Request for review: 7166048: remove the embedded epoll data structure (original) (raw)

Alan Bateman Alan.Bateman at oracle.com
Fri May 4 00:59:09 PDT 2012

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On 04/05/2012 08:35, Sean Chou wrote:

Hi all,

I found the src/solaris/native/sun/nio/ch/EPollArrayWrapper.c embedded the epoll data structure epolldata and epollevent . It is duplicated with the definition in sys/epoll.h . This redundancy would cause failure if the underlying system has different epoll data structure (eg. different alignment) . I reported 7166048 for it and made a patch: http://cr.openjdk.java.net/~zhouyx/7166048/webrev.00/ <http://cr.openjdk.java.net/%7Ezhouyx/7166048/webrev.00/> . As background, when the epoll Selector was added then the JDK had to be build on distributions that were still 2.4 based and didn't have epoll.h. We had meant to go back and clear this up in JDK7 but didn't get around to it. So thanks for taking this on now. I looked at your patch but it doesn't seem to be complete as it doesn't change the usages to call the epoll functions directly. Attached is the patch that I had for cleaning this up, it should still be current because this code has not changed. The only thing I notice is that it doesn't remove the include of dlfcn.h, that shouldn't be needed now.

On the RFE that you submitted, I've moved this to the right place as:

7166048: (se) EPollArrayWrapper.c no longer needs to define epoll data structures

-Alan.

diff --git a/src/solaris/native/sun/nio/ch/EPollArrayWrapper.c b/src/solaris/native/sun/nio/ch/EPollArrayWrapper.c --- a/src/solaris/native/sun/nio/ch/EPollArrayWrapper.c +++ b/src/solaris/native/sun/nio/ch/EPollArrayWrapper.c @@ -34,55 +34,13 @@ #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;

-/* x86-64 has same alignment as 32-bit */ -#ifdef x86_64

-#define EPOLL_PACKED attribute((packed)) -#else -#define EPOLL_PACKED -#endif

-struct epoll_event { - __uint32_t events; /* Epoll events / - epoll_data_t data; / User data variable */ -} EPOLL_PACKED;

-#ifdef __cplusplus -} -#endif +#include <sys/epoll.h>

#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) @@ -96,7 +54,7 @@ iepoll(int epfd, struct epoll_event *eve start = t.tv_sec * 1000 + t.tv_usec / 1000;

  for (;;) {

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

   int res = epoll_wait(epfd, events, numfds, timeout);
    if (res < 0 && errno == EINTR) {
        if (remaining >= 0) {
            gettimeofday(&t, NULL);

@@ -117,14 +75,6 @@ JNIEXPORT void JNICALL 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 @@ -134,7 +84,7 @@ Java_sun_nio_ch_EPollArrayWrapper_epollC * 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);

int epfd = epoll_create(256); if (epfd < 0) { JNU_ThrowIOExceptionWithLastError(env, "epoll_create failed"); } @@ -173,7 +123,7 @@ Java_sun_nio_ch_EPollArrayWrapper_epollC event.events = events; event.data.fd = fd;

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

res);

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

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

Selector @@ -199,7 +149,7 @@ Java_sun_nio_ch_EPollArrayWrapper_epollW int res;

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

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