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

#include "event_bsd.h"

#include "httprequest.h"

EVHandler* evhandler_create(EventHandlerConfig *cfg) {
    EVHandler *ev = malloc(sizeof(EVHandler));
    ev->current = 0;
    ev->instances = calloc(cfg->nthreads, sizeof(void*));
    ev->numins = cfg->nthreads;
    
    for(int i=0;i<cfg->nthreads;i++) {
        EventHandler *handler = malloc(sizeof(EventHandler));
        ev->instances[i] = handler;
        
        handler->kqueue = kqueue();
        if(handler->kqueue < 0) {
            log_ereport(LOG_FAILURE, "evhandler_create: kqueue: %s", strerror(errno));
            return NULL;
        }
        
        SYS_THREAD t = systhread_start(
                0,
                0,
                (thrstartfunc)ev_handle_events,
                handler);
        systhread_detach(t);
    }
    
    return ev;
}


void ev_handle_events(EventHandler *ev) {
    struct timespec timeout;
    timeout.tv_nsec = 0;
    timeout.tv_sec = 600;
    
    struct kevent events[EV_MAX_EVENTS];
    struct kevent changes[EV_MAX_EVENTS*2];
    Event *finished[EV_MAX_EVENTS];
    int numchanges = 0;
    int numfinished;
    
    for(;;) {
        // wait for events
        int nev = kevent(ev->kqueue, changes, numchanges, events, EV_MAX_EVENTS, &timeout);  
        if(nev == -1) {
            log_ereport(LOG_FAILURE, "kevent: %s", strerror(errno));
            continue;
        }
        
        numchanges = 0;
        int numfinished = 0;
        ev->numret = 0;
        for(int i=0;i<nev;i++) {
            Event *event = (Event*)events[i].udata;
            if(!event) {
                if(events[i].flags == 0) {
                    log_ereport(LOG_WARN, "Unknown kevent (ident=%d)", (int)events[i].ident);
                }
                // don't warn in case flags is not 0, because socket EOF events
                // are triggered even if we apply EV_DELETE in the changelist
                // the only way to stop this is to apply the changelist without
                // getting new events, but that comes with a performance penalty
                
                continue;
            }
            int event_events = event->events;
            
            if(event->fn) {
                int saved_ev = event->events;
                if(!event->fn(ev, event)) {
                    // ret 0 => remove event
                    
                    if(event->finish) {
                        finished[numfinished++] = event;
                    }
                    
                    event_events = 0;
                } else {
                    event_events = event->events;
                }
                
                // if events have changed, we need to add/remove filters
                if(saved_ev != event_events) {
                    int e = event_events;
                    int e_fd = events[i].ident;
                    if((e & EVENT_POLLIN) != (saved_ev & EVENT_POLLIN)) {
                        if((e & EVENT_POLLIN) == EVENT_POLLIN) {
                            // add
                            EV_SET(&changes[numchanges++], e_fd, EVFILT_READ, EV_ADD, 0, 0, event);
                        } else {
                            // deleteh
                            EV_SET(&changes[numchanges++], e_fd, EVFILT_READ, EV_DELETE, 0, 0, NULL);
                        }
                    }
                    if((e & EVENT_POLLOUT) != (saved_ev & EVENT_POLLOUT)) {
                        if((e & EVENT_POLLOUT) == EVENT_POLLOUT) {
                            // add
                            EV_SET(&changes[numchanges++], e_fd, EVFILT_WRITE, EV_ADD, 0, 0, event);
                        } else {
                            // delete
                            EV_SET(&changes[numchanges++], e_fd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
                        }
                    }
                }
            }
        }
        // call event finish handlers
        for(int i=0;i<numfinished;i++) {
            Event *event = finished[i];
            // check again if the finish callback is set
            if(finished[i]->finish) {
                finished[i]->finish(ev, event);
            }
        }
        // execute return calls
        for(int i=0;i<ev->numret;i++) {
            EVReturn ret = ev->fnreturn[i];
            nsapi_saf_return(ret.sn, ret.rq, ret.ret);
        }
    }
}

int ev_pollin(EventHandler *h, int fd, Event *event) {
    event->events = EVENT_POLLIN;
    struct kevent kev;
    EV_SET(&kev, fd, EVFILT_READ, EV_ADD, 0, 0, event);
    return kevent(h->kqueue, &kev, 1, NULL, 0, NULL);
}

int ev_pollout(EventHandler *h, int fd, Event *event) {
    event->events = EVENT_POLLOUT;
    struct kevent kev;
    EV_SET(&kev, fd, EVFILT_WRITE, EV_ADD, 0, 0, event);
    return kevent(h->kqueue, &kev, 1, NULL, 0, NULL);
}

int ev_remove_poll(EventHandler *h, int fd) {
    struct kevent kev;
    EV_SET(&kev, fd, EVFILT_READ, EV_DELETE, 0, 0, NULL);
    int r1 = kevent(h->kqueue, &kev, 1, NULL, 0, NULL);
    EV_SET(&kev, fd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
    int r2 = kevent(h->kqueue, &kev, 1, NULL, 0, NULL);
    // in case r1 or r2 was successful, we return 0 (no error)
    return r1 != -1 || r2 != -1 ? 0 : 1;
}

int event_send(EventHandler *h, Event *event) {
    return 0;
}

// TODO: remove this fake aio
int ev_aioread(int fd, aiocb_s *cb) {
    ssize_t result = pread(fd, cb->buf, cb->nbytes, cb->offset);
    cb->result = result;
    if(result < 0) {
        cb->result_errno = errno;
    }
    return event_send(cb->evhandler, cb->event);
}

int ev_aiowrite(int fd, aiocb_s *cb) {
    ssize_t result = pwrite(fd, cb->buf, cb->nbytes, cb->offset);
    cb->result = result;
    if(result < 0) {
        cb->result_errno = errno;
    }
    return event_send(cb->evhandler, cb->event);
}


int event_pollin(EventHandler *ev, SYS_NETFD fd, Event *event) {
    return ((IOStream*)fd)->poll(fd, ev, IO_POLL_IN, event);
}

int event_pollout(EventHandler *ev, SYS_NETFD fd, Event *event) {
    return ((IOStream*)fd)->poll(fd, ev, IO_POLL_OUT, event);
}

int event_removepoll(EventHandler *ev, SYS_NETFD fd) {
    return ((IOStream*)fd)->poll(fd, ev, IO_POLL_NONE, NULL);
}


void ev_saf_return(EventHandler *h, Session *sn, Request *rq, int ret) {
    h->fnreturn[h->numret++] = (EVReturn){ sn, rq, ret };
}