From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Teach the win32 backend to register a watch on the working tree
root directory (recursively). Also watch the <gitdir> if it is
not inside the working tree. And to collect path change notifications
into batches and publish.
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
compat/fsmonitor/fsmonitor-fs-listen-win32.c | 532 +++++++++++++++++++
1 file changed, 532 insertions(+)
diff --git a/compat/fsmonitor/fsmonitor-fs-listen-win32.c b/compat/fsmonitor/fsmonitor-fs-listen-win32.c
index 880446b49e35..ba087b292df6 100644
--- a/compat/fsmonitor/fsmonitor-fs-listen-win32.c
+++ b/compat/fsmonitor/fsmonitor-fs-listen-win32.c
@@ -2,20 +2,552 @@
#include "config.h"
#include "fsmonitor.h"
#include "fsmonitor-fs-listen.h"
+#include "fsmonitor--daemon.h"
+
+/*
+ * The documentation of ReadDirectoryChangesW() states that the maximum
+ * buffer size is 64K when the monitored directory is remote.
+ *
+ * Larger buffers may be used when the monitored directory is local and
+ * will help us receive events faster from the kernel and avoid dropped
+ * events.
+ *
+ * So we try to use a very large buffer and silently fallback to 64K if
+ * we get an error.
+ */
+#define MAX_RDCW_BUF_FALLBACK (65536)
+#define MAX_RDCW_BUF (65536 * 8)
+
+struct one_watch
+{
+ char buffer[MAX_RDCW_BUF];
+ DWORD buf_len;
+ DWORD count;
+
+ struct strbuf path;
+ HANDLE hDir;
+ HANDLE hEvent;
+ OVERLAPPED overlapped;
+
+ /*
+ * Is there an active ReadDirectoryChangesW() call pending. If so, we
+ * need to later call GetOverlappedResult() and possibly CancelIoEx().
+ */
+ BOOL is_active;
+};
+
+struct fsmonitor_daemon_backend_data
+{
+ struct one_watch *watch_worktree;
+ struct one_watch *watch_gitdir;
+
+ HANDLE hEventShutdown;
+
+ HANDLE hListener[3]; /* we don't own these handles */
+#define LISTENER_SHUTDOWN 0
+#define LISTENER_HAVE_DATA_WORKTREE 1
+#define LISTENER_HAVE_DATA_GITDIR 2
+ int nr_listener_handles;
+};
+
+/*
+ * Convert the WCHAR path from the notification into UTF8 and
+ * then normalize it.
+ */
+static int normalize_path_in_utf8(FILE_NOTIFY_INFORMATION *info,
+ struct strbuf *normalized_path)
+{
+ int reserve;
+ int len = 0;
+
+ strbuf_reset(normalized_path);
+ if (!info->FileNameLength)
+ goto normalize;
+
+ /*
+ * Pre-reserve enough space in the UTF8 buffer for
+ * each Unicode WCHAR character to be mapped into a
+ * sequence of 2 UTF8 characters. That should let us
+ * avoid ERROR_INSUFFICIENT_BUFFER 99.9+% of the time.
+ */
+ reserve = info->FileNameLength + 1;
+ strbuf_grow(normalized_path, reserve);
+
+ for (;;) {
+ len = WideCharToMultiByte(CP_UTF8, 0, info->FileName,
+ info->FileNameLength / sizeof(WCHAR),
+ normalized_path->buf,
+ strbuf_avail(normalized_path) - 1,
+ NULL, NULL);
+ if (len > 0)
+ goto normalize;
+ if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
+ error("[GLE %ld] could not convert path to UTF-8: '%.*ls'",
+ GetLastError(),
+ (int)(info->FileNameLength / sizeof(WCHAR)),
+ info->FileName);
+ return -1;
+ }
+
+ strbuf_grow(normalized_path,
+ strbuf_avail(normalized_path) + reserve);
+ }
+
+normalize:
+ strbuf_setlen(normalized_path, len);
+ return strbuf_normalize_path(normalized_path);
+}
void fsmonitor_fs_listen__stop_async(struct fsmonitor_daemon_state *state)
{
+ SetEvent(state->backend_data->hListener[LISTENER_SHUTDOWN]);
+}
+
+static struct one_watch *create_watch(struct fsmonitor_daemon_state *state,
+ const char *path)
+{
+ struct one_watch *watch = NULL;
+ DWORD desired_access = FILE_LIST_DIRECTORY;
+ DWORD share_mode =
+ FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE;
+ HANDLE hDir;
+
+ hDir = CreateFileA(path,
+ desired_access, share_mode, NULL, OPEN_EXISTING,
+ FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,
+ NULL);
+ if (hDir == INVALID_HANDLE_VALUE) {
+ error(_("[GLE %ld] could not watch '%s'"),
+ GetLastError(), path);
+ return NULL;
+ }
+
+ CALLOC_ARRAY(watch, 1);
+
+ watch->buf_len = sizeof(watch->buffer); /* assume full MAX_RDCW_BUF */
+
+ strbuf_init(&watch->path, 0);
+ strbuf_addstr(&watch->path, path);
+
+ watch->hDir = hDir;
+ watch->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
+
+ return watch;
+}
+
+static void destroy_watch(struct one_watch *watch)
+{
+ if (!watch)
+ return;
+
+ strbuf_release(&watch->path);
+ if (watch->hDir != INVALID_HANDLE_VALUE)
+ CloseHandle(watch->hDir);
+ if (watch->hEvent != INVALID_HANDLE_VALUE)
+ CloseHandle(watch->hEvent);
+
+ free(watch);
+}
+
+static int start_rdcw_watch(struct fsmonitor_daemon_backend_data *data,
+ struct one_watch *watch)
+{
+ DWORD dwNotifyFilter =
+ FILE_NOTIFY_CHANGE_FILE_NAME |
+ FILE_NOTIFY_CHANGE_DIR_NAME |
+ FILE_NOTIFY_CHANGE_ATTRIBUTES |
+ FILE_NOTIFY_CHANGE_SIZE |
+ FILE_NOTIFY_CHANGE_LAST_WRITE |
+ FILE_NOTIFY_CHANGE_CREATION;
+
+ ResetEvent(watch->hEvent);
+
+ memset(&watch->overlapped, 0, sizeof(watch->overlapped));
+ watch->overlapped.hEvent = watch->hEvent;
+
+start_watch:
+ /*
+ * Queue an async call using Overlapped IO. This returns immediately.
+ * Our event handle will be signalled when the real result is available.
+ *
+ * The return value here just means that we successfully queued it.
+ * We won't know if the Read...() actually produces data until later.
+ */
+ watch->is_active = ReadDirectoryChangesW(
+ watch->hDir, watch->buffer, watch->buf_len, TRUE,
+ dwNotifyFilter, &watch->count, &watch->overlapped, NULL);
+
+ /*
+ * The kernel throws an invalid parameter error when our buffer
+ * is too big and we are pointed at a remote directory (and possibly
+ * for other reasons). Quietly set it down and try again.
+ *
+ * See note about MAX_RDCW_BUF at the top.
+ */
+ if (!watch->is_active &&
+ GetLastError() == ERROR_INVALID_PARAMETER &&
+ watch->buf_len > MAX_RDCW_BUF_FALLBACK) {
+ watch->buf_len = MAX_RDCW_BUF_FALLBACK;
+ goto start_watch;
+ }
+
+ if (watch->is_active)
+ return 0;
+
+ error("ReadDirectoryChangedW failed on '%s' [GLE %ld]",
+ watch->path.buf, GetLastError());
+ return -1;
+}
+
+static int recv_rdcw_watch(struct one_watch *watch)
+{
+ watch->is_active = FALSE;
+
+ /*
+ * The overlapped result is ready. If the Read...() was successful
+ * we finally receive the actual result into our buffer.
+ */
+ if (GetOverlappedResult(watch->hDir, &watch->overlapped, &watch->count,
+ TRUE))
+ return 0;
+
+ /*
+ * NEEDSWORK: If an external <gitdir> is deleted, the above
+ * returns an error. I'm not sure that there's anything that
+ * we can do here other than failing -- the <worktree>/.git
+ * link file would be broken anyway. We might try to check
+ * for that and return a better error message, but I'm not
+ * sure it is worth it.
+ */
+
+ error("GetOverlappedResult failed on '%s' [GLE %ld]",
+ watch->path.buf, GetLastError());
+ return -1;
+}
+
+static void cancel_rdcw_watch(struct one_watch *watch)
+{
+ DWORD count;
+
+ if (!watch || !watch->is_active)
+ return;
+
+ /*
+ * The calls to ReadDirectoryChangesW() and GetOverlappedResult()
+ * form a "pair" (my term) where we queue an IO and promise to
+ * hang around and wait for the kernel to give us the result.
+ *
+ * If for some reason after we queue the IO, we have to quit
+ * or otherwise not stick around for the second half, we must
+ * tell the kernel to abort the IO. This prevents the kernel
+ * from writing to our buffer and/or signalling our event
+ * after we free them.
+ *
+ * (Ask me how much fun it was to track that one down).
+ */
+ CancelIoEx(watch->hDir, &watch->overlapped);
+ GetOverlappedResult(watch->hDir, &watch->overlapped, &count, TRUE);
+ watch->is_active = FALSE;
+}
+
+/*
+ * Process filesystem events that happen anywhere (recursively) under the
+ * <worktree> root directory. For a normal working directory, this includes
+ * both version controlled files and the contents of the .git/ directory.
+ *
+ * If <worktree>/.git is a file, then we only see events for the file
+ * itself.
+ */
+static int process_worktree_events(struct fsmonitor_daemon_state *state)
+{
+ struct fsmonitor_daemon_backend_data *data = state->backend_data;
+ struct one_watch *watch = data->watch_worktree;
+ struct strbuf path = STRBUF_INIT;
+ struct string_list cookie_list = STRING_LIST_INIT_DUP;
+ struct fsmonitor_batch *batch = NULL;
+ const char *p = watch->buffer;
+
+ /*
+ * If the kernel gets more events than will fit in the kernel
+ * buffer associated with our RDCW handle, it drops them and
+ * returns a count of zero.
+ *
+ * Yes, the call returns WITHOUT error and with length zero.
+ *
+ * (The "overflow" case is not ambiguous with the "no data" case
+ * because we did an INFINITE wait.)
+ *
+ * This means we have a gap in coverage. Tell the daemon layer
+ * to resync.
+ */
+ if (!watch->count) {
+ trace2_data_string("fsmonitor", NULL, "fsm-listen/kernel",
+ "overflow");
+ fsmonitor_force_resync(state);
+ return LISTENER_HAVE_DATA_WORKTREE;
+ }
+
+ /*
+ * On Windows, `info` contains an "array" of paths that are
+ * relative to the root of whichever directory handle received
+ * the event.
+ */
+ for (;;) {
+ FILE_NOTIFY_INFORMATION *info = (void *)p;
+ const char *slash;
+ enum fsmonitor_path_type t;
+
+ strbuf_reset(&path);
+ if (normalize_path_in_utf8(info, &path) == -1)
+ goto skip_this_path;
+
+ t = fsmonitor_classify_path_workdir_relative(path.buf);
+
+ switch (t) {
+ case IS_INSIDE_DOT_GIT_WITH_COOKIE_PREFIX:
+ /* special case cookie files within .git */
+
+ /* Use just the filename of the cookie file. */
+ slash = find_last_dir_sep(path.buf);
+ string_list_append(&cookie_list,
+ slash ? slash + 1 : path.buf);
+ break;
+
+ case IS_INSIDE_DOT_GIT:
+ /* ignore everything inside of "<worktree>/.git/" */
+ break;
+
+ case IS_DOT_GIT:
+ /* "<worktree>/.git" was deleted (or renamed away) */
+ if ((info->Action == FILE_ACTION_REMOVED) ||
+ (info->Action == FILE_ACTION_RENAMED_OLD_NAME)) {
+ trace2_data_string("fsmonitor", NULL,
+ "fsm-listen/dotgit",
+ "removed");
+ goto force_shutdown;
+ }
+ break;
+
+ case IS_WORKDIR_PATH:
+ /* queue normal pathname */
+ if (!batch)
+ batch = fsmonitor_batch__new();
+ fsmonitor_batch__add_path(batch, path.buf);
+ break;
+
+ case IS_GITDIR:
+ case IS_INSIDE_GITDIR:
+ case IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX:
+ default:
+ BUG("unexpected path classification '%d' for '%s'",
+ t, path.buf);
+ }
+
+skip_this_path:
+ if (!info->NextEntryOffset)
+ break;
+ p += info->NextEntryOffset;
+ }
+
+ fsmonitor_publish(state, batch, &cookie_list);
+ batch = NULL;
+ string_list_clear(&cookie_list, 0);
+ strbuf_release(&path);
+ return LISTENER_HAVE_DATA_WORKTREE;
+
+force_shutdown:
+ fsmonitor_batch__pop(batch);
+ string_list_clear(&cookie_list, 0);
+ strbuf_release(&path);
+ return LISTENER_SHUTDOWN;
+}
+
+/*
+ * Process filesystem events that happened anywhere (recursively) under the
+ * external <gitdir> (such as non-primary worktrees or submodules).
+ * We only care about cookie files that our client threads created here.
+ *
+ * Note that we DO NOT get filesystem events on the external <gitdir>
+ * itself (it is not inside something that we are watching). In particular,
+ * we do not get an event if the external <gitdir> is deleted.
+ */
+static int process_gitdir_events(struct fsmonitor_daemon_state *state)
+{
+ struct fsmonitor_daemon_backend_data *data = state->backend_data;
+ struct one_watch *watch = data->watch_gitdir;
+ struct strbuf path = STRBUF_INIT;
+ struct string_list cookie_list = STRING_LIST_INIT_DUP;
+ const char *p = watch->buffer;
+
+ if (!watch->count) {
+ trace2_data_string("fsmonitor", NULL, "fsm-listen/kernel",
+ "overflow");
+ fsmonitor_force_resync(state);
+ return LISTENER_HAVE_DATA_GITDIR;
+ }
+
+ for (;;) {
+ FILE_NOTIFY_INFORMATION *info = (void *)p;
+ const char *slash;
+ enum fsmonitor_path_type t;
+
+ strbuf_reset(&path);
+ if (normalize_path_in_utf8(info, &path) == -1)
+ goto skip_this_path;
+
+ t = fsmonitor_classify_path_gitdir_relative(path.buf);
+
+ trace_printf_key(&trace_fsmonitor, "BBB: %s", path.buf);
+
+ switch (t) {
+ case IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX:
+ /* special case cookie files within gitdir */
+
+ /* Use just the filename of the cookie file. */
+ slash = find_last_dir_sep(path.buf);
+ string_list_append(&cookie_list,
+ slash ? slash + 1 : path.buf);
+ break;
+
+ case IS_INSIDE_GITDIR:
+ goto skip_this_path;
+
+ default:
+ BUG("unexpected path classification '%d' for '%s'",
+ t, path.buf);
+ }
+
+skip_this_path:
+ if (!info->NextEntryOffset)
+ break;
+ p += info->NextEntryOffset;
+ }
+
+ fsmonitor_publish(state, NULL, &cookie_list);
+ string_list_clear(&cookie_list, 0);
+ strbuf_release(&path);
+ return LISTENER_HAVE_DATA_GITDIR;
}
void fsmonitor_fs_listen__loop(struct fsmonitor_daemon_state *state)
{
+ struct fsmonitor_daemon_backend_data *data = state->backend_data;
+ DWORD dwWait;
+
+ state->error_code = 0;
+
+ if (start_rdcw_watch(data, data->watch_worktree) == -1)
+ goto force_error_stop;
+
+ if (data->watch_gitdir &&
+ start_rdcw_watch(data, data->watch_gitdir) == -1)
+ goto force_error_stop;
+
+ for (;;) {
+ dwWait = WaitForMultipleObjects(data->nr_listener_handles,
+ data->hListener,
+ FALSE, INFINITE);
+
+ if (dwWait == WAIT_OBJECT_0 + LISTENER_HAVE_DATA_WORKTREE) {
+ if (recv_rdcw_watch(data->watch_worktree) == -1)
+ goto force_error_stop;
+ if (process_worktree_events(state) == LISTENER_SHUTDOWN)
+ goto force_shutdown;
+ if (start_rdcw_watch(data, data->watch_worktree) == -1)
+ goto force_error_stop;
+ continue;
+ }
+
+ if (dwWait == WAIT_OBJECT_0 + LISTENER_HAVE_DATA_GITDIR) {
+ if (recv_rdcw_watch(data->watch_gitdir) == -1)
+ goto force_error_stop;
+ if (process_gitdir_events(state) == LISTENER_SHUTDOWN)
+ goto force_shutdown;
+ if (start_rdcw_watch(data, data->watch_gitdir) == -1)
+ goto force_error_stop;
+ continue;
+ }
+
+ if (dwWait == WAIT_OBJECT_0 + LISTENER_SHUTDOWN)
+ goto clean_shutdown;
+
+ error(_("could not read directory changes [GLE %ld]"),
+ GetLastError());
+ goto force_error_stop;
+ }
+
+force_error_stop:
+ state->error_code = -1;
+
+force_shutdown:
+ /*
+ * Tell the IPC thead pool to stop (which completes the await
+ * in the main thread (which will also signal this thread (if
+ * we are still alive))).
+ */
+ ipc_server_stop_async(state->ipc_server_data);
+
+clean_shutdown:
+ cancel_rdcw_watch(data->watch_worktree);
+ cancel_rdcw_watch(data->watch_gitdir);
}
int fsmonitor_fs_listen__ctor(struct fsmonitor_daemon_state *state)
{
+ struct fsmonitor_daemon_backend_data *data;
+
+ CALLOC_ARRAY(data, 1);
+
+ data->hEventShutdown = CreateEvent(NULL, TRUE, FALSE, NULL);
+
+ data->watch_worktree = create_watch(state,
+ state->path_worktree_watch.buf);
+ if (!data->watch_worktree)
+ goto failed;
+
+ if (state->nr_paths_watching > 1) {
+ data->watch_gitdir = create_watch(state,
+ state->path_gitdir_watch.buf);
+ if (!data->watch_gitdir)
+ goto failed;
+ }
+
+ data->hListener[LISTENER_SHUTDOWN] = data->hEventShutdown;
+ data->nr_listener_handles++;
+
+ data->hListener[LISTENER_HAVE_DATA_WORKTREE] =
+ data->watch_worktree->hEvent;
+ data->nr_listener_handles++;
+
+ if (data->watch_gitdir) {
+ data->hListener[LISTENER_HAVE_DATA_GITDIR] =
+ data->watch_gitdir->hEvent;
+ data->nr_listener_handles++;
+ }
+
+ state->backend_data = data;
+ return 0;
+
+failed:
+ CloseHandle(data->hEventShutdown);
+ destroy_watch(data->watch_worktree);
+ destroy_watch(data->watch_gitdir);
+
return -1;
}
void fsmonitor_fs_listen__dtor(struct fsmonitor_daemon_state *state)
{
+ struct fsmonitor_daemon_backend_data *data;
+
+ if (!state || !state->backend_data)
+ return;
+
+ data = state->backend_data;
+
+ CloseHandle(data->hEventShutdown);
+ destroy_watch(data->watch_worktree);
+ destroy_watch(data->watch_gitdir);
+
+ FREE_AND_NULL(state->backend_data);
}
--
gitgitgadget
