From 1cb1364145aa9925f1b3bba64bf21b17a5dbc31f Mon Sep 17 00:00:00 2001
From: Keuin <keuinx@gmail.com>
Date: Mon, 23 Oct 2023 23:08:42 +0800
Subject: increase write delay when no real player is online

---
 src/main/java/com/keuin/blame/Blame.java        | 15 +++++++++
 src/main/java/com/keuin/blame/SubmitWorker.java | 45 +++++++++++++++++++++----
 2 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/src/main/java/com/keuin/blame/Blame.java b/src/main/java/com/keuin/blame/Blame.java
index 4031e65..1374913 100644
--- a/src/main/java/com/keuin/blame/Blame.java
+++ b/src/main/java/com/keuin/blame/Blame.java
@@ -17,11 +17,13 @@ import net.fabricmc.api.ModInitializer;
 import net.fabricmc.fabric.api.command.v1.CommandRegistrationCallback;
 import net.fabricmc.fabric.api.event.lifecycle.v1.ServerLifecycleEvents;
 import net.fabricmc.fabric.api.event.player.*;
+import net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents;
 import net.minecraft.command.CommandSource;
 import net.minecraft.command.argument.BlockPosArgumentType;
 import net.minecraft.command.argument.DimensionArgumentType;
 import net.minecraft.server.command.CommandManager;
 import net.minecraft.server.command.ServerCommandSource;
+import net.minecraft.server.network.ServerPlayerEntity;
 
 import java.io.File;
 import java.io.IOException;
@@ -82,6 +84,19 @@ public class Blame implements ModInitializer {
             SubmitWorker.INSTANCE.stop();
         });
 
+        ServerPlayConnectionEvents.JOIN.register((handler, sender, server) -> {
+            // does not take carpet fake players into account
+            var isNormalPlayer = handler.player.getClass() == ServerPlayerEntity.class;
+            if (!isNormalPlayer) return;
+            SubmitWorker.INSTANCE.playerJoin();
+        });
+
+        ServerPlayConnectionEvents.DISCONNECT.register((handler, server) -> {
+            var isNormalPlayer = handler.player.getClass() == ServerPlayerEntity.class;
+            if (!isNormalPlayer) return;
+            SubmitWorker.INSTANCE.playerQuit();
+        });
+
         // hook game events
         AttackEntityCallback.EVENT.register(new AttackEntityAdapter(EventHandler.INSTANCE));
         PlaceBlockHandler.EVENT.register(EventHandler.INSTANCE);
diff --git a/src/main/java/com/keuin/blame/SubmitWorker.java b/src/main/java/com/keuin/blame/SubmitWorker.java
index 103fc9c..3582688 100644
--- a/src/main/java/com/keuin/blame/SubmitWorker.java
+++ b/src/main/java/com/keuin/blame/SubmitWorker.java
@@ -17,6 +17,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 
 public class SubmitWorker {
 
@@ -29,6 +30,28 @@ public class SubmitWorker {
     private static final int batchSize = 1024;
     private static final int maxWaitMillis = 3000;
 
+    private static final int idleMaxWaitMillis = 600 * 1000;
+
+    private final AtomicInteger playerCounter = new AtomicInteger();
+    private final AtomicBoolean isPlayerPresent = new AtomicBoolean(false);
+
+    private final AtomicBoolean playerJoin = new AtomicBoolean(false);
+
+    public void playerJoin() {
+        if (isStopped.get()) return;
+        playerCounter.incrementAndGet();
+        playerJoin.set(true);
+        isPlayerPresent.set(true);
+        thread.interrupt(); // interrupt if sleeping
+    }
+
+    public void playerQuit() {
+        var cnt = playerCounter.decrementAndGet();
+        if (cnt == 0) {
+            isPlayerPresent.set(false);
+        }
+    }
+
 
     private SubmitWorker() {
         thread.setUncaughtExceptionHandler((t, e) ->
@@ -53,6 +76,10 @@ public class SubmitWorker {
         thread.interrupt();
     }
 
+    private long getSleepDuration() {
+        return isPlayerPresent.get() ? maxWaitMillis : idleMaxWaitMillis;
+    }
+
     /**
      * Ensures the buffer is ready to consume from.
      *
@@ -63,7 +90,7 @@ public class SubmitWorker {
         while (true) {
             if (
                     buffer.size() >= batchSize ||
-                            (accumulateStart > 0 && System.currentTimeMillis() - accumulateStart > maxWaitMillis)
+                            (accumulateStart > 0 && System.currentTimeMillis() - accumulateStart > getSleepDuration())
             ) {
                 // buffer is full, or max accumulate time reached, flush it
                 break;
@@ -75,7 +102,9 @@ public class SubmitWorker {
                     el = queue.take();
                 } else {
                     // try to read more entries with timeout
-                    el = queue.poll(maxWaitMillis, TimeUnit.MILLISECONDS);
+                    var duration = getSleepDuration();
+                    logger.info("Sleep duration: " + duration);
+                    el = queue.poll(duration, TimeUnit.MILLISECONDS);
                 }
             }
             if (el == null) {
@@ -193,10 +222,14 @@ public class SubmitWorker {
                 accumulateBuffer(buffer);
             }
         } catch (InterruptedException ignored) {
-            // server is closing, flush the buffer immediately
-            // decline new write requests
-            isStopped.set(true);
-            interrupted = true;
+            // check if the interruption is triggered by player join
+            // in this case, we don't stop, but try to write the buffer immediately
+            if (!playerJoin.getAndSet(false)) {
+                // server is closing, flush the buffer immediately
+                // decline new write requests
+                isStopped.set(true);
+                interrupted = true;
+            }
         }
         try {
             bulkWrite(buffer, req);
-- 
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