Java example source code file (PollArrayWrapper.c)

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Java - Java tags/keywords

bounded, eintr, indefinite, java_sun_nio_ch_pollarraywrapper_interrupt, java_sun_nio_ch_pollarraywrapper_poll0, jnicall, jniexport, jnu_throwioexceptionwithlasterror, null, restartable, write

The PollArrayWrapper.c Java example source code

/*
 * Copyright (c) 2001, 2005, Oracle and/or its affiliates. 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.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_PollArrayWrapper.h"
#include <poll.h>
#include <unistd.h>
#include <sys/time.h>

#define RESTARTABLE(_cmd, _result) do { \
  do { \
    _result = _cmd; \
  } while((_result == -1) && (errno == EINTR)); \
} while(0)

static int
ipoll(struct pollfd fds[], unsigned int nfds, int 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 = poll(fds, nfds, remaining);
        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 jint JNICALL
Java_sun_nio_ch_PollArrayWrapper_poll0(JNIEnv *env, jobject this,
                                       jlong address, jint numfds,
                                       jlong timeout)
{
    struct pollfd *a;
    int err = 0;

    a = (struct pollfd *) jlong_to_ptr(address);

    if (timeout <= 0) {           /* Indefinite or no wait */
        RESTARTABLE (poll(a, numfds, timeout), err);
    } else {                     /* Bounded wait; bounded restarts */
        err = ipoll(a, numfds, timeout);
    }

    if (err < 0) {
        JNU_ThrowIOExceptionWithLastError(env, "Poll failed");
    }
    return (jint)err;
}

JNIEXPORT void JNICALL
Java_sun_nio_ch_PollArrayWrapper_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");
    }
}