]> git.samba.org - sahlberg/ctdb.git/blobdiff - libctdb/ctdb.c
LIBCTDB: add support for traverse
[sahlberg/ctdb.git] / libctdb / ctdb.c
index 5461d3c132d21323ac38ed29377987f66fb950b2..7115982d1a119651a2d270b06426e80c635a29dd 100644 (file)
@@ -24,6 +24,7 @@
 #include <stdlib.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <sys/ioctl.h>
 #include "libctdb_private.h"
 #include "io_elem.h"
 #include "local_tdb.h"
 
 /* Remove type-safety macros. */
 #undef ctdb_attachdb_send
-#undef ctdb_readrecordlock_send
+#undef ctdb_readrecordlock_async
+#undef ctdb_connect
+
+struct ctdb_lock {
+       struct ctdb_lock *next, *prev;
+
+       struct ctdb_db *ctdb_db;
+       TDB_DATA key;
+
+       /* This will always be set by the time user sees this. */
+       unsigned long held_magic;
+       struct ctdb_ltdb_header *hdr;
+
+       /* For convenience, we stash original callback here. */
+       ctdb_rrl_callback_t callback;
+};
+
+struct ctdb_db {
+       struct ctdb_connection *ctdb;
+       bool persistent;
+       uint32_t tdb_flags;
+       uint32_t id;
+       struct tdb_context *tdb;
+
+       ctdb_callback_t callback;
+       void *private_data;
+};
+
+static void remove_lock(struct ctdb_connection *ctdb, struct ctdb_lock *lock)
+{
+       DLIST_REMOVE(ctdb->locks, lock);
+}
+
+/* FIXME: for thread safety, need tid info too. */
+static bool holding_lock(struct ctdb_connection *ctdb)
+{
+       /* For the moment, you can't ever hold more than 1 lock. */
+       return (ctdb->locks != NULL);
+}
+
+static void add_lock(struct ctdb_connection *ctdb, struct ctdb_lock *lock)
+{
+       DLIST_ADD(ctdb->locks, lock);
+}
+
+static void cleanup_locks(struct ctdb_connection *ctdb, struct ctdb_db *db)
+{
+       struct ctdb_lock *i, *next;
+
+       for (i = ctdb->locks; i; i = next) {
+               /* Grab next pointer, as release_lock will free i */
+               next = i->next;
+               if (i->ctdb_db == db) {
+                       ctdb_release_lock(db, i);
+               }
+       }
+}
 
 /* FIXME: Could be in shared util code with rest of ctdb */
 static void close_noerr(int fd)
@@ -71,25 +128,39 @@ static void set_pnn(struct ctdb_connection *ctdb,
                    struct ctdb_request *req,
                    void *unused)
 {
-       if (ctdb_getpnn_recv(req, &ctdb->pnn) != 0) {
-               /* FIXME: Report error. */
+       if (!ctdb_getpnn_recv(ctdb, req, &ctdb->pnn)) {
+               DEBUG(ctdb, LOG_CRIT,
+                     "ctdb_connect(async): failed to get pnn");
                ctdb->broken = true;
        }
+       ctdb_request_free(ctdb, req);
 }
 
-struct ctdb_connection *ctdb_connect(const char *addr)
+struct ctdb_connection *ctdb_connect(const char *addr,
+                                    ctdb_log_fn_t log_fn, void *log_priv)
 {
        struct ctdb_connection *ctdb;
        struct sockaddr_un sun;
 
        ctdb = malloc(sizeof(*ctdb));
-       if (!ctdb)
+       if (!ctdb) {
+               /* With no format string, we hope it doesn't use ap! */
+               va_list ap;
+               memset(&ap, 0, sizeof(ap));
+               errno = ENOMEM;
+               log_fn(log_priv, LOG_ERR, "ctdb_connect: no memory", ap);
                goto fail;
+       }
        ctdb->outq = NULL;
        ctdb->doneq = NULL;
-       ctdb->immediateq = NULL;
        ctdb->in = NULL;
+       ctdb->inqueue = NULL;
        ctdb->message_handlers = NULL;
+       ctdb->next_id = 0;
+       ctdb->broken = false;
+       ctdb->log = log_fn;
+       ctdb->log_priv = log_priv;
+       ctdb->locks = NULL;
 
        memset(&sun, 0, sizeof(sun));
        sun.sun_family = AF_UNIX;
@@ -120,6 +191,33 @@ fail:
        return NULL;
 }
 
+void ctdb_disconnect(struct ctdb_connection *ctdb)
+{
+       struct ctdb_request *i;
+
+       DEBUG(ctdb, LOG_DEBUG, "ctdb_disconnect");
+
+       while ((i = ctdb->outq) != NULL) {
+               DLIST_REMOVE(ctdb->outq, i);
+               ctdb_request_free(ctdb, i);
+       }
+
+       while ((i = ctdb->doneq) != NULL) {
+               DLIST_REMOVE(ctdb->doneq, i);
+               ctdb_request_free(ctdb, i);
+       }
+
+       if (ctdb->in)
+               free_io_elem(ctdb->in);
+
+       remove_message_handlers(ctdb);
+
+       close(ctdb->fd);
+       /* Just in case they try to reuse */
+       ctdb->fd = -1;
+       free(ctdb);
+}
+
 int ctdb_get_fd(struct ctdb_connection *ctdb)
 {
        return ctdb->fd;
@@ -154,10 +252,17 @@ struct ctdb_request *new_ctdb_request(size_t len,
        return req;
 }
 
-void ctdb_request_free(struct ctdb_request *req)
+void ctdb_request_free(struct ctdb_connection *ctdb, struct ctdb_request *req)
 {
+       if (req->next || req->prev) {
+               DEBUG(ctdb, LOG_ALERT,
+                     "ctdb_request_free: request not complete! ctdb_cancel? %p (id %u)",
+                     req, req->hdr.hdr ? req->hdr.hdr->reqid : 0);
+               ctdb_cancel(ctdb, req);
+               return;
+       }
        if (req->extra_destructor) {
-               req->extra_destructor(req);
+               req->extra_destructor(ctdb, req);
        }
        if (req->reply) {
                free_io_elem(req->reply);
@@ -166,54 +271,81 @@ void ctdb_request_free(struct ctdb_request *req)
        free(req);
 }
 
-/* Sanity-checking wrapper for reply.
- * FIXME: logging! */
-static struct ctdb_reply_call *unpack_reply_call(struct ctdb_request *req,
+/* Sanity-checking wrapper for reply. */
+static struct ctdb_reply_call *unpack_reply_call(struct ctdb_connection *ctdb,
+                                                struct ctdb_request *req,
                                                 uint32_t callid)
 {
        size_t len;
        struct ctdb_reply_call *inhdr = io_elem_data(req->reply, &len);
 
-       /* ctdbd or our error if this isn't a reply call. */
-       if (len < sizeof(*inhdr) || inhdr->hdr.operation != CTDB_REPLY_CALL) {
-               errno = EIO;
+       /* Library user error if this isn't a reply to a call. */
+       if (req->hdr.hdr->operation != CTDB_REQ_CALL) {
+               errno = EINVAL;
+               DEBUG(ctdb, LOG_ALERT,
+                     "This was not a ctdbd call request: operation %u",
+                     req->hdr.hdr->operation);
                return NULL;
        }
 
-       /* Library user error if this isn't a reply to a call. */
-       if (req->hdr.hdr->operation != CTDB_REQ_CALL
-           || req->hdr.call->callid != callid) {
+       if (req->hdr.call->callid != callid) {
                errno = EINVAL;
+               DEBUG(ctdb, LOG_ALERT,
+                     "This was not a ctdbd %u call request: %u",
+                     callid, req->hdr.call->callid);
+               return NULL;
+       }
+
+       /* ctdbd or our error if this isn't a reply call. */
+       if (len < sizeof(*inhdr) || inhdr->hdr.operation != CTDB_REPLY_CALL) {
+               errno = EIO;
+               DEBUG(ctdb, LOG_CRIT,
+                     "Invalid ctdbd call reply: len %zu, operation %u",
+                     len, inhdr->hdr.operation);
                return NULL;
        }
 
        return inhdr;
 }
 
-/* Sanity-checking wrapper for reply.
- * FIXME: logging! */
-struct ctdb_reply_control *unpack_reply_control(struct ctdb_request *req,
+/* Sanity-checking wrapper for reply. */
+struct ctdb_reply_control *unpack_reply_control(struct ctdb_connection *ctdb,
+                                               struct ctdb_request *req,
                                                enum ctdb_controls control)
 {
        size_t len;
        struct ctdb_reply_control *inhdr = io_elem_data(req->reply, &len);
 
        /* Library user error if this isn't a reply to a call. */
-       if (len < sizeof(*inhdr)
-           || req->hdr.hdr->operation != CTDB_REQ_CONTROL) {
+       if (len < sizeof(*inhdr)) {
                errno = EINVAL;
+               DEBUG(ctdb, LOG_ALERT,
+                     "Short ctdbd control reply: %zu bytes", len);
+               return NULL;
+       }
+       if (req->hdr.hdr->operation != CTDB_REQ_CONTROL) {
+               errno = EINVAL;
+               DEBUG(ctdb, LOG_ALERT,
+                     "This was not a ctdbd control request: operation %u",
+                     req->hdr.hdr->operation);
                return NULL;
        }
 
        /* ... or if it was a different control from what we expected. */
        if (req->hdr.control->opcode != control) {
                errno = EINVAL;
+               DEBUG(ctdb, LOG_ALERT,
+                     "This was not an opcode %u ctdbd control request: %u",
+                     control, req->hdr.control->opcode);
                return NULL;
        }
 
        /* ctdbd or our error if this isn't a reply call. */
        if (inhdr->hdr.operation != CTDB_REPLY_CONTROL) {
                errno = EIO;
+               DEBUG(ctdb, LOG_CRIT,
+                     "Invalid ctdbd control reply: operation %u",
+                     inhdr->hdr.operation);
                return NULL;
        }
 
@@ -242,7 +374,9 @@ static void handle_incoming(struct ctdb_connection *ctdb, struct io_elem *in)
                        return;
                }
        }
-       /* FIXME: report this error. */
+       DEBUG(ctdb, LOG_WARNING,
+             "Unexpected ctdbd request reply: operation %u reqid %u",
+             hdr->operation, hdr->reqid);
        free_io_elem(in);
 }
 
@@ -254,36 +388,58 @@ static ssize_t real_error(ssize_t ret)
        return ret;
 }
 
-int ctdb_service(struct ctdb_connection *ctdb, int revents)
+bool ctdb_service(struct ctdb_connection *ctdb, int revents)
 {
        if (ctdb->broken) {
-               return -1;
+               return false;
+       }
+
+       if (holding_lock(ctdb)) {
+               DEBUG(ctdb, LOG_ALERT, "Do not block while holding lock!");
        }
 
        if (revents & POLLOUT) {
                while (ctdb->outq) {
                        if (real_error(write_io_elem(ctdb->fd,
                                                     ctdb->outq->io)) < 0) {
+                               DEBUG(ctdb, LOG_ERR,
+                                     "ctdb_service: error writing to ctdbd");
                                ctdb->broken = true;
-                               return -1;
+                               return false;
                        }
                        if (io_elem_finished(ctdb->outq->io)) {
                                struct ctdb_request *done = ctdb->outq;
                                DLIST_REMOVE(ctdb->outq, done);
-                               DLIST_ADD_END(ctdb->doneq, done,
-                                             struct ctdb_request);
+                               /* We add at the head: any dead ones
+                                * sit and end. */
+                               DLIST_ADD(ctdb->doneq, done);
                        }
                }
        }
 
        while (revents & POLLIN) {
                int ret;
+               int num_ready = 0;
+
+               if (ioctl(ctdb->fd, FIONREAD, &num_ready) != 0) {
+                       DEBUG(ctdb, LOG_ERR,
+                             "ctdb_service: ioctl(FIONREAD) %d", errno);
+                       ctdb->broken = true;
+                       return false;
+               }
+               if (num_ready == 0) {
+                       /* the descriptor has been closed or we have all our data */
+                       break;
+               }
+
 
                if (!ctdb->in) {
                        ctdb->in = new_io_elem(sizeof(struct ctdb_req_header));
                        if (!ctdb->in) {
+                               DEBUG(ctdb, LOG_ERR,
+                                     "ctdb_service: allocating readbuf");
                                ctdb->broken = true;
-                               return -1;
+                               return false;
                        }
                }
 
@@ -292,24 +448,28 @@ int ctdb_service(struct ctdb_connection *ctdb, int revents)
                        /* They closed fd? */
                        if (ret == 0)
                                errno = EBADF;
+                       DEBUG(ctdb, LOG_ERR,
+                             "ctdb_service: error reading from ctdbd");
                        ctdb->broken = true;
-                       return -1;
+                       return false;
                } else if (ret < 0) {
                        /* No progress, stop loop. */
-                       revents = 0;
+                       break;
                } else if (io_elem_finished(ctdb->in)) {
-                       handle_incoming(ctdb, ctdb->in);
+                       io_elem_queue(ctdb, ctdb->in);
                        ctdb->in = NULL;
                }
        }
 
-       while (ctdb->immediateq) {
-               struct ctdb_request *imm = ctdb->immediateq;
-               imm->callback(ctdb, imm, imm->priv_data);
-               DLIST_REMOVE(ctdb->immediateq, imm);
+
+       while (ctdb->inqueue != NULL) {
+               struct io_elem *io = ctdb->inqueue;
+
+               io_elem_dequeue(ctdb, io);
+               handle_incoming(ctdb, io);
        }
 
-       return 0;
+       return true;
 }
 
 /* This is inefficient.  We could pull in idtree.c. */
@@ -349,7 +509,7 @@ struct ctdb_request *new_ctdb_control_request(struct ctdb_connection *ctdb,
        struct ctdb_request *req;
        struct ctdb_req_control *pkt;
 
-       req = new_ctdb_request(sizeof(*pkt) + extra, callback, cbdata);
+       req = new_ctdb_request(offsetof(struct ctdb_req_control, data) + extra, callback, cbdata);
        if (!req)
                return NULL;
 
@@ -357,13 +517,14 @@ struct ctdb_request *new_ctdb_control_request(struct ctdb_connection *ctdb,
                                CTDB_REQ_CONTROL, destnode, new_reqid(ctdb));
 
        pkt = req->hdr.control;
+       pkt->pad = 0;
        pkt->opcode = opcode;
        pkt->srvid = 0;
        pkt->client_id = 0;
        pkt->flags = 0;
        pkt->datalen = extra;
        memcpy(pkt->data, extra_data, extra);
-       DLIST_ADD_END(ctdb->outq, req, struct ctdb_request);
+       DLIST_ADD(ctdb->outq, req);
        return req;
 }
 
@@ -371,26 +532,32 @@ void ctdb_cancel_callback(struct ctdb_connection *ctdb,
                          struct ctdb_request *req,
                          void *unused)
 {
-       ctdb_request_free(req);
+       ctdb_request_free(ctdb, req);
 }
 
-int ctdb_cancel(struct ctdb_request *req)
+void ctdb_cancel(struct ctdb_connection *ctdb, struct ctdb_request *req)
 {
+       if (!req->next && !req->prev) {
+               DEBUG(ctdb, LOG_ALERT,
+                     "ctdb_cancel: request completed! ctdb_request_free? %p (id %u)",
+                     req, req->hdr.hdr ? req->hdr.hdr->reqid : 0);
+               ctdb_request_free(ctdb, req);
+               return;
+       }
+
+       DEBUG(ctdb, LOG_DEBUG, "ctdb_cancel: %p (id %u)",
+             req, req->hdr.hdr ? req->hdr.hdr->reqid : 0);
+
        /* FIXME: If it's not sent, we could just free it right now. */
        req->callback = ctdb_cancel_callback;
-       return 0;
 }
 
-struct ctdb_db {
-       struct ctdb_connection *ctdb;
-       bool persistent;
-       uint32_t tdb_flags;
-       uint32_t id;
-       struct tdb_context *tdb;
-
-       ctdb_callback_t callback;
-       void *private_data;
-};
+void ctdb_detachdb(struct ctdb_connection *ctdb, struct ctdb_db *db)
+{
+       cleanup_locks(ctdb, db);
+       tdb_close(db->tdb);
+       free(db);
+}
 
 static void attachdb_getdbpath_done(struct ctdb_connection *ctdb,
                                    struct ctdb_request *req,
@@ -402,12 +569,14 @@ static void attachdb_getdbpath_done(struct ctdb_connection *ctdb,
        db->callback(ctdb, req->extra, db->private_data);
 }
 
-struct ctdb_db *ctdb_attachdb_recv(struct ctdb_request *req)
+struct ctdb_db *ctdb_attachdb_recv(struct ctdb_connection *ctdb,
+                                  struct ctdb_request *req)
 {
        struct ctdb_request *dbpath_req = req->extra;
        struct ctdb_reply_control *reply;
        struct ctdb_db *db = req->priv_data;
        uint32_t tdb_flags = db->tdb_flags;
+       struct tdb_logging_context log;
 
        /* Never sent the dbpath request?  We've failed. */
        if (!dbpath_req) {
@@ -416,21 +585,34 @@ struct ctdb_db *ctdb_attachdb_recv(struct ctdb_request *req)
                return NULL;
        }
 
-       reply = unpack_reply_control(dbpath_req, CTDB_CONTROL_GETDBPATH);
-       if (!reply || reply->status != 0) {
+       reply = unpack_reply_control(ctdb, dbpath_req, CTDB_CONTROL_GETDBPATH);
+       if (!reply) {
+               return NULL;
+       }
+       if (reply->status != 0) {
+               DEBUG(db->ctdb, LOG_ERR,
+                     "ctdb_attachdb_recv: reply status %i", reply->status);
                return NULL;
        }
 
        tdb_flags = db->persistent ? TDB_DEFAULT : TDB_NOSYNC;
        tdb_flags |= TDB_DISALLOW_NESTING;
 
-       db->tdb = tdb_open((char *)reply->data, 0, tdb_flags, O_RDWR, 0);
+       log.log_fn = ctdb_tdb_log_bridge;
+       log.log_private = ctdb;
+       db->tdb = tdb_open_ex((char *)reply->data, 0, tdb_flags, O_RDWR, 0,
+                             &log, NULL);
        if (db->tdb == NULL) {
+               DEBUG(db->ctdb, LOG_ERR,
+                     "ctdb_attachdb_recv: failed to tdb_open %s",
+                     (char *)reply->data);
                return NULL;
        }
 
        /* Finally, separate the db from the request (see destroy_req_db). */
        req->priv_data = NULL;
+       DEBUG(db->ctdb, LOG_DEBUG,
+             "ctdb_attachdb_recv: db %p, tdb %s", db, (char *)reply->data);
        return db;
 }
 
@@ -447,11 +629,16 @@ static void attachdb_done(struct ctdb_connection *ctdb,
                control = CTDB_CONTROL_DB_ATTACH_PERSISTENT;
        }
 
-       reply = unpack_reply_control(req, control);
+       reply = unpack_reply_control(ctdb, req, control);
        if (!reply || reply->status != 0) {
+               if (reply) {
+                       DEBUG(ctdb, LOG_ERR,
+                             "ctdb_attachdb_send(async): DB_ATTACH status %i",
+                             reply->status);
+               }
                /* We failed.  Hand request to user and have them discover it
                 * via ctdb_attachdb_recv. */
-               db->callback(ctdb, req, db);
+               db->callback(ctdb, req, db->private_data);
                return;
        }
        db->id = *(uint32_t *)reply->data;
@@ -462,26 +649,31 @@ static void attachdb_done(struct ctdb_connection *ctdb,
                                        &db->id, sizeof(db->id),
                                        attachdb_getdbpath_done, db);
        if (!req2) {
-               db->callback(ctdb, req, db);
+               DEBUG(db->ctdb, LOG_ERR,
+                     "ctdb_attachdb_send(async): failed to allocate");
+               db->callback(ctdb, req, db->private_data);
                return;
        }
        req->extra = req2;
        req2->extra = req;
+       DEBUG(db->ctdb, LOG_DEBUG,
+             "ctdb_attachdb_send(async): created getdbpath request");
 }
 
-static void destroy_req_db(struct ctdb_request *req)
+static void destroy_req_db(struct ctdb_connection *ctdb,
+                          struct ctdb_request *req)
 {
        /* Incomplete db is in priv_data. */
        free(req->priv_data);
        /* second request is chained off this one. */
        if (req->extra) {
-               ctdb_request_free(req->extra);
+               ctdb_request_free(ctdb, req->extra);
        }
 }
 
 struct ctdb_request *
 ctdb_attachdb_send(struct ctdb_connection *ctdb,
-                  const char *name, int persistent, uint32_t tdb_flags,
+                  const char *name, bool persistent, uint32_t tdb_flags,
                   ctdb_callback_t callback, void *private_data)
 {
        struct ctdb_request *req;
@@ -503,6 +695,8 @@ ctdb_attachdb_send(struct ctdb_connection *ctdb,
        req = new_ctdb_control_request(ctdb, opcode, CTDB_CURRENT_NODE, name,
                                       strlen(name) + 1, attachdb_done, db);
        if (!req) {
+               DEBUG(ctdb, LOG_ERR,
+                     "ctdb_attachdb_send: failed allocating DB_ATTACH");
                free(db);
                return NULL;
        }
@@ -519,44 +713,70 @@ ctdb_attachdb_send(struct ctdb_connection *ctdb,
 
        /* Flags get overloaded into srvid. */
        req->hdr.control->srvid = tdb_flags;
+       DEBUG(db->ctdb, LOG_DEBUG,
+             "ctdb_attachdb_send: DB_ATTACH request %p", req);
        return req;
 }
 
-struct ctdb_lock {
-       struct ctdb_db *ctdb_db;
-       TDB_DATA key;
+static unsigned long lock_magic(struct ctdb_lock *lock)
+{
+       /* A non-zero magic specific to this structure. */
+       return ((unsigned long)lock->key.dptr
+               ^ (((unsigned long)lock->key.dptr) << 16)
+               ^ 0xBADC0FFEEBADC0DEULL)
+               | 1;
+}
 
-       /* This will always be true by the time user sees this. */
-       bool held;
-       struct ctdb_ltdb_header *hdr;
-       TDB_DATA data;
+/* This is only called on locks before they're held. */
+static void free_lock(struct ctdb_lock *lock)
+{
+       if (lock->held_magic) {
+               DEBUG(lock->ctdb_db->ctdb, LOG_ALERT,
+                     "free_lock invalid lock %p", lock);
+       }
+       free(lock->hdr);
+       free(lock);
+}
 
-       /* For convenience, we stash original callback here. */
-       ctdb_callback_t callback;
-};
 
-void ctdb_release_lock(struct ctdb_lock *lock)
+void ctdb_release_lock(struct ctdb_db *ctdb_db, struct ctdb_lock *lock)
 {
-       if (lock->held) {
+       if (lock->held_magic != lock_magic(lock)) {
+               DEBUG(lock->ctdb_db->ctdb, LOG_ALERT,
+                     "ctdb_release_lock invalid lock %p", lock);
+       } else if (lock->ctdb_db != ctdb_db) {
+               errno = EBADF;
+               DEBUG(ctdb_db->ctdb, LOG_ALERT,
+                     "ctdb_release_lock: wrong ctdb_db.");
+       } else {
                tdb_chainunlock(lock->ctdb_db->tdb, lock->key);
+               DEBUG(lock->ctdb_db->ctdb, LOG_DEBUG,
+                     "ctdb_release_lock %p", lock);
+               remove_lock(lock->ctdb_db->ctdb, lock);
        }
-       free(lock->hdr); /* Also frees data */
-       free(lock);
+       lock->held_magic = 0;
+       free_lock(lock);
 }
 
+
 /* We keep the lock if local node is the dmaster. */
-static bool try_readrecordlock(struct ctdb_lock *lock)
+static bool try_readrecordlock(struct ctdb_lock *lock, TDB_DATA *data)
 {
        struct ctdb_ltdb_header *hdr;
 
        if (tdb_chainlock(lock->ctdb_db->tdb, lock->key) != 0) {
+               DEBUG(lock->ctdb_db->ctdb, LOG_WARNING,
+                     "ctdb_readrecordlock_async: failed to chainlock");
                return NULL;
        }
 
-       hdr = ctdb_local_fetch(lock->ctdb_db->tdb, lock->key, &lock->data);
+       hdr = ctdb_local_fetch(lock->ctdb_db->tdb, lock->key, data);
        if (hdr && hdr->dmaster == lock->ctdb_db->ctdb->pnn) {
-               lock->held = true;
+               DEBUG(lock->ctdb_db->ctdb, LOG_DEBUG,
+                     "ctdb_readrecordlock_async: got local lock");
+               lock->held_magic = lock_magic(lock);
                lock->hdr = hdr;
+               add_lock(lock->ctdb_db->ctdb, lock);
                return true;
        }
 
@@ -565,28 +785,11 @@ static bool try_readrecordlock(struct ctdb_lock *lock)
        return NULL;
 }
 
-/* If they cancel *before* we hand them the lock from
- * ctdb_readrecordlock_recv, we free it here. */
-static void destroy_lock(struct ctdb_request *req)
+/* If they shutdown before we hand them the lock, we free it here. */
+static void destroy_lock(struct ctdb_connection *ctdb,
+                        struct ctdb_request *req)
 {
-       ctdb_release_lock(req->extra);
-}
-
-struct ctdb_lock *ctdb_readrecordlock_recv(struct ctdb_db *ctdb_db,
-                                          struct ctdb_request *req,
-                                          TDB_DATA *data)
-{
-       struct ctdb_lock *lock = req->extra;
-
-       if (!lock->held) {
-               /* Something went wrong. */
-               return NULL;
-       }
-
-       /* Now it's their responsibility to free! */
-       req->extra_destructor = NULL;
-       *data = lock->data;
-       return lock;
+       free_lock(req->extra);
 }
 
 static void readrecordlock_retry(struct ctdb_connection *ctdb,
@@ -594,65 +797,82 @@ static void readrecordlock_retry(struct ctdb_connection *ctdb,
 {
        struct ctdb_lock *lock = req->extra;
        struct ctdb_reply_call *reply;
+       TDB_DATA data;
 
        /* OK, we've received reply to noop migration */
-       reply = unpack_reply_call(req, CTDB_NULL_FUNC);
+       reply = unpack_reply_call(ctdb, req, CTDB_NULL_FUNC);
        if (!reply || reply->status != 0) {
-               lock->callback(ctdb, req, private);
+               if (reply) {
+                       DEBUG(ctdb, LOG_ERR,
+                             "ctdb_readrecordlock_async(async):"
+                             " NULL_FUNC returned %i", reply->status);
+               }
+               lock->callback(lock->ctdb_db, NULL, tdb_null, private);
+               ctdb_request_free(ctdb, req); /* Also frees lock. */
                return;
        }
 
        /* Can we get lock now? */
-       if (try_readrecordlock(lock)) {
-               lock->callback(ctdb, req, private);
+       if (try_readrecordlock(lock, &data)) {
+               /* Now it's their responsibility to free lock & request! */
+               req->extra_destructor = NULL;
+               lock->callback(lock->ctdb_db, lock, data, private);
+               ctdb_request_free(ctdb, req);
                return;
        }
 
        /* Retransmit the same request again (we lost race). */
        io_elem_reset(req->io);
-       DLIST_ADD_END(ctdb->outq, req, struct ctdb_request);
-       return;
+       DLIST_ADD(ctdb->outq, req);
 }
 
-struct ctdb_request *
-ctdb_readrecordlock_send(struct ctdb_db *ctdb_db, TDB_DATA key,
-                        ctdb_callback_t callback, void *cbdata)
+bool
+ctdb_readrecordlock_async(struct ctdb_db *ctdb_db, TDB_DATA key,
+                         ctdb_rrl_callback_t callback, void *cbdata)
 {
        struct ctdb_request *req;
        struct ctdb_lock *lock;
+       TDB_DATA data;
 
-       /* Setup lock. */
+       if (holding_lock(ctdb_db->ctdb)) {
+               DEBUG(ctdb_db->ctdb, LOG_ALERT,
+                     "ctdb_readrecordlock_async: already holding lock");
+               return false;
+       }
+
+       /* Setup lock */
        lock = malloc(sizeof(*lock) + key.dsize);
        if (!lock) {
-               return NULL;
+               DEBUG(ctdb_db->ctdb, LOG_ERR,
+                     "ctdb_readrecordlock_async: lock allocation failed");
+               return false;
        }
        lock->key.dptr = (void *)(lock + 1);
        memcpy(lock->key.dptr, key.dptr, key.dsize);
        lock->key.dsize = key.dsize;
        lock->ctdb_db = ctdb_db;
        lock->hdr = NULL;
-       lock->held = false;
+       lock->held_magic = 0;
 
-       /* Get ready in case we need to send a migrate request. */
-       req = new_ctdb_request(sizeof(*req->hdr.call)
-                              + key.dsize, callback, cbdata);
+       /* Fast path. */
+       if (try_readrecordlock(lock, &data)) {
+               callback(ctdb_db, lock, data, cbdata);
+               return true;
+       }
+
+       /* Slow path: create request. */
+       req = new_ctdb_request(offsetof(struct ctdb_req_call, data)
+                              + key.dsize, readrecordlock_retry, cbdata);
        if (!req) {
-               ctdb_release_lock(lock);
+               DEBUG(ctdb_db->ctdb, LOG_ERR,
+                     "ctdb_readrecordlock_async: allocation failed");
+               free_lock(lock);
                return NULL;
        }
        req->extra = lock;
        req->extra_destructor = destroy_lock;
-
-       if (try_readrecordlock(lock)) {
-               /* Already got it: prepare for immediate callback. */
-               DLIST_ADD_END(ctdb_db->ctdb->immediateq,
-                             req, struct ctdb_request);
-               return req;
-       }
-
        /* We store the original callback in the lock, and use our own. */
        lock->callback = callback;
-       req->callback = readrecordlock_retry;
 
        io_elem_init_req_header(req->io, CTDB_REQ_CALL, CTDB_CURRENT_NODE,
                                new_reqid(ctdb_db->ctdb));
@@ -664,17 +884,238 @@ ctdb_readrecordlock_send(struct ctdb_db *ctdb_db, TDB_DATA key,
        req->hdr.call->keylen = key.dsize;
        req->hdr.call->calldatalen = 0;
        memcpy(req->hdr.call->data, key.dptr, key.dsize);
-       DLIST_ADD_END(ctdb_db->ctdb->outq, req, struct ctdb_request);
-       return req;
+       DLIST_ADD(ctdb_db->ctdb->outq, req);
+       return true;
+}
+
+bool ctdb_writerecord(struct ctdb_db *ctdb_db,
+                     struct ctdb_lock *lock, TDB_DATA data)
+{
+       if (lock->ctdb_db != ctdb_db) {
+               errno = EBADF;
+               DEBUG(ctdb_db->ctdb, LOG_ALERT,
+                     "ctdb_writerecord: Can not write, wrong ctdb_db.");
+               return false;
+       }
+
+       if (lock->held_magic != lock_magic(lock)) {
+               errno = EBADF;
+               DEBUG(ctdb_db->ctdb, LOG_ALERT,
+                     "ctdb_writerecord: Can not write. Lock has been released.");
+               return false;
+       }
+               
+       if (ctdb_db->persistent) {
+               errno = EINVAL;
+               DEBUG(ctdb_db->ctdb, LOG_ALERT,
+                     "ctdb_writerecord: cannot write to persistent db");
+               return false;
+       }
+
+       switch (ctdb_local_store(ctdb_db->tdb, lock->key, lock->hdr, data)) {
+       case 0:
+               DEBUG(ctdb_db->ctdb, LOG_DEBUG,
+                     "ctdb_writerecord: optimized away noop write.");
+               /* fall thru */
+       case 1:
+               return true;
+
+       default:
+               switch (errno) {
+               case ENOMEM:
+                       DEBUG(ctdb_db->ctdb, LOG_CRIT,
+                             "ctdb_writerecord: out of memory.");
+                       break;
+               case EINVAL:
+                       DEBUG(ctdb_db->ctdb, LOG_ALERT,
+                             "ctdb_writerecord: record changed under lock?");
+                       break;
+               default: /* TDB already logged. */
+                       break;
+               }
+               return false;
+       }
+}
+
+
+struct ctdb_traverse_state {
+       struct ctdb_request *handle;
+       struct ctdb_db *ctdb_db;
+       uint64_t srvid;
+
+       ctdb_traverse_callback_t callback;
+       void *cbdata;
+};
+
+static void traverse_remhnd_cb(struct ctdb_connection *ctdb,
+                        struct ctdb_request *req, void *private_data)
+{
+       struct ctdb_traverse_state *state = private_data;
+
+       if (!ctdb_remove_message_handler_recv(ctdb, state->handle)) {
+               DEBUG(ctdb, LOG_ERR,
+                               "Failed to remove message handler for"
+                               " traverse.");
+               state->callback(state->ctdb_db->ctdb, state->ctdb_db,
+                               TRAVERSE_STATUS_ERROR,
+                               tdb_null, tdb_null,
+                               state->cbdata);
+       }
+       ctdb_request_free(ctdb, state->handle);
+       state->handle = NULL;
+       free(state);
+}
+       
+static void msg_h(struct ctdb_connection *ctdb, uint64_t srvid,
+          TDB_DATA data, void *private_data)
+{
+       struct ctdb_traverse_state *state = private_data;
+       struct ctdb_db *ctdb_db = state->ctdb_db;
+       struct ctdb_rec_data *d = (struct ctdb_rec_data *)data.dptr;
+       TDB_DATA key;
+
+       if (data.dsize < sizeof(uint32_t) ||
+           d->length != data.dsize) {
+               DEBUG(ctdb, LOG_ERR,
+                       "Bad data size %u in traverse_handler",
+                       (unsigned)data.dsize);
+               state->callback(state->ctdb_db->ctdb, state->ctdb_db,
+                               TRAVERSE_STATUS_ERROR,
+                               tdb_null, tdb_null,
+                               state->cbdata);
+               state->handle = ctdb_remove_message_handler_send(
+                               state->ctdb_db->ctdb, state->srvid,
+                               msg_h, state,
+                               traverse_remhnd_cb, state);
+               return;
+       }
+
+       key.dsize = d->keylen;
+       key.dptr  = &d->data[0];
+       data.dsize = d->datalen;
+       data.dptr = &d->data[d->keylen];
+
+       if (key.dsize == 0 && data.dsize == 0) {
+               state->callback(state->ctdb_db->ctdb, state->ctdb_db,
+                               TRAVERSE_STATUS_FINISHED,
+                               tdb_null, tdb_null,
+                               state->cbdata);
+               state->handle = ctdb_remove_message_handler_send(
+                               state->ctdb_db->ctdb, state->srvid,
+                               msg_h, state,
+                               traverse_remhnd_cb, state);
+               return;
+       }
+
+       if (data.dsize <= sizeof(struct ctdb_ltdb_header)) {
+               /* empty records are deleted records in ctdb */
+               return;
+       }
+
+       data.dsize -= sizeof(struct ctdb_ltdb_header);
+       data.dptr  += sizeof(struct ctdb_ltdb_header);
+
+       if (state->callback(ctdb, ctdb_db,
+                       TRAVERSE_STATUS_RECORD,
+                       key, data, state->cbdata) != 0) {
+               state->handle = ctdb_remove_message_handler_send(
+                               state->ctdb_db->ctdb, state->srvid,
+                               msg_h, state,
+                               traverse_remhnd_cb, state);
+               return;
+       }
 }
 
-int ctdb_writerecord(struct ctdb_lock *lock, TDB_DATA data)
+static void traverse_start_cb(struct ctdb_connection *ctdb,
+                        struct ctdb_request *req, void *private_data)
 {
-       if (lock->ctdb_db->persistent) {
-               /* FIXME: Report error. */
-               return -1;
+       struct ctdb_traverse_state *state = private_data;
+
+        ctdb_request_free(ctdb, state->handle);
+       state->handle = NULL;
+}
+
+static void traverse_msghnd_cb(struct ctdb_connection *ctdb,
+                        struct ctdb_request *req, void *private_data)
+{
+       struct ctdb_traverse_state *state = private_data;
+       struct ctdb_db *ctdb_db = state->ctdb_db;
+       struct ctdb_traverse_start t;
+
+       if (!ctdb_set_message_handler_recv(ctdb, state->handle)) {
+               DEBUG(ctdb, LOG_ERR,
+                               "Failed to register message handler for"
+                               " traverse.");
+               state->callback(state->ctdb_db->ctdb, state->ctdb_db,
+                               TRAVERSE_STATUS_ERROR,
+                               tdb_null, tdb_null,
+                               state->cbdata);
+               ctdb_request_free(ctdb, state->handle);
+               state->handle = NULL;
+               free(state);
+               return;
+        }
+        ctdb_request_free(ctdb, state->handle);
+       state->handle = NULL;
+
+       t.db_id = ctdb_db->id;
+       t.srvid = state->srvid;
+       t.reqid = 0;
+
+       state->handle = new_ctdb_control_request(ctdb,
+                               CTDB_CONTROL_TRAVERSE_START,
+                               CTDB_CURRENT_NODE,
+                               &t, sizeof(t),
+                               traverse_start_cb, state);
+       if (state->handle == NULL) {
+               DEBUG(ctdb, LOG_ERR,
+                               "ctdb_traverse_async:"
+                               " failed to send traverse_start control");
+               state->callback(state->ctdb_db->ctdb, state->ctdb_db,
+                               TRAVERSE_STATUS_ERROR,
+                               tdb_null, tdb_null,
+                               state->cbdata);
+               state->handle = ctdb_remove_message_handler_send(
+                               state->ctdb_db->ctdb, state->srvid,
+                               msg_h, state,
+                               traverse_remhnd_cb, state);
+               return;
+       }
+}
+
+bool ctdb_traverse_async(struct ctdb_db *ctdb_db,
+                        ctdb_traverse_callback_t callback, void *cbdata)
+{
+       struct ctdb_connection *ctdb = ctdb_db->ctdb;
+       struct ctdb_traverse_state *state;
+       static uint32_t tid = 0;
+
+       state = malloc(sizeof(struct ctdb_traverse_state));
+       if (state == NULL) {
+               DEBUG(ctdb, LOG_ERR,
+                               "ctdb_traverse_async: no memory."
+                               " allocate state failed");
+               return false;
+       }
+
+       tid++;
+       state->srvid = CTDB_SRVID_TRAVERSE_RANGE|tid;
+
+       state->callback = callback;
+       state->cbdata   = cbdata;
+       state->ctdb_db  = ctdb_db;
+
+       state->handle = ctdb_set_message_handler_send(ctdb_db->ctdb,
+                               state->srvid,
+                               msg_h, state,
+                               traverse_msghnd_cb, state);
+       if (state->handle == NULL) {
+               DEBUG(ctdb, LOG_ERR,
+                       "ctdb_traverse_async:"
+                       " failed ctdb_set_message_handler_send");
+               free(state);
+               return false;
        }
 
-       return ctdb_local_store(lock->ctdb_db->tdb, lock->key, lock->hdr,
-                               data);
+       return true;
 }