Netty3 源码分析 - AbstractChannel
Netty3 源码分析 - AbstractChannel
AbstractChannel 是Channel的部分实现，维护了一个通道相关的资源，如channel id, pipeline等；而且实现了对该套接字的IO操作，以及设置interestOps；这里还没有牵扯到底层的细节，只是这个框架的结构。（Channels中的具体实现有待分析）
源码能说明一切：
/**
* A skeletal Channel implementation.
*/
public
abstract
class
AbstractChannel
implements
org.jboss.netty.channel.Channel {
static
final
ConcurrentMap<Integer, Channel>
allChannels
=
new
ConcurrentHashMap<Integer, Channel>();
private
static
final
Random
random
=
new
Random();
private
static
Integer allocateId(Channel channel) {
Integer id =
random
.nextInt();
for
(;;) {
// 循环直到得到一个唯一的ID.
// It should be found in one loop practically.
if
(
allChannels
.putIfAbsent(id, channel) ==
null
) {
// Successfully acquired.
return
id;
}
else
{
// Taken by other channel at almost the same moment.
id = id.intValue() + 1;
}
}
}
private
final
Integer
id
;
private
final
Channel
parent
;
//
private
final
ChannelFactory
factory
;
private
final
ChannelPipeline
pipeline
;
//
private
final
ChannelFuture
succeededFuture
=
new
SucceededChannelFuture(
this
);
private
final
ChannelCloseFuture
closeFuture
=
new
ChannelCloseFuture();
private volatile int interestOps = OP_READ;
/** Cache for the string representation of this channel */
private
boolean
strValConnected
;
private
String
strVal
;
private
volatile
Object
attachment
;
/**
* 创建实例，注意各个参数的含义，特别是ChannelSink
*
*
@param
parent
* the parent of this channel. {@code null} if there's no parent.
*
@param
factory
* the factory which created this channel
*
@param
pipeline
* the pipeline which is going to be attached to this channel
*
@param
sink
* the sink which will receive downstream events from the
* pipeline and send upstream events to the pipeline
*/
protected
AbstractChannel(Channel parent, ChannelFactory factory,
ChannelPipeline pipeline, ChannelSink sink) {
this
.
parent
= parent;
this
.
factory
= factory;
this
.
pipeline
= pipeline;
id
= allocateId(
this
);
pipeline.attach(
this
, sink);
}
// (Internal use only) Creates a new temporary instance with the specified
// ID.
protected
AbstractChannel(Integer id, Channel parent,
ChannelFactory factory, ChannelPipeline pipeline, ChannelSink sink) {
this
.
id
= id;
this
.
parent
= parent;
this
.
factory
= factory;
this
.
pipeline
= pipeline;
pipeline.attach(
this
, sink);
}
public
final
Integer getId() {
return
id
;
}
public
Channel getParent() {
return
parent
;
}
public
ChannelFactory getFactory() {
return
factory
;
}
public
ChannelPipeline getPipeline() {
return
pipeline
;
}
/**
* Returns the cached SucceededChannelFuture instance.
*/
protected
ChannelFuture getSucceededFuture() {
return
succeededFuture
;
}
/**
* Returns the FailedChannelFuture whose cause is an
* UnsupportedOperationException.
*/
protected
ChannelFuture getUnsupportedOperationFuture() {
return
new
FailedChannelFuture(
this
,
new
UnsupportedOperationException());
}
/**
* Returns the ID of this channel.
*/
@Override
public
final
int
hashCode() {
return
id
;
}
// 引用相等
@Override
public
final
boolean
equals(Object o) {
return
this
== o;
}
// 用ID来比较
public
final
int
compareTo(Channel o) {
return
getId().compareTo(o.getId());
}
public
boolean
isOpen() {
return
!
closeFuture
.isDone();
}
/**
* Marks this channel as closed. This method is intended to be called by an
* internal component
-
please do not call it unless you know what you are
* doing.
*
*
@return
{@code true} if and only if this channel was not marked as closed
* yet
*/
protected
boolean
setClosed() {
// Deallocate the current channel's ID from allChannels so that other
// new channels can use it.
allChannels
.remove(
id
);
return
closeFuture
.setClosed();
}
// 下面都是调用辅助函数来完成套接字的基本操作逻辑
public
ChannelFuture bind(SocketAddress localAddress) {
return
Channels.bind(
this
, localAddress);
}
public
ChannelFuture unbind() {
return
Channels.unbind(
this
);
}
public
ChannelFuture close() {
ChannelFuture returnedCloseFuture = Channels.close(
this
);
assert
closeFuture
== returnedCloseFuture;
return
closeFuture
;
}
public
ChannelFuture getCloseFuture() {
return
closeFuture
;
}
public
ChannelFuture connect(SocketAddress remoteAddress) {
return
Channels.connect(
this
, remoteAddress);
}
public
ChannelFuture disconnect() {
return
Channels.disconnect(
this
);
}
public
int
getInterestOps() {
return
interestOps
;
}
public
ChannelFuture setInterestOps(
int
interestOps) {
return
Channels.setInterestOps(
this
, interestOps);
}
/**
* Sets the interestOps property of this channel immediately. This method is
* intended to be called by an internal component
-
please do not call it
* unless you know what you are doing. 直接改变的成员变量，而不是通过发送请求码到最后一个handler
*/
protected
void
setInterestOpsNow(
int
interestOps) {
this
.
interestOps
= interestOps;
}
public
boolean
isReadable() {
return
(getInterestOps() &
OP_READ
) != 0;
}
public
boolean
isWritable() {
return
(getInterestOps() &
OP_WRITE
) == 0;
}
public
ChannelFuture setReadable(
boolean
readable) {
if
(readable) {
return
setInterestOps(getInterestOps() |
OP_READ
);
}
else
{
return
setInterestOps(getInterestOps() & ~
OP_READ
);
}
}
public
ChannelFuture write(Object message) {
return
Channels.write(
this
, message);
}
public
ChannelFuture write(Object message, SocketAddress remoteAddress) {
return
Channels.write(
this
, message, remoteAddress);
}
public
Object getAttachment() {
return
attachment
;
}
public
void
setAttachment(Object attachment) {
this
.
attachment
= attachment;
}
/**
* Returns the String representation of this channel. The returned string
* contains the ID, local address, and remote address of this channel for
* easier identification.
*/
@Override
public
String toString() {
boolean
connected = isConnected();
if
(
strValConnected
== connected &&
strVal
!=
null
) {
return
strVal
;
}
StringBuilder buf =
new
StringBuilder(128);
buf.append(
"[id: 0x"
);
buf.append(getIdString());
SocketAddress localAddress = getLocalAddress();
SocketAddress remoteAddress = getRemoteAddress();
if
(remoteAddress !=
null
) {
buf.append(
", "
);
if
(getParent() ==
null
) {
buf.append(localAddress);
buf.append(connected ?
" => "
:
" :> "
);
buf.append(remoteAddress);
}
else
{
buf.append(remoteAddress);
buf.append(connected ?
" => "
:
" :> "
);
buf.append(localAddress);
}
}
else
if
(localAddress !=
null
) {
buf.append(
", "
);
buf.append(localAddress);
}
buf.append(
']'
);
String strVal = buf.toString();
this
.
strVal
= strVal;
strValConnected
= connected;
return
strVal;
}
private
String getIdString() {
String answer = Integer.toHexString(
id
.intValue());
switch
(answer.length()) {
case
0:
answer =
"00000000"
;
break
;
case
1:
answer =
"0000000"
+ answer;
break
;
case
2:
answer =
"000000"
+ answer;
break
;
case
3:
answer =
"00000"
+ answer;
break
;
case
4:
answer =
"0000"
+ answer;
break
;
case
5:
answer =
"000"
+ answer;
break
;
case
6:
answer =
"00"
+ answer;
break
;
case
7:
answer =
'0'
+ answer;
break
;
}
return
answer;
}
private
final
class
ChannelCloseFuture
extends
DefaultChannelFuture {
public
ChannelCloseFuture() {
super
(AbstractChannel.
this
,
false
);
}
@Override
public
boolean
setSuccess() {
// User is not supposed to call this method - ignore silently.
return
false
;
}
@Override
public
boolean
setFailure(Throwable cause) {
// User is not supposed to call this method - ignore silently.
return
false
;
}
boolean
setClosed() {
return
super
.setSuccess();
}
}
}