watch-deps watches (and hashes) all files in project

The default behaviors of https://github.com/nextjournal/beholder and https://github.com/gmethvin/directory-watcher cause watched folders to register watches on all subfolders recursively, and 'watching' a folder reads and hashes every file within it at startup and rehashes any created/modified files on every modification. Due to this, the DirectoryWatcher created by watch-deps is reading and hashing everything under the project folder recursively (including .git, node_modules, etc) and rehashing all modified files even though the callback registered by watch-deps ultimately ignores everything but modifications to deps.edn. This can cause a long delay when watch-deps is invoked for projects with large numbers of files or just large files (e.g. data files under resources/) due the hashing on startup, and unnecessary resource usage caused by rehashing every git commit, asset file update, etc.

DirectoryWatcher can be configured not to hash or to use the file modified timestamp instead of hashing, but these options are not exposed by beholder. It doesn't appear to be possible to watch a single folder without its children using DirectoryWatcher

Would a PR that uses the native java.nio.file.WatchService directly instead of beholder/DirectoryWatcher be welcome? It appears the downside would be that WatchService uses a polling implementation on MacOS, but since it would be possible to watch the project root without any children, I would think it would still be a net win for performance.

从 watch-deps 创建的 DirectoryWatcher 入手，检查 beholder 和 directory-watcher 当前如何注册递归监视并对文件进行哈希处理。将该行为与 java.nio.file.WatchService 进行比较；完成的实现应避免扫描和重新哈希不相关的项目文件，同时仍能检测到对 deps.edn 的修改。