linux-kernel - Suggested addition to epoll interface

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Message-ID: <2517f1930909150559p505b583fpf3501a1c7dad6634@mail.gmail.com>
Date:	Tue, 15 Sep 2009 15:59:00 +0300
From:	adi hodos <thefatredguy@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: Suggested addition to epoll interface - epoll_post_notification()

Hello everyone. Thank you for your time in reading this.
I have been playing with epoll lately and I would like to make a suggestion
regarding the epoll interface.
It would be nice to have a function to wake up a thread/process that is blocked
on an epoll_wait() call and sent it some
user defined data in the form of a struct epoll_event parameter ( something
similar with PostQueuedCompletionStatus() from Windows ).
My suggestion is for a function like this : int epoll_post_notification( int
epoll_descriptor , struct epoll_event* event );
It could be of much help in scenarios like these :

int e_accept;
int e_clients;

typedef enum {
 keycode_client_connection ,
 keycode_signal ,
 keycode_socketio ,
 keycode_fileio ,
 keycode_event ,
 keycode_timer
 ....
} event_key_type;

struct event_key {
  event_key_type keycode;
};

struct eventfd_wrapper {
 struct eventkey ek;
 int fd_event;
};

struct signalfd_wrapper {
 struct eventkey ek;
 int fd_signal;
};

struct client {
 struct event_key ek;
 int sock;
 ....
};

struct user_posted_event {
 struct event_key ek;
 union {
  void*    ptr_data;
  int      i_data;
  uint32_t u32;
  uint32_t u64;
 } u;
};


// thread A - waits for client connections using an epoll interface
for ( ; ; ) {
 epoll_wait( e_accept , ... );

 int s = accept();
 struct client* new_client = allocate_newclient();
 new_client->sock = s;
 struct user_posted_event* ue = allocate_newuserevent();
 ue->ek.keycode = keycode_client_connection;
 ue->u.ptr_data = new_client;

 struct epoll_event e;
 e.data.ptr = ue;
 epoll_post_notification( e_clients , &e );
}

// thread b - serves clients
for( ; ; ) {
 struct epoll_event[..] e;
 epoll_wait( e_clients , e , ... );

 struct event_key* key = ( struct event_key* )( e.data.ptr );
 if( key->keycode == keycode_client_connection ) {
   // handle new client connection
 } else if( key->keycode == keycode_signal ) {
   // handle signal
 } else if( .... ) {
  ...
 }

Again , thank you for your time in reviewing this.
--
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