ctdb_call.c

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	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);
}