"struct dir" manages inotify file descriptor and forms a tree. "struct
file" manages a file. When a file is watched, all dirs up to the file
is watched. Any changes on a directory impacts all subdirs and files.
The way data structure is made might be inotify-specific. I haven't
thought of how other file notification mechanisms may be
implemented. So there may be some refactoring later when a new OS is
supported.
Room for improvement: consecutive watched paths likely share the same
directory part (even though they are sorted by mtime, not name). Try
remember the last "dir" sequence and reduce lookups.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
Documentation/git-file-watcher.txt | 13 +++
file-watcher.c | 226 ++++++++++++++++++++++++++++++++++++-
2 files changed, 238 insertions(+), 1 deletion(-)
diff --git a/Documentation/git-file-watcher.txt b/Documentation/git-file-watcher.txt
index d91caf3..d694fea 100644
--- a/Documentation/git-file-watcher.txt
+++ b/Documentation/git-file-watcher.txt
@@ -18,11 +18,24 @@ lstat(2) to detect that itself. Config key filewatcher.path needs to
be set to `<socket directory>` so Git knows how to contact to the file
watcher.
+This program is only supported under Linux with inotify(7) support.
+
OPTIONS
-------
--detach::
Run in background.
+BUGS
+----
+On Linux, file watcher may fail to detect changes if you move the work
+tree from outside. For example if you have work tree at
+`/tmp/foo/work`, you move `/tmp/foo` to `/tmp/bar`, make some changes
+in `/tmp/bar/work` and move `/tmp/bar` back to `/tmp/foo`, changes
+won't get noticed. Moving `/tmp/foo/work` to something else is fine.
+
+inotify may not work well with network filesystems and a few special
+others. Check inotify documents.
+
SEE ALSO
--------
linkgit:git-update-index[1],
diff --git a/file-watcher.c b/file-watcher.c
index aa2daf6..d0762e6 100644
--- a/file-watcher.c
+++ b/file-watcher.c
@@ -11,6 +11,28 @@ static const char *const file_watcher_usage[] = {
NULL
};
+struct dir;
+struct repository;
+
+struct file {
+ char *name;
+ struct dir *parent;
+ struct repository *repo;
+ struct file *next;
+};
+
+struct dir {
+ char *name;
+ struct dir *parent;
+ struct dir **subdirs;
+ struct file **files;
+ struct repository *repo; /* only for root note */
+ int wd, nr_subdirs, nr_files;
+};
+
+static struct dir **wds;
+static int wds_alloc;
+
struct repository {
char *work_tree;
char index_signature[41];
@@ -25,6 +47,7 @@ struct repository {
struct string_list updated;
int updated_sorted;
int updating;
+ struct dir *root;
};
const char *invalid_signature = "0000000000000000000000000000000000000000";
@@ -42,10 +65,199 @@ struct connection {
static struct connection **conns;
static struct pollfd *pfd;
static int conns_alloc, pfd_nr, pfd_alloc;
+static int inotify_fd;
+
+/*
+ * IN_DONT_FOLLOW does not matter now as we do not monitor
+ * symlinks. See ce_watchable().
+ */
+#define INOTIFY_MASKS (IN_DELETE_SELF | IN_MOVE_SELF | \
+ IN_CREATE | IN_ATTRIB | IN_DELETE | IN_MODIFY | \
+ IN_MOVED_FROM | IN_MOVED_TO)
+static struct dir *create_dir(struct dir *parent, const char *path,
+ const char *basename)
+{
+ struct dir *d;
+ int wd = inotify_add_watch(inotify_fd, path, INOTIFY_MASKS);
+ if (wd < 0)
+ return NULL;
+
+ d = xmalloc(sizeof(*d));
+ memset(d, 0, sizeof(*d));
+ d->wd = wd;
+ d->parent = parent;
+ d->name = xstrdup(basename);
+
+ ALLOC_GROW(wds, wd + 1, wds_alloc);
+ wds[wd] = d;
+ return d;
+}
+
+static int get_dir_pos(struct dir *d, const char *name)
+{
+ int first, last;
+
+ first = 0;
+ last = d->nr_subdirs;
+ while (last > first) {
+ int next = (last + first) >> 1;
+ int cmp = strcmp(name, d->subdirs[next]->name);
+ if (!cmp)
+ return next;
+ if (cmp < 0) {
+ last = next;
+ continue;
+ }
+ first = next+1;
+ }
+
+ return -first-1;
+}
+
+static void free_file(struct dir *d, int pos, int topdown);
+static void free_dir(struct dir *d, int topdown)
+{
+ struct dir *p = d->parent;
+ int pos;
+ if (!topdown && p && (pos = get_dir_pos(p, d->name)) < 0)
+ die("How come this directory is not registered in its parent?");
+ if (d->repo)
+ d->repo->root = NULL;
+ wds[d->wd] = NULL;
+ inotify_rm_watch(inotify_fd, d->wd);
+ if (topdown) {
+ int i;
+ for (i = 0; i < d->nr_subdirs; i++)
+ free_dir(d->subdirs[i], topdown);
+ for (i = 0; i < d->nr_files; i++)
+ free_file(d, i, topdown);
+ }
+ free(d->name);
+ free(d->subdirs);
+ free(d->files);
+ free(d);
+ if (p && !topdown) {
+ p->nr_subdirs--;
+ memmove(p->subdirs + pos, p->subdirs + pos + 1,
+ (p->nr_subdirs - pos) * sizeof(*p->subdirs));
+ if (!p->nr_subdirs && !p->nr_files)
+ free_dir(p, topdown);
+ }
+}
+
+static int get_file_pos(struct dir *d, const char *name)
+{
+ int first, last;
+
+ first = 0;
+ last = d->nr_files;
+ while (last > first) {
+ int next = (last + first) >> 1;
+ int cmp = strcmp(name, d->files[next]->name);
+ if (!cmp)
+ return next;
+ if (cmp < 0) {
+ last = next;
+ continue;
+ }
+ first = next+1;
+ }
+
+ return -first-1;
+}
+
+static void free_file(struct dir *d, int pos, int topdown)
+{
+ struct file *f = d->files[pos];
+ free(f->name);
+ free(f);
+ if (!topdown) {
+ d->nr_files--;
+ memmove(d->files + pos, d->files + pos + 1,
+ (d->nr_files - pos) * sizeof(*d->files));
+ if (!d->nr_subdirs && !d->nr_files)
+ free_dir(d, topdown);
+ }
+}
+
+static struct dir *add_dir(struct dir *d,
+ const char *path, const char *basename)
+{
+ struct dir *new;
+ int pos = get_dir_pos(d, basename);
+ if (pos >= 0)
+ return d->subdirs[pos];
+ pos = -pos-1;
+
+ new = create_dir(d, path, basename);
+ if (!new)
+ return NULL;
+
+ d->nr_subdirs++;
+ d->subdirs = xrealloc(d->subdirs, sizeof(*d->subdirs) * d->nr_subdirs);
+ if (d->nr_subdirs > pos + 1)
+ memmove(d->subdirs + pos + 1, d->subdirs + pos,
+ (d->nr_subdirs - pos - 1) * sizeof(*d->subdirs));
+ d->subdirs[pos] = new;
+ return new;
+}
+
+static struct file *add_file(struct dir *d, const char *name)
+{
+ struct file *new;
+ int pos = get_file_pos(d, name);
+ if (pos >= 0)
+ return d->files[pos];
+ pos = -pos-1;
+
+ new = xmalloc(sizeof(*new));
+ memset(new, 0, sizeof(*new));
+ new->parent = d;
+ new->name = xstrdup(name);
+
+ d->nr_files++;
+ d->files = xrealloc(d->files, sizeof(*d->files) * d->nr_files);
+ if (d->nr_files > pos + 1)
+ memmove(d->files + pos + 1, d->files + pos,
+ (d->nr_files - pos - 1) * sizeof(*d->files));
+ d->files[pos] = new;
+ return new;
+}
static int watch_path(struct repository *repo, char *path)
{
- return -1;
+ struct dir *d = repo->root;
+ char *p = path;
+
+ if (!d) {
+ d = create_dir(NULL, ".", "");
+ if (!d)
+ return -1;
+ repo->root = d;
+ d->repo = repo;
+ }
+
+ for (;;) {
+ char *next, *sep;
+ sep = strchr(p, '/');
+ if (!sep) {
+ struct file *file;
+ file = add_file(d, p);
+ if (!file->repo)
+ file->repo = repo;
+ break;
+ }
+
+ next = sep + 1;
+ *sep = '\0';
+ d = add_dir(d, path, p);
+ if (!d)
+ /* we could free oldest watches and try again */
+ return -1;
+ *sep = '/';
+ p = next;
+ }
+ return 0;
}
static void get_changed_list(int conn_id)
@@ -195,8 +407,15 @@ static struct repository *get_repo(const char *work_tree)
return repo;
}
+static void reset_watches(struct repository *repo)
+{
+ if (repo->root)
+ free_dir(repo->root, 1);
+}
+
static void reset_repo(struct repository *repo, ino_t inode)
{
+ reset_watches(repo);
string_list_clear(&repo->updated, 0);
memcpy(repo->index_signature, invalid_signature, 40);
repo->inode = inode;
@@ -497,6 +716,11 @@ int main(int argc, const char **argv)
git_extract_argv0_path(argv[0]);
git_setup_gettext();
+
+ inotify_fd = inotify_init();
+ if (inotify_fd < 0)
+ die_errno("unable to initialize inotify");
+
argc = parse_options(argc, argv, NULL, options,
file_watcher_usage, 0);
if (argc < 1)
--
1.8.5.2.240.g8478abd
--
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