MixinPlayerChunkMapEntry_ChunkIO.java

/*
 * This file is part of Sponge, licensed under the MIT License (MIT).
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 * Copyright (c) SpongePowered <https://www.spongepowered.org>
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 * Permission is hereby granted, free of charge, to any person obtaining a copy
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 * furnished to do so, subject to the following conditions:
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 * The above copyright notice and this permission notice shall be included in
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package org.spongepowered.server.mixin.chunkio;

import net.minecraft.server.management.PlayerChunkMap;
import net.minecraft.server.management.PlayerChunkMapEntry;
import net.minecraft.util.math.ChunkPos;
import net.minecraft.world.chunk.Chunk;
import net.minecraft.world.gen.ChunkProviderServer;
import net.minecraftforge.common.chunkio.ChunkIOExecutor;
import org.spongepowered.asm.mixin.Final;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.Shadow;
import org.spongepowered.asm.mixin.injection.At;
import org.spongepowered.asm.mixin.injection.Inject;
import org.spongepowered.asm.mixin.injection.Redirect;
import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
import org.spongepowered.common.interfaces.IMixinChunk;
import org.spongepowered.server.interfaces.world.chunkio.IMixinChunkProviderServer;

import java.util.function.Consumer;

import javax.annotation.Nullable;

@Mixin(PlayerChunkMapEntry.class)
public abstract class MixinPlayerChunkMapEntry_ChunkIO implements Consumer<Chunk> {

    private static final String LOAD_CHUNK = "Lnet/minecraft/world/gen/ChunkProviderServer;loadChunk(II)Lnet/minecraft/world/chunk/Chunk;";
    private static final String PROVIDE_CHUNK = "Lnet/minecraft/world/gen/ChunkProviderServer;provideChunk(II)Lnet/minecraft/world/chunk/Chunk;";

    @Shadow @Final private PlayerChunkMap playerChunkMap;
    @Shadow @Final private ChunkPos pos;
    @Shadow @Nullable private Chunk chunk;

    private boolean loading;

    @Nullable
    private Chunk loadChunkAsync(ChunkProviderServer provider, int x, int z) {
        if (this.loading) {
            return null;
        }

        this.loading = true;
        return ((IMixinChunkProviderServer) provider).loadChunk(x, z, this);
    }

    @Override
    public void accept(@Nullable Chunk chunk) {
        this.chunk = chunk;
        this.loading = false;

        if (chunk != null) {
            ((IMixinChunk) chunk).setScheduledForUnload(-1);
        }
    }

    @Nullable
    @Redirect(method = "<init>", at = @At(value = "INVOKE", target = LOAD_CHUNK))
    private Chunk onLoadChunkInit(ChunkProviderServer provider, int x, int z) {
        return loadChunkAsync(provider, x, z);
    }

    @Inject(method = "removePlayer", at = @At(value = "INVOKE", target = "Lnet/minecraft/server/management/PlayerChunkMap;removeEntry"
            + "(Lnet/minecraft/server/management/PlayerChunkMapEntry;)V"))
    private void onRemoveEntry(CallbackInfo ci) {
        if (this.loading) {
            // Don't load the chunk if we haven't loaded it yet
            ChunkIOExecutor.dropQueuedChunkLoad(this.playerChunkMap.getWorldServer(), this.pos.chunkXPos, this.pos.chunkZPos, this);
        }
    }

    @Nullable
    @Redirect(method = "providePlayerChunk", at = @At(value = "INVOKE", target = PROVIDE_CHUNK))
    private Chunk onProvideChunk(ChunkProviderServer provider, int x, int z) {
        return this.loading ? null : provider.provideChunk(x, z); // Don't try to generate while still attempting to load
    }

    @Nullable
    @Redirect(method = "providePlayerChunk", at = @At(value = "INVOKE", target = LOAD_CHUNK))
    private Chunk onLoadChunkProvide(ChunkProviderServer provider, int x, int z) {
        return loadChunkAsync(provider, x, z);
    }

}