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Feature: Redefine "inUse" definition #79

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Feature: Redefine "inUse" definition #79

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75b6ace
first impl
infeo Aug 2, 2023
7d1daf4
reduce unnecessary object tunneling
infeo Aug 2, 2023
4cde4aa
use AtomicLong to store last used time
infeo Sep 20, 2023
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7 changes: 7 additions & 0 deletions src/main/java/org/cryptomator/frontend/fuse/FuseNioAdapter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,13 @@ public interface FuseNioAdapter extends FuseOperations, AutoCloseable {
*/
int DEFAULT_MAX_FILENAMELENGTH = 254; // 255 is preferred, but nautilus checks for this value + 1

/**
* The default value until an {@link OpenFile} is considered active.
*
* @see OpenFileFactory#hasActiveFiles(long)
*/
long DEFAULT_ACTIVE_THRESHOLD = Long.MAX_VALUE;

/**
* Checks if the filesystem is in use (and therefore an unmount attempt should be avoided).
* <p>
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9 changes: 9 additions & 0 deletions src/main/java/org/cryptomator/frontend/fuse/OpenFile.java
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Expand Up @@ -10,14 +10,17 @@
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.attribute.FileAttribute;
import java.time.Instant;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;

public class OpenFile implements Closeable {

private static final Logger LOG = LoggerFactory.getLogger(OpenFile.class);

private final Path path;
private final FileChannel channel;
private final AtomicReference<Instant> lastUsed = new AtomicReference(Instant.now());
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AtomicLong is more lightweight (e.g. using System.nanoTime() instead of Instant)


private OpenFile(Path path, FileChannel channel) {
this.path = path;
Expand All @@ -39,6 +42,7 @@ static OpenFile create(Path path, Set<? extends OpenOption> options, FileAttribu
* @throws IOException If an exception occurs during read.
*/
public int read(ByteBuffer buf, long num, long offset) throws IOException {
lastUsed.set(Instant.now());
long size = channel.size();
if (offset >= size) {
return 0;
Expand Down Expand Up @@ -69,6 +73,7 @@ public int read(ByteBuffer buf, long num, long offset) throws IOException {
* @throws IOException If an exception occurs during write.
*/
public int write(ByteBuffer buf, long num, long offset) throws IOException {
lastUsed.set(Instant.now());
if (num > Integer.MAX_VALUE) {
throw new IOException("Requested too many bytes");
}
Expand All @@ -80,6 +85,10 @@ public int write(ByteBuffer buf, long num, long offset) throws IOException {
return written;
}

public Instant lastUsed() {
return lastUsed.get();
}

@Override
public void close() throws IOException {
channel.close();
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15 changes: 13 additions & 2 deletions src/main/java/org/cryptomator/frontend/fuse/OpenFileFactory.java
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Expand Up @@ -8,6 +8,7 @@
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.attribute.FileAttribute;
import java.time.Instant;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
Expand Down Expand Up @@ -67,8 +68,18 @@ public void close(long fileHandle) throws ClosedChannelException, IOException {
}
}

public int getOpenFileCount(){
return openFiles.size();
/**
* Checks, if any active {@link OpenFile} exists.
* <p>
* An OpenFile is active, if its read or write methods were called in the last threshold given seconds.
* To get atomicity guarantees this method must be externally synchronized.
*
* @param activeThreshold number of seconds defining the threshold an OpenFile is considered active
* @return {@code true} if at least one active OpenFile exists, otherwise {@code false}
*/
public boolean hasActiveFiles(long activeThreshold) {
var comparsion = Instant.now().minusSeconds(activeThreshold);
return openFiles.values().stream().anyMatch(openFile -> openFile.lastUsed().isAfter(comparsion));
}

/**
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19 changes: 11 additions & 8 deletions src/main/java/org/cryptomator/frontend/fuse/ReadOnlyAdapter.java
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Expand Up @@ -43,39 +43,42 @@ public sealed class ReadOnlyAdapter implements FuseNioAdapter permits ReadWriteA
private final int maxFileNameLength;
protected final FileStore fileStore;
protected final LockManager lockManager;
protected final OpenFileFactory openFiles;
protected final FileNameTranscoder fileNameTranscoder;
private final ReadOnlyDirectoryHandler dirHandler;
private final ReadOnlyFileHandler fileHandler;
private final ReadOnlyLinkHandler linkHandler;
private final BooleanSupplier hasOpenFiles;
private final BooleanSupplier inUseCheck;

protected ReadOnlyAdapter(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, FileStore fileStore, OpenFileFactory openFiles, ReadOnlyDirectoryHandler dirHandler, ReadOnlyFileHandler fileHandler) {
protected ReadOnlyAdapter(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, FileStore fileStore, BooleanSupplier inUseCheck, ReadOnlyDirectoryHandler dirHandler, ReadOnlyFileHandler fileHandler) {
this.errno = errno;
this.root = root;
this.maxFileNameLength = maxFileNameLength;
this.fileNameTranscoder = fileNameTranscoder;
this.fileStore = fileStore;
this.lockManager = new LockManager();
this.openFiles = openFiles;
this.dirHandler = dirHandler;
this.fileHandler = fileHandler;
this.linkHandler = new ReadOnlyLinkHandler(fileNameTranscoder);
this.hasOpenFiles = () -> openFiles.getOpenFileCount() != 0;
this.inUseCheck = inUseCheck;
}

public static ReadOnlyAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder) {
public static ReadOnlyAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, long activeOpenFileThreshold) {
try {
var fileStore = Files.getFileStore(root);
var openFiles = new OpenFileFactory();
var dirHandler = new ReadOnlyDirectoryHandler(fileNameTranscoder);
var fileHandler = new ReadOnlyFileHandler(openFiles);
return new ReadOnlyAdapter(errno, root, maxFileNameLength, fileNameTranscoder, fileStore, openFiles, dirHandler, fileHandler);
BooleanSupplier inUseCheck = () -> openFiles.hasActiveFiles(activeOpenFileThreshold);
return new ReadOnlyAdapter(errno, root, maxFileNameLength, fileNameTranscoder, fileStore, inUseCheck, dirHandler, fileHandler);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}

public static ReadOnlyAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder) {
return create(errno, root, maxFileNameLength, fileNameTranscoder, DEFAULT_ACTIVE_THRESHOLD);
}

@Override
public Errno errno() {
return errno;
Expand Down Expand Up @@ -305,7 +308,7 @@ public void destroy() {
@Override
public boolean isInUse() {
try (PathLock pLock = lockManager.tryLockForWriting("/")) {
return hasOpenFiles.getAsBoolean();
return inUseCheck.getAsBoolean();
} catch (AlreadyLockedException e) {
return true;
}
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14 changes: 10 additions & 4 deletions src/main/java/org/cryptomator/frontend/fuse/ReadWriteAdapter.java
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Expand Up @@ -29,6 +29,7 @@
import java.nio.file.attribute.PosixFilePermissions;
import java.util.EnumSet;
import java.util.Set;
import java.util.function.BooleanSupplier;

/**
*
Expand All @@ -38,23 +39,28 @@ public final class ReadWriteAdapter extends ReadOnlyAdapter {
private static final Logger LOG = LoggerFactory.getLogger(ReadWriteAdapter.class);
private final ReadWriteFileHandler fileHandler;

private ReadWriteAdapter(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, FileStore fileStore, OpenFileFactory openFiles, ReadWriteDirectoryHandler dirHandler, ReadWriteFileHandler fileHandler) {
super(errno, root, maxFileNameLength, fileNameTranscoder, fileStore, openFiles, dirHandler, fileHandler);
private ReadWriteAdapter(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, FileStore fileStore, BooleanSupplier inUseCheck, ReadWriteDirectoryHandler dirHandler, ReadWriteFileHandler fileHandler) {
super(errno, root, maxFileNameLength, fileNameTranscoder, fileStore, inUseCheck, dirHandler, fileHandler);
this.fileHandler = fileHandler;
}

public static ReadWriteAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder) {
public static ReadWriteAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder, long activeOpenFileThreshold) {
try {
var fileStore = Files.getFileStore(root);
var openFiles = new OpenFileFactory();
var dirHandler = new ReadWriteDirectoryHandler(fileNameTranscoder);
var fileHandler = new ReadWriteFileHandler(openFiles);
return new ReadWriteAdapter(errno, root, maxFileNameLength, fileNameTranscoder, fileStore, openFiles, dirHandler, fileHandler);
BooleanSupplier inUseCheck = () -> openFiles.hasActiveFiles(activeOpenFileThreshold);
return new ReadWriteAdapter(errno, root, maxFileNameLength, fileNameTranscoder, fileStore, inUseCheck, dirHandler, fileHandler);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}

public static ReadWriteAdapter create(Errno errno, Path root, int maxFileNameLength, FileNameTranscoder fileNameTranscoder) {
return create(errno, root, maxFileNameLength, fileNameTranscoder, DEFAULT_ACTIVE_THRESHOLD);
}

@Override
public Set<Operation> supportedOperations() {
var ops = EnumSet.copyOf(super.supportedOperations());
Expand Down