r23806: update Samba4 with the latest ctdb code.

This doesn't get the ctdb code fully working in Samba4, it just gets
it building and not breaking non-clustered use of Samba. It will take
a bit longer to update some of the calling ctdb_cluster.c code to make
it work correctly in Samba4.

Note also that Samba4 now only links to the client portion of
ctdb. For the moment I am leaving the ctdbd as a separate daemon,
which you install separately from http://ctdb.samba.org/.
(This used to be commit b196077cbb55cbecad87065133c2d67198e31066)

1 files changed, 737 insertions, 0 deletions

diff --git a/source4/cluster/ctdb/server/ctdb_call.c b/source4/cluster/ctdb/server/ctdb_call.c
new file mode 100644
index 0000000000..bbe07717ed
--- /dev/null
+++ b/source4/cluster/ctdb/server/ctdb_call.c
@@ -0,0 +1,737 @@
+/* 
+   ctdb_call protocol code
+
+   Copyright (C) Andrew Tridgell  2006
+
+   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/>.
+*/
+/*
+  see http://wiki.samba.org/index.php/Samba_%26_Clustering for
+  protocol design and packet details
+*/
+#include "includes.h"
+#include "lib/events/events.h"
+#include "lib/tdb/include/tdb.h"
+#include "lib/util/dlinklist.h"
+#include "system/network.h"
+#include "system/filesys.h"
+#include "../include/ctdb_private.h"
+
+/*
+  find the ctdb_db from a db index
+ */
+ struct ctdb_db_context *find_ctdb_db(struct ctdb_context *ctdb, uint32_t id)
+{
+	struct ctdb_db_context *ctdb_db;
+
+	for (ctdb_db=ctdb->db_list; ctdb_db; ctdb_db=ctdb_db->next) {
+		if (ctdb_db->db_id == id) {
+			break;
+		}
+	}
+	return ctdb_db;
+}
+
+
+/*
+  a varient of input packet that can be used in lock requeue
+*/
+static void ctdb_call_input_pkt(void *p, struct ctdb_req_header *hdr)
+{
+	struct ctdb_context *ctdb = talloc_get_type(p, struct ctdb_context);
+	ctdb_input_pkt(ctdb, hdr);
+}
+
+
+/*
+  send an error reply
+*/
+static void ctdb_send_error(struct ctdb_context *ctdb, 
+			    struct ctdb_req_header *hdr, uint32_t status,
+			    const char *fmt, ...) PRINTF_ATTRIBUTE(4,5);
+static void ctdb_send_error(struct ctdb_context *ctdb, 
+			    struct ctdb_req_header *hdr, uint32_t status,
+			    const char *fmt, ...)
+{
+	va_list ap;
+	struct ctdb_reply_error *r;
+	char *msg;
+	int msglen, len;
+
+	va_start(ap, fmt);
+	msg = talloc_vasprintf(ctdb, fmt, ap);
+	if (msg == NULL) {
+		ctdb_fatal(ctdb, "Unable to allocate error in ctdb_send_error\n");
+	}
+	va_end(ap);
+
+	msglen = strlen(msg)+1;
+	len = offsetof(struct ctdb_reply_error, msg);
+	r = ctdb_transport_allocate(ctdb, msg, CTDB_REPLY_ERROR, len + msglen, 
+				    struct ctdb_reply_error);
+	CTDB_NO_MEMORY_FATAL(ctdb, r);
+
+	r->hdr.destnode  = hdr->srcnode;
+	r->hdr.reqid     = hdr->reqid;
+	r->status        = status;
+	r->msglen        = msglen;
+	memcpy(&r->msg[0], msg, msglen);
+
+	ctdb_queue_packet(ctdb, &r->hdr);
+
+	talloc_free(msg);
+}
+
+
+/*
+  send a redirect reply
+*/
+static void ctdb_call_send_redirect(struct ctdb_context *ctdb, 
+				    TDB_DATA key,
+				    struct ctdb_req_call *c, 
+				    struct ctdb_ltdb_header *header)
+{
+	
+	uint32_t lmaster = ctdb_lmaster(ctdb, &key);
+	if (ctdb->vnn == lmaster) {
+		c->hdr.destnode = header->dmaster;
+	} else if ((c->hopcount % ctdb->tunable.max_redirect_count) == 0) {
+		c->hdr.destnode = lmaster;
+	} else {
+		c->hdr.destnode = header->dmaster;
+	}
+	c->hopcount++;
+	ctdb_queue_packet(ctdb, &c->hdr);
+}
+
+
+/*
+  send a dmaster reply
+
+  caller must have the chainlock before calling this routine. Caller must be
+  the lmaster
+*/
+static void ctdb_send_dmaster_reply(struct ctdb_db_context *ctdb_db,
+				    struct ctdb_ltdb_header *header,
+				    TDB_DATA key, TDB_DATA data,
+				    uint32_t new_dmaster,
+				    uint32_t reqid)
+{
+	struct ctdb_context *ctdb = ctdb_db->ctdb;
+	struct ctdb_reply_dmaster *r;
+	int ret, len;
+	TALLOC_CTX *tmp_ctx;
+
+	if (ctdb->vnn != ctdb_lmaster(ctdb, &key)) {
+		DEBUG(0,(__location__ " Caller is not lmaster!\n"));
+		return;
+	}
+
+	header->dmaster = new_dmaster;
+	ret = ctdb_ltdb_store(ctdb_db, key, header, data);
+	if (ret != 0) {
+		ctdb_fatal(ctdb, "ctdb_req_dmaster unable to update dmaster");
+		return;
+	}
+
+	/* put the packet on a temporary context, allowing us to safely free
+	   it below even if ctdb_reply_dmaster() has freed it already */
+	tmp_ctx = talloc_new(ctdb);
+
+	/* send the CTDB_REPLY_DMASTER */
+	len = offsetof(struct ctdb_reply_dmaster, data) + key.dsize + data.dsize;
+	r = ctdb_transport_allocate(ctdb, tmp_ctx, CTDB_REPLY_DMASTER, len,
+				    struct ctdb_reply_dmaster);
+	CTDB_NO_MEMORY_FATAL(ctdb, r);
+
+	r->hdr.destnode  = new_dmaster;
+	r->hdr.reqid     = reqid;
+	r->rsn           = header->rsn;
+	r->keylen        = key.dsize;
+	r->datalen       = data.dsize;
+	r->db_id         = ctdb_db->db_id;
+	memcpy(&r->data[0], key.dptr, key.dsize);
+	memcpy(&r->data[key.dsize], data.dptr, data.dsize);
+
+	ctdb_queue_packet(ctdb, &r->hdr);
+
+	talloc_free(tmp_ctx);
+}
+
+/*
+  send a dmaster request (give another node the dmaster for a record)
+
+  This is always sent to the lmaster, which ensures that the lmaster
+  always knows who the dmaster is. The lmaster will then send a
+  CTDB_REPLY_DMASTER to the new dmaster
+*/
+static void ctdb_call_send_dmaster(struct ctdb_db_context *ctdb_db, 
+				   struct ctdb_req_call *c, 
+				   struct ctdb_ltdb_header *header,
+				   TDB_DATA *key, TDB_DATA *data)
+{
+	struct ctdb_req_dmaster *r;
+	struct ctdb_context *ctdb = ctdb_db->ctdb;
+	int len;
+	uint32_t lmaster = ctdb_lmaster(ctdb, key);
+
+	if (lmaster == ctdb->vnn) {
+		ctdb_send_dmaster_reply(ctdb_db, header, *key, *data, 
+					c->hdr.srcnode, c->hdr.reqid);
+		return;
+	}
+	
+	len = offsetof(struct ctdb_req_dmaster, data) + key->dsize + data->dsize;
+	r = ctdb_transport_allocate(ctdb, ctdb, CTDB_REQ_DMASTER, len, 
+				    struct ctdb_req_dmaster);
+	CTDB_NO_MEMORY_FATAL(ctdb, r);
+	r->hdr.destnode  = lmaster;
+	r->hdr.reqid     = c->hdr.reqid;
+	r->db_id         = c->db_id;
+	r->rsn           = header->rsn;
+	r->dmaster       = c->hdr.srcnode;
+	r->keylen        = key->dsize;
+	r->datalen       = data->dsize;
+	memcpy(&r->data[0], key->dptr, key->dsize);
+	memcpy(&r->data[key->dsize], data->dptr, data->dsize);
+
+	header->dmaster = c->hdr.srcnode;
+	if (ctdb_ltdb_store(ctdb_db, *key, header, *data) != 0) {
+		ctdb_fatal(ctdb, "Failed to store record in ctdb_call_send_dmaster");
+	}
+	
+	ctdb_queue_packet(ctdb, &r->hdr);
+
+	talloc_free(r);
+}
+
+/*
+  called when a CTDB_REPLY_DMASTER packet comes in, or when the lmaster
+  gets a CTDB_REQUEST_DMASTER for itself. We become the dmaster.
+
+  must be called with the chainlock held. This function releases the chainlock
+*/
+static void ctdb_become_dmaster(struct ctdb_db_context *ctdb_db, 
+				uint32_t reqid, TDB_DATA key, TDB_DATA data,
+				uint64_t rsn)
+{
+	struct ctdb_call_state *state;
+	struct ctdb_context *ctdb = ctdb_db->ctdb;
+	struct ctdb_ltdb_header header;
+
+	DEBUG(2,("vnn %u dmaster response %08x\n", ctdb->vnn, ctdb_hash(&key)));
+
+	ZERO_STRUCT(header);
+	header.rsn = rsn + 1;
+	header.dmaster = ctdb->vnn;
+
+	if (ctdb_ltdb_store(ctdb_db, key, &header, data) != 0) {
+		ctdb_fatal(ctdb, "ctdb_reply_dmaster store failed\n");
+		ctdb_ltdb_unlock(ctdb_db, key);
+		return;
+	}
+
+	state = ctdb_reqid_find(ctdb, reqid, struct ctdb_call_state);
+
+	if (state == NULL) {
+		DEBUG(0,("vnn %u Invalid reqid %u in ctdb_become_dmaster\n",
+			 ctdb->vnn, reqid));
+		ctdb_ltdb_unlock(ctdb_db, key);
+		return;
+	}
+
+	if (reqid != state->reqid) {
+		/* we found a record  but it was the wrong one */
+		DEBUG(0, ("Dropped orphan in ctdb_become_dmaster with reqid:%u\n",reqid));
+		ctdb_ltdb_unlock(ctdb_db, key);
+		return;
+	}
+
+	ctdb_call_local(ctdb_db, &state->call, &header, state, &data, ctdb->vnn);
+
+	ctdb_ltdb_unlock(ctdb_db, state->call.key);
+
+	state->state = CTDB_CALL_DONE;
+	if (state->async.fn) {
+		state->async.fn(state);
+	}
+}
+
+
+
+/*
+  called when a CTDB_REQ_DMASTER packet comes in
+
+  this comes into the lmaster for a record when the current dmaster
+  wants to give up the dmaster role and give it to someone else
+*/
+void ctdb_request_dmaster(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
+{
+	struct ctdb_req_dmaster *c = (struct ctdb_req_dmaster *)hdr;
+	TDB_DATA key, data, data2;
+	struct ctdb_ltdb_header header;
+	struct ctdb_db_context *ctdb_db;
+	int ret;
+
+	key.dptr = c->data;
+	key.dsize = c->keylen;
+	data.dptr = c->data + c->keylen;
+	data.dsize = c->datalen;
+
+	ctdb_db = find_ctdb_db(ctdb, c->db_id);
+	if (!ctdb_db) {
+		ctdb_send_error(ctdb, hdr, -1,
+				"Unknown database in request. db_id==0x%08x",
+				c->db_id);
+		return;
+	}
+	
+	/* fetch the current record */
+	ret = ctdb_ltdb_lock_fetch_requeue(ctdb_db, key, &header, hdr, &data2,
+					   ctdb_call_input_pkt, ctdb, False);
+	if (ret == -1) {
+		ctdb_fatal(ctdb, "ctdb_req_dmaster failed to fetch record");
+		return;
+	}
+	if (ret == -2) {
+		DEBUG(2,(__location__ " deferring ctdb_request_dmaster\n"));
+		return;
+	}
+
+	if (ctdb_lmaster(ctdb, &key) != ctdb->vnn) {
+		DEBUG(0,("vnn %u dmaster request to non-lmaster lmaster=%u gen=%u curgen=%u\n",
+			 ctdb->vnn, ctdb_lmaster(ctdb, &key), 
+			 hdr->generation, ctdb->vnn_map->generation));
+		ctdb_fatal(ctdb, "ctdb_req_dmaster to non-lmaster");
+	}
+
+	DEBUG(2,("vnn %u dmaster request on %08x for %u from %u\n", 
+		 ctdb->vnn, ctdb_hash(&key), c->dmaster, c->hdr.srcnode));
+
+	/* its a protocol error if the sending node is not the current dmaster */
+	if (header.dmaster != hdr->srcnode) {
+		DEBUG(0,("vnn %u dmaster request non-master %u dmaster=%u key %08x dbid 0x%08x gen=%u curgen=%u\n",
+			 ctdb->vnn, hdr->srcnode, header.dmaster, ctdb_hash(&key),
+			 ctdb_db->db_id, hdr->generation, ctdb->vnn_map->generation));
+		ctdb_fatal(ctdb, "ctdb_req_dmaster from non-master");
+		return;
+	}
+
+	/* use the rsn from the sending node */
+	header.rsn = c->rsn;
+
+	/* check if the new dmaster is the lmaster, in which case we
+	   skip the dmaster reply */
+	if (c->dmaster == ctdb->vnn) {
+		ctdb_become_dmaster(ctdb_db, hdr->reqid, key, data, c->rsn);
+	} else {
+		ctdb_send_dmaster_reply(ctdb_db, &header, key, data, c->dmaster, hdr->reqid);
+		ctdb_ltdb_unlock(ctdb_db, key);
+	}
+}
+
+
+/*
+  called when a CTDB_REQ_CALL packet comes in
+*/
+void ctdb_request_call(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
+{
+	struct ctdb_req_call *c = (struct ctdb_req_call *)hdr;
+	TDB_DATA data;
+	struct ctdb_reply_call *r;
+	int ret, len;
+	struct ctdb_ltdb_header header;
+	struct ctdb_call call;
+	struct ctdb_db_context *ctdb_db;
+
+	ctdb_db = find_ctdb_db(ctdb, c->db_id);
+	if (!ctdb_db) {
+		ctdb_send_error(ctdb, hdr, -1,
+				"Unknown database in request. db_id==0x%08x",
+				c->db_id);
+		return;
+	}
+
+	call.call_id  = c->callid;
+	call.key.dptr = c->data;
+	call.key.dsize = c->keylen;
+	call.call_data.dptr = c->data + c->keylen;
+	call.call_data.dsize = c->calldatalen;
+
+	/* determine if we are the dmaster for this key. This also
+	   fetches the record data (if any), thus avoiding a 2nd fetch of the data 
+	   if the call will be answered locally */
+
+	ret = ctdb_ltdb_lock_fetch_requeue(ctdb_db, call.key, &header, hdr, &data,
+					   ctdb_call_input_pkt, ctdb, False);
+	if (ret == -1) {
+		ctdb_send_error(ctdb, hdr, ret, "ltdb fetch failed in ctdb_request_call");
+		return;
+	}
+	if (ret == -2) {
+		DEBUG(2,(__location__ " deferred ctdb_request_call\n"));
+		return;
+	}
+
+	/* if we are not the dmaster, then send a redirect to the
+	   requesting node */
+	if (header.dmaster != ctdb->vnn) {
+		talloc_free(data.dptr);
+		ctdb_call_send_redirect(ctdb, call.key, c, &header);
+		ctdb_ltdb_unlock(ctdb_db, call.key);
+		return;
+	}
+
+	if (c->hopcount > ctdb->statistics.max_hop_count) {
+		ctdb->statistics.max_hop_count = c->hopcount;
+	}
+
+	/* if this nodes has done enough consecutive calls on the same record
+	   then give them the record
+	   or if the node requested an immediate migration
+	*/
+	if ( c->hdr.srcnode != ctdb->vnn &&
+	     ((header.laccessor == c->hdr.srcnode
+	       && header.lacount >= ctdb->tunable.max_lacount)
+	      || (c->flags & CTDB_IMMEDIATE_MIGRATION)) ) {
+		DEBUG(2,("vnn %u starting migration of %08x to %u\n", 
+			 ctdb->vnn, ctdb_hash(&call.key), c->hdr.srcnode));
+		ctdb_call_send_dmaster(ctdb_db, c, &header, &call.key, &data);
+		talloc_free(data.dptr);
+		ctdb_ltdb_unlock(ctdb_db, call.key);
+		return;
+	}
+
+	ctdb_call_local(ctdb_db, &call, &header, hdr, &data, c->hdr.srcnode);
+
+	ctdb_ltdb_unlock(ctdb_db, call.key);
+
+	len = offsetof(struct ctdb_reply_call, data) + call.reply_data.dsize;
+	r = ctdb_transport_allocate(ctdb, ctdb, CTDB_REPLY_CALL, len, 
+				    struct ctdb_reply_call);
+	CTDB_NO_MEMORY_FATAL(ctdb, r);
+	r->hdr.destnode  = hdr->srcnode;
+	r->hdr.reqid     = hdr->reqid;
+	r->status        = call.status;
+	r->datalen       = call.reply_data.dsize;
+	if (call.reply_data.dsize) {
+		memcpy(&r->data[0], call.reply_data.dptr, call.reply_data.dsize);
+	}
+
+	ctdb_queue_packet(ctdb, &r->hdr);
+
+	talloc_free(r);
+}
+
+/*
+  called when a CTDB_REPLY_CALL packet comes in
+
+  This packet comes in response to a CTDB_REQ_CALL request packet. It
+  contains any reply data from the call
+*/
+void ctdb_reply_call(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
+{
+	struct ctdb_reply_call *c = (struct ctdb_reply_call *)hdr;
+	struct ctdb_call_state *state;
+
+	state = ctdb_reqid_find(ctdb, hdr->reqid, struct ctdb_call_state);
+	if (state == NULL) {
+		DEBUG(0, (__location__ " reqid %u not found\n", hdr->reqid));
+		return;
+	}
+
+	if (hdr->reqid != state->reqid) {
+		/* we found a record  but it was the wrong one */
+		DEBUG(0, ("Dropped orphaned call reply with reqid:%u\n",hdr->reqid));
+		return;
+	}
+
+	state->call.reply_data.dptr = c->data;
+	state->call.reply_data.dsize = c->datalen;
+	state->call.status = c->status;
+
+	talloc_steal(state, c);
+
+	state->state = CTDB_CALL_DONE;
+	if (state->async.fn) {
+		state->async.fn(state);
+	}
+}
+
+
+/*
+  called when a CTDB_REPLY_DMASTER packet comes in
+
+  This packet comes in from the lmaster response to a CTDB_REQ_CALL
+  request packet. It means that the current dmaster wants to give us
+  the dmaster role
+*/
+void ctdb_reply_dmaster(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
+{
+	struct ctdb_reply_dmaster *c = (struct ctdb_reply_dmaster *)hdr;
+	struct ctdb_db_context *ctdb_db;
+	TDB_DATA key, data;
+	int ret;
+
+	ctdb_db = find_ctdb_db(ctdb, c->db_id);
+	if (ctdb_db == NULL) {
+		DEBUG(0,("Unknown db_id 0x%x in ctdb_reply_dmaster\n", c->db_id));
+		return;
+	}
+	
+	key.dptr = c->data;
+	key.dsize = c->keylen;
+	data.dptr = &c->data[key.dsize];
+	data.dsize = c->datalen;
+
+	ret = ctdb_ltdb_lock_requeue(ctdb_db, key, hdr,
+				     ctdb_call_input_pkt, ctdb, False);
+	if (ret == -2) {
+		return;
+	}
+	if (ret != 0) {
+		DEBUG(0,(__location__ " Failed to get lock in ctdb_reply_dmaster\n"));
+		return;
+	}
+
+	ctdb_become_dmaster(ctdb_db, hdr->reqid, key, data, c->rsn);
+}
+
+
+/*
+  called when a CTDB_REPLY_ERROR packet comes in
+*/
+void ctdb_reply_error(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
+{
+	struct ctdb_reply_error *c = (struct ctdb_reply_error *)hdr;
+	struct ctdb_call_state *state;
+
+	state = ctdb_reqid_find(ctdb, hdr->reqid, struct ctdb_call_state);
+	if (state == NULL) {
+		DEBUG(0,("vnn %u Invalid reqid %u in ctdb_reply_error\n",
+			 ctdb->vnn, hdr->reqid));
+		return;
+	}
+
+	if (hdr->reqid != state->reqid) {
+		/* we found a record  but it was the wrong one */
+		DEBUG(0, ("Dropped orphaned error reply with reqid:%u\n",hdr->reqid));
+		return;
+	}
+
+	talloc_steal(state, c);
+
+	state->state  = CTDB_CALL_ERROR;
+	state->errmsg = (char *)c->msg;
+	if (state->async.fn) {
+		state->async.fn(state);
+	}
+}
+
+
+/*
+  destroy a ctdb_call
+*/
+static int ctdb_call_destructor(struct ctdb_call_state *state)
+{
+	DLIST_REMOVE(state->ctdb_db->ctdb->pending_calls, state);
+	ctdb_reqid_remove(state->ctdb_db->ctdb, state->reqid);
+	return 0;
+}
+
+
+/*
+  called when a ctdb_call needs to be resent after a reconfigure event
+*/
+static void ctdb_call_resend(struct ctdb_call_state *state)
+{
+	struct ctdb_context *ctdb = state->ctdb_db->ctdb;
+
+	state->generation = ctdb->vnn_map->generation;
+
+	/* use a new reqid, in case the old reply does eventually come in */
+	ctdb_reqid_remove(ctdb, state->reqid);
+	state->reqid = ctdb_reqid_new(ctdb, state);
+	state->c->hdr.reqid = state->reqid;
+
+	/* update the generation count for this request, so its valid with the new vnn_map */
+	state->c->hdr.generation = state->generation;
+
+	/* send the packet to ourselves, it will be redirected appropriately */
+	state->c->hdr.destnode = ctdb->vnn;
+
+	ctdb_queue_packet(ctdb, &state->c->hdr);
+	DEBUG(0,("resent ctdb_call\n"));
+}
+
+/*
+  resend all pending calls on recovery
+ */
+void ctdb_call_resend_all(struct ctdb_context *ctdb)
+{
+	struct ctdb_call_state *state, *next;
+	for (state=ctdb->pending_calls;state;state=next) {
+		next = state->next;
+		ctdb_call_resend(state);
+	}
+}
+
+/*
+  this allows the caller to setup a async.fn 
+*/
+static void call_local_trigger(struct event_context *ev, struct timed_event *te, 
+		       struct timeval t, void *private_data)
+{
+	struct ctdb_call_state *state = talloc_get_type(private_data, struct ctdb_call_state);
+	if (state->async.fn) {
+		state->async.fn(state);
+	}
+}	
+
+
+/*
+  construct an event driven local ctdb_call
+
+  this is used so that locally processed ctdb_call requests are processed
+  in an event driven manner
+*/
+struct ctdb_call_state *ctdb_call_local_send(struct ctdb_db_context *ctdb_db, 
+					     struct ctdb_call *call,
+					     struct ctdb_ltdb_header *header,
+					     TDB_DATA *data)
+{
+	struct ctdb_call_state *state;
+	struct ctdb_context *ctdb = ctdb_db->ctdb;
+	int ret;
+
+	state = talloc_zero(ctdb_db, struct ctdb_call_state);
+	CTDB_NO_MEMORY_NULL(ctdb, state);
+
+	talloc_steal(state, data->dptr);
+
+	state->state = CTDB_CALL_DONE;
+	state->call = *call;
+	state->ctdb_db = ctdb_db;
+
+	ret = ctdb_call_local(ctdb_db, &state->call, header, state, data, ctdb->vnn);
+
+	event_add_timed(ctdb->ev, state, timeval_zero(), call_local_trigger, state);
+
+	return state;
+}
+
+
+/*
+  make a remote ctdb call - async send. Called in daemon context.
+
+  This constructs a ctdb_call request and queues it for processing. 
+  This call never blocks.
+*/
+struct ctdb_call_state *ctdb_daemon_call_send_remote(struct ctdb_db_context *ctdb_db, 
+						     struct ctdb_call *call, 
+						     struct ctdb_ltdb_header *header)
+{
+	uint32_t len;
+	struct ctdb_call_state *state;
+	struct ctdb_context *ctdb = ctdb_db->ctdb;
+
+	state = talloc_zero(ctdb_db, struct ctdb_call_state);
+	CTDB_NO_MEMORY_NULL(ctdb, state);
+	state->reqid = ctdb_reqid_new(ctdb, state);
+	state->ctdb_db = ctdb_db;
+	talloc_set_destructor(state, ctdb_call_destructor);
+
+	len = offsetof(struct ctdb_req_call, data) + call->key.dsize + call->call_data.dsize;
+	state->c = ctdb_transport_allocate(ctdb, state, CTDB_REQ_CALL, len, 
+					   struct ctdb_req_call);
+	CTDB_NO_MEMORY_NULL(ctdb, state->c);
+	state->c->hdr.destnode  = header->dmaster;
+
+	/* this limits us to 16k outstanding messages - not unreasonable */
+	state->c->hdr.reqid     = state->reqid;
+	state->c->flags         = call->flags;
+	state->c->db_id         = ctdb_db->db_id;
+	state->c->callid        = call->call_id;
+	state->c->hopcount      = 0;
+	state->c->keylen        = call->key.dsize;
+	state->c->calldatalen   = call->call_data.dsize;
+	memcpy(&state->c->data[0], call->key.dptr, call->key.dsize);
+	memcpy(&state->c->data[call->key.dsize], 
+	       call->call_data.dptr, call->call_data.dsize);
+	state->call                = *call;
+	state->call.call_data.dptr = &state->c->data[call->key.dsize];
+	state->call.key.dptr       = &state->c->data[0];
+
+	state->state  = CTDB_CALL_WAIT;
+	state->generation = ctdb->vnn_map->generation;
+
+	DLIST_ADD(ctdb->pending_calls, state);
+
+	ctdb_queue_packet(ctdb, &state->c->hdr);
+
+	return state;
+}
+
+/*
+  make a remote ctdb call - async recv - called in daemon context
+
+  This is called when the program wants to wait for a ctdb_call to complete and get the 
+  results. This call will block unless the call has already completed.
+*/
+int ctdb_daemon_call_recv(struct ctdb_call_state *state, struct ctdb_call *call)
+{
+	while (state->state < CTDB_CALL_DONE) {
+		event_loop_once(state->ctdb_db->ctdb->ev);
+	}
+	if (state->state != CTDB_CALL_DONE) {
+		ctdb_set_error(state->ctdb_db->ctdb, "%s", state->errmsg);
+		talloc_free(state);
+		return -1;
+	}
+
+	if (state->call.reply_data.dsize) {
+		call->reply_data.dptr = talloc_memdup(state->ctdb_db->ctdb,
+						      state->call.reply_data.dptr,
+						      state->call.reply_data.dsize);
+		call->reply_data.dsize = state->call.reply_data.dsize;
+	} else {
+		call->reply_data.dptr = NULL;
+		call->reply_data.dsize = 0;
+	}
+	call->status = state->call.status;
+	talloc_free(state);
+	return 0;
+}
+
+
+/* 
+   send a keepalive packet to the other node
+*/
+void ctdb_send_keepalive(struct ctdb_context *ctdb, uint32_t destnode)
+{
+	struct ctdb_req_keepalive *r;
+	
+	r = ctdb_transport_allocate(ctdb, ctdb, CTDB_REQ_KEEPALIVE,
+				    sizeof(struct ctdb_req_keepalive), 
+				    struct ctdb_req_keepalive);
+	CTDB_NO_MEMORY_FATAL(ctdb, r);
+	r->hdr.destnode  = destnode;
+	r->hdr.reqid     = 0;
+	
+	ctdb->statistics.keepalive_packets_sent++;
+
+	ctdb_queue_packet(ctdb, &r->hdr);
+
+	talloc_free(r);
+}