/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.channel.epoll;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.buffer.ByteBufUtil;
import io.netty.buffer.Unpooled;
import io.netty.channel.AbstractChannel;
import io.netty.channel.Channel;
import io.netty.channel.ChannelConfig;
import io.netty.channel.ChannelException;
import io.netty.channel.ChannelMetadata;
import io.netty.channel.EventLoop;
import io.netty.channel.RecvByteBufAllocator;
import io.netty.channel.socket.ChannelInputShutdownEvent;
import io.netty.channel.socket.ChannelInputShutdownReadComplete;
import io.netty.channel.unix.FileDescriptor;
import io.netty.channel.unix.Socket;
import io.netty.channel.unix.UnixChannel;
import io.netty.util.ReferenceCountUtil;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.NotYetConnectedException;
import java.nio.channels.UnresolvedAddressException;
import static io.netty.util.internal.ObjectUtil.checkNotNull;
abstract class AbstractEpollChannel extends AbstractChannel implements UnixChannel {
private static final ChannelMetadata METADATA = new ChannelMetadata(false);
private final int readFlag;
final LinuxSocket socket;
protected int flags = Native.EPOLLET;
boolean inputClosedSeenErrorOnRead;
boolean epollInReadyRunnablePending;
protected volatile boolean active;
AbstractEpollChannel(LinuxSocket fd, int flag) {
this(null, fd, flag, false);
}
AbstractEpollChannel(Channel parent, LinuxSocket fd, int flag, boolean active) {
super(parent);
socket = checkNotNull(fd, "fd");
readFlag = flag;
flags |= flag;
this.active = active;
}
static boolean isSoErrorZero(Socket fd) {
try {
return fd.getSoError() == 0;
} catch (IOException e) {
throw new ChannelException(e);
}
}
void setFlag(int flag) throws IOException {
if (!isFlagSet(flag)) {
flags |= flag;
modifyEvents();
}
}
void clearFlag(int flag) throws IOException {
if (isFlagSet(flag)) {
flags &= ~flag;
modifyEvents();
}
}
boolean isFlagSet(int flag) {
return (flags & flag) != 0;
}
@Override
public final FileDescriptor fd() {
return socket;
}
@Override
public abstract EpollChannelConfig config();
@Override
public boolean isActive() {
return active;
}
@Override
public ChannelMetadata metadata() {
return METADATA;
}
@Override
protected void doClose() throws Exception {
active = false;
// Even if we allow half closed sockets we should give up on reading. Otherwise we may allow a read attempt on a
// socket which has not even been connected yet. This has been observed to block during unit tests.
inputClosedSeenErrorOnRead = true;
try {
doDeregister();
} finally {
socket.close();
}
}
@Override
protected void doDisconnect() throws Exception {
doClose();
}
@Override
protected boolean isCompatible(EventLoop loop) {
return loop instanceof EpollEventLoop;
}
@Override
public boolean isOpen() {
return socket.isOpen();
}
@Override
protected void doDeregister() throws Exception {
((EpollEventLoop) eventLoop()).remove(this);
}
@Override
protected final void doBeginRead() throws Exception {
// Channel.read() or ChannelHandlerContext.read() was called
final AbstractEpollUnsafe unsafe = (AbstractEpollUnsafe) unsafe();
unsafe.readPending = true;
// We must set the read flag here as it is possible the user didn't read in the last read loop, the
// executeEpollInReadyRunnable could read nothing, and if the user doesn't explicitly call read they will
// never get data after this.
setFlag(readFlag);
// If EPOLL ET mode is enabled and auto read was toggled off on the last read loop then we may not be notified
// again if we didn't consume all the data. So we force a read operation here if there maybe more data.
if (unsafe.maybeMoreDataToRead) {
unsafe.executeEpollInReadyRunnable(config());
}
}
final boolean shouldBreakEpollInReady(ChannelConfig config) {
return socket.isInputShutdown() && (inputClosedSeenErrorOnRead || !isAllowHalfClosure(config));
}
final boolean isAllowHalfClosure(ChannelConfig config) {
return config instanceof EpollSocketChannelConfig &&
((EpollSocketChannelConfig) config).isAllowHalfClosure();
}
final void clearEpollIn() {
// Only clear if registered with an EventLoop as otherwise
if (isRegistered()) {
final EventLoop loop = eventLoop();
final AbstractEpollUnsafe unsafe = (AbstractEpollUnsafe) unsafe();
if (loop.inEventLoop()) {
unsafe.clearEpollIn0();
} else {
// schedule a task to clear the EPOLLIN as it is not safe to modify it directly
loop.execute(new Runnable() {
@Override
public void run() {
if (!unsafe.readPending && !config().isAutoRead()) {
// Still no read triggered so clear it now
unsafe.clearEpollIn0();
}
}
});
}
} else {
// The EventLoop is not registered atm so just update the flags so the correct value
// will be used once the channel is registered
flags &= ~readFlag;
}
}
private void modifyEvents() throws IOException {
if (isOpen() && isRegistered()) {
((EpollEventLoop) eventLoop()).modify(this);
}
}
@Override
protected void doRegister() throws Exception {
// Just in case the previous EventLoop was shutdown abruptly, or an event is still pending on the old EventLoop
// make sure the epollInReadyRunnablePending variable is reset so we will be able to execute the Runnable on the
// new EventLoop.
epollInReadyRunnablePending = false;
((EpollEventLoop) eventLoop()).add(this);
}
@Override
protected abstract AbstractEpollUnsafe newUnsafe();
/**
* Returns an off-heap copy of the specified {@link ByteBuf}, and releases the original one.
*/
protected final ByteBuf newDirectBuffer(ByteBuf buf) {
return newDirectBuffer(buf, buf);
}
/**
* Returns an off-heap copy of the specified {@link ByteBuf}, and releases the specified holder.
* The caller must ensure that the holder releases the original {@link ByteBuf} when the holder is released by
* this method.
*/
protected final ByteBuf newDirectBuffer(Object holder, ByteBuf buf) {
final int readableBytes = buf.readableBytes();
if (readableBytes == 0) {
ReferenceCountUtil.safeRelease(holder);
return Unpooled.EMPTY_BUFFER;
}
final ByteBufAllocator alloc = alloc();
if (alloc.isDirectBufferPooled()) {
return newDirectBuffer0(holder, buf, alloc, readableBytes);
}
final ByteBuf directBuf = ByteBufUtil.threadLocalDirectBuffer();
if (directBuf == null) {
return newDirectBuffer0(holder, buf, alloc, readableBytes);
}
directBuf.writeBytes(buf, buf.readerIndex(), readableBytes);
ReferenceCountUtil.safeRelease(holder);
return directBuf;
}
private static ByteBuf newDirectBuffer0(Object holder, ByteBuf buf, ByteBufAllocator alloc, int capacity) {
final ByteBuf directBuf = alloc.directBuffer(capacity);
directBuf.writeBytes(buf, buf.readerIndex(), capacity);
ReferenceCountUtil.safeRelease(holder);
return directBuf;
}
protected static void checkResolvable(InetSocketAddress addr) {
if (addr.isUnresolved()) {
throw new UnresolvedAddressException();
}
}
/**
* Read bytes into the given {@link ByteBuf} and return the amount.
*/
protected final int doReadBytes(ByteBuf byteBuf) throws Exception {
int writerIndex = byteBuf.writerIndex();
int localReadAmount;
unsafe().recvBufAllocHandle().attemptedBytesRead(byteBuf.writableBytes());
if (byteBuf.hasMemoryAddress()) {
localReadAmount = socket.readAddress(byteBuf.memoryAddress(), writerIndex, byteBuf.capacity());
} else {
ByteBuffer buf = byteBuf.internalNioBuffer(writerIndex, byteBuf.writableBytes());
localReadAmount = socket.read(buf, buf.position(), buf.limit());
}
if (localReadAmount > 0) {
byteBuf.writerIndex(writerIndex + localReadAmount);
}
return localReadAmount;
}
protected final int doWriteBytes(ByteBuf buf, int writeSpinCount) throws Exception {
int readableBytes = buf.readableBytes();
int writtenBytes = 0;
if (buf.hasMemoryAddress()) {
long memoryAddress = buf.memoryAddress();
int readerIndex = buf.readerIndex();
int writerIndex = buf.writerIndex();
for (int i = writeSpinCount; i > 0; --i) {
int localFlushedAmount = socket.writeAddress(memoryAddress, readerIndex, writerIndex);
if (localFlushedAmount > 0) {
writtenBytes += localFlushedAmount;
if (writtenBytes == readableBytes) {
return writtenBytes;
}
readerIndex += localFlushedAmount;
} else {
break;
}
}
} else {
ByteBuffer nioBuf;
if (buf.nioBufferCount() == 1) {
nioBuf = buf.internalNioBuffer(buf.readerIndex(), buf.readableBytes());
} else {
nioBuf = buf.nioBuffer();
}
for (int i = writeSpinCount; i > 0; --i) {
int pos = nioBuf.position();
int limit = nioBuf.limit();
int localFlushedAmount = socket.write(nioBuf, pos, limit);
if (localFlushedAmount > 0) {
nioBuf.position(pos + localFlushedAmount);
writtenBytes += localFlushedAmount;
if (writtenBytes == readableBytes) {
return writtenBytes;
}
} else {
break;
}
}
}
if (writtenBytes < readableBytes) {
// Returned EAGAIN need to set EPOLLOUT
setFlag(Native.EPOLLOUT);
}
return writtenBytes;
}
protected abstract class AbstractEpollUnsafe extends AbstractUnsafe {
boolean readPending;
boolean maybeMoreDataToRead;
private EpollRecvByteAllocatorHandle allocHandle;
private final Runnable epollInReadyRunnable = new Runnable() {
@Override
public void run() {
epollInReadyRunnablePending = false;
epollInReady();
}
};
/**
* Called once EPOLLIN event is ready to be processed
*/
abstract void epollInReady();
final void epollInBefore() { maybeMoreDataToRead = false; }
final void epollInFinally(ChannelConfig config) {
maybeMoreDataToRead = allocHandle.isEdgeTriggered() && allocHandle.maybeMoreDataToRead();
// Check if there is a readPending which was not processed yet.
// This could be for two reasons:
// * The user called Channel.read() or ChannelHandlerContext.read() in channelRead(...) method
// * The user called Channel.read() or ChannelHandlerContext.read() in channelReadComplete(...) method
//
// See https://github.com/netty/netty/issues/2254
if (!readPending && !config.isAutoRead()) {
clearEpollIn();
} else if (readPending && maybeMoreDataToRead) {
// trigger a read again as there may be something left to read and because of epoll ET we
// will not get notified again until we read everything from the socket
//
// It is possible the last fireChannelRead call could cause the user to call read() again, or if
// autoRead is true the call to channelReadComplete would also call read, but maybeMoreDataToRead is set
// to false before every read operation to prevent re-entry into epollInReady() we will not read from
// the underlying OS again unless the user happens to call read again.
executeEpollInReadyRunnable(config);
}
}
final void executeEpollInReadyRunnable(ChannelConfig config) {
if (epollInReadyRunnablePending || !isActive() || shouldBreakEpollInReady(config)) {
return;
}
epollInReadyRunnablePending = true;
eventLoop().execute(epollInReadyRunnable);
}
/**
* Called once EPOLLRDHUP event is ready to be processed
*/
final void epollRdHupReady() {
// This must happen before we attempt to read. This will ensure reading continues until an error occurs.
recvBufAllocHandle().receivedRdHup();
if (isActive()) {
// If it is still active, we need to call epollInReady as otherwise we may miss to
// read pending data from the underlying file descriptor.
// See https://github.com/netty/netty/issues/3709
epollInReady();
} else {
// Just to be safe make sure the input marked as closed.
shutdownInput(true);
}
// Clear the EPOLLRDHUP flag to prevent continuously getting woken up on this event.
clearEpollRdHup();
}
/**
* Clear the {@link Native#EPOLLRDHUP} flag from EPOLL, and close on failure.
*/
private void clearEpollRdHup() {
try {
clearFlag(Native.EPOLLRDHUP);
} catch (IOException e) {
pipeline().fireExceptionCaught(e);
close(voidPromise());
}
}
/**
* Shutdown the input side of the channel.
*/
void shutdownInput(boolean rdHup) {
if (!socket.isInputShutdown()) {
if (isAllowHalfClosure(config())) {
try {
socket.shutdown(true, false);
} catch (IOException ignored) {
// We attempted to shutdown and failed, which means the input has already effectively been
// shutdown.
fireEventAndClose(ChannelInputShutdownEvent.INSTANCE);
return;
} catch (NotYetConnectedException ignore) {
// We attempted to shutdown and failed, which means the input has already effectively been
// shutdown.
}
clearEpollIn();
pipeline().fireUserEventTriggered(ChannelInputShutdownEvent.INSTANCE);
} else {
close(voidPromise());
}
} else if (!rdHup) {
inputClosedSeenErrorOnRead = true;
pipeline().fireUserEventTriggered(ChannelInputShutdownReadComplete.INSTANCE);
}
}
private void fireEventAndClose(Object evt) {
pipeline().fireUserEventTriggered(evt);
close(voidPromise());
}
@Override
public EpollRecvByteAllocatorHandle recvBufAllocHandle() {
if (allocHandle == null) {
allocHandle = newEpollHandle((RecvByteBufAllocator.ExtendedHandle) super.recvBufAllocHandle());
}
return allocHandle;
}
/**
* Create a new {@link EpollRecvByteAllocatorHandle} instance.
* @param handle The handle to wrap with EPOLL specific logic.
*/
EpollRecvByteAllocatorHandle newEpollHandle(RecvByteBufAllocator.ExtendedHandle handle) {
return new EpollRecvByteAllocatorHandle(handle);
}
@Override
protected void flush0() {
// Flush immediately only when there's no pending flush.
// If there's a pending flush operation, event loop will call forceFlush() later,
// and thus there's no need to call it now.
if (isFlagSet(Native.EPOLLOUT)) {
return;
}
super.flush0();
}
/**
* Called once a EPOLLOUT event is ready to be processed
*/
void epollOutReady() {
if (socket.isOutputShutdown()) {
return;
}
// directly call super.flush0() to force a flush now
super.flush0();
}
protected final void clearEpollIn0() {
assert eventLoop().inEventLoop();
try {
readPending = false;
clearFlag(readFlag);
} catch (IOException e) {
// When this happens there is something completely wrong with either the filedescriptor or epoll,
// so fire the exception through the pipeline and close the Channel.
pipeline().fireExceptionCaught(e);
unsafe().close(unsafe().voidPromise());
}
}
}
}