spacejam/sled

implement actual parallel IO trait for windows

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#243 opened on Feb 11, 2018

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help wantednewbie

Description

We need to support parallel writes for building on windows.

I believe the way to go about this is through https://retep998.github.io/doc/kernel32/fn.WriteFile.html and passing in an OVERLAPPED struct, as per SO.

Here's the current, global-lock driven approach on windows, which may not even compile: https://github.com/spacejam/sled/pull/242/commits/2906673fe6755f18bebf5d90a63eca6ff75a2036#diff-f23996d5649981fd238dd760793391c1R78

Contributor guide

Tech stack
rust
Domain
backendperformance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Familiarity with Rust async/IOWindows API knowledgeUnderstanding of sled's internal IO trait
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
The issue requires implementing parallel writes on Windows using the WriteFile function with an OVERLAPPED structure. Start by examining the linked commit (https://github.com/spacejam/sled/pull/242/commits/2906673fe6755f18bebf5d90a63eca6ff75a2036) to understand the current global lock approach and the changes attempted before. Then research Windows overlapped IO documentation and how to integrate it safely with Rust's ownership model. The goal is to replace the global mutex with per file async operations that allow concurrent writes, similar to the Linux implementation using preadv/pwritev.