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+/*
+ * Unix SMB/CIFS implementation.
+ *
+ * Copyright (C) Volker Lendecke 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __NOTIFYD_NOTIFYD_H__
+#define __NOTIFYD_NOTIFYD_H__
+
+#include "includes.h"
+#include "librpc/gen_ndr/notify.h"
+#include "librpc/gen_ndr/messaging.h"
+#include "lib/dbwrap/dbwrap.h"
+#include "lib/dbwrap/dbwrap_rbt.h"
+#include "messages.h"
+#include "tdb.h"
+#include "util_tdb.h"
+
+/*
+ * Filechangenotify based on asynchronous messages
+ *
+ * smbds talk to local notify daemons to inform them about paths they are
+ * interested in. They also tell local notify daemons about changes they have
+ * done to the file system. There's two message types from smbd to
+ * notifyd. The first is used to inform notifyd about changes in notify
+ * interest. These are only sent from smbd to notifyd if the SMB client issues
+ * FileChangeNotify requests.
+ */
+
+/*
+ * The notifyd implementation is designed to cope with multiple daemons taking
+ * care of just a subset of smbds. The goal is to minimize the traffic between
+ * the notify daemons. The idea behind this is a samba/ctdb cluster, but it
+ * could also be used to spread the load of notifyd instances on a single
+ * node, should this become a bottleneck. The following diagram illustrates
+ * the setup. The numbers in the boxes are node:process ids.
+ *
+ * +-----------+ +-----------+
+ * |notifyd 0:5|------------------|notifyd 1:6|
+ * +-----------+ +-----------+
+ * / | \ / \
+ * / | \ / \
+ * +--------+ | +--------+ +--------+ +--------+
+ * |smbd 0:1| | |smbd 0:4| |smbd 1:7| |smbd 1:2|
+ * +--------+ | +--------+ +--------+ +--------+
+ * |
+ * +---------+
+ * |smbd 0:20|
+ * +---------+
+ *
+ * Suppose 0:1 and 0:4 are interested in changes for /foo and 0:20 creates the
+ * file /foo/bar, if everything fully connected, 0:20 would have to send two
+ * local messages, one to 0:1 and one to 0:4. With the notifyd design, 0:20
+ * only has to send one message, it lets notifyd 0:5 do the hard work to
+ * multicast the change to 0:1 and 0:4.
+ *
+ * Now lets assume 1:7 on the other node creates /foo/baz. It tells its
+ * notifyd 1:6 about this change. All 1:6 will know about is that its peer
+ * notifyd 0:5 is interested in the change. Thus it forwards the event to 0:5,
+ * which sees it as if it came from just another local event creator. 0:5 will
+ * multicast the change to 0:1 and 0:4. To prevent notify loops, the message
+ * from 1:6 to 0:5 will carry a "proxied" flag, so that 0:5 will only forward
+ * the event to local clients.
+ */
+
+/*
+ * Data that notifyd maintains per smbd notify instance
+ */
+struct notify_instance {
+ struct timespec creation_time;
+ uint32_t filter;
+ uint32_t subdir_filter;
+ void *private_data;
+};
+
+/* MSG_SMB_NOTIFY_REC_CHANGE payload */
+struct notify_rec_change_msg {
+ struct notify_instance instance;
+ char path[];
+};
+
+/*
+ * The second message from smbd to notifyd is sent whenever an smbd makes a
+ * file system change. It tells notifyd to inform all interested parties about
+ * that change. This is the message that needs to be really fast in smbd
+ * because it is called a lot.
+ */
+
+/* MSG_SMB_NOTIFY_TRIGGER payload */
+struct notify_trigger_msg {
+ struct timespec when;
+ uint32_t action;
+ uint32_t filter;
+ char path[];
+};
+
+/*
+ * In response to a MSG_SMB_NOTIFY_TRIGGER message notifyd walks its database
+ * and sends out the following message to all interested clients
+ */
+
+/* MSG_PVFS_NOTIFY payload */
+struct notify_event_msg {
+ struct timespec when;
+ void *private_data;
+ uint32_t action;
+ char path[];
+};
+
+struct sys_notify_context;
+struct ctdbd_connection;
+
+typedef int (*sys_notify_watch_fn)(TALLOC_CTX *mem_ctx,
+ struct sys_notify_context *ctx,
+ const char *path,
+ uint32_t *filter,
+ uint32_t *subdir_filter,
+ void (*callback)(struct sys_notify_context *ctx,
+ void *private_data,
+ struct notify_event *ev,
+ uint32_t filter),
+ void *private_data,
+ void *handle_p);
+
+struct tevent_req *notifyd_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
+ struct messaging_context *msg_ctx,
+ struct ctdbd_connection *ctdbd_conn,
+ sys_notify_watch_fn sys_notify_watch,
+ struct sys_notify_context *sys_notify_ctx);
+int notifyd_recv(struct tevent_req *req);
+
+#endif