- All Implemented Interfaces:
Closeable
,AutoCloseable
This class encapsulates the low-level machinery required to implement
the interruption of selection operations. A concrete selector class must
invoke the begin
and end
methods before and
after, respectively, invoking an I/O operation that might block
indefinitely. In order to ensure that the end
method is always
invoked, these methods should be used within a
try
... finally
block:
try {
begin();
// Perform blocking I/O operation here
...
} finally {
end();
}
This class also defines methods for maintaining a selector's
cancelled-key set and for removing a key from its channel's key set, and
declares the abstract register
method that is invoked by a
selectable channel's register
method in order to perform the actual work of registering a channel.
- Since:
- 1.4
-
Constructor Summary
ModifierConstructorDescriptionprotected
AbstractSelector
(SelectorProvider provider) Initializes a new instance of this class. -
Method Summary
Modifier and TypeMethodDescriptionprotected final void
begin()
Marks the beginning of an I/O operation that might block indefinitely.protected final Set
<SelectionKey> Retrieves this selector's cancelled-key set.final void
close()
Closes this selector.protected final void
Removes the given key from its channel's key set.protected final void
end()
Marks the end of an I/O operation that might block indefinitely.protected abstract void
Closes this selector.final boolean
isOpen()
Tells whether or not this selector is open.final SelectorProvider
provider()
Returns the provider that created this channel.protected abstract SelectionKey
register
(AbstractSelectableChannel ch, int ops, Object att) Registers the given channel with this selector.
-
Constructor Details
-
AbstractSelector
Initializes a new instance of this class.- Parameters:
provider
- The provider that created this selector
-
-
Method Details
-
close
Closes this selector.If the selector has already been closed then this method returns immediately. Otherwise it marks the selector as closed and then invokes the
implCloseSelector
method in order to complete the close operation.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in classSelector
- Throws:
IOException
- If an I/O error occurs
-
implCloseSelector
Closes this selector.This method is invoked by the
close
method in order to perform the actual work of closing the selector. This method is only invoked if the selector has not yet been closed, and it is never invoked more than once.An implementation of this method must arrange for any other thread that is blocked in a selection operation upon this selector to return immediately as if by invoking the
wakeup
method.- Throws:
IOException
- If an I/O error occurs while closing the selector
-
isOpen
-
provider
Returns the provider that created this channel. -
cancelledKeys
Retrieves this selector's cancelled-key set.This set should only be used while synchronized upon it.
- Returns:
- The cancelled-key set
-
register
Registers the given channel with this selector.This method is invoked by a channel's
register
method in order to perform the actual work of registering the channel with this selector.- Parameters:
ch
- The channel to be registeredops
- The initial interest set, which must be validatt
- The initial attachment for the resulting key- Returns:
- A new key representing the registration of the given channel with this selector
-
deregister
Removes the given key from its channel's key set.This method must be invoked by the selector for each channel that it deregisters.
- Parameters:
key
- The selection key to be removed
-
begin
protected final void begin()Marks the beginning of an I/O operation that might block indefinitely.This method should be invoked in tandem with the
end
method, using atry
...finally
block as shown above, in order to implement interruption for this selector.Invoking this method arranges for the selector's
wakeup
method to be invoked if a thread'sinterrupt
method is invoked while the thread is blocked in an I/O operation upon the selector. -
end
-