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dbwrap_ctdb: handle read-only records.

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The new read-only record flags make determining if we can use a record
a bit more complex, so extract it into its own function.

The OLD logic was:
1) If the record doesn't exist, we can't use it.
2) If we are the dmaster for the record, we can use it.

The new logic is:
1) If the record doesn't exist, we can't use it.
2) If we are the dmaster for the record, we can use it IF we only
   want read-only access, OR there are no read-only delegations.
3) If we are not dmaster, we can only use it if we want read-only
   access and it is marked as a read-only copy.

This logic is unused until the next patches which begin to ask
for read-only copies of records.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2012-02-03 10:53:27 +11:00 committed by Amitay Isaacs
parent c23b2bdea1
commit a3e6f55065
1 changed files with 26 additions and 9 deletions
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35
source3/lib/dbwrap/dbwrap_ctdb.c
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@ -1001,6 +1001,27 @@ static int db_ctdb_record_destr(struct db_record* data)
return 0;
}
/* Do I own this record? */
static bool db_ctdb_own_record(TDB_DATA ctdb_data, bool read_only)
{
struct ctdb_ltdb_header *hdr;
if (ctdb_data.dptr == NULL)
return false;
if (ctdb_data.dsize < sizeof(struct ctdb_ltdb_header))
return false;
hdr = (struct ctdb_ltdb_header *)ctdb_data.dptr;
if (hdr->dmaster != get_my_vnn()) {
/* If we're not dmaster, it must be r/o copy. */
return read_only && (hdr->flags & CTDB_REC_RO_HAVE_READONLY);
}
/* If we want write access, noone can have r/o copies. */
return read_only || !(hdr->flags & CTDB_REC_RO_HAVE_DELEGATIONS);
}
static struct db_record *fetch_locked_internal(struct db_ctdb_ctx *ctx,
TALLOC_CTX *mem_ctx,
TDB_DATA key)
@ -1064,9 +1085,7 @@ again:
* take the shortcut and just return it.
*/
if ((ctdb_data.dptr == NULL) ||
(ctdb_data.dsize < sizeof(struct ctdb_ltdb_header)) ||
((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster != get_my_vnn()
if (!db_ctdb_own_record(ctdb_data, false)
#if 0
|| (random() % 2 != 0)
#endif
@ -1077,10 +1096,11 @@ again:
migrate_attempts += 1;
DEBUG(10, ("ctdb_data.dptr = %p, dmaster = %u (%u)\n",
DEBUG(10, ("ctdb_data.dptr = %p, dmaster = %u (%u) %u\n",
ctdb_data.dptr, ctdb_data.dptr ?
((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster : -1,
get_my_vnn()));
get_my_vnn(),
((struct ctdb_ltdb_header *)ctdb_data.dptr)->flags));
status = ctdbd_migrate(messaging_ctdbd_connection(), ctx->db_id,
key);
@ -1164,10 +1184,7 @@ static NTSTATUS db_ctdb_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
* take the shortcut and just return it.
* we bypass the dmaster check for persistent databases
*/
if ((ctdb_data.dptr != NULL) &&
(ctdb_data.dsize >= sizeof(struct ctdb_ltdb_header)) &&
((struct ctdb_ltdb_header *)ctdb_data.dptr)->dmaster == get_my_vnn())
{
if (db_ctdb_own_record(ctdb_data, true)) {
/* we are the dmaster - avoid the ctdb protocol op */
data->dsize = ctdb_data.dsize - sizeof(struct ctdb_ltdb_header);