fix #3013

changelog.md

@@ -1,6 +1,7 @@
 ## Fixes/improvements
 
 * [#3620] Fixed OC 1.8.0+ regression involving API arguments and numbers.
+* [#3013] Fixed rare server-side deadlock when sending disk activity update packets.
 
 ## OpenOS fixes/improvements
 
@@ -9,4 +10,4 @@
 
 ## List of contributors
 
-asie, Possseidon
+asie, ds84182, Possseidon

src/main/resources/application.conf

@@ -1401,6 +1401,10 @@ opencomputers {
     # operation, it will block the computer for a duration matching the
     # limit set in this config option.
     transposerFluidTransferRate=4000
+
+    # Disk activity update packet delay specified in milliseconds.
+    # If set to -1, no disk activity update packets are sent.
+    diskActivityPacketDelay=500
   }
 
   # Settings for mod integration (the mod previously known as OpenComponents).

src/main/scala/li/cil/oc/Settings.scala

@@ -478,6 +478,9 @@ class Settings(val config: Config) {
   }
 
   val bitbltCost: Double = if (config.hasPath("gpu.bitbltCost")) config.getDouble("gpu.bitbltCost") else 0.5
+
+  // >= 1.8.2
+  val diskActivityPacketDelay: Int = config.getInt("misc.diskActivityPacketDelay") max -1
 }
 
 object Settings {

src/main/scala/li/cil/oc/server/PacketSender.scala

@@ -1,7 +1,7 @@
 package li.cil.oc.server
 
-import li.cil.oc.api
+import li.cil.oc.{Settings, api}
-import li.cil.oc.api.event.{NetworkActivityEvent, FileSystemAccessEvent}
+import li.cil.oc.api.event.{FileSystemAccessEvent, NetworkActivityEvent}
 import li.cil.oc.api.network.EnvironmentHost
 import li.cil.oc.api.network.Node
 import li.cil.oc.common._
@@ -20,6 +20,7 @@ import net.minecraft.world.World
 import net.minecraftforge.common.MinecraftForge
 import net.minecraftforge.common.util.ForgeDirection
 
+import java.util.concurrent.ConcurrentHashMap
 import scala.collection.mutable
 
 object PacketSender {
@@ -125,19 +126,22 @@ object PacketSender {
   }
 
   // Avoid spamming the network with disk activity notices.
-  val fileSystemAccessTimeouts = mutable.WeakHashMap.empty[Node, mutable.Map[String, Long]]
+  private val fileSystemAccessTimeouts = mutable.WeakHashMap.empty[Node, ConcurrentHashMap[String, Long]]
 
-  def sendFileSystemActivity(node: Node, host: EnvironmentHost, name: String) = fileSystemAccessTimeouts.synchronized {
+  def sendFileSystemActivity(node: Node, host: EnvironmentHost, name: String) = {
-    fileSystemAccessTimeouts.get(node) match {
+    val diskActivityPacketDelay = Settings.get.diskActivityPacketDelay
-      case Some(hostTimeouts) if hostTimeouts.getOrElse(name, 0L) > System.currentTimeMillis() => // Cooldown.
+    if (diskActivityPacketDelay >= 0) {
-      case _ =>
+      val hostTimeouts = fileSystemAccessTimeouts.synchronized {
+        fileSystemAccessTimeouts.getOrElseUpdate(node, new ConcurrentHashMap[String, Long](16, 0.75f, Settings.get.threads))
+      }
+      if (hostTimeouts.getOrDefault(name, 0L) <= System.currentTimeMillis()) {
         val event = host match {
           case t: net.minecraft.tileentity.TileEntity => new FileSystemAccessEvent.Server(name, t, node)
           case _ => new FileSystemAccessEvent.Server(name, host.world, host.xPosition, host.yPosition, host.zPosition, node)
         }
         MinecraftForge.EVENT_BUS.post(event)
         if (!event.isCanceled) {
-          fileSystemAccessTimeouts.getOrElseUpdate(node, mutable.Map.empty) += name -> (System.currentTimeMillis() + 500)
+          hostTimeouts.put(name, System.currentTimeMillis() + diskActivityPacketDelay)
 
           val pb = new SimplePacketBuilder(PacketType.FileSystemActivity)
 
@@ -157,8 +161,9 @@ object PacketSender {
 
           pb.sendToPlayersNearHost(host, Option(64))
         }
+      }
     }
-  }
+}
 
   def sendNetworkActivity(node: Node, host: EnvironmentHost) = {