Fix potential missed updates in the level emitter. (#173)

* Fix potential missed updates in the level emitter.

This makes the emitter tickable, but sleeping most of the time so the performance impact should be minimal.
If an update is ignored due to the configured delay, ticking is scheduled to make sure that the update happens if no further network updates happen until the next delay period.

* Attempt #2: Delay the first tick of the level emitter on load

* Revert "NetworkMonitor optimization - do not rebuild cache more than once per tick"

This reverts commit 09b2531.

* spaces->tabs to match existing code

src/main/java/appeng/me/cache/NetworkMonitor.java

@@ -56,7 +56,6 @@ public class NetworkMonitor<T extends IAEStack<T>> implements IMEMonitor<T>
 
 	private boolean sendEvent = false;
 	private boolean hasChanged = false;
-	private boolean ticked = true;
 	@Nonnegative
 	private int localDepthSemaphore = 0;
 
@@ -134,10 +133,9 @@ public int getSlot()
 	@Override
 	public IItemList<T> getStorageList()
 	{
-		if( hasChanged && ticked )
+		if( this.hasChanged )
 		{
 			this.hasChanged = false;
-			ticked = false;
 			this.cachedList.resetStatus();
 			return this.getAvailableItems( this.cachedList );
 		}
@@ -331,7 +329,6 @@ void forceUpdate()
 
 	void onTick()
 	{
-		ticked = true;
 		if( this.sendEvent )
 		{
 			this.sendEvent = false;

src/main/java/appeng/parts/automation/PartLevelEmitter.java

@@ -20,6 +20,7 @@
 
 
 import appeng.api.config.*;
+import appeng.api.networking.IGridNode;
 import appeng.api.networking.crafting.*;
 import appeng.api.networking.energy.IEnergyGrid;
 import appeng.api.networking.energy.IEnergyWatcher;
@@ -32,6 +33,9 @@
 import appeng.api.networking.storage.IBaseMonitor;
 import appeng.api.networking.storage.IStackWatcher;
 import appeng.api.networking.storage.IStackWatcherHost;
+import appeng.api.networking.ticking.IGridTickable;
+import appeng.api.networking.ticking.TickRateModulation;
+import appeng.api.networking.ticking.TickingRequest;
 import appeng.api.parts.IPartCollisionHelper;
 import appeng.api.parts.IPartRenderHelper;
 import appeng.api.storage.IMEMonitor;
@@ -44,6 +48,7 @@
 import appeng.api.util.IConfigManager;
 import appeng.client.texture.CableBusTextures;
 import appeng.core.AEConfig;
+import appeng.core.AELog;
 import appeng.core.sync.GuiBridge;
 import appeng.helpers.Reflected;
 import appeng.me.GridAccessException;
@@ -71,7 +76,7 @@
 
 
 public class PartLevelEmitter extends PartUpgradeable
-		implements IEnergyWatcherHost, IStackWatcherHost, ICraftingWatcherHost, IMEMonitorHandlerReceiver<IAEItemStack>, ICraftingProvider
+		implements IEnergyWatcherHost, IStackWatcherHost, ICraftingWatcherHost, IMEMonitorHandlerReceiver<IAEItemStack>, ICraftingProvider, IGridTickable
 {
 
 	private static final int FLAG_ON = 8;
@@ -91,6 +96,7 @@ public class PartLevelEmitter extends PartUpgradeable
 	private double centerZ;
 
 	private int lastWorkingTick = 0;
+	private boolean delayedUpdatesQueued = false;
 
 	@Reflected
 	public PartLevelEmitter( final ItemStack is )
@@ -101,6 +107,10 @@ public PartLevelEmitter( final ItemStack is )
 		this.getConfigManager().registerSetting( Settings.FUZZY_MODE, FuzzyMode.IGNORE_ALL );
 		this.getConfigManager().registerSetting( Settings.LEVEL_TYPE, LevelType.ITEM_LEVEL );
 		this.getConfigManager().registerSetting( Settings.CRAFT_VIA_REDSTONE, YesNo.NO );
+
+		// Workaround the emitter randomly breaking on world load
+		delayedUpdatesQueued = true;
+		lastWorkingTick = MinecraftServer.getServer().getTickCounter();
 	}
 
 	public long getReportingValue()
@@ -371,13 +381,57 @@ public boolean isValid( final Object effectiveGrid )
 	}
 
 	@Override
-	public void postChange( final IBaseMonitor<IAEItemStack> monitor, final Iterable<IAEItemStack> change, final BaseActionSource actionSource )
+	public TickingRequest getTickingRequest( IGridNode node )
+	{
+		return new TickingRequest( AEConfig.instance.levelEmitterDelay / 2, AEConfig.instance.levelEmitterDelay, !delayedUpdatesQueued, true );
+	}
+
+	private boolean canDoWork()
 	{
 		int currentTick = MinecraftServer.getServer().getTickCounter();
-		if (currentTick - lastWorkingTick > AEConfig.instance.levelEmitterDelay)
+		return ( currentTick - lastWorkingTick ) > AEConfig.instance.levelEmitterDelay;
+	}
+
+	@Override
+	public TickRateModulation tickingRequest( IGridNode node, int TicksSinceLastCall )
+	{
+		if( delayedUpdatesQueued && canDoWork() )
+		{
+			delayedUpdatesQueued = false;
+			lastWorkingTick = MinecraftServer.getServer().getTickCounter();
+			this.onListUpdate();
+		}
+		return delayedUpdatesQueued ? TickRateModulation.IDLE : TickRateModulation.SLEEP;
+	}
+
+	@Override
+	public void postChange( final IBaseMonitor<IAEItemStack> monitor, final Iterable<IAEItemStack> change, final BaseActionSource actionSource )
+	{
+		if( canDoWork() )
 		{
-			this.updateReportingValue((IMEMonitor<IAEItemStack>) monitor);
-			lastWorkingTick = currentTick;
+			if ( delayedUpdatesQueued )
+			{
+				delayedUpdatesQueued = false;
+				try
+				{
+					this.getProxy().getTick().sleepDevice( this.getProxy().getNode() );
+				} catch( GridAccessException e )
+				{
+					AELog.error( e, "Couldn't put level emitter to sleep after cancelling delayed updates" );
+				}
+			}
+			lastWorkingTick = MinecraftServer.getServer().getTickCounter();
+			this.updateReportingValue( (IMEMonitor<IAEItemStack>) monitor );
+		} else if( !delayedUpdatesQueued )
+		{
+			delayedUpdatesQueued = true;
+			try
+			{
+				this.getProxy().getTick().alertDevice( this.getProxy().getNode() );
+			} catch( GridAccessException e )
+			{
+				AELog.error( e, "Couldn't wake up level emitter for delayed updates" );
+			}
 		}
 	}