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Code

handle two special cases

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1) when all nodes write the same value to the record, or when writing
   a value that is already there, we can skip the write and save
   ourselves a network transactions

2) when all remote nodes fail an update, and we then fail a replay, we
   don't need to trigger a recovery. This solves a corner case where
   we could get into a recovery loop
(This used to be commit 2481bfce4307274806584b0d8e295cc7f638e184)
This commit is contained in:
Andrew Tridgell 2008-08-08 09:58:15 +10:00 committed by Michael Adam
parent bd47edc8d6
commit 2592565bde
1 changed files with 42 additions and 16 deletions
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58
source3/lib/dbwrap_ctdb.c
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@ -460,6 +460,14 @@ static int db_ctdb_transaction_store(struct db_ctdb_transaction_handle *h,
header.dmaster = get_my_vnn();
} else {
memcpy(&header, rec.dptr, sizeof(struct ctdb_ltdb_header));
rec.dsize -= sizeof(struct ctdb_ltdb_header);
/* a special case, we are writing the same data that is there now */
if (data.dsize == rec.dsize &&
memcmp(data.dptr, rec.dptr + sizeof(struct ctdb_ltdb_header), data.dsize) == 0) {
SAFE_FREE(rec.dptr);
talloc_free(tmp_ctx);
return 0;
}
SAFE_FREE(rec.dptr);
}
@ -472,13 +480,13 @@ static int db_ctdb_transaction_store(struct db_ctdb_transaction_handle *h,
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;
}
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.dsize = data.dsize + sizeof(struct ctdb_ltdb_header);
@ -541,6 +549,8 @@ static int ctdb_replay_transaction(struct db_ctdb_transaction_handle *h)
struct ctdb_rec_data *rec = NULL;
h->in_replay = true;
talloc_free(h->m_write);
h->m_write = NULL;
ret = db_ctdb_transaction_fetch_start(h);
if (ret != 0) {
@ -599,6 +609,7 @@ static int db_ctdb_transaction_commit(struct db_context *db)
int status;
int retries = 0;
struct db_ctdb_transaction_handle *h = ctx->transaction;
enum ctdb_controls failure_control = CTDB_CONTROL_TRANS2_ERROR;
if (h == NULL) {
DEBUG(0,(__location__ " transaction commit with no open transaction on db 0x%08x\n", ctx->db_id));
@ -607,13 +618,6 @@ static int db_ctdb_transaction_commit(struct db_context *db)
DEBUG(5,(__location__ " Commit transaction on db 0x%08x\n", ctx->db_id));
if (h->m_write == NULL) {
/* no changes were made */
talloc_free(h);
ctx->transaction = NULL;
return 0;
}
talloc_set_destructor(h, NULL);
/* our commit strategy is quite complex.
@ -632,6 +636,14 @@ static int db_ctdb_transaction_commit(struct db_context *db)
*/
again:
if (h->m_write == NULL) {
/* no changes were made, potentially after a retry */
tdb_transaction_cancel(h->ctx->wtdb->tdb);
talloc_free(h);
ctx->transaction = NULL;
return 0;
}
/* tell ctdbd to commit to the other nodes */
rets = ctdbd_control_local(messaging_ctdbd_connection(),
CTDB_CONTROL_TRANS2_COMMIT, h->ctx->db_id, 0,
@ -639,9 +651,23 @@ again:
if (!NT_STATUS_IS_OK(rets) || status != 0) {
tdb_transaction_cancel(h->ctx->wtdb->tdb);
sleep(1);
/* work out what error code we will give if we
have to fail the operation */
switch ((enum ctdb_trans2_commit_error)status) {
case CTDB_TRANS2_COMMIT_SUCCESS:
case CTDB_TRANS2_COMMIT_SOMEFAIL:
case CTDB_TRANS2_COMMIT_TIMEOUT:
failure_control = CTDB_CONTROL_TRANS2_ERROR;
break;
case CTDB_TRANS2_COMMIT_ALLFAIL:
failure_control = CTDB_CONTROL_TRANS2_FINISHED;
break;
}
if (ctdb_replay_transaction(h) != 0) {
DEBUG(0,(__location__ " Failed to replay transaction\n"));
ctdbd_control_local(messaging_ctdbd_connection(), CTDB_CONTROL_TRANS2_ERROR,
ctdbd_control_local(messaging_ctdbd_connection(), failure_control,
h->ctx->db_id, CTDB_CTRL_FLAG_NOREPLY,
tdb_null, NULL, NULL, NULL);
h->ctx->transaction = NULL;
@ -649,10 +675,10 @@ again:
ctx->transaction = NULL;
return -1;
}
if (retries++ == 10) {
if (++retries == 10) {
DEBUG(0,(__location__ " Giving up transaction on db 0x%08x after %d retries\n",
h->ctx->db_id, retries));
ctdbd_control_local(messaging_ctdbd_connection(), CTDB_CONTROL_TRANS2_ERROR,
ctdbd_control_local(messaging_ctdbd_connection(), failure_control,
h->ctx->db_id, CTDB_CTRL_FLAG_NOREPLY,
tdb_null, NULL, NULL, NULL);
h->ctx->transaction = NULL;