/*

 * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

#include "jni.h"

#include "jni_util.h"

#include "jvm.h"

#include "jlong.h"

#include "sun_nio_ch_EPollArrayWrapper.h"

#include <dlfcn.h>

#include <unistd.h>

#include <sys/resource.h>

#include <sys/time.h>

#ifdef  __cplusplus

extern "C" {

#endif

/* epoll_wait(2) man page */

typedef union epoll_data {

    void *ptr;

    int fd;

    __uint32_t u32;

    __uint64_t u64;

} epoll_data_t;

struct epoll_event {

    __uint32_t events;  /* Epoll events */

    epoll_data_t data;  /* User data variable */

} __attribute__ ((__packed__));

#ifdef  __cplusplus

}

#endif

#define RESTARTABLE(_cmd, _result) do { \

  do { \

    _result = _cmd; \

  } while((_result == -1) && (errno == EINTR)); \

} while(0)

/*

 * epoll event notification is new in 2.6 kernel. As the offical build

 * platform for the JDK is on a 2.4-based distribution then we must

 * obtain the addresses of the epoll functions dynamically.

 */

typedef int (*epoll_create_t)(int size);

typedef int (*epoll_ctl_t)   (int epfd, int op, int fd, struct epoll_event *event);

typedef int (*epoll_wait_t)  (int epfd, struct epoll_event *events, int maxevents, int timeout);

static epoll_create_t epoll_create_func;

static epoll_ctl_t    epoll_ctl_func;

static epoll_wait_t   epoll_wait_func;

static int

iepoll(int epfd, struct epoll_event *events, int numfds, jlong timeout)

{

    jlong start, now;

    int remaining = timeout;

    struct timeval t;

    int diff;

    gettimeofday(&t, NULL);

    start = t.tv_sec * 1000 + t.tv_usec / 1000;

    for (;;) {

        int res = (*epoll_wait_func)(epfd, events, numfds, timeout);

        if (res < 0 && errno == EINTR) {

            if (remaining >= 0) {

                gettimeofday(&t, NULL);

                now = t.tv_sec * 1000 + t.tv_usec / 1000;

                diff = now - start;

                remaining -= diff;

                if (diff < 0 || remaining <= 0) {

                    return 0;

                }

                start = now;

            }

        } else {

            return res;

        }

    }

}

JNIEXPORT void JNICALL

Java_sun_nio_ch_EPollArrayWrapper_init(JNIEnv *env, jclass this)

{

    epoll_create_func = (epoll_create_t) dlsym(RTLD_DEFAULT, "epoll_create");

    epoll_ctl_func    = (epoll_ctl_t)    dlsym(RTLD_DEFAULT, "epoll_ctl");

    epoll_wait_func   = (epoll_wait_t)   dlsym(RTLD_DEFAULT, "epoll_wait");

    if ((epoll_create_func == NULL) || (epoll_ctl_func == NULL) ||

        (epoll_wait_func == NULL)) {

        JNU_ThrowInternalError(env, "unable to get address of epoll functions, pre-2.6 kernel?");

    }

}

JNIEXPORT jint JNICALL

Java_sun_nio_ch_EPollArrayWrapper_epollCreate(JNIEnv *env, jobject this)

{

    /*

     * epoll_create expects a size as a hint to the kernel about how to

     * dimension internal structures. We can't predict the size in advance.

     */

    int epfd = (*epoll_create_func)(256);

    if (epfd < 0) {

       JNU_ThrowIOExceptionWithLastError(env, "epoll_create failed");

    }

    return epfd;

}

JNIEXPORT jint JNICALL

Java_sun_nio_ch_EPollArrayWrapper_fdLimit(JNIEnv *env, jclass this)

{

    struct rlimit rlp;

    if (getrlimit(RLIMIT_NOFILE, &rlp) < 0) {

        JNU_ThrowIOExceptionWithLastError(env, "getrlimit failed");

    }

    return (jint)rlp.rlim_max;

}

JNIEXPORT void JNICALL

Java_sun_nio_ch_EPollArrayWrapper_epollCtl(JNIEnv *env, jobject this, jint epfd,

                                           jint opcode, jint fd, jint events)

{

    struct epoll_event event;

    int res;

    event.events = events;

    event.data.fd = fd;

    RESTARTABLE((*epoll_ctl_func)(epfd, (int)opcode, (int)fd, &event), res);

    /*

     * A channel may be registered with several Selectors. When each Selector

     * is polled a EPOLL_CTL_DEL op will be inserted into its pending update

     * list to remove the file descriptor from epoll. The "last" Selector will

     * close the file descriptor which automatically unregisters it from each

     * epoll descriptor. To avoid costly synchronization between Selectors we

     * allow pending updates to be processed, ignoring errors. The errors are

     * harmless as the last update for the file descriptor is guaranteed to

     * be EPOLL_CTL_DEL.

     */

    if (res < 0 && errno != EBADF && errno != ENOENT && errno != EPERM) {

        JNU_ThrowIOExceptionWithLastError(env, "epoll_ctl failed");

    }

}

JNIEXPORT jint JNICALL

Java_sun_nio_ch_EPollArrayWrapper_epollWait(JNIEnv *env, jobject this,

                                            jlong address, jint numfds,

                                            jlong timeout, jint epfd)

{

    struct epoll_event *events = jlong_to_ptr(address);

    int res;

    if (timeout <= 0) {           /* Indefinite or no wait */

        RESTARTABLE((*epoll_wait_func)(epfd, events, numfds, timeout), res);

    } else {                      /* Bounded wait; bounded restarts */

        res = iepoll(epfd, events, numfds, timeout);

    }

    if (res < 0) {

        JNU_ThrowIOExceptionWithLastError(env, "epoll_wait failed");

    }

    return res;

}

JNIEXPORT void JNICALL

Java_sun_nio_ch_EPollArrayWrapper_interrupt(JNIEnv *env, jobject this, jint fd)

{

    int fakebuf[1];

    fakebuf[0] = 1;

    if (write(fd, fakebuf, 1) < 0) {

        JNU_ThrowIOExceptionWithLastError(env,"write to interrupt fd failed");

    }

}