From 0f41961e4ffaa602a5b19a1e0899bffa491c886f Mon Sep 17 00:00:00 2001 From: Andrew Tridgell Date: Thu, 7 Aug 2008 16:20:05 +1000 Subject: first cut at adding full transactions for ctdb to samba3 (This used to be commit f91a3e0f7b7737c1d0667cd961ea950e2b93e592) --- source3/lib/dbwrap_ctdb.c | 603 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 600 insertions(+), 3 deletions(-) (limited to 'source3/lib/dbwrap_ctdb.c') diff --git a/source3/lib/dbwrap_ctdb.c b/source3/lib/dbwrap_ctdb.c index 77319464f9..c1ca350de9 100644 --- a/source3/lib/dbwrap_ctdb.c +++ b/source3/lib/dbwrap_ctdb.c @@ -23,9 +23,20 @@ #include "ctdb_private.h" #include "ctdbd_conn.h" +struct db_ctdb_transaction_handle { + struct db_ctdb_ctx *ctx; + bool in_replay; + /* we store the reads and writes done under a transaction one + list stores both reads and writes, the other just writes + */ + struct ctdb_marshall_buffer *m_all; + struct ctdb_marshall_buffer *m_write; +}; + struct db_ctdb_ctx { struct tdb_wrap *wtdb; uint32 db_id; + struct db_ctdb_transaction_handle *transaction; }; struct db_ctdb_rec { @@ -58,6 +69,584 @@ static NTSTATUS tdb_error_to_ntstatus(struct tdb_context *tdb) return status; } + + +/* + form a ctdb_rec_data record from a key/data pair + + note that header may be NULL. If not NULL then it is included in the data portion + of the record + */ +static struct ctdb_rec_data *db_ctdb_marshall_record(TALLOC_CTX *mem_ctx, uint32_t reqid, + TDB_DATA key, + struct ctdb_ltdb_header *header, + TDB_DATA data) +{ + size_t length; + struct ctdb_rec_data *d; + + length = offsetof(struct ctdb_rec_data, data) + key.dsize + + data.dsize + (header?sizeof(*header):0); + d = (struct ctdb_rec_data *)talloc_size(mem_ctx, length); + if (d == NULL) { + return NULL; + } + d->length = length; + d->reqid = reqid; + d->keylen = key.dsize; + memcpy(&d->data[0], key.dptr, key.dsize); + if (header) { + d->datalen = data.dsize + sizeof(*header); + memcpy(&d->data[key.dsize], header, sizeof(*header)); + memcpy(&d->data[key.dsize+sizeof(*header)], data.dptr, data.dsize); + } else { + d->datalen = data.dsize; + memcpy(&d->data[key.dsize], data.dptr, data.dsize); + } + return d; +} + + +/* helper function for marshalling multiple records */ +static struct ctdb_marshall_buffer *db_ctdb_marshall_add(TALLOC_CTX *mem_ctx, + struct ctdb_marshall_buffer *m, + uint64_t db_id, + uint32_t reqid, + TDB_DATA key, + struct ctdb_ltdb_header *header, + TDB_DATA data) +{ + struct ctdb_rec_data *r; + size_t m_size, r_size; + struct ctdb_marshall_buffer *m2; + + r = db_ctdb_marshall_record(mem_ctx, reqid, key, header, data); + if (r == NULL) { + talloc_free(m); + return NULL; + } + + if (m == NULL) { + m = talloc_zero_size(mem_ctx, offsetof(struct ctdb_marshall_buffer, data)); + if (m == NULL) { + return NULL; + } + m->db_id = db_id; + } + + m_size = talloc_get_size(m); + r_size = talloc_get_size(r); + + m2 = talloc_realloc_size(mem_ctx, m, m_size + r_size); + if (m2 == NULL) { + talloc_free(m); + return NULL; + } + + memcpy(m_size + (uint8_t *)m2, r, r_size); + + talloc_free(r); + + m2->count++; + + return m2; +} + +/* we've finished marshalling, return a data blob with the marshalled records */ +static TDB_DATA db_ctdb_marshall_finish(struct ctdb_marshall_buffer *m) +{ + TDB_DATA data; + data.dptr = (uint8_t *)m; + data.dsize = talloc_get_size(m); + return data; +} + +/* + loop over a marshalling buffer + + - pass r==NULL to start + - loop the number of times indicated by m->count +*/ +static struct ctdb_rec_data *db_ctdb_marshall_loop_next(struct ctdb_marshall_buffer *m, struct ctdb_rec_data *r, + uint32_t *reqid, + struct ctdb_ltdb_header *header, + TDB_DATA *key, TDB_DATA *data) +{ + if (r == NULL) { + r = (struct ctdb_rec_data *)&m->data[0]; + } else { + r = (struct ctdb_rec_data *)(r->length + (uint8_t *)r); + } + + if (reqid != NULL) { + *reqid = r->reqid; + } + + if (key != NULL) { + key->dptr = &r->data[0]; + key->dsize = r->keylen; + } + if (data != NULL) { + data->dptr = &r->data[r->keylen]; + data->dsize = r->datalen; + if (header != NULL) { + data->dptr += sizeof(*header); + data->dsize -= sizeof(*header); + } + } + + if (header != NULL) { + if (r->datalen < sizeof(*header)) { + return NULL; + } + *header = *(struct ctdb_ltdb_header *)&r->data[r->keylen]; + } + + return r; +} + + + +/* start a transaction on a database */ +static int db_ctdb_transaction_destructor(struct db_ctdb_transaction_handle *h) +{ + tdb_transaction_cancel(h->ctx->wtdb->tdb); + return 0; +} + +/* start a transaction on a database */ +static int db_ctdb_transaction_fetch_start(struct db_ctdb_transaction_handle *h) +{ + struct db_record *rh; + TDB_DATA key; + struct ctdb_ltdb_header header; + TALLOC_CTX *tmp_ctx; + const char *keyname = CTDB_TRANSACTION_LOCK_KEY; + int ret; + struct db_ctdb_ctx *ctx = h->ctx; + TDB_DATA data; + + key.dptr = discard_const(keyname); + key.dsize = strlen(keyname); + +again: + tmp_ctx = talloc_new(h); + + rh = fetch_locked_internal(ctx, tmp_ctx, key, true); + if (rh == NULL) { + DEBUG(0,(__location__ " Failed to fetch_lock database\n")); + talloc_free(tmp_ctx); + return -1; + } + talloc_free(rh); + + ret = tdb_transaction_start(ctx->wtdb->tdb); + if (ret != 0) { + DEBUG(0,(__location__ " Failed to start tdb transaction\n")); + talloc_free(tmp_ctx); + return -1; + } + + data = tdb_fetch(ctx->wtdb->tdb, key); + if ((data.dptr == NULL) || + (data.dsize < sizeof(struct ctdb_ltdb_header)) || + ((struct ctdb_ltdb_header *)data.dptr)->dmaster != get_my_vnn()) { + SAFE_FREE(data.dptr); + tdb_transaction_cancel(ctx->wtdb->tdb); + talloc_free(tmp_ctx); + goto again; + } + + SAFE_FREE(data.dptr); + talloc_free(tmp_ctx); + + return 0; +} + + +/* start a transaction on a database */ +static int db_ctdb_transaction_start(struct db_context *db) +{ + struct db_ctdb_transaction_handle *h; + int ret; + struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data, + struct db_ctdb_ctx); + + if (!db->persistent) { + DEBUG(0,("transactions not supported on non-persistent database 0x%08x\n", + ctx->db_id)); + return -1; + } + + if (ctx->transaction) { + DEBUG(0,("Nested transactions not supported on db 0x%08x\n", ctx->db_id)); + return -1; + } + + h = talloc_zero(db, struct db_ctdb_transaction_handle); + if (h == NULL) { + DEBUG(0,(__location__ " oom for transaction handle\n")); + return -1; + } + + h->ctx = ctx; + + ret = db_ctdb_transaction_fetch_start(h); + if (ret != 0) { + talloc_free(h); + return -1; + } + + talloc_set_destructor(h, db_ctdb_transaction_destructor); + + ctx->transaction = h; + + return 0; +} + + + +/* + fetch a record inside a transaction + */ +static int db_ctdb_transaction_fetch(struct db_ctdb_ctx *db, + TALLOC_CTX *mem_ctx, + TDB_DATA key, TDB_DATA *data) +{ + struct db_ctdb_transaction_handle *h = db->transaction; + + *data = tdb_fetch(h->ctx->wtdb->tdb, key); + + if (data->dptr != NULL) { + uint8_t *oldptr = (uint8_t *)data->dptr; + data->dsize -= sizeof(struct ctdb_ltdb_header); + data->dptr = (uint8 *) + talloc_memdup( + mem_ctx, data->dptr+sizeof(struct ctdb_ltdb_header), + data->dsize); + SAFE_FREE(oldptr); + if (data->dptr == NULL) { + return -1; + } + } + + if (!h->in_replay) { + h->m_all = db_ctdb_marshall_add(h, h->m_all, h->ctx->db_id, 1, key, NULL, *data); + if (h->m_all == NULL) { + DEBUG(0,(__location__ " Failed to add to marshalling record\n")); + data->dsize = 0; + talloc_free(data->dptr); + return -1; + } + } + + return 0; +} + + +static NTSTATUS db_ctdb_store_transaction(struct db_record *rec, TDB_DATA data, int flag); +static NTSTATUS db_ctdb_delete_transaction(struct db_record *rec); + +static struct db_record *db_ctdb_fetch_locked_transaction(struct db_ctdb_ctx *ctx, + TALLOC_CTX *mem_ctx, + TDB_DATA key) +{ + struct db_record *result; + NTSTATUS status; + TDB_DATA ctdb_data; + int migrate_attempts = 0; + + if (!(result = talloc(mem_ctx, struct db_record))) { + DEBUG(0, ("talloc failed\n")); + return NULL; + } + + result->private_data = ctx->transaction; + + result->key.dsize = key.dsize; + result->key.dptr = (uint8 *)talloc_memdup(result, key.dptr, key.dsize); + if (result->key.dptr == NULL) { + DEBUG(0, ("talloc failed\n")); + TALLOC_FREE(result); + return NULL; + } + + result->store = db_ctdb_store_transaction; + result->delete_rec = db_ctdb_delete_transaction; + + ctdb_data = tdb_fetch(ctx->wtdb->tdb, key); + if (ctdb_data.dptr == NULL) { + /* create the record */ + result->value = tdb_null; + return result; + } + + result->value.dsize = ctdb_data.dsize - sizeof(struct ctdb_ltdb_header); + result->value.dptr = NULL; + + if ((result->value.dsize != 0) + && !(result->value.dptr = (uint8 *)talloc_memdup( + result, ctdb_data.dptr + sizeof(struct ctdb_ltdb_header), + result->value.dsize))) { + DEBUG(0, ("talloc failed\n")); + TALLOC_FREE(result); + } + + SAFE_FREE(ctdb_data.dptr); + + return result; +} + + +/* + stores a record inside a transaction + */ +static int db_ctdb_transaction_store(struct db_ctdb_transaction_handle *h, + TDB_DATA key, TDB_DATA data) +{ + TALLOC_CTX *tmp_ctx = talloc_new(h); + int ret; + TDB_DATA rec; + struct ctdb_ltdb_header header; + + /* we need the header so we can update the RSN */ + rec = tdb_fetch(h->ctx->wtdb->tdb, key); + if (rec.dptr == NULL) { + /* the record doesn't exist - create one with us as dmaster. + This is only safe because we are in a transaction and this + is a persistent database */ + ZERO_STRUCT(header); + header.dmaster = get_my_vnn(); + } else { + memcpy(&header, rec.dptr, sizeof(struct ctdb_ltdb_header)); + SAFE_FREE(rec.dptr); + } + + header.rsn++; + + if (!h->in_replay) { + h->m_all = db_ctdb_marshall_add(h, h->m_all, h->ctx->db_id, 0, key, NULL, data); + if (h->m_all == NULL) { + DEBUG(0,(__location__ " Failed to add to marshalling record\n")); + talloc_free(tmp_ctx); + return -1; + } + + h->m_write = db_ctdb_marshall_add(h, h->m_write, h->ctx->db_id, 0, key, &header, data); + if (h->m_write == NULL) { + DEBUG(0,(__location__ " Failed to add to marshalling record\n")); + talloc_free(tmp_ctx); + return -1; + } + } + + rec.dptr = talloc_size(tmp_ctx, data.dsize + sizeof(struct ctdb_ltdb_header)); + if (rec.dptr == NULL) { + DEBUG(0,(__location__ " Failed to alloc record\n")); + talloc_free(tmp_ctx); + return -1; + } + memcpy(rec.dptr, &header, sizeof(struct ctdb_ltdb_header)); + memcpy(sizeof(struct ctdb_ltdb_header) + (uint8_t *)rec.dptr, data.dptr, data.dsize); + + ret = tdb_store(h->ctx->wtdb->tdb, key, rec, TDB_REPLACE); + + talloc_free(tmp_ctx); + + return ret; +} + + +/* + a record store inside a transaction + */ +static NTSTATUS db_ctdb_store_transaction(struct db_record *rec, TDB_DATA data, int flag) +{ + struct db_ctdb_transaction_handle *h = talloc_get_type_abort( + rec->private_data, struct db_ctdb_transaction_handle); + int ret; + + ret = db_ctdb_transaction_store(h, rec->key, data); + if (ret != 0) { + return tdb_error_to_ntstatus(h->ctx->wtdb->tdb); + } + return NT_STATUS_OK; +} + +/* + a record delete inside a transaction + */ +static NTSTATUS db_ctdb_delete_transaction(struct db_record *rec) +{ + struct db_ctdb_transaction_handle *h = talloc_get_type_abort( + rec->private_data, struct db_ctdb_transaction_handle); + int ret; + + ret = db_ctdb_transaction_store(h, rec->key, tdb_null); + if (ret != 0) { + return tdb_error_to_ntstatus(h->ctx->wtdb->tdb); + } + return NT_STATUS_OK; +} + + +/* + replay a transaction + */ +static int ctdb_replay_transaction(struct db_ctdb_transaction_handle *h) +{ + int ret, i; + struct ctdb_rec_data *rec = NULL; + + h->in_replay = true; + + ret = db_ctdb_transaction_fetch_start(h); + if (ret != 0) { + return ret; + } + + for (i=0;im_all->count;i++) { + TDB_DATA key, data; + + rec = db_ctdb_marshall_loop_next(h->m_all, rec, NULL, NULL, &key, &data); + if (rec == NULL) { + DEBUG(0, (__location__ " Out of records in ctdb_replay_transaction?\n")); + goto failed; + } + + if (rec->reqid == 0) { + /* its a store */ + if (db_ctdb_transaction_store(h, key, data) != 0) { + goto failed; + } + } else { + TDB_DATA data2; + TALLOC_CTX *tmp_ctx = talloc_new(h); + + if (db_ctdb_transaction_fetch(h->ctx, tmp_ctx, key, &data2) != 0) { + talloc_free(tmp_ctx); + goto failed; + } + if (data2.dsize != data.dsize || + memcmp(data2.dptr, data.dptr, data.dsize) != 0) { + /* the record has changed on us - we have to give up */ + talloc_free(tmp_ctx); + goto failed; + } + talloc_free(tmp_ctx); + } + } + + return 0; + +failed: + tdb_transaction_cancel(h->ctx->wtdb->tdb); + return -1; +} + + +/* + commit a transaction + */ +static int db_ctdb_transaction_commit(struct db_context *db) +{ + struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data, + struct db_ctdb_ctx); + NTSTATUS rets; + int ret; + int status; + struct timeval timeout; + struct db_ctdb_transaction_handle *h = ctx->transaction; + + if (h == NULL) { + DEBUG(0,(__location__ " transaction commit with no open transaction on db 0x%08x\n", ctx->db_id)); + return -1; + } + + talloc_set_destructor(h, NULL); + + if (h->m_write == NULL) { + /* no changes were made */ + talloc_free(h); + return 0; + } + + /* our commit strategy is quite complex. + + - we first try to commit the changes to all other nodes + + - if that works, then we commit locally and we are done + + - if a commit on another node fails, then we need to cancel + the transaction, then restart the transaction (thus + opening a window of time for a pending recovery to + complete), then replay the transaction, checking all the + reads and writes (checking that reads give the same data, + and writes succeed). Then we retry the transaction to the + other nodes + */ + +again: + /* tell ctdbd to commit to the other nodes */ + rets = ctdbd_control_local(messaging_ctdbd_connection(), + CTDB_CONTROL_TRANS2_COMMIT, h->ctx->db_id, 0, + db_ctdb_marshall_finish(h->m_write), NULL, NULL, &status); + if (!NT_STATUS_IS_OK(rets) || status != 0) { + tdb_transaction_cancel(h->ctx->wtdb->tdb); + sleep(1); + if (ctdb_replay_transaction(h) != 0) { + DEBUG(0,(__location__ " Failed to replay transaction\n")); + ctdbd_control_local(messaging_ctdbd_connection(), CTDB_CONTROL_TRANS2_ERROR, + h->ctx->db_id, CTDB_CTRL_FLAG_NOREPLY, + tdb_null, NULL, NULL, NULL); + h->ctx->transaction = NULL; + talloc_free(h); + return -1; + } + goto again; + } + + /* do the real commit locally */ + ret = tdb_transaction_commit(h->ctx->wtdb->tdb); + if (ret != 0) { + DEBUG(0,(__location__ " Failed to commit transaction\n")); + ctdbd_control_local(messaging_ctdbd_connection(), CTDB_CONTROL_TRANS2_ERROR, h->ctx->db_id, + CTDB_CTRL_FLAG_NOREPLY, tdb_null, NULL, NULL, NULL); + h->ctx->transaction = NULL; + talloc_free(h); + return ret; + } + + /* tell ctdbd that we are finished with our local commit */ + ctdbd_control_local(messaging_ctdbd_connection(), CTDB_CONTROL_TRANS2_FINISHED, + h->ctx->db_id, CTDB_CTRL_FLAG_NOREPLY, + tdb_null, NULL, NULL, NULL); + h->ctx->transaction = NULL; + talloc_free(h); + return 0; +} + + +/* + cancel a transaction + */ +static int db_ctdb_transaction_cancel(struct db_context *db) +{ + struct db_ctdb_ctx *ctx = talloc_get_type_abort(db->private_data, + struct db_ctdb_ctx); + struct db_ctdb_transaction_handle *h = ctx->transaction; + + if (h == NULL) { + DEBUG(0,(__location__ " transaction cancel with no open transaction on db 0x%08x\n", ctx->db_id)); + return -1; + } + + ctx->transaction = NULL; + talloc_free(h); + return 0; +} + + static NTSTATUS db_ctdb_store(struct db_record *rec, TDB_DATA data, int flag) { struct db_ctdb_rec *crec = talloc_get_type_abort( @@ -269,6 +858,10 @@ static struct db_record *fetch_locked_internal(struct db_ctdb_ctx *ctx, TDB_DATA ctdb_data; int migrate_attempts = 0; + if (ctx->transaction != NULL) { + return db_ctdb_fetch_locked_transaction(ctx, mem_ctx, key); + } + if (!(result = talloc(mem_ctx, struct db_record))) { DEBUG(0, ("talloc failed\n")); return NULL; @@ -400,6 +993,10 @@ static int db_ctdb_fetch(struct db_context *db, TALLOC_CTX *mem_ctx, NTSTATUS status; TDB_DATA ctdb_data; + if (ctx->transaction) { + return db_ctdb_transaction_fetch(ctx, mem_ctx, key, data); + } + /* try a direct fetch */ ctdb_data = tdb_fetch(ctx->wtdb->tdb, key); @@ -643,9 +1240,9 @@ struct db_context *db_open_ctdb(TALLOC_CTX *mem_ctx, result->traverse = db_ctdb_traverse; result->traverse_read = db_ctdb_traverse_read; result->get_seqnum = db_ctdb_get_seqnum; - result->transaction_start = db_ctdb_trans_dummy; - result->transaction_commit = db_ctdb_trans_dummy; - result->transaction_cancel = db_ctdb_trans_dummy; + result->transaction_start = db_ctdb_transaction_start; + result->transaction_commit = db_ctdb_transaction_commit; + result->transaction_cancel = db_ctdb_transaction_cancel; DEBUG(3,("db_open_ctdb: opened database '%s' with dbid 0x%x\n", name, db_ctdb->db_id)); -- cgit