From 07a9c35ee29a9aedde6bbc603cc6b47d0e798ffc Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Tue, 5 Mar 2019 13:10:17 +0000
Subject: [PATCH] RegionLoader: Use objects instead of arrays

---
 .../level/format/io/region/RegionLoader.php   | 72 +++++++-------
 .../io/region/RegionLocationTableEntry.php    | 98 +++++++++++++++++++
 2 files changed, 133 insertions(+), 37 deletions(-)
 create mode 100644 src/pocketmine/level/format/io/region/RegionLocationTableEntry.php

diff --git a/src/pocketmine/level/format/io/region/RegionLoader.php b/src/pocketmine/level/format/io/region/RegionLoader.php
index 3bf7acedb..7e8662b5f 100644
--- a/src/pocketmine/level/format/io/region/RegionLoader.php
+++ b/src/pocketmine/level/format/io/region/RegionLoader.php
@@ -26,7 +26,6 @@ namespace pocketmine\level\format\io\region;
 use pocketmine\level\format\ChunkException;
 use pocketmine\level\format\io\exception\CorruptedChunkException;
 use pocketmine\utils\Binary;
-use function array_fill;
 use function ceil;
 use function chr;
 use function fclose;
@@ -39,6 +38,7 @@ use function fseek;
 use function ftruncate;
 use function fwrite;
 use function is_resource;
+use function max;
 use function ord;
 use function pack;
 use function str_pad;
@@ -66,7 +66,7 @@ class RegionLoader{
 	protected $filePointer;
 	/** @var int */
 	protected $lastSector;
-	/** @var int[][] [offset in sectors, chunk size in sectors, timestamp] */
+	/** @var RegionLocationTableEntry[] */
 	protected $locationTable = [];
 	/** @var int */
 	public $lastUsed = 0;
@@ -106,7 +106,7 @@ class RegionLoader{
 	}
 
 	protected function isChunkGenerated(int $index) : bool{
-		return !($this->locationTable[$index][0] === 0 or $this->locationTable[$index][1] === 0);
+		return !$this->locationTable[$index]->isNull();
 	}
 
 	/**
@@ -126,23 +126,25 @@ class RegionLoader{
 			return null;
 		}
 
-		fseek($this->filePointer, $this->locationTable[$index][0] << 12);
+		fseek($this->filePointer, $this->locationTable[$index]->getFirstSector() << 12);
+
 		$prefix = fread($this->filePointer, 4);
 		if($prefix === false or strlen($prefix) !== 4){
 			throw new CorruptedChunkException("Corrupted chunk header detected (unexpected end of file reading length prefix)");
 		}
 		$length = Binary::readInt($prefix);
 
-		if($length <= 0 or $length > self::MAX_SECTOR_LENGTH){ //Not yet generated / corrupted
-			if($length >= self::MAX_SECTOR_LENGTH){
-				throw new CorruptedChunkException("Corrupted chunk header detected (sector count $length larger than max " . self::MAX_SECTOR_LENGTH . ")");
-			}
+		if($length <= 0){ //TODO: if we reached here, the locationTable probably needs updating
 			return null;
 		}
+		if($length > self::MAX_SECTOR_LENGTH){ //corrupted
+			throw new CorruptedChunkException("Length for chunk x=$x,z=$z ($length) is larger than maximum " . self::MAX_SECTOR_LENGTH);
+		}
 
-		if($length > ($this->locationTable[$index][1] << 12)){ //Invalid chunk, bigger than defined number of sectors
-			\GlobalLogger::get()->error("Chunk x=$x,z=$z length mismatch (expected " . ($this->locationTable[$index][1] << 12) . " sectors, got $length sectors)");
-			$this->locationTable[$index][1] = $length >> 12;
+		if($length > ($this->locationTable[$index]->getSectorCount() << 12)){ //Invalid chunk, bigger than defined number of sectors
+			\GlobalLogger::get()->error("Chunk x=$x,z=$z length mismatch (expected " . ($this->locationTable[$index]->getSectorCount() << 12) . " sectors, got $length sectors)");
+			$old = $this->locationTable[$index];
+			$this->locationTable[$index] = new RegionLocationTableEntry($old->getFirstSector(), $length >> 12, time());
 			$this->writeLocationIndex($index);
 		}
 
@@ -185,26 +187,22 @@ class RegionLoader{
 		if($length + 4 > self::MAX_SECTOR_LENGTH){
 			throw new ChunkException("Chunk is too big! " . ($length + 4) . " > " . self::MAX_SECTOR_LENGTH);
 		}
-		$sectors = (int) ceil(($length + 4) / 4096);
+
+		$newSize = (int) ceil(($length + 4) / 4096);
 		$index = self::getChunkOffset($x, $z);
-		$indexChanged = false;
-		if($this->locationTable[$index][1] < $sectors){
-			$this->locationTable[$index][0] = $this->lastSector + 1;
-			$this->lastSector += $sectors; //The GC will clean this shift "later"
-			$indexChanged = true;
-		}elseif($this->locationTable[$index][1] != $sectors){
-			$indexChanged = true;
+		$offset = $this->locationTable[$index]->getFirstSector();
+
+		if($this->locationTable[$index]->getSectorCount() < $newSize){
+			$offset = $this->lastSector + 1;
 		}
 
-		$this->locationTable[$index][1] = $sectors;
-		$this->locationTable[$index][2] = time();
+		$this->locationTable[$index] = new RegionLocationTableEntry($offset, $newSize, time());
+		$this->lastSector = max($this->lastSector, $this->locationTable[$index]->getLastSector());
 
-		fseek($this->filePointer, $this->locationTable[$index][0] << 12);
-		fwrite($this->filePointer, str_pad(Binary::writeInt($length) . chr(self::COMPRESSION_ZLIB) . $chunkData, $sectors << 12, "\x00", STR_PAD_RIGHT));
+		fseek($this->filePointer, $offset << 12);
+		fwrite($this->filePointer, str_pad(Binary::writeInt($length) . chr(self::COMPRESSION_ZLIB) . $chunkData, $newSize << 12, "\x00", STR_PAD_RIGHT));
 
-		if($indexChanged){
-			$this->writeLocationIndex($index);
-		}
+		$this->writeLocationIndex($index);
 	}
 
 	/**
@@ -215,8 +213,7 @@ class RegionLoader{
 	 */
 	public function removeChunk(int $x, int $z) : void{
 		$index = self::getChunkOffset($x, $z);
-		$this->locationTable[$index][0] = 0;
-		$this->locationTable[$index][1] = 0;
+		$this->locationTable[$index] = new RegionLocationTableEntry(0, 0, 0);
 	}
 
 	/**
@@ -276,6 +273,7 @@ class RegionLoader{
 		for($i = 0; $i < 1024; ++$i){
 			$index = $data[$i + 1];
 			$offset = $index >> 8;
+			$timestamp = $data[$i + 1025];
 			if($offset !== 0){
 				self::getChunkCoords($i, $x, $z);
 				$fileOffset = $offset << 12;
@@ -291,10 +289,8 @@ class RegionLoader{
 				}
 			}
 
-			$this->locationTable[$i] = [$index >> 8, $index & 0xff, $data[1024 + $i + 1]];
-			if(($this->locationTable[$i][0] + $this->locationTable[$i][1] - 1) > $this->lastSector){
-				$this->lastSector = $this->locationTable[$i][0] + $this->locationTable[$i][1] - 1;
-			}
+			$this->locationTable[$i] = new RegionLocationTableEntry($offset, $index & 0xff, $timestamp);
+			$this->lastSector = max($this->lastSector, $this->locationTable[$i]->getLastSector());
 		}
 
 		fseek($this->filePointer, 0);
@@ -304,10 +300,10 @@ class RegionLoader{
 		$write = [];
 
 		for($i = 0; $i < 1024; ++$i){
-			$write[] = (($this->locationTable[$i][0] << 8) | $this->locationTable[$i][1]);
+			$write[] = (($this->locationTable[$i]->getFirstSector() << 8) | $this->locationTable[$i]->getSectorCount());
 		}
 		for($i = 0; $i < 1024; ++$i){
-			$write[] = $this->locationTable[$i][2];
+			$write[] = $this->locationTable[$i]->getTimestamp();
 		}
 		fseek($this->filePointer, 0);
 		fwrite($this->filePointer, pack("N*", ...$write), 4096 * 2);
@@ -315,16 +311,18 @@ class RegionLoader{
 
 	protected function writeLocationIndex(int $index) : void{
 		fseek($this->filePointer, $index << 2);
-		fwrite($this->filePointer, Binary::writeInt(($this->locationTable[$index][0] << 8) | $this->locationTable[$index][1]), 4);
+		fwrite($this->filePointer, Binary::writeInt(($this->locationTable[$index]->getFirstSector() << 8) | $this->locationTable[$index]->getSectorCount()), 4);
 		fseek($this->filePointer, 4096 + ($index << 2));
-		fwrite($this->filePointer, Binary::writeInt($this->locationTable[$index][2]), 4);
+		fwrite($this->filePointer, Binary::writeInt($this->locationTable[$index]->getTimestamp()), 4);
 	}
 
 	protected function createBlank() : void{
 		fseek($this->filePointer, 0);
 		ftruncate($this->filePointer, 8192); // this fills the file with the null byte
 		$this->lastSector = 1;
-		$this->locationTable = array_fill(0, 1024, [0, 0, 0]);
+		for($i = 0; $i < 1024; ++$i){
+			$this->locationTable[$i] = new RegionLocationTableEntry(0, 0, 0);
+		}
 	}
 
 	public function getFilePath() : string{
diff --git a/src/pocketmine/level/format/io/region/RegionLocationTableEntry.php b/src/pocketmine/level/format/io/region/RegionLocationTableEntry.php
new file mode 100644
index 000000000..f17ae5bdc
--- /dev/null
+++ b/src/pocketmine/level/format/io/region/RegionLocationTableEntry.php
@@ -0,0 +1,98 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\level\format\io\region;
+
+use function range;
+
+class RegionLocationTableEntry{
+
+	/** @var int */
+	private $firstSector;
+	/** @var int */
+	private $sectorCount;
+	/** @var int */
+	private $timestamp;
+
+	/**
+	 * @param int $firstSector
+	 * @param int $sectorCount
+	 * @param int $timestamp
+	 *
+	 * @throws \InvalidArgumentException
+	 */
+	public function __construct(int $firstSector, int $sectorCount, int $timestamp){
+		if($firstSector < 0){
+			throw new \InvalidArgumentException("Start sector must be positive, got $firstSector");
+		}
+		$this->firstSector = $firstSector;
+		if($sectorCount < 0 or $sectorCount > 255){
+			throw new \InvalidArgumentException("Sector count must be in range 0...255, got $sectorCount");
+		}
+		$this->sectorCount = $sectorCount;
+		$this->timestamp = $timestamp;
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getFirstSector() : int{
+		return $this->firstSector;
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getLastSector() : int{
+		return $this->firstSector + $this->sectorCount - 1;
+	}
+
+	/**
+	 * Returns an array of sector offsets reserved by this chunk.
+	 * @return int[]
+	 */
+	public function getUsedSectors() : array{
+		return range($this->getFirstSector(), $this->getLastSector());
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getSectorCount() : int{
+		return $this->sectorCount;
+	}
+
+	/**
+	 * @return int
+	 */
+	public function getTimestamp() : int{
+		return $this->timestamp;
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function isNull() : bool{
+		return $this->firstSector === 0 or $this->sectorCount === 0;
+	}
+}