[v3,07/34] fsmonitor: use IPC to query the builtin FSMonitor daemon

Commit Message

Jeff Hostetler July 1, 2021, 2:47 p.m. UTC

From: Jeff Hostetler <[e-mail]>

Use simple IPC to directly communicate with the new builtin file
system monitor daemon when `core.useBuiltinFSMonitor` is set.

The `core.fsmonitor` setting has already been defined as a HOOK
pathname.  Historically, this has been set to a HOOK script that will
talk with Watchman.  For compatibility reasons, we do not want to
overload that definition (and cause problems if users have multiple
versions of Git installed).

Signed-off-by: Johannes Schindelin <[e-mail]>
Signed-off-by: Jeff Hostetler <[e-mail]>
---
 fsmonitor.c | 41 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

Patch

diff --git a/fsmonitor.c b/fsmonitor.c
index 374189be7d9..3719ddfeec9 100644
--- a/fsmonitor.c
+++ b/fsmonitor.c
@@ -256,8 +256,44 @@  void refresh_fsmonitor(struct index_state *istate)
 	trace_printf_key(&trace_fsmonitor, "refresh fsmonitor");
 
 	if (r->settings.fsmonitor_mode == FSMONITOR_MODE_IPC) {
-		/* TODO */
-		return;
+		query_success = !fsmonitor_ipc__send_query(
+			istate->fsmonitor_last_update ?
+			istate->fsmonitor_last_update : "builtin:fake",
+			&query_result);
+		if (query_success) {
+			/*
+			 * The response contains a series of nul terminated
+			 * strings.  The first is the new token.
+			 *
+			 * Use `char *buf` as an interlude to trick the CI
+			 * static analysis to let us use `strbuf_addstr()`
+			 * here (and only copy the token) rather than
+			 * `strbuf_addbuf()`.
+			 */
+			buf = query_result.buf;
+			strbuf_addstr(&last_update_token, buf);
+			bol = last_update_token.len + 1;
+		} else {
+			/*
+			 * The builtin daemon is not available on this
+			 * platform -OR- we failed to get a response.
+			 *
+			 * Generate a fake token (rather than a V1
+			 * timestamp) for the index extension.  (If
+			 * they switch back to the hook API, we don't
+			 * want ambiguous state.)
+			 */
+			strbuf_addstr(&last_update_token, "builtin:fake");
+		}
+
+		/*
+		 * Regardless of whether we successfully talked to a
+		 * fsmonitor daemon or not, we skip over and do not
+		 * try to use the hook.  The "core.useBuiltinFSMonitor"
+		 * config setting ALWAYS overrides the "core.fsmonitor"
+		 * hook setting.
+		 */
+		goto apply_results;
 	}
 
 	assert(r->settings.fsmonitor_mode == FSMONITOR_MODE_HOOK);
@@ -323,6 +359,7 @@  void refresh_fsmonitor(struct index_state *istate)
 				 query_success ? "success" : "failure");
 	}
 
+apply_results:
 	/* a fsmonitor process can return '/' to indicate all entries are invalid */
 	if (query_success && query_result.buf[bol] != '/') {
 		/* Mark all entries returned by the monitor as dirty */