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Try postgres reconnect on database connection lost #339

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Apr 20, 2018
Merged

Try postgres reconnect on database connection lost #339

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b2140fd
added a connection reset if postgres database connection failing
Apr 9, 2018
d311c1b
added a log message when trying to reconnect to postgres database due…
Apr 9, 2018
4eedf76
fixed interface definition for memcached
Apr 9, 2018
24a4f20
Merge branch 'master' of github.com:jpmens/mosquitto-auth-plug into p…
Apr 9, 2018
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27 changes: 24 additions & 3 deletions be-postgres.c
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Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,12 @@ int be_pg_getuser(void *handle, const char *username, const char *password, char

if (PQresultStatus(res) != PGRES_TUPLES_OK) {
_log(LOG_DEBUG, "%s\n", PQresultErrorMessage(res));
if(PQstatus(conf->conn) == CONNECTION_BAD){
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What if this was executed prior to running a query - will that still work?

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@jklimke jklimke Apr 9, 2018 •
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I am not sure if i understand your comment correctly. How should that be possible at that position ? I understand that all postgres queries are currently performed synchronously. That means that the query has been finished (not sucessfully) when this piece of code comes into play.

On line 174 there is a check if the database connection has been initialized

if (!conf || !conf->userquery || !username || !*username)
		return BACKEND_DEFER;

That means a connection should exist a the moment and a query has finished

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I've looked at the source, and you are of course correct.

_log(LOG_NOTICE, "Noticed a postgres connection loss. Trying to reconnect ...\n");
//try to reinitiate the database connection
PQreset(conf->conn);
}

goto out;
}
if ((nrows = PQntuples(res)) != 1) {
Expand All @@ -194,7 +200,7 @@ int be_pg_getuser(void *handle, const char *username, const char *password, char
}
if ((v = PQgetvalue(res, 0, 0)) == NULL) {
goto out;
}
}
value = (v) ? strdup(v) : NULL;


Expand Down Expand Up @@ -233,6 +239,13 @@ int be_pg_superuser(void *handle, const char *username)
if (PQresultStatus(res) != PGRES_TUPLES_OK) {
fprintf(stderr, "%s\n", PQresultErrorMessage(res));
issuper = BACKEND_ERROR;
//try to reset connection if failing because of database connection lost
if(PQstatus(conf->conn) == CONNECTION_BAD){
_log(LOG_NOTICE, "Noticed a postgres connection loss. Trying to reconnect ...\n");
//try to reinitiate the database connection
PQreset(conf->conn);
}

goto out;
}
if ((nrows = PQntuples(res)) != 1) {
Expand Down Expand Up @@ -296,6 +309,14 @@ int be_pg_aclcheck(void *handle, const char *clientid, const char *username, con
if (PQresultStatus(res) != PGRES_TUPLES_OK) {
fprintf(stderr, "%s\n", PQresultErrorMessage(res));
match = BACKEND_ERROR;

//try to reset connection if failing because of database connection lost
if(PQstatus(conf->conn) == CONNECTION_BAD){
_log(LOG_NOTICE, "Noticed a postgres connection loss. Trying to reconnect ...\n");
//try to reinitiate the database connection
PQreset(conf->conn);
}

goto out;
}
if (PQnfields(res) != 1) {
Expand Down Expand Up @@ -413,8 +434,8 @@ int addKeyValue(char **keywords, char **values, char *key, char *value,
n++;

// In case of not zero-terminated dictionary
keywords[n] = '\0';
values[n] = '\0';
keywords[n] = 0;
values[n] = 0;

return n;
}
Expand Down