Paper/src/main/java/net/minecraft/server/RegionFile.java
Travis Watkins 24143ef6a1 Load chunks asynchronously for players.
When a player triggers a chunk load via walking around or teleporting there
is no need to stop everything and get this chunk on the main thread. The
client is used to having to wait some time for this chunk and the server
doesn't immediately do anything with it except send it to the player. At
the same time chunk loading is the last major source of file IO that still
runs on the main thread.

These two facts make it possible to offload chunks loaded for this reason
to another thread. However, not all parts of chunk loading can happen off
the main thread. For this we use the new AsynchronousExecutor system to
split chunk loading in to three pieces. The first is loading data from
disk, decompressing it, and parsing it in to an NBT structure.  The second
piece is creating entities and tile entities in the chunk and adding them
to the world, this is still done on the main thread. The third piece is
informing everyone who requested a chunk load that the load is finished.
For this we register callbacks and then run them on the main thread once
the previous two stages are finished.

There are still cases where a chunk is needed immediately and these will
still trigger chunk loading entirely on the main thread. The most obvious
case is plugins using the API to request a chunk load. We also must load
the chunk immediately when something in the world tries to access it. In
these cases we ignore any possibly pending or in progress chunk loading
that is happening asynchronously as we will have the chunk loaded by the
time they are finished.

The hope is that overall this system will result in less CPU time and
pauses due to blocking file IO on the main thread thus giving more
consistent performance. Testing so far has shown that this also speeds up
chunk loading client side although some of this is likely to be because
we are sending less chunks at once for the client to process.

Thanks for @ammaraskar for help with the implementation of this feature.
2012-12-12 19:35:53 -06:00

290 Zeilen
8.6 KiB
Java

package net.minecraft.server;
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.GZIPInputStream;
import java.util.zip.InflaterInputStream;
public class RegionFile {
private static final byte[] a = new byte[4096];
private final File b;
private RandomAccessFile c;
private final int[] d = new int[1024];
private final int[] e = new int[1024];
private ArrayList f;
private int g;
private long h = 0L;
public RegionFile(File file1) {
this.b = file1;
this.g = 0;
try {
if (file1.exists()) {
this.h = file1.lastModified();
}
this.c = new RandomAccessFile(file1, "rw");
int i;
if (this.c.length() < 4096L) {
for (i = 0; i < 1024; ++i) {
this.c.writeInt(0);
}
for (i = 0; i < 1024; ++i) {
this.c.writeInt(0);
}
this.g += 8192;
}
if ((this.c.length() & 4095L) != 0L) {
for (i = 0; (long) i < (this.c.length() & 4095L); ++i) {
this.c.write(0);
}
}
i = (int) this.c.length() / 4096;
this.f = new ArrayList(i);
int j;
for (j = 0; j < i; ++j) {
this.f.add(Boolean.valueOf(true));
}
this.f.set(0, Boolean.valueOf(false));
this.f.set(1, Boolean.valueOf(false));
this.c.seek(0L);
int k;
for (j = 0; j < 1024; ++j) {
k = this.c.readInt();
this.d[j] = k;
if (k != 0 && (k >> 8) + (k & 255) <= this.f.size()) {
for (int l = 0; l < (k & 255); ++l) {
this.f.set((k >> 8) + l, Boolean.valueOf(false));
}
}
}
for (j = 0; j < 1024; ++j) {
k = this.c.readInt();
this.e[j] = k;
}
} catch (IOException ioexception) {
ioexception.printStackTrace();
}
}
// CraftBukkit start - this is a copy (sort of) of the method below it, make sure they stay in sync
public synchronized boolean chunkExists(int i, int j) {
if (this.d(i, j)) {
return false;
} else {
try {
int k = this.e(i, j);
if (k == 0) {
return false;
} else {
int l = k >> 8;
int i1 = k & 255;
if (l + i1 > this.f.size()) {
return false;
}
this.c.seek((long) (l * 4096));
int j1 = this.c.readInt();
if (j1 > 4096 * i1 || j1 <= 0) {
return false;
}
byte b0 = this.c.readByte();
if (b0 == 1 || b0 == 2) {
return true;
}
}
} catch (IOException ioexception) {
return false;
}
}
return false;
}
// CraftBukkit end
public synchronized DataInputStream a(int i, int j) {
if (this.d(i, j)) {
return null;
} else {
try {
int k = this.e(i, j);
if (k == 0) {
return null;
} else {
int l = k >> 8;
int i1 = k & 255;
if (l + i1 > this.f.size()) {
return null;
} else {
this.c.seek((long) (l * 4096));
int j1 = this.c.readInt();
if (j1 > 4096 * i1) {
return null;
} else if (j1 <= 0) {
return null;
} else {
byte b0 = this.c.readByte();
byte[] abyte;
if (b0 == 1) {
abyte = new byte[j1 - 1];
this.c.read(abyte);
return new DataInputStream(new BufferedInputStream(new GZIPInputStream(new ByteArrayInputStream(abyte))));
} else if (b0 == 2) {
abyte = new byte[j1 - 1];
this.c.read(abyte);
return new DataInputStream(new BufferedInputStream(new InflaterInputStream(new ByteArrayInputStream(abyte))));
} else {
return null;
}
}
}
}
} catch (IOException ioexception) {
return null;
}
}
}
public DataOutputStream b(int i, int j) {
return this.d(i, j) ? null : new DataOutputStream(new DeflaterOutputStream(new ChunkBuffer(this, i, j)));
}
protected synchronized void a(int i, int j, byte[] abyte, int k) {
try {
int l = this.e(i, j);
int i1 = l >> 8;
int j1 = l & 255;
int k1 = (k + 5) / 4096 + 1;
if (k1 >= 256) {
return;
}
if (i1 != 0 && j1 == k1) {
this.a(i1, abyte, k);
} else {
int l1;
for (l1 = 0; l1 < j1; ++l1) {
this.f.set(i1 + l1, Boolean.valueOf(true));
}
l1 = this.f.indexOf(Boolean.valueOf(true));
int i2 = 0;
int j2;
if (l1 != -1) {
for (j2 = l1; j2 < this.f.size(); ++j2) {
if (i2 != 0) {
if (((Boolean) this.f.get(j2)).booleanValue()) {
++i2;
} else {
i2 = 0;
}
} else if (((Boolean) this.f.get(j2)).booleanValue()) {
l1 = j2;
i2 = 1;
}
if (i2 >= k1) {
break;
}
}
}
if (i2 >= k1) {
i1 = l1;
this.a(i, j, l1 << 8 | k1);
for (j2 = 0; j2 < k1; ++j2) {
this.f.set(i1 + j2, Boolean.valueOf(false));
}
this.a(i1, abyte, k);
} else {
this.c.seek(this.c.length());
i1 = this.f.size();
for (j2 = 0; j2 < k1; ++j2) {
this.c.write(a);
this.f.add(Boolean.valueOf(false));
}
this.g += 4096 * k1;
this.a(i1, abyte, k);
this.a(i, j, i1 << 8 | k1);
}
}
this.b(i, j, (int) (System.currentTimeMillis() / 1000L));
} catch (IOException ioexception) {
ioexception.printStackTrace();
}
}
private void a(int i, byte[] abyte, int j) throws IOException { // CraftBukkit - added throws
this.c.seek((long) (i * 4096));
this.c.writeInt(j + 1);
this.c.writeByte(2);
this.c.write(abyte, 0, j);
}
private boolean d(int i, int j) {
return i < 0 || i >= 32 || j < 0 || j >= 32;
}
private int e(int i, int j) {
return this.d[i + j * 32];
}
public boolean c(int i, int j) {
return this.e(i, j) != 0;
}
private void a(int i, int j, int k) throws IOException { // CraftBukkit - added throws
this.d[i + j * 32] = k;
this.c.seek((long) ((i + j * 32) * 4));
this.c.writeInt(k);
}
private void b(int i, int j, int k) throws IOException { // CraftBukkit - added throws
this.e[i + j * 32] = k;
this.c.seek((long) (4096 + (i + j * 32) * 4));
this.c.writeInt(k);
}
public void c() throws IOException { // CraftBukkit - added throws
if (this.c != null) {
this.c.close();
}
}
}