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[MDEV-34009] Client-side implementation of instant failover mechanism #246

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[MDEV-34009] Client-side implementation of instant failover mechanism #246

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f294514
[MDEV-34009] Follow instant failover error packets
dlenski Jun 20, 2023
1860c71
Allow clients to disable server-initiated instant failovers
dlenski Jul 5, 2023
f81e7a9
Limit number of server-initiated instant failovers followed by client
dlenski Jul 5, 2023
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4 changes: 4 additions & 0 deletions include/mysql.h
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Original file line number Diff line number Diff line change
Expand Up @@ -228,6 +228,8 @@ extern const char *SQLSTATE_UNKNOWN;
/* MariaDB specific */
MYSQL_PROGRESS_CALLBACK=5999,
MYSQL_OPT_NONBLOCK,
MARIADB_OPT_FOLLOW_INSTANT_FAILOVERS,

/* MariaDB Connector/C specific */
MYSQL_DATABASE_DRIVER=7000,
MARIADB_OPT_SSL_FP, /* deprecated, use MARIADB_OPT_TLS_PEER_FP instead */
Expand Down Expand Up @@ -340,6 +342,8 @@ struct st_mysql_options {
char *bind_address;
my_bool secure_auth;
my_bool report_data_truncation;
my_bool follow_instant_failovers;

/* function pointers for local infile support */
int (*local_infile_init)(void **, const char *, void *);
int (*local_infile_read)(void *, char *, unsigned int);
Expand Down
3 changes: 2 additions & 1 deletion include/mysqld_error.h
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Expand Up @@ -1236,5 +1236,6 @@
#define ER_JSON_HISTOGRAM_PARSE_FAILED 4186
#define ER_SF_OUT_INOUT_ARG_NOT_ALLOWED 4187
#define ER_INCONSISTENT_SLAVE_TEMP_TABLE 4188
#define ER_ERROR_LAST 4188
#define ER_INSTANT_FAILOVER 4200
#define ER_ERROR_LAST 4200
#endif /* ER_ERROR_FIRST */
48 changes: 47 additions & 1 deletion libmariadb/mariadb_lib.c
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Expand Up @@ -85,6 +85,7 @@
#define MA_RPL_VERSION_HACK "5.5.5-"

#define CHARSET_NAME_LEN 64
#define INSTANT_FAILOVER_LIMIT 8

#undef max_allowed_packet
#undef net_buffer_length
Expand Down Expand Up @@ -668,6 +669,7 @@ struct st_default_options mariadb_defaults[] =
{{MYSQL_SET_CHARSET_NAME}, MARIADB_OPTION_STR, "default-character-set"},
{{MARIADB_OPT_INTERACTIVE}, MARIADB_OPTION_NONE, "interactive-timeout"},
{{MYSQL_OPT_CONNECT_TIMEOUT}, MARIADB_OPTION_INT, "connect-timeout"},
{{MARIADB_OPT_FOLLOW_INSTANT_FAILOVERS}, MARIADB_OPTION_BOOL, "follow-instant-failovers"},
{{MYSQL_OPT_LOCAL_INFILE}, MARIADB_OPTION_BOOL, "local-infile"},
{{0}, 0 ,"disable-local-infile",},
{{MYSQL_OPT_SSL_CIPHER}, MARIADB_OPTION_STR, "ssl-cipher"},
Expand Down Expand Up @@ -1304,6 +1306,7 @@ mysql_init(MYSQL *mysql)
goto error;
mysql->options.report_data_truncation= 1;
mysql->options.connect_timeout=CONNECT_TIMEOUT;
mysql->options.follow_instant_failovers= TRUE;
mysql->charset= mysql_find_charset_name(MARIADB_DEFAULT_CHARSET);
mysql->methods= &MARIADB_DEFAULT_METHODS;
strcpy(mysql->net.sqlstate, "00000");
Expand Down Expand Up @@ -1591,7 +1594,7 @@ MYSQL *mthd_my_real_connect(MYSQL *mysql, const char *host, const char *user,
my_bool is_multi= 0;
char *host_copy= NULL;
struct st_host *host_list= NULL;
int connect_attempts= 0;
int connect_attempts= 0, instant_failovers=0;

if (!mysql->methods)
mysql->methods= &MARIADB_DEFAULT_METHODS;
Expand Down Expand Up @@ -1731,6 +1734,7 @@ MYSQL *mthd_my_real_connect(MYSQL *mysql, const char *host, const char *user,
else
#endif
{
tcp_redirect:
cinfo.unix_socket=0; /* This is not used */
if (!port)
port=mysql_port;
Expand Down Expand Up @@ -1963,7 +1967,46 @@ MYSQL *mthd_my_real_connect(MYSQL *mysql, const char *host, const char *user,

if (run_plugin_auth(mysql, scramble_data, scramble_len,
scramble_plugin, db))
{
if (mysql->net.last_errno == ER_INSTANT_FAILOVER)
{
if (!mysql->options.follow_instant_failovers)
{
/* Client has disabled instant failover. Fall through and treat this
* as a "normal" error. */
}
else if (instant_failovers >= INSTANT_FAILOVER_LIMIT)
{
/* Too many instant failovers */
my_set_error(mysql, ER_INSTANT_FAILOVER, SQLSTATE_UNKNOWN,
"Too many instant failovers (>= %d)",
INSTANT_FAILOVER_LIMIT);
}
else
{
char *p= mysql->net.last_error; /* Should look like '|message|host[:port]' */
if (p && p[0] == '|')
p= strchr(p + 1, '|') ? : NULL;
if (p && *++p) {
host= p;
p= strchr(p, ':') ? : NULL;
if (p) {
*p++ = '\0';
port= atoi(p);
}
else
{
/* Restore to the default port, rather than reusing our current one */
port= 0;
}
fprintf(stderr, "Got instant failover to '%s' (port %d)\n", host, port);
++instant_failovers;
goto tcp_redirect;
}
}
}
goto error;
}

if (mysql->client_flag & CLIENT_COMPRESS ||
mysql->client_flag & CLIENT_ZSTD_COMPRESSION)
Expand Down Expand Up @@ -3470,6 +3513,9 @@ mysql_optionsv(MYSQL *mysql,enum mysql_option option, ...)
case MYSQL_OPT_RECONNECT:
mysql->options.reconnect= *(my_bool *)arg1;
break;
case MARIADB_OPT_FOLLOW_INSTANT_FAILOVERS:
mysql->options.follow_instant_failovers= *(my_bool *)arg1;
break;
case MYSQL_OPT_PROTOCOL:
mysql->options.protocol= *((uint *)arg1);
break;
Expand Down