unisonweb/unison

externally updated `_head` isn't detected in `ucm`

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#886 创建于 2019年10月23日

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bugcodebase-manager / ucmhelp wanted

描述

This can cause weirdness if there are two instances of ucm running backed by the same codebase.

I think the code to do anything about it is commented out (which we should fix) but there is code to display a warning, which also isn't firing.

If the external change leaves multiple heads, ucm should first:

  • issue a message to the console, including the short hashes of the previous loopstate root hash, and of the newly detected heads (see reflog implementation for example of printing short hashes).
  • merge the multiple heads (Branch.merge?)

Then (multiple heads or single head), ucm should:

  • write the external change to the reflog
  • update LoopState

贡献者指南

技术栈
无
领域
clitooling
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-2 days
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
Knowledge of Unison's ucm internals
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
35
研究方向
Examine the codebase for commented out sections related to detecting external changes to ` head` in `ucm`. Look at the reflog implementation (e.g., in files like `Reflog.hs`) to understand how short hashes are printed. Investigate `Branch.merge` for merging multiple heads. The warning code that isn't firing should be located and fixed. Ensure all checkboxes in the issue are addressed.