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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2013 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/epoll.h>

#include "../util/systhr.h"
#include "../util/atomic.h"


#include "event.h"
#include "event_linux.h"


event_handler_t* evhandler_create(int numthreads) {
    event_handler_t *ev = malloc(sizeof(event_handler_t));
    if(ev == NULL) {
        return NULL;
    }
    
    ev->ep = calloc(numthreads, sizeof(int));
    if(ev->ep == NULL) {
        free(ev);
        return NULL;
    }
    ev->nep = numthreads;
    ev->lep = 0;
    
    /* create ports event threads */
    for(int i=0;i<numthreads;i++) {
        /* create port */
        ev->ep[i] = epoll_create(64);
        if(ev->ep[i] == 0) {
            free(ev->ep);
            free(ev);
            return NULL;
        }
        
        /*
         * start a new handler thread
         * the thread needs the event port and a pointer to the event handler
         */
        ev_thr_conf_t *conf = malloc(sizeof(ev_thr_conf_t));
        if(conf == NULL) {
            free(ev->ep);
            free(ev);
            return NULL;
        }
        conf->handler = ev;
        conf->ep = ev->ep[i];
        
        systhread_start(0, 0, (thrstartfunc)ev_handle_events, conf);
        /* TODO: error handling */
    }
    
    return ev;
}


void ev_handle_events(ev_thr_conf_t *conf) {
    event_handler_t *ev = conf->handler;
    int ep = conf->ep;
    
    free(conf);
    
    //port_event_t events[16];
    struct epoll_event events[16];
    
    for(;;) {
        /* wait for events */
        int ret = epoll_wait(ep, events, 16, 100000);
        if(ret == -1 && errno != EINTR) {
            log_ereport(LOG_FAILURE, "epoll_wait failed: %s", strerror(errno));
            continue;
        }
        
        for(int i=0;i<ret;i++) {
            event_t *event = events[i].data.ptr;
            if(event->fn) {
                int saved_ev = event->poll;
                if(!event->fn(ev, event)) {
                    // event fn returned 0 -> remove event from epoll
                    if(epoll_ctl(ep, EPOLL_CTL_DEL, event->object, NULL)) {
                        event->error = 1;
                        log_ereport(
                                LOG_FAILURE,
                                "epoll_ctl failed: fd: %d error: %s",
                                event->object,
                                strerror(errno));
                    }
                    
                    // if set, execute event->finish
                    if(event->finish) {
                        event->finish(ev, event);
                    }
                } else {
                    if(saved_ev != event->poll) {
                        // event type changed
                        struct epoll_event epev;
                        epev.events = EPOLLET;
                        epev.data.ptr = event;
                        
                        // adjust epoll events
                        if((event->poll & EVENT_POLLIN) == EVENT_POLLIN) {
                            epev.events |= EPOLLIN;
                        }
                        if((event->poll & EVENT_POLLOUT) == EVENT_POLLOUT) {
                            epev.events |= EPOLLOUT;
                        }
                        
                        if(epoll_ctl(ep, EPOLL_CTL_MOD, event->object, NULL)) {
                            log_ereport(
                                    LOG_FAILURE,
                                    "epoll_wait failed: %s",
                                    strerror(errno));
                        }
                    }
                }
            }
        }
    }
}

/* returns a event handler port */
int ev_get_port(event_handler_t *h) {
    int nps = h->nep;
    if(nps == 1) {
        return h->ep[0];
    }
    
    int cp = h->lep % nps;
    ws_atomic_inc32(&h->lep);
    
    return h->ep[cp];
}

int ev_pollin(event_handler_t *h, int fd, event_t *event) {
    event->object = (intptr_t)fd;
    event->poll = EVENT_POLLIN;
    struct epoll_event epev;
    epev.events = EPOLLIN | EPOLLET; // input event, edge triggered
    epev.data.ptr = event;
    return epoll_ctl(ev_get_port(h), EPOLL_CTL_ADD, fd, &epev);
}

int ev_pollout(event_handler_t *h, int fd, event_t *event) {
    event->object = (intptr_t)fd;
    event->poll = EVENT_POLLOUT;
    struct epoll_event epev;
    epev.events = EPOLLOUT | EPOLLET; // input event, edge triggered
    epev.data.ptr = event;
    return epoll_ctl(ev_get_port(h), EPOLL_CTL_ADD, fd, &epev);
}

int evt_send(event_handler_t *h, event_t *event) {
    event->object = 0;
    // TODO: implement using threadpool or eventfd
    fprintf(stderr, "Warning: evt_send not implemented\n");
    return 0;
}