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Merge pull request #184 from mikeprimm/master

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Add file access read/write locking to avoid conflicting tile updates, dirty reads by internal web server
This commit is contained in:
mikeprimm 2011-05-31 19:27:15 -07:00
commit c97b373fa5
5 changed files with 135 additions and 2 deletions
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6
src/main/java/org/dynmap/flat/FlatMap.java
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@ -27,6 +27,7 @@ import org.dynmap.debug.Debug;
import org.dynmap.kzedmap.KzedMap;
import org.dynmap.kzedmap.KzedMap.KzedBufferedImage;
import org.dynmap.MapChunkCache;
import org.dynmap.utils.FileLockManager;
import org.json.simple.JSONObject;
public class FlatMap extends MapType {
@ -236,6 +237,7 @@ public class FlatMap extends MapType {
}
}
/* Test to see if we're unchanged from older tile */
FileLockManager.getWriteLock(outputFile);
TileHashManager hashman = MapManager.mapman.hashman;
long crc = hashman.calculateTileHash(argb_buf);
boolean tile_update = false;
@ -257,12 +259,13 @@ public class FlatMap extends MapType {
Debug.debug("skipping image " + outputFile.getPath() + " - hash match");
}
KzedMap.freeBufferedImage(im);
FileLockManager.releaseWriteLock(outputFile);
MapManager.mapman.updateStatistics(tile, null, true, tile_update, !rendered);
/* If day too, handle it */
if(night_and_day) {
File dayfile = new File(outputFile.getParent(), tile.getDayFilename());
FileLockManager.getWriteLock(dayfile);
crc = hashman.calculateTileHash(argb_buf_day);
if((!dayfile.exists()) || (crc != hashman.getImageHashCode(tile.getKey(), "day", t.x, t.y))) {
Debug.debug("saving image " + dayfile.getPath());
@ -282,6 +285,7 @@ public class FlatMap extends MapType {
tile_update = false;
}
KzedMap.freeBufferedImage(im_day);
FileLockManager.releaseWriteLock(dayfile);
MapManager.mapman.updateStatistics(tile, "day", true, tile_update, !rendered);
}

9
src/main/java/org/dynmap/kzedmap/DefaultTileRenderer.java
View File

@ -20,6 +20,7 @@ import org.dynmap.TileHashManager;
import org.dynmap.debug.Debug;
import org.dynmap.MapChunkCache;
import org.dynmap.kzedmap.KzedMap.KzedBufferedImage;
import org.dynmap.utils.FileLockManager;
import org.json.simple.JSONObject;
public class DefaultTileRenderer implements MapTileRenderer {
@ -228,6 +229,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
int oy = (mtile.py == zmtile.getTileY())?0:KzedMap.tileHeight/2;
/* Test to see if we're unchanged from older tile */
FileLockManager.getWriteLock(fname);
TileHashManager hashman = MapManager.mapman.hashman;
long crc = hashman.calculateTileHash(img.argb_buf);
boolean updated_fname = false;
@ -245,6 +247,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
updated_fname = true;
}
KzedMap.freeBufferedImage(img);
FileLockManager.releaseWriteLock(fname);
MapManager.mapman.updateStatistics(mtile, null, true, updated_fname, !rendered);
mtile.file = fname;
@ -252,6 +255,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
boolean updated_dfname = false;
File dfname = new File(fname.getParent(), mtile.getDayFilename());
if(img_day != null) {
FileLockManager.getWriteLock(dfname);
crc = hashman.calculateTileHash(img.argb_buf);
if((!dfname.exists()) || (crc != hashman.getImageHashCode(mtile.getKey(), "day", mtile.px, mtile.py))) {
Debug.debug("saving image " + dfname.getPath());
@ -267,12 +271,14 @@ public class DefaultTileRenderer implements MapTileRenderer {
updated_dfname = true;
}
KzedMap.freeBufferedImage(img_day);
FileLockManager.releaseWriteLock(dfname);
MapManager.mapman.updateStatistics(mtile, "day", true, updated_dfname, !rendered);
}
// Since we've already got the new tile, and we're on an async thread, just
// make the zoomed tile here
boolean ztile_updated = false;
FileLockManager.getWriteLock(zoomFile);
if(updated_fname || (!zoomFile.exists())) {
saveZoomedTile(zmtile, zoomFile, zimg, ox, oy);
MapManager.mapman.pushUpdate(zmtile.getWorld(),
@ -280,11 +286,13 @@ public class DefaultTileRenderer implements MapTileRenderer {
ztile_updated = true;
}
KzedMap.freeBufferedImage(zimg);
FileLockManager.releaseWriteLock(zoomFile);
MapManager.mapman.updateStatistics(zmtile, null, true, ztile_updated, !rendered);
if(zimg_day != null) {
File zoomFile_day = new File(zoomFile.getParent(), zmtile.getDayFilename());
ztile_updated = false;
FileLockManager.getWriteLock(zoomFile_day);
if(updated_dfname || (!zoomFile_day.exists())) {
saveZoomedTile(zmtile, zoomFile_day, zimg_day, ox, oy);
MapManager.mapman.pushUpdate(zmtile.getWorld(),
@ -292,6 +300,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
ztile_updated = true;
}
KzedMap.freeBufferedImage(zimg_day);
FileLockManager.releaseWriteLock(zoomFile_day);
MapManager.mapman.updateStatistics(zmtile, "day", true, ztile_updated, !rendered);
}
}

105
src/main/java/org/dynmap/utils/FileLockManager.java Normal file
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@ -0,0 +1,105 @@
package org.dynmap.utils;
import java.io.File;
import java.util.HashMap;
import org.dynmap.Log;
/**
* Implements soft-locks for prevent concurrency issues with file updates
*/
public class FileLockManager {
private static Object lock = new Object();
private static HashMap<String, Integer> filelocks = new HashMap<String, Integer>();
private static final Integer WRITELOCK = new Integer(-1);
/**
* Get write lock on file - exclusive lock, no other writers or readers
* @throws InterruptedException
*/
public static void getWriteLock(File f) {
String fn = f.getPath();
synchronized(lock) {
boolean got_lock = false;
while(!got_lock) {
Integer lockcnt = filelocks.get(fn); /* Get lock count */
if(lockcnt != null) { /* If any locks, can't get write lock */
try {
lock.wait();
} catch (InterruptedException ix) {
Log.severe("getWriteLock(" + fn + ") interrupted");
}
}
else {
filelocks.put(fn, WRITELOCK);
got_lock = true;
}
}
}
//Log.info("getWriteLock(" + f + ")");
}
/**
* Release write lock
*/
public static void releaseWriteLock(File f) {
String fn = f.getPath();
synchronized(lock) {
Integer lockcnt = filelocks.get(fn); /* Get lock count */
if(lockcnt == null)
Log.severe("releaseWriteLock(" + fn + ") on unlocked file");
else if(lockcnt.equals(WRITELOCK)) {
filelocks.remove(fn); /* Remove lock */
lock.notifyAll(); /* Wake up folks waiting for locks */
}
else
Log.severe("releaseWriteLock(" + fn + ") on read-locked file");
}
//Log.info("releaseWriteLock(" + f + ")");
}
/**
* Get read lock on file - multiple readers allowed, blocks writers
*/
public static void getReadLock(File f) {
String fn = f.getPath();
synchronized(lock) {
boolean got_lock = false;
while(!got_lock) {
Integer lockcnt = filelocks.get(fn); /* Get lock count */
if(lockcnt == null) {
filelocks.put(fn, Integer.valueOf(1)); /* First lock */
got_lock = true;
}
else if(!lockcnt.equals(WRITELOCK)) { /* Other read locks */
filelocks.put(fn, Integer.valueOf(lockcnt+1));
got_lock = true;
}
else { /* Write lock in place */
try {
lock.wait();
} catch (InterruptedException ix) {
Log.severe("getReadLock(" + fn + ") interrupted");
}
}
}
}
//Log.info("getReadLock(" + f + ")");
}
/**
* Release read lock
*/
public static void releaseReadLock(File f) {
String fn = f.getPath();
synchronized(lock) {
Integer lockcnt = filelocks.get(fn); /* Get lock count */
if(lockcnt == null)
Log.severe("releaseReadLock(" + fn + ") on unlocked file");
else if(lockcnt.equals(WRITELOCK))
Log.severe("releaseReadLock(" + fn + ") on write-locked file");
else if(lockcnt > 1) {
filelocks.put(fn, Integer.valueOf(lockcnt-1));
}
else {
filelocks.remove(fn); /* Remove lock */
lock.notifyAll(); /* Wake up folks waiting for locks */
}
}
//Log.info("releaseReadLock(" + f + ")");
}
}

7
src/main/java/org/dynmap/web/handlers/FileHandler.java
View File

@ -13,6 +13,7 @@ import org.dynmap.web.HttpHandler;
import org.dynmap.web.HttpRequest;
import org.dynmap.web.HttpResponse;
import org.dynmap.web.HttpStatus;
import org.dynmap.utils.FileLockManager;
public abstract class FileHandler implements HttpHandler {
protected static final Logger log = Logger.getLogger("Minecraft");
@ -43,6 +44,10 @@ public abstract class FileHandler implements HttpHandler {
protected abstract InputStream getFileInput(String path, HttpRequest request, HttpResponse response);
protected void closeFileInput(String path, InputStream in) throws IOException {
in.close();
}
protected String getExtension(String path) {
int dotindex = path.lastIndexOf('.');
if (dotindex > 0)
@ -113,7 +118,7 @@ public abstract class FileHandler implements HttpHandler {
} finally {
freeReadBuffer(readBuffer);
}
fileInput.close();
closeFileInput(path, fileInput);
} catch (Exception e) {
if (fileInput != null) {
try { fileInput.close(); } catch (IOException ex) { }

10
src/main/java/org/dynmap/web/handlers/FilesystemHandler.java
View File

@ -3,8 +3,10 @@ package org.dynmap.web.handlers;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import org.dynmap.utils.FileLockManager;
import org.dynmap.web.HttpField;
import org.dynmap.web.HttpRequest;
import org.dynmap.web.HttpResponse;
@ -20,6 +22,7 @@ public class FilesystemHandler extends FileHandler {
@Override
protected InputStream getFileInput(String path, HttpRequest request, HttpResponse response) {
File file = new File(root, path);
FileLockManager.getReadLock(file);
if (file.getAbsolutePath().startsWith(root.getAbsolutePath()) && file.isFile()) {
FileInputStream result;
try {
@ -30,6 +33,13 @@ public class FilesystemHandler extends FileHandler {
response.fields.put(HttpField.ContentLength, Long.toString(file.length()));
return result;
}
FileLockManager.releaseReadLock(file);
return null;
}
protected void closeFileInput(String path, InputStream in) throws IOException {
super.closeFileInput(path, in);
File file = new File(root, path);
FileLockManager.releaseReadLock(file);
}
}