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Improve handling

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not sure if we need to store the electoral term...
This commit is contained in:
Ian Barwick
2017-06-30 13:40:19 +09:00
parent 3514e20367
commit fc4f276844
6 changed files with 247 additions and 127 deletions
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75
repmgr.c
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@@ -48,6 +48,7 @@ typedef struct repmgrdSharedState
LWLockId lock; /* protects search/modification */
NodeState node_state;
NodeVotingStatus voting_status;
int current_electoral_term;
int candidate_node_id;
} repmgrdSharedState;
@@ -144,6 +145,7 @@ repmgr_shmem_startup(void)
shared_state->voting_status = VS_NO_VOTE;
shared_state->candidate_node_id = UNKNOWN_NODE_ID;
shared_state->current_electoral_term = 0;
}
LWLockRelease(AddinShmemInitLock);
@@ -153,59 +155,63 @@ repmgr_shmem_startup(void)
Datum
request_vote(PG_FUNCTION_ARGS)
{
StringInfoData query;
XLogRecPtr our_lsn = InvalidXLogRecPtr;
/* node_id used for logging purposes */
int requesting_node_id = PG_GETARG_INT32(0);
XLogRecPtr requesting_node_last_lsn = PG_GETARG_LSN(1);
StringInfoData query;
int current_electoral_term = PG_GETARG_INT32(1);
int ret;
bool isnull;
int lsn_diff;
NodeVotingStatus voting_status;
LWLockAcquire(shared_state->lock, LW_SHARED);
voting_status = shared_state->voting_status;
LWLockRelease(shared_state->lock);
// keep lock until end of function?
/* this node has initiated voting or already responded to another node */
if (voting_status != VS_NO_VOTE)
PG_RETURN_NULL();
if (shared_state->voting_status != VS_NO_VOTE)
{
LWLockRelease(shared_state->lock);
elog(INFO, "id is %i, lsn: %X/%X",
requesting_node_id,
(uint32) (requesting_node_last_lsn >> 32),
(uint32) requesting_node_last_lsn);
PG_RETURN_NULL();
}
elog(INFO, "requesting node id is %i", requesting_node_id);
SPI_connect();
initStringInfo(&query);
appendStringInfo(
&query,
"SELECT ('%X/%X'::pg_lsn - pg_catalog.pg_last_wal_receive_lsn()::pg_lsn)::INT",
(uint32) (requesting_node_last_lsn >> 32),
(uint32) requesting_node_last_lsn);
"SELECT pg_catalog.pg_last_wal_receive_lsn()"
);
elog(INFO, "query: %s", query.data);
ret = SPI_execute(query.data, true, 0);
// xxx handle errors
lsn_diff = DatumGetInt32(SPI_getbinval(SPI_tuptable->vals[0],
SPI_tuptable->tupdesc,
1, &isnull));
our_lsn = DatumGetLSN(SPI_getbinval(SPI_tuptable->vals[0],
SPI_tuptable->tupdesc,
1, &isnull));
elog(INFO, "XXX diff is %i",
lsn_diff);
elog(INFO, "Our LSN is %X/%X",
(uint32) (our_lsn >> 32),
(uint32) our_lsn);
SPI_finish();
/* indicate this node has responded to a vote request */
LWLockAcquire(shared_state->lock, LW_SHARED);
shared_state->voting_status = VS_VOTE_REQUEST_RECEIVED;
shared_state->current_electoral_term += 1;
LWLockRelease(shared_state->lock);
PG_RETURN_INT32(lsn_diff);
// should we free "query" here?
PG_RETURN_LSN(our_lsn);
}
@@ -225,26 +231,35 @@ get_voting_status(PG_FUNCTION_ARGS)
Datum
set_voting_status_initiated(PG_FUNCTION_ARGS)
{
int electoral_term;
LWLockAcquire(shared_state->lock, LW_SHARED);
shared_state->voting_status = VS_VOTE_INITIATED;
shared_state->current_electoral_term += 1;
electoral_term = shared_state->current_electoral_term;
LWLockRelease(shared_state->lock);
PG_RETURN_VOID();
PG_RETURN_INT32(electoral_term);
}
Datum
other_node_is_candidate(PG_FUNCTION_ARGS)
{
int requesting_node_id = PG_GETARG_INT32(0);
int electoral_term = PG_GETARG_INT32(1);
LWLockAcquire(shared_state->lock, LW_SHARED);
if (shared_state->candidate_node_id != UNKNOWN_NODE_ID)
if (shared_state->current_electoral_term == electoral_term)
{
elog(INFO, "node %i requesting candidature, but node %i already candidate",
requesting_node_id,
shared_state->candidate_node_id);
PG_RETURN_BOOL(false);
if (shared_state->candidate_node_id != UNKNOWN_NODE_ID)
{
elog(INFO, "node %i requesting candidature, but node %i already candidate",
requesting_node_id,
shared_state->candidate_node_id);
PG_RETURN_BOOL(false);
}
}
shared_state->candidate_node_id = requesting_node_id;