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Issue #1663: The mod_sql_mysql module should attempt to retry state… #1668

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Issue #1663: The mod_sql_mysql module should attempt to retry state… #1668

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117 changes: 104 additions & 13 deletions contrib/mod_sql_mysql.c
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
/*
* ProFTPD: mod_sql_mysql -- Support for connecting to MySQL databases.
* Copyright (c) 2001 Andrew Houghton
* Copyright (c) 2004-2022 TJ Saunders
* Copyright (c) 2004-2023 TJ Saunders
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
Expand Down Expand Up @@ -124,15 +124,16 @@
/* Internal define used for debug and logging. All backends are encouraged
* to use the same format.
*/
#define MOD_SQL_MYSQL_VERSION "mod_sql_mysql/4.0.9"
#define MOD_SQL_MYSQL_VERSION "mod_sql_mysql/4.0.10"

#define _MYSQL_PORT "3306"

#include "conf.h"
#include "../contrib/mod_sql.h"

#include <mysql.h>
#include <stdbool.h>
#include <mysql.h>
#include <mysqld_error.h>

/* The my_make_scrambled_password{,_323} functions are not part of the public
* MySQL API and are not declared in any of the MySQL header files. But the
Expand Down Expand Up @@ -201,7 +202,8 @@ struct conn_entry_struct {

typedef struct conn_entry_struct conn_entry_t;

#define DEF_CONN_POOL_SIZE 10
#define DEF_CONN_POOL_SIZE 10
#define MAX_LOCK_ATTEMPTS 10

static pool *conn_pool = NULL;
static array_header *conn_cache = NULL;
Expand Down Expand Up @@ -306,6 +308,43 @@ static int sql_timer_cb(CALLBACK_FRAME) {
return 0;
}

static int process_query_error(db_conn_t *conn, const char *query_text,
unsigned int nattempts) {
int error_code, res = -1;
const char *error_text;

error_code = mysql_errno(conn->mysql);
error_text = mysql_error(conn->mysql);

pr_trace_msg(trace_channel, 7, "'%s' query error: %s (%d)", query_text,
error_text, error_code);

switch (error_code) {
case ER_LOCK_DEADLOCK:
case ER_LOCK_WAIT_TIMEOUT:
case ER_LOCK_OR_ACTIVE_TRANSACTION:
/* Locking issue. Wait for a short time, then try again. */
if (nattempts < MAX_LOCK_ATTEMPTS) {
sql_log(DEBUG_FUNC,
"deadlock detected (%d %s), attempt %u/%u, retrying", error_code,
error_text, nattempts, MAX_LOCK_ATTEMPTS);
pr_timer_usleep(200 * 1000);
res = 0;

} else {
sql_log(DEBUG_FUNC,
"deadlock detected (%d %s), attempt %u/%u, failing", error_code,
error_text, nattempts, MAX_LOCK_ATTEMPTS);
}
break;

default:
break;
}

return res;
}

/* build_error: constructs a modret_t filled with error information;
* mod_sql_mysql calls this function and returns the resulting mod_ret_t
* whenever a call to the database results in an error. Other backends
Expand Down Expand Up @@ -1158,7 +1197,7 @@ MODRET cmd_select(cmd_rec *cmd) {
}

/* Log the query string */
sql_log(DEBUG_INFO, "query \"%s\"", query);
sql_log(DEBUG_INFO, "SELECT query \"%s\"", query);

/* Perform the query. if it doesn't work, log the error, close the
* connection then return the error from the query processing.
Expand Down Expand Up @@ -1229,11 +1268,14 @@ MODRET cmd_select(cmd_rec *cmd) {
* none
*/
MODRET cmd_insert(cmd_rec *cmd) {
int res;
unsigned int nattempts = 0;
conn_entry_t *entry = NULL;
db_conn_t *conn = NULL;
modret_t *cmr = NULL;
modret_t *dmr = NULL;
char *query = NULL;
size_t query_len;
cmd_rec *close_cmd;

sql_log(DEBUG_FUNC, "%s", "entering \tmysql cmd_insert");
Expand Down Expand Up @@ -1272,13 +1314,28 @@ MODRET cmd_insert(cmd_rec *cmd) {
cmd->argv[2], ") VALUES (", cmd->argv[3], ")", NULL);
}

sql_log(DEBUG_INFO, "query \"%s\"", query);
/* Log the query string. */
sql_log(DEBUG_INFO, "INSERT query \"%s\"", query);

/* perform the query. if it doesn't work, log the error, close the
/* Perform the query. If it doesn't work, log the error, close the
* connection (and log any errors there, too) then return the error
* from the query processing.
*/
if (mysql_real_query(conn->mysql, query, strlen(query)) != 0) {
query_len = strlen(query);

nattempts++;
res = mysql_real_query(conn->mysql, query, query_len);
while (res != 0) {
if (process_query_error(conn, query, nattempts) == 0) {
nattempts++;
res = mysql_real_query(conn->mysql, query, query_len);
continue;
}

break;
}

if (res != 0) {
dmr = build_error(cmd, conn);

close_cmd = sql_make_cmd(cmd->tmp_pool, 1, entry->name);
Expand Down Expand Up @@ -1329,11 +1386,14 @@ MODRET cmd_insert(cmd_rec *cmd) {
* make sure this is handled correctly.
*/
MODRET cmd_update(cmd_rec *cmd) {
int res;
unsigned int nattempts = 0;
conn_entry_t *entry = NULL;
db_conn_t *conn = NULL;
modret_t *cmr = NULL;
modret_t *dmr = NULL;
char *query = NULL;
size_t query_len;
cmd_rec *close_cmd;

sql_log(DEBUG_FUNC, "%s", "entering \tmysql cmd_update");
Expand Down Expand Up @@ -1376,12 +1436,26 @@ MODRET cmd_update(cmd_rec *cmd) {
}

/* Log the query string */
sql_log(DEBUG_INFO, "query \"%s\"", query);
sql_log(DEBUG_INFO, "UPDATE query \"%s\"", query);

/* Perform the query. if it doesn't work close the connection, then
/* Perform the query. If it doesn't work close the connection, then
* return the error from the query processing.
*/
if (mysql_real_query(conn->mysql, query, strlen(query)) != 0) {
query_len = strlen(query);

nattempts++;
res = mysql_real_query(conn->mysql, query, query_len);
while (res != 0) {
if (process_query_error(conn, query, nattempts) == 0) {
nattempts++;
res = mysql_real_query(conn->mysql, query, query_len);
continue;
}

break;
}

if (res != 0) {
dmr = build_error(cmd, conn);

close_cmd = sql_make_cmd(cmd->tmp_pool, 1, entry->name);
Expand Down Expand Up @@ -1457,11 +1531,14 @@ MODRET cmd_procedure(cmd_rec *cmd) {
* None.
*/
MODRET cmd_query(cmd_rec *cmd) {
int res;
unsigned int nattempts = 0;
conn_entry_t *entry = NULL;
db_conn_t *conn = NULL;
modret_t *cmr = NULL;
modret_t *dmr = NULL;
char *query = NULL;
size_t query_len;
cmd_rec *close_cmd;

sql_log(DEBUG_FUNC, "%s", "entering \tmysql cmd_query");
Expand Down Expand Up @@ -1491,12 +1568,26 @@ MODRET cmd_query(cmd_rec *cmd) {
query = pstrcat(cmd->tmp_pool, cmd->argv[1], NULL);

/* Log the query string */
sql_log(DEBUG_INFO, "query \"%s\"", query);
sql_log(DEBUG_INFO, "FREEFORM query \"%s\"", query);

/* Perform the query. if it doesn't work close the connection, then
* return the error from the query processing.
*/
if (mysql_real_query(conn->mysql, query, strlen(query)) != 0) {
query_len = strlen(query);

nattempts++;
res = mysql_real_query(conn->mysql, query, query_len);
while (res != 0) {
if (process_query_error(conn, query, nattempts) == 0) {
nattempts++;
res = mysql_real_query(conn->mysql, query, query_len);
continue;
}

break;
}

if (res != 0) {
dmr = build_error(cmd, conn);

close_cmd = sql_make_cmd(cmd->tmp_pool, 1, entry->name);
Expand Down