[Bleeding] Add autosave interval setting in bukkit.yml. Adds BUKKIT-2507

The new setting is located at "ticks-per.autosave". By changing this
value, it affects how often a full save is automatically executed,
measured in ticks.

This value is defaulting to 0 (off) because we believe that the vast
majority of servers already have a third-party solution to automatically
saving the server at set intervals. Having the built in auto-save disabled
by default ensures that we are not saving things twice; doing so leads to
absolutely no benefits, but results in detrimental and noticeable
unnecessary performance decrease.

For servers that do not use an automated external script to perform saves,
this setting can be turned on by setting the value higher than 0, with 900
being the value used in vanilla.

src/main/java/net/minecraft/server/MinecraftServer.java

@@ -80,6 +80,7 @@ public abstract class MinecraftServer implements Runnable, IMojangStatistics, IC
     public static int currentTick;
     public final Thread primaryThread;
     public java.util.Queue<PlayerChatEvent> chatQueue = new java.util.concurrent.ConcurrentLinkedQueue<PlayerChatEvent>();
+    public int autosavePeriod;
     // CraftBukkit end
 
     public MinecraftServer(OptionSet options) { // CraftBukkit - signature file -> OptionSet
@@ -472,7 +473,7 @@ public abstract class MinecraftServer implements Runnable, IMojangStatistics, IC
 
         this.methodProfiler.a("root");
         this.q();
-        if (this.ticks % 900 == 0) {
+        if ((this.autosavePeriod > 0) && ((this.ticks % this.autosavePeriod) == 0)) { // CraftBukkit
             this.methodProfiler.a("save");
             this.t.savePlayers();
             this.saveChunks(true);

src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -186,6 +186,7 @@ public final class CraftServer implements Server {
         monsterSpawn = configuration.getInt("spawn-limits.monsters");
         animalSpawn = configuration.getInt("spawn-limits.animals");
         waterAnimalSpawn = configuration.getInt("spawn-limits.water-animals");
+        console.autosavePeriod = configuration.getInt("ticks-per.autosave");
         warningState = WarningState.value(configuration.getString("settings.deprecated-verbose"));
 
         updater = new AutoUpdater(new BukkitDLUpdaterService(configuration.getString("auto-updater.host")), getLogger(), configuration.getString("auto-updater.preferred-channel"));
@@ -522,6 +523,7 @@ public final class CraftServer implements Server {
         animalSpawn = configuration.getInt("spawn-limits.animals");
         waterAnimalSpawn = configuration.getInt("spawn-limits.water-animals");
         warningState = WarningState.value(configuration.getString("settings.deprecated-verbose"));
+        console.autosavePeriod = configuration.getInt("ticks-per.autosave");
 
         for (WorldServer world : console.worlds) {
             world.difficulty = difficulty;

src/main/resources/configurations/bukkit.yml

@@ -32,6 +32,7 @@ spawn-limits:
 ticks-per:
     animal-spawns: 400
     monster-spawns: 1
+    autosave: 0
 auto-updater:
     enabled: true
     on-broken: [warn-console, warn-ops]