From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Implement file system event listener on MacOS using FSEvent,
CoreFoundation, and CoreServices.
Co-authored-by: Kevin Willford <Kevin.Willford@xxxxxxxxxxxxx>
Co-authored-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Signed-off-by: Junio C Hamano <gitster@xxxxxxxxx>
---
compat/fsmonitor/fsm-listen-darwin.c | 383 +++++++++++++++++++++++++++
1 file changed, 383 insertions(+)
diff --git a/compat/fsmonitor/fsm-listen-darwin.c b/compat/fsmonitor/fsm-listen-darwin.c
index d2ce942cade..0741fe834c3 100644
--- a/compat/fsmonitor/fsm-listen-darwin.c
+++ b/compat/fsmonitor/fsm-listen-darwin.c
@@ -25,20 +25,403 @@
#include "cache.h"
#include "fsmonitor.h"
#include "fsm-listen.h"
+#include "fsmonitor--daemon.h"
+
+struct fsmonitor_daemon_backend_data
+{
+ CFStringRef cfsr_worktree_path;
+ CFStringRef cfsr_gitdir_path;
+
+ CFArrayRef cfar_paths_to_watch;
+ int nr_paths_watching;
+
+ FSEventStreamRef stream;
+
+ CFRunLoopRef rl;
+
+ enum shutdown_style {
+ SHUTDOWN_EVENT = 0,
+ FORCE_SHUTDOWN,
+ FORCE_ERROR_STOP,
+ } shutdown_style;
+
+ unsigned int stream_scheduled:1;
+ unsigned int stream_started:1;
+};
+
+static void log_flags_set(const char *path, const FSEventStreamEventFlags flag)
+{
+ struct strbuf msg = STRBUF_INIT;
+
+ if (flag & kFSEventStreamEventFlagMustScanSubDirs)
+ strbuf_addstr(&msg, "MustScanSubDirs|");
+ if (flag & kFSEventStreamEventFlagUserDropped)
+ strbuf_addstr(&msg, "UserDropped|");
+ if (flag & kFSEventStreamEventFlagKernelDropped)
+ strbuf_addstr(&msg, "KernelDropped|");
+ if (flag & kFSEventStreamEventFlagEventIdsWrapped)
+ strbuf_addstr(&msg, "EventIdsWrapped|");
+ if (flag & kFSEventStreamEventFlagHistoryDone)
+ strbuf_addstr(&msg, "HistoryDone|");
+ if (flag & kFSEventStreamEventFlagRootChanged)
+ strbuf_addstr(&msg, "RootChanged|");
+ if (flag & kFSEventStreamEventFlagMount)
+ strbuf_addstr(&msg, "Mount|");
+ if (flag & kFSEventStreamEventFlagUnmount)
+ strbuf_addstr(&msg, "Unmount|");
+ if (flag & kFSEventStreamEventFlagItemChangeOwner)
+ strbuf_addstr(&msg, "ItemChangeOwner|");
+ if (flag & kFSEventStreamEventFlagItemCreated)
+ strbuf_addstr(&msg, "ItemCreated|");
+ if (flag & kFSEventStreamEventFlagItemFinderInfoMod)
+ strbuf_addstr(&msg, "ItemFinderInfoMod|");
+ if (flag & kFSEventStreamEventFlagItemInodeMetaMod)
+ strbuf_addstr(&msg, "ItemInodeMetaMod|");
+ if (flag & kFSEventStreamEventFlagItemIsDir)
+ strbuf_addstr(&msg, "ItemIsDir|");
+ if (flag & kFSEventStreamEventFlagItemIsFile)
+ strbuf_addstr(&msg, "ItemIsFile|");
+ if (flag & kFSEventStreamEventFlagItemIsHardlink)
+ strbuf_addstr(&msg, "ItemIsHardlink|");
+ if (flag & kFSEventStreamEventFlagItemIsLastHardlink)
+ strbuf_addstr(&msg, "ItemIsLastHardlink|");
+ if (flag & kFSEventStreamEventFlagItemIsSymlink)
+ strbuf_addstr(&msg, "ItemIsSymlink|");
+ if (flag & kFSEventStreamEventFlagItemModified)
+ strbuf_addstr(&msg, "ItemModified|");
+ if (flag & kFSEventStreamEventFlagItemRemoved)
+ strbuf_addstr(&msg, "ItemRemoved|");
+ if (flag & kFSEventStreamEventFlagItemRenamed)
+ strbuf_addstr(&msg, "ItemRenamed|");
+ if (flag & kFSEventStreamEventFlagItemXattrMod)
+ strbuf_addstr(&msg, "ItemXattrMod|");
+ if (flag & kFSEventStreamEventFlagOwnEvent)
+ strbuf_addstr(&msg, "OwnEvent|");
+ if (flag & kFSEventStreamEventFlagItemCloned)
+ strbuf_addstr(&msg, "ItemCloned|");
+
+ trace_printf_key(&trace_fsmonitor, "fsevent: '%s', flags=%u %s",
+ path, flag, msg.buf);
+
+ strbuf_release(&msg);
+}
+
+static int ef_is_root_delete(const FSEventStreamEventFlags ef)
+{
+ return (ef & kFSEventStreamEventFlagItemIsDir &&
+ ef & kFSEventStreamEventFlagItemRemoved);
+}
+
+static int ef_is_root_renamed(const FSEventStreamEventFlags ef)
+{
+ return (ef & kFSEventStreamEventFlagItemIsDir &&
+ ef & kFSEventStreamEventFlagItemRenamed);
+}
+
+static int ef_is_dropped(const FSEventStreamEventFlags ef)
+{
+ return (ef & kFSEventStreamEventFlagMustScanSubDirs ||
+ ef & kFSEventStreamEventFlagKernelDropped ||
+ ef & kFSEventStreamEventFlagUserDropped);
+}
+
+static void fsevent_callback(ConstFSEventStreamRef streamRef,
+ void *ctx,
+ size_t num_of_events,
+ void *event_paths,
+ const FSEventStreamEventFlags event_flags[],
+ const FSEventStreamEventId event_ids[])
+{
+ struct fsmonitor_daemon_state *state = ctx;
+ struct fsmonitor_daemon_backend_data *data = state->backend_data;
+ char **paths = (char **)event_paths;
+ struct fsmonitor_batch *batch = NULL;
+ struct string_list cookie_list = STRING_LIST_INIT_DUP;
+ const char *path_k;
+ const char *slash;
+ int k;
+ struct strbuf tmp = STRBUF_INIT;
+
+ /*
+ * Build a list of all filesystem changes into a private/local
+ * list and without holding any locks.
+ */
+ for (k = 0; k < num_of_events; k++) {
+ /*
+ * On Mac, we receive an array of absolute paths.
+ */
+ path_k = paths[k];
+
+ /*
+ * If you want to debug FSEvents, log them to GIT_TRACE_FSMONITOR.
+ * Please don't log them to Trace2.
+ *
+ * trace_printf_key(&trace_fsmonitor, "Path: '%s'", path_k);
+ */
+
+ /*
+ * If event[k] is marked as dropped, we assume that we have
+ * lost sync with the filesystem and should flush our cached
+ * data. We need to:
+ *
+ * [1] Abort/wake any client threads waiting for a cookie and
+ * flush the cached state data (the current token), and
+ * create a new token.
+ *
+ * [2] Discard the batch that we were locally building (since
+ * they are conceptually relative to the just flushed
+ * token).
+ */
+ if (ef_is_dropped(event_flags[k])) {
+ if (trace_pass_fl(&trace_fsmonitor))
+ log_flags_set(path_k, event_flags[k]);
+
+ fsmonitor_force_resync(state);
+ fsmonitor_batch__free_list(batch);
+ string_list_clear(&cookie_list, 0);
+
+ /*
+ * We assume that any events that we received
+ * in this callback after this dropped event
+ * may still be valid, so we continue rather
+ * than break. (And just in case there is a
+ * delete of ".git" hiding in there.)
+ */
+ continue;
+ }
+
+ switch (fsmonitor_classify_path_absolute(state, path_k)) {
+
+ case IS_INSIDE_DOT_GIT_WITH_COOKIE_PREFIX:
+ case IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX:
+ /* special case cookie files within .git or gitdir */
+
+ /* Use just the filename of the cookie file. */
+ slash = find_last_dir_sep(path_k);
+ string_list_append(&cookie_list,
+ slash ? slash + 1 : path_k);
+ break;
+
+ case IS_INSIDE_DOT_GIT:
+ case IS_INSIDE_GITDIR:
+ /* ignore all other paths inside of .git or gitdir */
+ break;
+
+ case IS_DOT_GIT:
+ case IS_GITDIR:
+ /*
+ * If .git directory is deleted or renamed away,
+ * we have to quit.
+ */
+ if (ef_is_root_delete(event_flags[k])) {
+ trace_printf_key(&trace_fsmonitor,
+ "event: gitdir removed");
+ goto force_shutdown;
+ }
+ if (ef_is_root_renamed(event_flags[k])) {
+ trace_printf_key(&trace_fsmonitor,
+ "event: gitdir renamed");
+ goto force_shutdown;
+ }
+ break;
+
+ case IS_WORKDIR_PATH:
+ /* try to queue normal pathnames */
+
+ if (trace_pass_fl(&trace_fsmonitor))
+ log_flags_set(path_k, event_flags[k]);
+
+ /*
+ * Because of the implicit "binning" (the
+ * kernel calls us at a given frequency) and
+ * de-duping (the kernel is free to combine
+ * multiple events for a given pathname), an
+ * individual fsevent could be marked as both
+ * a file and directory. Add it to the queue
+ * with both spellings so that the client will
+ * know how much to invalidate/refresh.
+ */
+
+ if (event_flags[k] & kFSEventStreamEventFlagItemIsFile) {
+ const char *rel = path_k +
+ state->path_worktree_watch.len + 1;
+
+ if (!batch)
+ batch = fsmonitor_batch__new();
+ fsmonitor_batch__add_path(batch, rel);
+ }
+
+ if (event_flags[k] & kFSEventStreamEventFlagItemIsDir) {
+ const char *rel = path_k +
+ state->path_worktree_watch.len + 1;
+
+ strbuf_reset(&tmp);
+ strbuf_addstr(&tmp, rel);
+ strbuf_addch(&tmp, '/');
+
+ if (!batch)
+ batch = fsmonitor_batch__new();
+ fsmonitor_batch__add_path(batch, tmp.buf);
+ }
+
+ break;
+
+ case IS_OUTSIDE_CONE:
+ default:
+ trace_printf_key(&trace_fsmonitor,
+ "ignoring '%s'", path_k);
+ break;
+ }
+ }
+
+ fsmonitor_publish(state, batch, &cookie_list);
+ string_list_clear(&cookie_list, 0);
+ strbuf_release(&tmp);
+ return;
+
+force_shutdown:
+ fsmonitor_batch__free_list(batch);
+ string_list_clear(&cookie_list, 0);
+
+ data->shutdown_style = FORCE_SHUTDOWN;
+ CFRunLoopStop(data->rl);
+ strbuf_release(&tmp);
+ return;
+}
+
+/*
+ * In the call to `FSEventStreamCreate()` to setup our watch, the
+ * `latency` argument determines the frequency of calls to our callback
+ * with new FS events. Too slow and events get dropped; too fast and
+ * we burn CPU unnecessarily. Since it is rather obscure, I don't
+ * think this needs to be a config setting. I've done extensive
+ * testing on my systems and chosen the value below. It gives good
+ * results and I've not seen any dropped events.
+ *
+ * With a latency of 0.1, I was seeing lots of dropped events during
+ * the "touch 100000" files test within t/perf/p7519, but with a
+ * latency of 0.001 I did not see any dropped events. So I'm going
+ * to assume that this is the "correct" value.
+ *
+ * https://developer.apple.com/documentation/coreservices/1443980-fseventstreamcreate
+ */
int fsm_listen__ctor(struct fsmonitor_daemon_state *state)
{
+ FSEventStreamCreateFlags flags = kFSEventStreamCreateFlagNoDefer |
+ kFSEventStreamCreateFlagWatchRoot |
+ kFSEventStreamCreateFlagFileEvents;
+ FSEventStreamContext ctx = {
+ 0,
+ state,
+ NULL,
+ NULL,
+ NULL
+ };
+ struct fsmonitor_daemon_backend_data *data;
+ const void *dir_array[2];
+
+ CALLOC_ARRAY(data, 1);
+ state->backend_data = data;
+
+ data->cfsr_worktree_path = CFStringCreateWithCString(
+ NULL, state->path_worktree_watch.buf, kCFStringEncodingUTF8);
+ dir_array[data->nr_paths_watching++] = data->cfsr_worktree_path;
+
+ if (state->nr_paths_watching > 1) {
+ data->cfsr_gitdir_path = CFStringCreateWithCString(
+ NULL, state->path_gitdir_watch.buf,
+ kCFStringEncodingUTF8);
+ dir_array[data->nr_paths_watching++] = data->cfsr_gitdir_path;
+ }
+
+ data->cfar_paths_to_watch = CFArrayCreate(NULL, dir_array,
+ data->nr_paths_watching,
+ NULL);
+ data->stream = FSEventStreamCreate(NULL, fsevent_callback, &ctx,
+ data->cfar_paths_to_watch,
+ kFSEventStreamEventIdSinceNow,
+ 0.001, flags);
+ if (data->stream == NULL)
+ goto failed;
+
+ /*
+ * `data->rl` needs to be set inside the listener thread.
+ */
+
+ return 0;
+
+failed:
+ error(_("Unable to create FSEventStream."));
+
+ FREE_AND_NULL(state->backend_data);
return -1;
}
void fsm_listen__dtor(struct fsmonitor_daemon_state *state)
{
+ struct fsmonitor_daemon_backend_data *data;
+
+ if (!state || !state->backend_data)
+ return;
+
+ data = state->backend_data;
+
+ if (data->stream) {
+ if (data->stream_started)
+ FSEventStreamStop(data->stream);
+ if (data->stream_scheduled)
+ FSEventStreamInvalidate(data->stream);
+ FSEventStreamRelease(data->stream);
+ }
+
+ FREE_AND_NULL(state->backend_data);
}
void fsm_listen__stop_async(struct fsmonitor_daemon_state *state)
{
+ struct fsmonitor_daemon_backend_data *data;
+
+ data = state->backend_data;
+ data->shutdown_style = SHUTDOWN_EVENT;
+
+ CFRunLoopStop(data->rl);
}
void fsm_listen__loop(struct fsmonitor_daemon_state *state)
{
+ struct fsmonitor_daemon_backend_data *data;
+
+ data = state->backend_data;
+
+ data->rl = CFRunLoopGetCurrent();
+
+ FSEventStreamScheduleWithRunLoop(data->stream, data->rl, kCFRunLoopDefaultMode);
+ data->stream_scheduled = 1;
+
+ if (!FSEventStreamStart(data->stream)) {
+ error(_("Failed to start the FSEventStream"));
+ goto force_error_stop_without_loop;
+ }
+ data->stream_started = 1;
+
+ CFRunLoopRun();
+
+ switch (data->shutdown_style) {
+ case FORCE_ERROR_STOP:
+ state->error_code = -1;
+ /* fall thru */
+ case FORCE_SHUTDOWN:
+ ipc_server_stop_async(state->ipc_server_data);
+ /* fall thru */
+ case SHUTDOWN_EVENT:
+ default:
+ break;
+ }
+ return;
+
+force_error_stop_without_loop:
+ state->error_code = -1;
+ ipc_server_stop_async(state->ipc_server_data);
+ return;
}
--
gitgitgadget
