some quick performance measurements with Criterion, and the
elapsed-time check takes about 16ns on my machine (Linux, 12900k). I
think the performance impact of checking that for every item will be
negligible.
---
 crates/nu-command/src/viewers/table.rs | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/crates/nu-command/src/viewers/table.rs b/crates/nu-command/src/viewers/table.rs
index b0f75c105d..853e0554e4 100644
--- a/crates/nu-command/src/viewers/table.rs
+++ b/crates/nu-command/src/viewers/table.rs
@@ -19,7 +19,6 @@ use terminal_size::{Height, Width};
 use url::Url;
 
 const STREAM_PAGE_SIZE: usize = 1000;
-const STREAM_TIMEOUT_CHECK_INTERVAL: usize = 100;
 const INDEX_COLUMN_NAME: &str = "index";
 
 type NuText = (String, TextStyle);
@@ -1685,13 +1684,9 @@ impl Iterator for PagingTableCreator {
             batch.push(item);
             idx += 1;
 
-            if idx % STREAM_TIMEOUT_CHECK_INTERVAL == 0 {
-                let end_time = Instant::now();
-
-                // If we've been buffering over a second, go ahead and send out what we have so far
-                if (end_time - start_time).as_secs() >= 1 {
-                    break;
-                }
+            // If we've been buffering over a second, go ahead and send out what we have so far
+            if (Instant::now() - start_time).as_secs() >= 1 {
+                break;
             }
 
             if idx == STREAM_PAGE_SIZE {