[PATCH 18/23] fsmonitor--daemon:: introduce client delay for testing

From: Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>
Date: Apr 1, 2021, 15:41 UTC
Message-ID: <c6d5f045fb5644306a3676e5fa4145ba4c6e9b93.1617291666.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.923.git.1617291666.gitgitgadget@gmail.com>

From: Jeff Hostetler <jeffhost@microsoft.com>

Define GIT_TEST_FSMONITOR_CLIENT_DELAY as a millisecond delay.

Introduce an artificial delay when processing client requests. This make the CI/PR test suite a little more stable and avoids the need to load up test scripts with sleep statements to avoid racy failures. This was mostly seen on 1 or 2 core CI build machines where the test script would create a file and quickly try to confirm that the daemon had seen it *before* the daemon had received the kernel event and causing a test failure.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 builtin/fsmonitor--daemon.c | 38 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c
index e9a9aea59ad6..0cb09ef0b984 100644
--- a/builtin/fsmonitor--daemon.c
+++ b/builtin/fsmonitor--daemon.c
@@ -150,6 +150,30 @@ static int do_as_client__send_flush(void)
 	return 0;
 }
 
+static int lookup_client_test_delay(void)
+{
+	static int delay_ms = -1;
+
+	const char *s;
+	int ms;
+
+	if (delay_ms >= 0)
+		return delay_ms;
+
+	delay_ms = 0;
+
+	s = getenv("GIT_TEST_FSMONITOR_CLIENT_DELAY");
+	if (!s)
+		return delay_ms;
+
+	ms = atoi(s);
+	if (ms < 0)
+		return delay_ms;
+
+	delay_ms = ms;
+	return delay_ms;
+}
+
 /*
  * Requests to and from a FSMonitor Protocol V2 provider use an opaque
  * "token" as a virtual timestamp.  Clients can request a summary of all
@@ -526,6 +550,18 @@ static int do_handle_client(struct fsmonitor_daemon_state *state,
 		return SIMPLE_IPC_QUIT;
 	}
 
+	/*
+	 * For testing purposes, introduce an artificial delay in this
+	 * worker to allow the filesystem listener thread to receive
+	 * any fs events that may have been generated by the client
+	 * process on the other end of the pipe/socket.  This helps
+	 * make the CI/PR test suite runs a little more predictable
+	 * and hopefully eliminates the need to introduce `sleep`
+	 * commands in the test scripts.
+	 */
+	if (state->test_client_delay_ms)
+		sleep_millisec(state->test_client_delay_ms);
+
 	if (!strcmp(command, "flush")) {
 		/*
 		 * Flush all of our cached data and generate a new token
@@ -1038,7 +1074,7 @@ static int fsmonitor_run_daemon(void)
 	pthread_mutex_init(&state.main_lock, NULL);
 	state.error_code = 0;
 	state.current_token_data = fsmonitor_new_token_data();
-	state.test_client_delay_ms = 0;
+	state.test_client_delay_ms = lookup_client_test_delay();
 
 	/* Prepare to (recursively) watch the <worktree-root> directory. */
 	strbuf_init(&state.path_worktree_watch, 0);

-- 
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