From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Implement `run` and `start` commands to try to
begin listening for file system events.
This version defines the thread structure with a single
fsmonitor_fs_listen thread to watch for file system events
and a simple IPC thread pool to wait for connections from
Git clients over a well-known named pipe or Unix domain
socket.
This version does not actually do anything yet because the
backends are still just stubs.
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
builtin/fsmonitor--daemon.c | 390 +++++++++++++++++++++++++++++++++++-
fsmonitor--daemon.h | 34 ++++
2 files changed, 423 insertions(+), 1 deletion(-)
create mode 100644 fsmonitor--daemon.h
diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c
index 16ff68b65407..85f99dba861f 100644
--- a/builtin/fsmonitor--daemon.c
+++ b/builtin/fsmonitor--daemon.c
@@ -3,16 +3,52 @@
#include "parse-options.h"
#include "fsmonitor.h"
#include "fsmonitor-ipc.h"
+#include "compat/fsmonitor/fsmonitor-fs-listen.h"
+#include "fsmonitor--daemon.h"
#include "simple-ipc.h"
#include "khash.h"
static const char * const builtin_fsmonitor__daemon_usage[] = {
+ N_("git fsmonitor--daemon start [<options>]"),
+ N_("git fsmonitor--daemon run [<options>]"),
N_("git fsmonitor--daemon stop"),
N_("git fsmonitor--daemon status"),
NULL
};
#ifdef HAVE_FSMONITOR_DAEMON_BACKEND
+/*
+ * Global state loaded from config.
+ */
+#define FSMONITOR__IPC_THREADS "fsmonitor.ipcthreads"
+static int fsmonitor__ipc_threads = 8;
+
+#define FSMONITOR__START_TIMEOUT "fsmonitor.starttimeout"
+static int fsmonitor__start_timeout_sec = 60;
+
+static int fsmonitor_config(const char *var, const char *value, void *cb)
+{
+ if (!strcmp(var, FSMONITOR__IPC_THREADS)) {
+ int i = git_config_int(var, value);
+ if (i < 1)
+ return error(_("value of '%s' out of range: %d"),
+ FSMONITOR__IPC_THREADS, i);
+ fsmonitor__ipc_threads = i;
+ return 0;
+ }
+
+ if (!strcmp(var, FSMONITOR__START_TIMEOUT)) {
+ int i = git_config_int(var, value);
+ if (i < 0)
+ return error(_("value of '%s' out of range: %d"),
+ FSMONITOR__START_TIMEOUT, i);
+ fsmonitor__start_timeout_sec = i;
+ return 0;
+ }
+
+ return git_default_config(var, value, cb);
+}
+
/*
* Acting as a CLIENT.
*
@@ -55,11 +91,354 @@ static int do_as_client__status(void)
}
}
+static ipc_server_application_cb handle_client;
+
+static int handle_client(void *data,
+ const char *command, size_t command_len,
+ ipc_server_reply_cb *reply,
+ struct ipc_server_reply_data *reply_data)
+{
+ /* struct fsmonitor_daemon_state *state = data; */
+ int result;
+
+ /*
+ * The Simple IPC API now supports {char*, len} arguments, but
+ * FSMonitor always uses proper null-terminated strings, so
+ * we can ignore the command_len argument. (Trust, but verify.)
+ */
+ if (command_len != strlen(command))
+ BUG("FSMonitor assumes text messages");
+
+ trace2_region_enter("fsmonitor", "handle_client", the_repository);
+ trace2_data_string("fsmonitor", the_repository, "request", command);
+
+ result = 0; /* TODO Do something here. */
+
+ trace2_region_leave("fsmonitor", "handle_client", the_repository);
+
+ return result;
+}
+
+static void *fsmonitor_fs_listen__thread_proc(void *_state)
+{
+ struct fsmonitor_daemon_state *state = _state;
+
+ trace2_thread_start("fsm-listen");
+
+ trace_printf_key(&trace_fsmonitor, "Watching: worktree '%s'",
+ state->path_worktree_watch.buf);
+ if (state->nr_paths_watching > 1)
+ trace_printf_key(&trace_fsmonitor, "Watching: gitdir '%s'",
+ state->path_gitdir_watch.buf);
+
+ fsmonitor_fs_listen__loop(state);
+
+ trace2_thread_exit();
+ return NULL;
+}
+
+static int fsmonitor_run_daemon_1(struct fsmonitor_daemon_state *state)
+{
+ struct ipc_server_opts ipc_opts = {
+ .nr_threads = fsmonitor__ipc_threads,
+
+ /*
+ * We know that there are no other active threads yet,
+ * so we can let the IPC layer temporarily chdir() if
+ * it needs to when creating the server side of the
+ * Unix domain socket.
+ */
+ .uds_disallow_chdir = 0
+ };
+
+ /*
+ * Start the IPC thread pool before the we've started the file
+ * system event listener thread so that we have the IPC handle
+ * before we need it.
+ */
+ if (ipc_server_run_async(&state->ipc_server_data,
+ fsmonitor_ipc__get_path(), &ipc_opts,
+ handle_client, state))
+ return error(_("could not start IPC thread pool"));
+
+ /*
+ * Start the fsmonitor listener thread to collect filesystem
+ * events.
+ */
+ if (pthread_create(&state->listener_thread, NULL,
+ fsmonitor_fs_listen__thread_proc, state) < 0) {
+ ipc_server_stop_async(state->ipc_server_data);
+ ipc_server_await(state->ipc_server_data);
+
+ return error(_("could not start fsmonitor listener thread"));
+ }
+
+ /*
+ * The daemon is now fully functional in background threads.
+ * Wait for the IPC thread pool to shutdown (whether by client
+ * request or from filesystem activity).
+ */
+ ipc_server_await(state->ipc_server_data);
+
+ /*
+ * The fsmonitor listener thread may have received a shutdown
+ * event from the IPC thread pool, but it doesn't hurt to tell
+ * it again. And wait for it to shutdown.
+ */
+ fsmonitor_fs_listen__stop_async(state);
+ pthread_join(state->listener_thread, NULL);
+
+ return state->error_code;
+}
+
+static int fsmonitor_run_daemon(void)
+{
+ struct fsmonitor_daemon_state state;
+ int err;
+
+ memset(&state, 0, sizeof(state));
+
+ pthread_mutex_init(&state.main_lock, NULL);
+ state.error_code = 0;
+ state.current_token_data = NULL;
+
+ /* Prepare to (recursively) watch the <worktree-root> directory. */
+ strbuf_init(&state.path_worktree_watch, 0);
+ strbuf_addstr(&state.path_worktree_watch, absolute_path(get_git_work_tree()));
+ state.nr_paths_watching = 1;
+
+ /*
+ * We create/delete cookie files inside the .git directory to
+ * help us keep sync with the file system. If ".git" is not a
+ * directory, then <gitdir> is not inside the cone of
+ * <worktree-root>, so set up a second watch for it.
+ */
+ strbuf_init(&state.path_gitdir_watch, 0);
+ strbuf_addbuf(&state.path_gitdir_watch, &state.path_worktree_watch);
+ strbuf_addstr(&state.path_gitdir_watch, "/.git");
+ if (!is_directory(state.path_gitdir_watch.buf)) {
+ strbuf_reset(&state.path_gitdir_watch);
+ strbuf_addstr(&state.path_gitdir_watch, absolute_path(get_git_dir()));
+ state.nr_paths_watching = 2;
+ }
+
+ /*
+ * Confirm that we can create platform-specific resources for the
+ * filesystem listener before we bother starting all the threads.
+ */
+ if (fsmonitor_fs_listen__ctor(&state)) {
+ err = error(_("could not initialize listener thread"));
+ goto done;
+ }
+
+ err = fsmonitor_run_daemon_1(&state);
+
+done:
+ pthread_mutex_destroy(&state.main_lock);
+ fsmonitor_fs_listen__dtor(&state);
+
+ ipc_server_free(state.ipc_server_data);
+
+ strbuf_release(&state.path_worktree_watch);
+ strbuf_release(&state.path_gitdir_watch);
+
+ return err;
+}
+
+static int try_to_run_foreground_daemon(void)
+{
+ /*
+ * Technically, we don't need to probe for an existing daemon
+ * process, since we could just call `fsmonitor_run_daemon()`
+ * and let it fail if the pipe/socket is busy.
+ *
+ * However, this method gives us a nicer error message for a
+ * common error case.
+ */
+ if (fsmonitor_ipc__get_state() == IPC_STATE__LISTENING)
+ die("fsmonitor--daemon is already running.");
+
+ return !!fsmonitor_run_daemon();
+}
+
+#ifndef GIT_WINDOWS_NATIVE
+/*
+ * This is adapted from `daemonize()`. Use `fork()` to directly create
+ * and run the daemon in a child process. The fork-parent returns the
+ * child PID so that we can wait for the child to startup before exiting.
+ */
+static int spawn_background_fsmonitor_daemon(pid_t *pid)
+{
+ *pid = fork();
+
+ switch (*pid) {
+ case 0:
+ if (setsid() == -1)
+ error_errno(_("setsid failed"));
+ close(0);
+ close(1);
+ close(2);
+ sanitize_stdfds();
+
+ return !!fsmonitor_run_daemon();
+
+ case -1:
+ return error_errno(_("could not spawn fsmonitor--daemon in the background"));
+
+ default:
+ return 0;
+ }
+}
+#else
+/*
+ * Conceptually like `daemonize()` but different because Windows does not
+ * have `fork(2)`. Spawn a normal Windows child process but without the
+ * limitations of `start_command()` and `finish_command()`.
+ */
+static int spawn_background_fsmonitor_daemon(pid_t *pid)
+{
+ char git_exe[MAX_PATH];
+ struct strvec args = STRVEC_INIT;
+ int in, out;
+
+ GetModuleFileNameA(NULL, git_exe, MAX_PATH);
+
+ in = open("/dev/null", O_RDONLY);
+ out = open("/dev/null", O_WRONLY);
+
+ strvec_push(&args, git_exe);
+ strvec_push(&args, "fsmonitor--daemon");
+ strvec_push(&args, "run");
+
+ *pid = mingw_spawnvpe(args.v[0], args.v, NULL, NULL, in, out, out);
+ close(in);
+ close(out);
+
+ strvec_clear(&args);
+
+ if (*pid < 0)
+ return error(_("could not spawn fsmonitor--daemon in the background"));
+
+ return 0;
+}
+#endif
+
+/*
+ * This is adapted from `wait_or_whine()`. Watch the child process and
+ * let it get started and begin listening for requests on the socket
+ * before reporting our success.
+ */
+static int wait_for_background_startup(pid_t pid_child)
+{
+ int status;
+ pid_t pid_seen;
+ enum ipc_active_state s;
+ time_t time_limit, now;
+
+ time(&time_limit);
+ time_limit += fsmonitor__start_timeout_sec;
+
+ for (;;) {
+ pid_seen = waitpid(pid_child, &status, WNOHANG);
+
+ if (pid_seen == -1)
+ return error_errno(_("waitpid failed"));
+ else if (pid_seen == 0) {
+ /*
+ * The child is still running (this should be
+ * the normal case). Try to connect to it on
+ * the socket and see if it is ready for
+ * business.
+ *
+ * If there is another daemon already running,
+ * our child will fail to start (possibly
+ * after a timeout on the lock), but we don't
+ * care (who responds) if the socket is live.
+ */
+ s = fsmonitor_ipc__get_state();
+ if (s == IPC_STATE__LISTENING)
+ return 0;
+
+ time(&now);
+ if (now > time_limit)
+ return error(_("fsmonitor--daemon not online yet"));
+ } else if (pid_seen == pid_child) {
+ /*
+ * The new child daemon process shutdown while
+ * it was starting up, so it is not listening
+ * on the socket.
+ *
+ * Try to ping the socket in the odd chance
+ * that another daemon started (or was already
+ * running) while our child was starting.
+ *
+ * Again, we don't care who services the socket.
+ */
+ s = fsmonitor_ipc__get_state();
+ if (s == IPC_STATE__LISTENING)
+ return 0;
+
+ /*
+ * We don't care about the WEXITSTATUS() nor
+ * any of the WIF*(status) values because
+ * `cmd_fsmonitor__daemon()` does the `!!result`
+ * trick on all function return values.
+ *
+ * So it is sufficient to just report the
+ * early shutdown as an error.
+ */
+ return error(_("fsmonitor--daemon failed to start"));
+ } else
+ return error(_("waitpid is confused"));
+ }
+}
+
+static int try_to_start_background_daemon(void)
+{
+ pid_t pid_child;
+ int ret;
+
+ /*
+ * Before we try to create a background daemon process, see
+ * if a daemon process is already listening. This makes it
+ * easier for us to report an already-listening error to the
+ * console, since our spawn/daemon can only report the success
+ * of creating the background process (and not whether it
+ * immediately exited).
+ */
+ if (fsmonitor_ipc__get_state() == IPC_STATE__LISTENING)
+ die("fsmonitor--daemon is already running.");
+
+ /*
+ * Run the actual daemon in a background process.
+ */
+ ret = spawn_background_fsmonitor_daemon(&pid_child);
+ if (pid_child <= 0)
+ return ret;
+
+ /*
+ * Wait (with timeout) for the background child process get
+ * started and begin listening on the socket/pipe. This makes
+ * the "start" command more synchronous and more reliable in
+ * tests.
+ */
+ ret = wait_for_background_startup(pid_child);
+
+ return ret;
+}
+
int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix)
{
const char *subcmd;
struct option options[] = {
+ OPT_INTEGER(0, "ipc-threads",
+ &fsmonitor__ipc_threads,
+ N_("use <n> ipc worker threads")),
+ OPT_INTEGER(0, "start-timeout",
+ &fsmonitor__start_timeout_sec,
+ N_("Max seconds to wait for background daemon startup")),
+
OPT_END()
};
@@ -69,7 +448,7 @@ int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix)
if (argc == 2 && !strcmp(argv[1], "-h"))
usage_with_options(builtin_fsmonitor__daemon_usage, options);
- git_config(git_default_config, NULL);
+ git_config(fsmonitor_config, NULL);
subcmd = argv[1];
argv--;
@@ -77,6 +456,15 @@ int cmd_fsmonitor__daemon(int argc, const char **argv, const char *prefix)
argc = parse_options(argc, argv, prefix, options,
builtin_fsmonitor__daemon_usage, 0);
+ if (fsmonitor__ipc_threads < 1)
+ die(_("invalid 'ipc-threads' value (%d)"),
+ fsmonitor__ipc_threads);
+
+ if (!strcmp(subcmd, "start"))
+ return !!try_to_start_background_daemon();
+
+ if (!strcmp(subcmd, "run"))
+ return !!try_to_run_foreground_daemon();
if (!strcmp(subcmd, "stop"))
return !!do_as_client__send_stop();
diff --git a/fsmonitor--daemon.h b/fsmonitor--daemon.h
new file mode 100644
index 000000000000..3009c1a83de7
--- /dev/null
+++ b/fsmonitor--daemon.h
@@ -0,0 +1,34 @@
+#ifndef FSMONITOR_DAEMON_H
+#define FSMONITOR_DAEMON_H
+
+#ifdef HAVE_FSMONITOR_DAEMON_BACKEND
+
+#include "cache.h"
+#include "dir.h"
+#include "run-command.h"
+#include "simple-ipc.h"
+#include "thread-utils.h"
+
+struct fsmonitor_batch;
+struct fsmonitor_token_data;
+
+struct fsmonitor_daemon_backend_data; /* opaque platform-specific data */
+
+struct fsmonitor_daemon_state {
+ pthread_t listener_thread;
+ pthread_mutex_t main_lock;
+
+ struct strbuf path_worktree_watch;
+ struct strbuf path_gitdir_watch;
+ int nr_paths_watching;
+
+ struct fsmonitor_token_data *current_token_data;
+
+ int error_code;
+ struct fsmonitor_daemon_backend_data *backend_data;
+
+ struct ipc_server_data *ipc_server_data;
+};
+
+#endif /* HAVE_FSMONITOR_DAEMON_BACKEND */
+#endif /* FSMONITOR_DAEMON_H */
--
gitgitgadget
