The interface is very much like the poll(2) system call in SVR4.
To poll for events across many sockets or file descriptors, create a SelectSet and initialize it with one or more SelectItems. The 'events' field of each SelectItem should be set to the mask of event types you wish to receive. The event types are specified by the constants in the Selectable class.
Calling the select
method (with an optional timeout) checks each of the file descriptors in the SelectSet for events, and sets the 'revents' field of each SelectItem accordingly. The getEvents
method is provided for convenience; it returns an array of SelectItems for which some event occurred.
Multiple implementations of SelectSet may be available on a given system. The particular implementation used is determined on the features of the underlying OS, but the default choice can be overridden by setting the nbio.SelectSetImpl
runtime property. See the subclasses of SelectSetImpl for details.
Public Member Functions | |
SelectSet () | |
Create a SelectSet with no SelectItems. | |
void | add (SelectItem sel) |
Add a SelectItem to this SelectSet. | |
void | add (SelectItem selarr[]) |
Add all of the SelectItems in the given array to the SelectSet. | |
void | remove (SelectItem sel) |
Remove a SelectItem from the SelectSet. | |
void | remove (SelectItem selarr[]) |
Remove all of the SelectItems in the given array from the SelectSet. | |
void | remove (int index) |
Remove the SelectItem at the given index from the SelectSet. | |
void | update () |
Update any changed 'events' fields in SelectItems registered with this SelectSet. | |
void | update (SelectItem sel) |
Update any changed 'events' fields in the given SelectItem. | |
int | size () |
Return the number of SelectItems in this SelectSet. | |
int | numActive () |
Return the number of active SelectItems in this SelectSet. | |
SelectItem | elementAt (int index) |
Return the SelectItem at the given index. | |
int | select (int timeout) |
Wait for events to occur on the SelectItems in this SelectSet. | |
SelectItem[] | getEvents (short mask) |
Returns an array of SelectItems for which events matching the given event mask have occurred (that is, that the revents field matches the given mask). | |
SelectItem[] | getEvents () |
Returns an array of SelectItems for which some events have occurred (that is, that the revents field is nonzero). | |
String | toString () |
Static Package Functions | |
[static initializer] | |
Private Attributes | |
SelectSetImpl | impl |
Static Private Attributes | |
final boolean | DEBUG = false |
final int | POLL_IMPL = 0 |
final int | DEVPOLL_IMPL = 1 |
int | IMPL_TO_USE |
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Create a SelectSet with no SelectItems.
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Add all of the SelectItems in the given array to the SelectSet.
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Add a SelectItem to this SelectSet.
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Return the SelectItem at the given index.
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Returns an array of SelectItems for which some events have occurred (that is, that the revents field is nonzero). This is a convenience method and is not meant to be optimized; since it scans the SelectItem array and creates a new reference array, it imposes higher overhead than the application scanning the SelectItem array directly, using the size() and elementAt() methods. |
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Returns an array of SelectItems for which events matching the given event mask have occurred (that is, that the revents field matches the given mask). This is a convenience method and is not meant to be optimized; since it scans the SelectItem array and creates a new reference array, it imposes higher overhead than the application scanning the SelectItem array directly, using the size() and elementAt() methods. |
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Return the number of active SelectItems in this SelectSet. An active SelectItem is defined as one with a non-zero events request mask. |
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Remove the SelectItem at the given index from the SelectSet.
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Remove all of the SelectItems in the given array from the SelectSet.
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Remove a SelectItem from the SelectSet.
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Wait for events to occur on the SelectItems in this SelectSet. Upon return, the 'revents' field of each SelectItem will be set to the mask of events that occurred. Note that this method does not set revents to 0 when called; after processing an event, it is the application's responsibility to clear the revents field. This is intentional: if the application wishes to delay the processing of an event, it can leave the revents field as-is so that subsequent calls to select will continue to indicate that the event is pending. IMPORTANT NOTE: If timeout is non-zero, this call will block the thread which invokes it. If you are using Green Threads, this will block the entire JVM. Unless you have a single-threaded application, you should only use SelectSet.select() with native threads.
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Return the number of SelectItems in this SelectSet.
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Update any changed 'events' fields in the given SelectItem. This method should be called if a SelectItem 'events' field is modified after adding it to this SelectSet. |
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Update any changed 'events' fields in SelectItems registered with this SelectSet. This method should be called if a SelectItem 'events' field is modified after adding it to this SelectSet. |
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