Add further notes and research

Author: gbroques

filesystem-watcher-comparison.md

@@ -4,3 +4,127 @@
 * [fswatch](https://github.com/emcrisostomo/fswatch) - requires filters for removing noisy inotify `PlatformSpecific` events, and more critically doesn't detect object file creation during recursive monitorying (e.g doesn't detect creation of `.git/objects/56/26abf0f72e58d7a153368ba57db4c673c0e171`). `inotifywait` detects this, but has additional code around `inotify` to do so (see [issue #330](https://github.com/emcrisostomo/fswatch/issues/330)).
 * [efsw](https://github.com/SpartanJ/efsw) - doesn't have a way to differentiate between files and directories (see [issue #191](https://github.com/SpartanJ/efsw/issues/191)).
 * [Node.js fs.watch](https://nodejs.org/docs/latest/api/fs.html#fswatchfilename-options-listener) - only reports `'rename'` or `'change'` `eventType`s instead of create, delete, and update, and move. It also has caveats, and triggered wrapper projects such as [`node-watch`](https://github.com/yuanchuan/node-watch) and [`chokidar`](https://github.com/paulmillr/chokidar).
+
+Both `fswatch` and Node.js `fs.watch` have issues that make them unworkable.
+
+`dmon` and `efswatch` are workable since we can detect files between directories for Git based on names, length, and other attributes.
+
+`efswatch` would be preferable since it's in Conan center, written in C++ as opposed to C, and seems a bit more popular and maintained.
+
+## git add Comparison
+
+Below is a comparison of output for the following command:
+```
+$ git add file
+```
+Where `file` is a plain-text file with the contents "`file`":
+```bash
+$ cat file
+file
+```
+
+`efsw` output:
+```
+DIR (.git/) FILE (index.lock) has event Added
+DIR (.git/objects/) FILE (f7) has event Added
+DIR (.git/objects/f7/) FILE (tmp_obj_JUp4eR) has event Modified
+DIR (.git/objects/f7/) FILE (tmp_obj_JUp4eR) has event Modified
+DIR (.git/objects/f7/) FILE (3f3093ff865c514c6c51f867e35f693487d0d3) has event Added
+DIR (.git/objects/f7/) FILE (tmp_obj_JUp4eR) has event Delete
+DIR (.git/) FILE (index.lock) has event Modified
+DIR (.git/) FILE (index.lock) has event Modified
+DIR (.git/) FILE (index.lock) has event Modified
+DIR (.git/) FILE (index) has event Moved from (index.lock)
+````
+
+`dmon` output:
+```
+{"filepath":".git/objects/f7","action":"CREATE"}
+{"filepath":".git/index","action":"MODIFY"}
+{"filepath":".git/objects/f7/3f3093ff865c514c6c51f867e35f693487d0d3","action":"CREATE"}
+```
+
+`inotifywait` output (used as a source of truth):
+```
+$ inotifywait -m .git/ -r
+.git/ ACCESS HEAD
+.git/ CLOSE_NOWRITE,CLOSE HEAD
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ CREATE index.lock
+.git/ OPEN index.lock
+.git/info/ OPEN exclude
+.git/info/ ACCESS exclude
+.git/info/ CLOSE_NOWRITE,CLOSE exclude
+.git/objects/ OPEN,ISDIR pack
+.git/objects/pack/ OPEN,ISDIR 
+.git/objects/ ACCESS,ISDIR pack
+.git/objects/pack/ ACCESS,ISDIR 
+.git/objects/ ACCESS,ISDIR pack
+.git/objects/pack/ ACCESS,ISDIR 
+.git/objects/ CLOSE_NOWRITE,CLOSE,ISDIR pack
+.git/objects/pack/ CLOSE_NOWRITE,CLOSE,ISDIR 
+.git/objects/ CREATE,ISDIR f7
+.git/objects/ OPEN,ISDIR f7
+.git/objects/ ACCESS,ISDIR f7
+.git/objects/ CLOSE_NOWRITE,CLOSE,ISDIR f7
+.git/objects/f7/ MODIFY tmp_obj_JUp4eR
+.git/objects/f7/ CLOSE_WRITE,CLOSE tmp_obj_JUp4eR
+.git/objects/f7/ CREATE 3f3093ff865c514c6c51f867e35f693487d0d3
+.git/objects/f7/ DELETE tmp_obj_JUp4eR
+.git/ MODIFY index.lock
+.git/ CLOSE_WRITE,CLOSE index.lock
+.git/ MOVED_FROM index.lock
+.git/ MOVED_TO index
+.git/ OPEN HEAD
+.git/ ACCESS HEAD
+.git/ CLOSE_NOWRITE,CLOSE HEAD
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN HEAD
+.git/ ACCESS HEAD
+.git/ CLOSE_NOWRITE,CLOSE HEAD
+.git/ OPEN HEAD
+.git/ ACCESS HEAD
+.git/ CLOSE_NOWRITE,CLOSE HEAD
+.git/ OPEN HEAD
+.git/ ACCESS HEAD
+.git/ CLOSE_NOWRITE,CLOSE HEAD
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN HEAD
+.git/ ACCESS HEAD
+.git/ CLOSE_NOWRITE,CLOSE HEAD
+.git/ OPEN HEAD
+.git/ ACCESS HEAD
+.git/ CLOSE_NOWRITE,CLOSE HEAD
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+.git/ OPEN config
+.git/ ACCESS config
+.git/ CLOSE_NOWRITE,CLOSE config
+```
+
+`dmon` doesn't detect git creating the `index.lock`, `index` or `tmp_obj_JUp4eR`. These aren't really important, but it's concerning that events are swallowed leading to an inaccurate picture.