@@ -168,17 +168,27 @@ struct fsmonitor_token_data {
uint64_t client_ref_count;
};
+struct fsmonitor_batch {
+ struct fsmonitor_batch *next;
+ uint64_t batch_seq_nr;
+ const char **interned_paths;
+ size_t nr, alloc;
+ time_t pinned_time;
+};
+
static struct fsmonitor_token_data *fsmonitor_new_token_data(void)
{
static int test_env_value = -1;
static uint64_t flush_count = 0;
struct fsmonitor_token_data *token;
+ struct fsmonitor_batch *batch;
CALLOC_ARRAY(token, 1);
+ batch = fsmonitor_batch__new();
strbuf_init(&token->token_id, 0);
- token->batch_head = NULL;
- token->batch_tail = NULL;
+ token->batch_head = batch;
+ token->batch_tail = batch;
token->client_ref_count = 0;
if (test_env_value < 0)
@@ -204,9 +214,143 @@ static struct fsmonitor_token_data *fsmonitor_new_token_data(void)
strbuf_addf(&token->token_id, "test_%08x", test_env_value++);
}
+ /*
+ * We created a new <token_id> and are starting a new series
+ * of tokens with a zero <seq_nr>.
+ *
+ * Since clients cannot guess our new (non test) <token_id>
+ * they will always receive a trivial response (because of the
+ * mismatch on the <token_id>). The trivial response will
+ * tell them our new <token_id> so that subsequent requests
+ * will be relative to our new series. (And when sending that
+ * response, we pin the current head of the batch list.)
+ *
+ * Even if the client correctly guesses the <token_id>, their
+ * request of "builtin:<token_id>:0" asks for all changes MORE
+ * RECENT than batch/bin 0.
+ *
+ * This implies that it is a waste to accumulate paths in the
+ * initial batch/bin (because they will never be transmitted).
+ *
+ * So the daemon could be running for days and watching the
+ * file system, but doesn't need to actually accumulate any
+ * paths UNTIL we need to set a reference point for a later
+ * relative request.
+ *
+ * However, it is very useful for testing to always have a
+ * reference point set. Pin batch 0 to force early file system
+ * events to accumulate.
+ */
+ if (test_env_value)
+ batch->pinned_time = time(NULL);
+
return token;
}
+struct fsmonitor_batch *fsmonitor_batch__new(void)
+{
+ struct fsmonitor_batch *batch;
+
+ CALLOC_ARRAY(batch, 1);
+
+ return batch;
+}
+
+void fsmonitor_batch__free_list(struct fsmonitor_batch *batch)
+{
+ while (batch) {
+ struct fsmonitor_batch *next = batch->next;
+
+ /*
+ * The actual strings within the array of this batch
+ * are interned, so we don't own them. We only own
+ * the array.
+ */
+ free(batch->interned_paths);
+ free(batch);
+
+ batch = 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)
+{
+ 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)
+{
+ if (!token)
+ return;
+
+ assert(token->client_ref_count == 0);
+
+ strbuf_release(&token->token_id);
+
+ fsmonitor_batch__free_list(token->batch_head);
+
+ 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 concurrent threads readering 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.
+ */
+static void with_lock__do_force_resync(struct fsmonitor_daemon_state *state)
+{
+ /* assert current thread holding state->main_lock */
+
+ struct fsmonitor_token_data *free_me = NULL;
+ struct fsmonitor_token_data *new_one = NULL;
+
+ new_one = fsmonitor_new_token_data();
+
+ if (state->current_token_data->client_ref_count == 0)
+ free_me = state->current_token_data;
+ state->current_token_data = new_one;
+
+ fsmonitor_free_token_data(free_me);
+}
+
+void fsmonitor_force_resync(struct fsmonitor_daemon_state *state)
+{
+ pthread_mutex_lock(&state->main_lock);
+ with_lock__do_force_resync(state);
+ pthread_mutex_unlock(&state->main_lock);
+}
+
static ipc_server_application_cb handle_client;
static int handle_client(void *data,
@@ -316,6 +460,81 @@ 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) {
+ BUG("token does not have 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->batch_seq_nr) {
+ /*
+ * Batch 0 is unpinned. See the note in
+ * `fsmonitor_new_token_data()` about why we
+ * don't need to accumulate these paths.
+ */
+ fsmonitor_batch__free_list(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 add the paths in the given
+ * batch onto the end of the current head batch.
+ */
+ fsmonitor_batch__combine(head, batch);
+ fsmonitor_batch__free_list(batch);
+ }
+ }
+
+ pthread_mutex_unlock(&state->main_lock);
+}
+
static void *fsm_listen__thread_proc(void *_state)
{
struct fsmonitor_daemon_state *state = _state;
@@ -330,6 +549,13 @@ static void *fsm_listen__thread_proc(void *_state)
fsm_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;
}
@@ -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 the list of batches starting with this one.
+ */
+void fsmonitor_batch__free_list(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 {
@@ -91,5 +112,24 @@ 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 */