microsoft/Terminal

[Performance] Fast path for `RenderData::IsCursorDoubleWidth`

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#10,470 opened on Jun 21, 2021

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Description

This is a sister issue of #10393.

Currently an unreasonable amount of CPU is wasted in checking IsCursorDoubleWidth in the buffer, due to the expensive construction of TextBufferCellIterator. I think it's fair to find a fast path for people who don't use width characters at all.

image

Contributor guide

Research direction
Profile the IsCursorDoubleWidth function and implement a fast path that skips expensive iteration when no wide characters are present.
Tech stack
cpp
Domain
performance
Issue type
Performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++Windows Terminal development
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60