From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Teach fsmonitor--daemon to build lists of changed paths and associate
them with a token-id. This will be used by the platform-specific
backends to accumulate changed paths in response to filesystem events.
The platform-specific event loops receive batches containing one or
more changed paths. Their fs listener thread will accumulate them in
a `fsmonitor_batch` (and without locking) and then "publish" them to
associate them with the current token and to make them visible to the
client worker threads.
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
builtin/fsmonitor--daemon.c | 192 ++++++++++++++++++++++++++++++++++++
fsmonitor--daemon.h | 40 ++++++++
2 files changed, 232 insertions(+)
diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c
index 2d25e36601fe..48071d445c49 100644
--- a/builtin/fsmonitor--daemon.c
+++ b/builtin/fsmonitor--daemon.c
@@ -255,6 +255,120 @@ static struct fsmonitor_token_data *fsmonitor_new_token_data(void)
return token;
}
+struct fsmonitor_batch {
+ struct fsmonitor_batch *next;
+ uint64_t batch_seq_nr;
+ const char **interned_paths;
+ size_t nr, alloc;
+ time_t pinned_time;
+};
+
+struct fsmonitor_batch *fsmonitor_batch__new(void)
+{
+ struct fsmonitor_batch *batch = xcalloc(1, sizeof(*batch));
+
+ return batch;
+}
+
+struct fsmonitor_batch *fsmonitor_batch__free(struct fsmonitor_batch *batch)
+{
+ struct fsmonitor_batch *next;
+
+ if (!batch)
+ return NULL;
+
+ next = batch->next;
+
+ /*
+ * The actual strings within the array are interned, so we don't
+ * own them.
+ */
+ free(batch->interned_paths);
+
+ return next;
+}
+
+void fsmonitor_batch__add_path(struct fsmonitor_batch *batch,
+ const char *path)
+{
+ const char *interned_path = strintern(path);
+
+ trace_printf_key(&trace_fsmonitor, "event: %s", interned_path);
+
+ ALLOC_GROW(batch->interned_paths, batch->nr + 1, batch->alloc);
+ batch->interned_paths[batch->nr++] = interned_path;
+}
+
+static void fsmonitor_batch__combine(struct fsmonitor_batch *batch_dest,
+ const struct fsmonitor_batch *batch_src)
+{
+ /* assert state->main_lock */
+
+ size_t k;
+
+ ALLOC_GROW(batch_dest->interned_paths,
+ batch_dest->nr + batch_src->nr + 1,
+ batch_dest->alloc);
+
+ for (k = 0; k < batch_src->nr; k++)
+ batch_dest->interned_paths[batch_dest->nr++] =
+ batch_src->interned_paths[k];
+}
+
+static void fsmonitor_free_token_data(struct fsmonitor_token_data *token)
+{
+ struct fsmonitor_batch *p;
+
+ if (!token)
+ return;
+
+ assert(token->client_ref_count == 0);
+
+ strbuf_release(&token->token_id);
+
+ for (p = token->batch_head; p; p = fsmonitor_batch__free(p))
+ ;
+
+ free(token);
+}
+
+/*
+ * Flush all of our cached data about the filesystem. Call this if we
+ * lose sync with the filesystem and miss some notification events.
+ *
+ * [1] If we are missing events, then we no longer have a complete
+ * history of the directory (relative to our current start token).
+ * We should create a new token and start fresh (as if we just
+ * booted up).
+ *
+ * If there are no readers of the the current token data series, we
+ * can free it now. Otherwise, let the last reader free it. Either
+ * way, the old token data series is no longer associated with our
+ * state data.
+ */
+void fsmonitor_force_resync(struct fsmonitor_daemon_state *state)
+{
+ struct fsmonitor_token_data *free_me = NULL;
+ struct fsmonitor_token_data *new_one = NULL;
+
+ new_one = fsmonitor_new_token_data();
+
+ pthread_mutex_lock(&state->main_lock);
+
+ trace_printf_key(&trace_fsmonitor,
+ "force resync [old '%s'][new '%s']",
+ state->current_token_data->token_id.buf,
+ new_one->token_id.buf);
+
+ if (state->current_token_data->client_ref_count == 0)
+ free_me = state->current_token_data;
+ state->current_token_data = new_one;
+
+ pthread_mutex_unlock(&state->main_lock);
+
+ fsmonitor_free_token_data(free_me);
+}
+
static ipc_server_application_cb handle_client;
static int handle_client(void *data, const char *command,
@@ -355,6 +469,77 @@ enum fsmonitor_path_type fsmonitor_classify_path_absolute(
return fsmonitor_classify_path_gitdir_relative(rel);
}
+/*
+ * We try to combine small batches at the front of the batch-list to avoid
+ * having a long list. This hopefully makes it a little easier when we want
+ * to truncate and maintain the list. However, we don't want the paths array
+ * to just keep growing and growing with realloc, so we insert an arbitrary
+ * limit.
+ */
+#define MY_COMBINE_LIMIT (1024)
+
+void fsmonitor_publish(struct fsmonitor_daemon_state *state,
+ struct fsmonitor_batch *batch,
+ const struct string_list *cookie_names)
+{
+ if (!batch && !cookie_names->nr)
+ return;
+
+ pthread_mutex_lock(&state->main_lock);
+
+ if (batch) {
+ struct fsmonitor_batch *head;
+
+ head = state->current_token_data->batch_head;
+ if (!head) {
+ batch->batch_seq_nr = 0;
+ batch->next = NULL;
+ state->current_token_data->batch_head = batch;
+ state->current_token_data->batch_tail = batch;
+ } else if (head->pinned_time) {
+ /*
+ * We cannot alter the current batch list
+ * because:
+ *
+ * [a] it is being transmitted to at least one
+ * client and the handle_client() thread has a
+ * ref-count, but not a lock on the batch list
+ * starting with this item.
+ *
+ * [b] it has been transmitted in the past to
+ * at least one client such that future
+ * requests are relative to this head batch.
+ *
+ * So, we can only prepend a new batch onto
+ * the front of the list.
+ */
+ batch->batch_seq_nr = head->batch_seq_nr + 1;
+ batch->next = head;
+ state->current_token_data->batch_head = batch;
+ } else if (head->nr + batch->nr > MY_COMBINE_LIMIT) {
+ /*
+ * The head batch in the list has never been
+ * transmitted to a client, but folding the
+ * contents of the new batch onto it would
+ * exceed our arbitrary limit, so just prepend
+ * the new batch onto the list.
+ */
+ batch->batch_seq_nr = head->batch_seq_nr + 1;
+ batch->next = head;
+ state->current_token_data->batch_head = batch;
+ } else {
+ /*
+ * We are free to append the paths in the given
+ * batch onto the end of the current head batch.
+ */
+ fsmonitor_batch__combine(head, batch);
+ fsmonitor_batch__free(batch);
+ }
+ }
+
+ pthread_mutex_unlock(&state->main_lock);
+}
+
static void *fsmonitor_fs_listen__thread_proc(void *_state)
{
struct fsmonitor_daemon_state *state = _state;
@@ -369,6 +554,13 @@ static void *fsmonitor_fs_listen__thread_proc(void *_state)
fsmonitor_fs_listen__loop(state);
+ pthread_mutex_lock(&state->main_lock);
+ if (state->current_token_data &&
+ state->current_token_data->client_ref_count == 0)
+ fsmonitor_free_token_data(state->current_token_data);
+ state->current_token_data = NULL;
+ pthread_mutex_unlock(&state->main_lock);
+
trace2_thread_exit();
return NULL;
}
diff --git a/fsmonitor--daemon.h b/fsmonitor--daemon.h
index 97ea3766e900..06563b6ed56c 100644
--- a/fsmonitor--daemon.h
+++ b/fsmonitor--daemon.h
@@ -12,6 +12,27 @@
struct fsmonitor_batch;
struct fsmonitor_token_data;
+/*
+ * Create a new batch of path(s). The returned batch is considered
+ * private and not linked into the fsmonitor daemon state. The caller
+ * should fill this batch with one or more paths and then publish it.
+ */
+struct fsmonitor_batch *fsmonitor_batch__new(void);
+
+/*
+ * Free this batch and return the value of the batch->next field.
+ */
+struct fsmonitor_batch *fsmonitor_batch__free(struct fsmonitor_batch *batch);
+
+/*
+ * Add this path to this batch of modified files.
+ *
+ * The batch should be private and NOT (yet) linked into the fsmonitor
+ * daemon state and therefore not yet visible to worker threads and so
+ * no locking is required.
+ */
+void fsmonitor_batch__add_path(struct fsmonitor_batch *batch, const char *path);
+
struct fsmonitor_daemon_backend_data; /* opaque platform-specific data */
struct fsmonitor_daemon_state {
@@ -93,5 +114,24 @@ enum fsmonitor_path_type fsmonitor_classify_path_absolute(
struct fsmonitor_daemon_state *state,
const char *path);
+/*
+ * Prepend the this batch of path(s) onto the list of batches associated
+ * with the current token. This makes the batch visible to worker threads.
+ *
+ * The caller no longer owns the batch and must not free it.
+ *
+ * Wake up the client threads waiting on these cookies.
+ */
+void fsmonitor_publish(struct fsmonitor_daemon_state *state,
+ struct fsmonitor_batch *batch,
+ const struct string_list *cookie_names);
+
+/*
+ * If the platform-specific layer loses sync with the filesystem,
+ * it should call this to invalidate cached data and abort waiting
+ * threads.
+ */
+void fsmonitor_force_resync(struct fsmonitor_daemon_state *state);
+
#endif /* HAVE_FSMONITOR_DAEMON_BACKEND */
#endif /* FSMONITOR_DAEMON_H */
--
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