8195059: Update java.net Socket and DatagramSocket implementations to use Cleaner
Reviewed-by: chegar, plevart
/*
* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.io;
import java.lang.ref.Cleaner;
import java.util.ArrayList;
import java.util.List;
import jdk.internal.misc.JavaIOFileDescriptorAccess;
import jdk.internal.misc.SharedSecrets;
import jdk.internal.ref.CleanerFactory;
import jdk.internal.ref.PhantomCleanable;
/**
* Instances of the file descriptor class serve as an opaque handle
* to the underlying machine-specific structure representing an open
* file, an open socket, or another source or sink of bytes.
* The main practical use for a file descriptor is to create a
* {@link FileInputStream} or {@link FileOutputStream} to contain it.
* <p>
* Applications should not create their own file descriptors.
*
* @author Pavani Diwanji
* @since 1.0
*/
public final class FileDescriptor {
private int fd;
private long handle;
private Closeable parent;
private List<Closeable> otherParents;
private boolean closed;
/**
* true, if file is opened for appending.
*/
private boolean append;
static {
initIDs();
}
// Set up JavaIOFileDescriptorAccess in SharedSecrets
static {
SharedSecrets.setJavaIOFileDescriptorAccess(
new JavaIOFileDescriptorAccess() {
public void set(FileDescriptor fdo, int fd) {
fdo.fd = fd;
}
public int get(FileDescriptor fdo) {
return fdo.fd;
}
public void setAppend(FileDescriptor fdo, boolean append) {
fdo.append = append;
}
public boolean getAppend(FileDescriptor fdo) {
return fdo.append;
}
public void close(FileDescriptor fdo) throws IOException {
fdo.close();
}
public void registerCleanup(FileDescriptor fdo) {
fdo.registerCleanup(null);
}
public void registerCleanup(FileDescriptor fdo, PhantomCleanable<Object> cleanup) {
fdo.registerCleanup(cleanup);
}
public void unregisterCleanup(FileDescriptor fdo) {
fdo.unregisterCleanup();
}
public void setHandle(FileDescriptor fdo, long handle) {
fdo.setHandle(handle);
}
public long getHandle(FileDescriptor fdo) {
return fdo.handle;
}
}
);
}
/**
* Cleanup in case FileDescriptor is not explicitly closed.
*/
private PhantomCleanable<Object> cleanup;
/**
* Constructs an (invalid) FileDescriptor
* object.
*/
public FileDescriptor() {
fd = -1;
handle = -1;
}
/**
* A handle to the standard input stream. Usually, this file
* descriptor is not used directly, but rather via the input stream
* known as {@code System.in}.
*
* @see java.lang.System#in
*/
public static final FileDescriptor in = standardStream(0);
/**
* A handle to the standard output stream. Usually, this file
* descriptor is not used directly, but rather via the output stream
* known as {@code System.out}.
* @see java.lang.System#out
*/
public static final FileDescriptor out = standardStream(1);
/**
* A handle to the standard error stream. Usually, this file
* descriptor is not used directly, but rather via the output stream
* known as {@code System.err}.
*
* @see java.lang.System#err
*/
public static final FileDescriptor err = standardStream(2);
/**
* Tests if this file descriptor object is valid.
*
* @return {@code true} if the file descriptor object represents a
* valid, open file, socket, or other active I/O connection;
* {@code false} otherwise.
*/
public boolean valid() {
return (handle != -1) || (fd != -1);
}
/**
* Force all system buffers to synchronize with the underlying
* device. This method returns after all modified data and
* attributes of this FileDescriptor have been written to the
* relevant device(s). In particular, if this FileDescriptor
* refers to a physical storage medium, such as a file in a file
* system, sync will not return until all in-memory modified copies
* of buffers associated with this FileDescriptor have been
* written to the physical medium.
*
* sync is meant to be used by code that requires physical
* storage (such as a file) to be in a known state For
* example, a class that provided a simple transaction facility
* might use sync to ensure that all changes to a file caused
* by a given transaction were recorded on a storage medium.
*
* sync only affects buffers downstream of this FileDescriptor. If
* any in-memory buffering is being done by the application (for
* example, by a BufferedOutputStream object), those buffers must
* be flushed into the FileDescriptor (for example, by invoking
* OutputStream.flush) before that data will be affected by sync.
*
* @exception SyncFailedException
* Thrown when the buffers cannot be flushed,
* or because the system cannot guarantee that all the
* buffers have been synchronized with physical media.
* @since 1.1
*/
public native void sync() throws SyncFailedException;
/* This routine initializes JNI field offsets for the class */
private static native void initIDs();
private static FileDescriptor standardStream(int fd) {
FileDescriptor desc = new FileDescriptor();
desc.handle = getHandle(fd);
return desc;
}
private static native long getHandle(int d);
/**
* Set the handle.
* If setting to -1, clear the cleaner.
* The {@link #registerCleanup()} method should be called for new handles.
* @param handle the handle or -1 to indicate closed
*/
@SuppressWarnings("unchecked")
void setHandle(long handle) {
if (handle == -1 && cleanup != null) {
cleanup.clear();
cleanup = null;
}
this.handle = handle;
}
/**
* Register a cleanup for the current handle.
* Used directly in java.io and indirectly via fdAccess.
* The cleanup should be registered after the handle is set in the FileDescriptor.
*/
@SuppressWarnings("unchecked")
void registerCleanup() {
registerCleanup(null);
}
/**
* Register a cleanup for the current handle.
* Used directly in java.io and indirectly via fdAccess.
* The cleanup should be registered after the handle is set in the FileDescriptor.
* @param newCleanable a PhantomCleanable to register
*/
@SuppressWarnings("unchecked")
synchronized void registerCleanup(PhantomCleanable<Object> newCleanable) {
if (cleanup != null) {
cleanup.clear();
}
cleanup = (newCleanable == null) ? FDCleanup.create(this) : newCleanable;
}
/**
* Unregister a cleanup for the current raw fd.
* Used directly in java.io and indirectly via fdAccess.
* Normally {@link #close()} should be used except in cases where
* it is certain the caller will close the raw fd and the cleanup
* must not close the raw fd. {@link #unregisterCleanup()} must be
* called before the raw fd is closed to prevent a race that makes
* it possible for the fd to be reallocated to another use and later
* the cleanup might be invoked.
*/
synchronized void unregisterCleanup() {
if (cleanup != null) {
cleanup.clear();
}
cleanup = null;
}
/**
* Close the raw file descriptor or handle, if it has not already been closed
* and set the fd and handle to -1.
* Clear the cleaner so the close does not happen twice.
* Package private to allow it to be used in java.io.
* @throws IOException if close fails
*/
@SuppressWarnings("unchecked")
synchronized void close() throws IOException {
if (cleanup != null) {
cleanup.clear();
cleanup = null;
}
close0();
}
/*
* Close the raw file descriptor or handle, if it has not already been closed
* and set the fd and handle to -1.
*/
private native void close0() throws IOException;
/*
* Raw close of the file handle.
* Used only for last chance cleanup.
*/
private static native void cleanupClose0(long handle) throws IOException;
/*
* Package private methods to track referents.
* If multiple streams point to the same FileDescriptor, we cycle
* through the list of all referents and call close()
*/
/**
* Attach a Closeable to this FD for tracking.
* parent reference is added to otherParents when
* needed to make closeAll simpler.
*/
synchronized void attach(Closeable c) {
if (parent == null) {
// first caller gets to do this
parent = c;
} else if (otherParents == null) {
otherParents = new ArrayList<>();
otherParents.add(parent);
otherParents.add(c);
} else {
otherParents.add(c);
}
}
/**
* Cycle through all Closeables sharing this FD and call
* close() on each one.
*
* The caller closeable gets to call close0().
*/
@SuppressWarnings("try")
synchronized void closeAll(Closeable releaser) throws IOException {
if (!closed) {
closed = true;
IOException ioe = null;
try (releaser) {
if (otherParents != null) {
for (Closeable referent : otherParents) {
try {
referent.close();
} catch(IOException x) {
if (ioe == null) {
ioe = x;
} else {
ioe.addSuppressed(x);
}
}
}
}
} catch(IOException ex) {
/*
* If releaser close() throws IOException
* add other exceptions as suppressed.
*/
if (ioe != null)
ex.addSuppressed(ioe);
ioe = ex;
} finally {
if (ioe != null)
throw ioe;
}
}
}
/**
* Cleanup for a FileDescriptor when it becomes phantom reachable.
* Create a cleanup if handle != -1.
* Windows closes files using handles and sockets via the fd.
* Network FileDescriptors using socket fd must provide their
* own PhantomCleanable to {@link #registerCleanup}.
* This implementation only clears thehandles.
* <p>
* Subclassed from {@code PhantomCleanable} so that {@code clear} can be
* called to disable the cleanup when the handle is closed by any means other
* than calling {@link FileDescriptor#close}.
* Otherwise, it may incorrectly close the handle after it has been reused.
*/
static final class FDCleanup extends PhantomCleanable<Object> {
private final long handle;
static FDCleanup create(FileDescriptor fdo) {
return fdo.handle == -1L
? null
: new FDCleanup(fdo, CleanerFactory.cleaner(), fdo.handle);
}
/**
* Constructor for a phantom cleanable reference.
* @param obj the object to monitor
* @param cleaner the cleaner
* @param handle file handle to close
*/
private FDCleanup(Object obj, Cleaner cleaner, long handle) {
super(obj, cleaner);
this.handle = handle;
}
/**
* Close the native handle.
*/
@Override
protected void performCleanup() {
try {
cleanupClose0(handle);
} catch (IOException ioe) {
throw new UncheckedIOException("close", ioe);
}
}
}
}