From b3a4885d6459bb7aee1d51b6ab30566308a9135c Mon Sep 17 00:00:00 2001
From: Lucien Sadi <luciensadi@gmail.com>
Date: Sun, 28 May 2017 21:24:41 -0700
Subject: [PATCH] Added MySQL DB cleanup on shutdown. Also added a potential
 error-recovery handler for error 2006 (DB has gone away).

---
 src/comm.cpp  |  3 +++
 src/db.cpp    |  6 ++++++
 src/newdb.cpp | 30 +++++++++++++++++++++++++++---
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/comm.cpp b/src/comm.cpp
index 2283510dc..5a49f7eee 100644
--- a/src/comm.cpp
+++ b/src/comm.cpp
@@ -123,6 +123,7 @@ char *colorize(struct descriptor_data *d, char *str);
 
 /* extern fcnts */
 extern void DBInit();
+extern void DBFinalize();
 void boot_world(void);
 void zone_update(void);
 void spec_update(void);
@@ -359,6 +360,8 @@ void init_game(int port)
   
   close(mother_desc);
   
+  DBFinalize();
+  
   if (circle_reboot) {
     log("Rebooting.");
     exit(52);                   /* what's so great about HHGTTG, anyhow? */
diff --git a/src/db.cpp b/src/db.cpp
index db81c1c3a..b1c28f77c 100644
--- a/src/db.cpp
+++ b/src/db.cpp
@@ -384,6 +384,12 @@ void DBInit()
   log("Boot db -- DONE.");
 }
 
+/* A simple method to clean up after our DB. */
+void DBFinalize() {
+  if (mysql)
+    mysql_close(mysql);
+}
+
 /* reset the time in the game from file
    weekday is lost on reboot.... implement
    something different if this is mission
diff --git a/src/newdb.cpp b/src/newdb.cpp
index 677488066..61e8c52ff 100644
--- a/src/newdb.cpp
+++ b/src/newdb.cpp
@@ -55,11 +55,35 @@ int mysql_wrapper(MYSQL *mysql, char *query)
 #endif
   
   int result = mysql_query(mysql, query);
-
-  if (mysql_errno(mysql)) {
+  int errnum = mysql_errno(mysql);
+  
+  if (errnum) {
     sprintf(buf, "MYSQLERROR: %s", mysql_error(mysql));
     log(buf);
-    // log(query);
+    sprintf(buf, "Offending query: %s", query);
+    log(buf);
+    
+    // Recovery procedures for certain errors.
+    switch (errnum) {
+      case 2006:
+        // 'MySQL server has gone away.'
+        log("The MySQL server connection appears to have dropped. Attempting to establish a new one.");
+        mysql_close(mysql);
+        mysql = mysql_init(NULL);
+        if (!mysql_real_connect(mysql, mysql_host, mysql_user, mysql_password, mysql_db, 0, NULL, 0)) {
+          sprintf(buf, "FATAL ERROR: %s\r\n", mysql_error(mysql));
+          log(buf);
+          log("Suggestion: Make sure your DB is running and that you've specified your connection info in src/mysql_config.cpp.\r\n");
+          
+          // High chance this won't succeed-- the calling function will likely attempt to read
+          //  the results of the query, but the query had no results and will refuse a read.
+          //  This is crash-inducing behavior 99% of the time.
+          shutdown();
+        }
+        break;
+      default:
+        break;
+    }
   }
   return result;
 }