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June 2, 2025 23:03
like #include <etcd/SyncClient.hpp>
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See this issue: https://linear.app/ultihash/issue/ENG-1037/etcd-watcher-misses-some-changes
TL;DR: The etcd client library's watcher implementation does not support multiple changes. This means the watcher can skip changes when there are multiple updates (it really skips!). The most vulnerable case occurs when creating a watcher using the revision (index) returned by ls(). The watcher needs to detect every change made after the ls call and trigger a callback, passing those changes as an argument.
I wrote a test in main.cpp and confirmed it works well.