1/*
2 * Copyright (c) 2005, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26#include "jni.h"
27#include "jni_util.h"
28#include "jvm.h"
29#include "jlong.h"
30
31#include "sun_nio_ch_EPollArrayWrapper.h"
32
33#include <unistd.h>
34#include <sys/time.h>
35#include <sys/epoll.h>
36
37#define RESTARTABLE(_cmd, _result) do { \
38  do { \
39    _result = _cmd; \
40  } while((_result == -1) && (errno == EINTR)); \
41} while(0)
42
43
44static int
45iepoll(int epfd, struct epoll_event *events, int numfds, jlong timeout)
46{
47    jlong start, now;
48    int remaining = timeout;
49    struct timeval t;
50    int diff;
51
52    gettimeofday(&t, NULL);
53    start = t.tv_sec * 1000 + t.tv_usec / 1000;
54
55    for (;;) {
56        int res = epoll_wait(epfd, events, numfds, remaining);
57        if (res < 0 && errno == EINTR) {
58            if (remaining >= 0) {
59                gettimeofday(&t, NULL);
60                now = t.tv_sec * 1000 + t.tv_usec / 1000;
61                diff = now - start;
62                remaining -= diff;
63                if (diff < 0 || remaining <= 0) {
64                    return 0;
65                }
66                start = now;
67            }
68        } else {
69            return res;
70        }
71    }
72}
73
74JNIEXPORT void JNICALL
75Java_sun_nio_ch_EPollArrayWrapper_init(JNIEnv *env, jclass this)
76{
77}
78
79JNIEXPORT jint JNICALL
80Java_sun_nio_ch_EPollArrayWrapper_epollCreate(JNIEnv *env, jobject this)
81{
82    /*
83     * epoll_create expects a size as a hint to the kernel about how to
84     * dimension internal structures. We can't predict the size in advance.
85     */
86    int epfd = epoll_create(256);
87    if (epfd < 0) {
88       JNU_ThrowIOExceptionWithLastError(env, "epoll_create failed");
89    }
90    return epfd;
91}
92
93JNIEXPORT jint JNICALL
94Java_sun_nio_ch_EPollArrayWrapper_sizeofEPollEvent(JNIEnv* env, jclass this)
95{
96    return sizeof(struct epoll_event);
97}
98
99JNIEXPORT jint JNICALL
100Java_sun_nio_ch_EPollArrayWrapper_offsetofData(JNIEnv* env, jclass this)
101{
102    return offsetof(struct epoll_event, data);
103}
104
105JNIEXPORT void JNICALL
106Java_sun_nio_ch_EPollArrayWrapper_epollCtl(JNIEnv *env, jobject this, jint epfd,
107                                           jint opcode, jint fd, jint events)
108{
109    struct epoll_event event;
110    int res;
111
112    event.events = events;
113    event.data.fd = fd;
114
115    RESTARTABLE(epoll_ctl(epfd, (int)opcode, (int)fd, &event), res);
116
117    /*
118     * A channel may be registered with several Selectors. When each Selector
119     * is polled a EPOLL_CTL_DEL op will be inserted into its pending update
120     * list to remove the file descriptor from epoll. The "last" Selector will
121     * close the file descriptor which automatically unregisters it from each
122     * epoll descriptor. To avoid costly synchronization between Selectors we
123     * allow pending updates to be processed, ignoring errors. The errors are
124     * harmless as the last update for the file descriptor is guaranteed to
125     * be EPOLL_CTL_DEL.
126     */
127    if (res < 0 && errno != EBADF && errno != ENOENT && errno != EPERM) {
128        JNU_ThrowIOExceptionWithLastError(env, "epoll_ctl failed");
129    }
130}
131
132JNIEXPORT jint JNICALL
133Java_sun_nio_ch_EPollArrayWrapper_epollWait(JNIEnv *env, jobject this,
134                                            jlong address, jint numfds,
135                                            jlong timeout, jint epfd)
136{
137    struct epoll_event *events = jlong_to_ptr(address);
138    int res;
139
140    if (timeout <= 0) {           /* Indefinite or no wait */
141        RESTARTABLE(epoll_wait(epfd, events, numfds, timeout), res);
142    } else {                      /* Bounded wait; bounded restarts */
143        res = iepoll(epfd, events, numfds, timeout);
144    }
145
146    if (res < 0) {
147        JNU_ThrowIOExceptionWithLastError(env, "epoll_wait failed");
148    }
149    return res;
150}
151
152JNIEXPORT void JNICALL
153Java_sun_nio_ch_EPollArrayWrapper_interrupt(JNIEnv *env, jobject this, jint fd)
154{
155    int fakebuf[1];
156    fakebuf[0] = 1;
157    if (write(fd, fakebuf, 1) < 0) {
158        JNU_ThrowIOExceptionWithLastError(env,"write to interrupt fd failed");
159    }
160}
161