[PATCH v3 09/14] fsmonitor: return invalidated cache-entry count on directory event

From: Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>
Date: Feb 26, 2024, 21:39 UTC
Message-ID: <5fea8b9476e6bf0e0635e886364f0d718deac97c.1708983566.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1662.v3.git.1708983565.gitgitgadget@gmail.com>

From: Jeff Hostetler <jeffhostetler@github.com>

Teach the refresh callback helper function for directory FSEvents to return the number of cache-entries that were invalidated in response to a directory event.

This will be used in a later commit to help determine if the observed pathname in the FSEvent was a (possibly) case-incorrect directory prefix (on a case-insensitive filesystem) of one or more actual cache-entries.

If there exists at least one case-insensitive prefix match, then we can assume that the directory is a (case-incorrect) prefix of at least one tracked item rather than a completely unknown/untracked file or directory.

Signed-off-by: Jeff Hostetler <jeffhostetler@github.com>
---
 fsmonitor.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/fsmonitor.c b/fsmonitor.c
index 2f58ee2fe5a..9424bd17230 100644
--- a/fsmonitor.c
+++ b/fsmonitor.c
@@ -253,11 +253,20 @@ static void handle_path_without_trailing_slash(
  * same way and just invalidate the cache-entry and the untracked
  * cache (and in this case, the forward cache-entry scan won't find
  * anything and it doesn't hurt to let it run).
+ *
+ * Return the number of cache-entries that we invalidated.  We will
+ * use this later to determine if we need to attempt a second
+ * case-insensitive search on case-insensitive file systems.  That is,
+ * if the search using the observed-case in the FSEvent yields any
+ * results, we assume the prefix is case-correct.  If there are no
+ * matches, we still don't know if the observed path is simply
+ * untracked or case-incorrect.
  */
-static void handle_path_with_trailing_slash(
+static size_t handle_path_with_trailing_slash(
 	struct index_state *istate, const char *name, int pos)
 {
 	int i;
+	size_t nr_in_cone = 0;
 
 	/*
 	 * Mark the untracked cache dirty for this directory path
@@ -276,7 +285,10 @@ static void handle_path_with_trailing_slash(
 		if (!starts_with(istate->cache[i]->name, name))
 			break;
 		istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
+		nr_in_cone++;
 	}
+
+	return nr_in_cone;
 }
 
 static void fsmonitor_refresh_callback(struct index_state *istate, char *name)

-- 
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