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Put timeout on read lock used by web server - make sure it can't be indefinite

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This commit is contained in:
Mike Primm 2011-06-28 22:33:11 -05:00
parent 48fea32500
commit 2863dd0acc
2 changed files with 19 additions and 2 deletions
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16
src/main/java/org/dynmap/utils/FileLockManager.java
View File

@ -63,9 +63,16 @@ public class FileLockManager {
* Get read lock on file - multiple readers allowed, blocks writers
*/
public static boolean getReadLock(File f) {
return getReadLock(f, -1);
}
/**
* Get read lock on file - multiple readers allowed, blocks writers - with timeout (msec)
*/
public static boolean getReadLock(File f, long timeout) {
String fn = f.getPath();
synchronized(lock) {
boolean got_lock = false;
boolean first_wait = true;
while(!got_lock) {
Integer lockcnt = filelocks.get(fn); /* Get lock count */
if(lockcnt == null) {
@ -78,7 +85,14 @@ public class FileLockManager {
}
else { /* Write lock in place */
try {
lock.wait();
if((timeout > 0) && (!first_wait)) { /* We already waited */
return false;
}
if(timeout < 0)
lock.wait();
else
lock.wait(timeout);
first_wait = false;
} catch (InterruptedException ix) {
Log.severe("getReadLock(" + fn + ") interrupted");
return false;

5
src/main/java/org/dynmap/web/handlers/FilesystemHandler.java
View File

@ -23,7 +23,10 @@ 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(!FileLockManager.getReadLock(file, 5000)) { /* Wait up to 5 seconds for lock */
Log.severe("Timeout waiting for lock on file " + file.getPath());
return null;
}
FileInputStream result = null;
try {
if (file.getCanonicalPath().startsWith(root.getAbsolutePath()) && file.isFile()) {