feat: block HTTP requests during active rebuilds via WatchLock#81
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- Add public `WatchLock` / `WatchLockGuard` types for coordinating rebuilds with external readers (e.g. HTTP handlers) - Add `Watch::lock()` to retrieve the watcher's shared lock handle - `Watch::run()` holds the write lock for the entire duration of each command sequence — readers calling `WatchLock::acquire()` block until the build finishes, including the very first one - Fix race condition: generation counter ensures stale `CommandSucceeded` messages from a killed build are ignored - Document lock lifecycle on `Watch::lock()` and `Watch` struct ## Why Allows consumers such as dev servers to block file-serving while a rebuild is in progress, without serving stale or mid-write artifacts. The lock handle is cloneable and `Send + Sync`, so it composes naturally with threaded HTTP handlers. Related to rustminded/xtask-wasm#81 --------- Co-authored-by: Cecile Tonglet <cecile.tonglet@cecton.com>
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Summary
WatchLockfrom the configured watcher before spawning the watch threadWatchLockandWatchLockGuardfromxtask-wasmso consumers don't need a directxtask-watchdependency to name the typesread_headeris intentionally called before acquiring the lock (connections are accepted and headers parsed during a build, reducing response latency once it finishes)Why
Without coordination, a browser refresh mid-rebuild could receive incomplete or inconsistent dist artifacts. Using the shared watcher lock ensures the dev server only serves files once the current build has fully written its output.
Closes #80
Requires rustminded/xtask-watch#34