RFR 8075484:SocketInputStream.socketRead0 can hang even with soTimeout set

[Mark Sheppard]

Hi
   perhaps there is an opportunity to do  some refactoring here (... for 
me a "goto " carries a code smell! )

along the lines

if (timeout) {
     nread =  NET_ReadWithTimeout(...);
} else {
      nread = NET_Read(...);
}


the NET_ReadWithTimeout (...) function will contain a restructuring of 
your goto loop

while (_timeout > 0) { nread = NET_Timeout(fd, _timeout);
           if (nread <= 0) {
               if (nread == 0) {
                   JNU_ThrowByName(env, JNU_JAVANETPKG "SocketTimeoutException",
                               "Read timed out");
               } else if (nread == -1) {
                   if (errno == EBADF) {
                        JNU_ThrowByName(env, JNU_JAVANETPKG "SocketException", "Socket closed");
                   } else if (errno == ENOMEM) {
                       JNU_ThrowOutOfMemoryError(env, "NET_Timeout native heap allocation failed");
                   } else {
                       JNU_ThrowByNameWithMessageAndLastError
                           (env, JNU_JAVANETPKG "SocketException", "select/poll failed");
                   }
               }
                 // release buffer in main call flow
//              if (bufP != BUF) {
//                  free(bufP);
//             }
              nread = -1;
              break;
           } else {
nread = NET_NonBlockingRead(fd, bufP, len);
if (nread == -1 && ((errno == EAGAIN) || (errno == EWOULDBLOCK))) {
               gettimeofday(&t, NULL);
newtime = t.tv_sec * 1000 + t.tv_usec / 1000;
_timeout -= newtime - prevtime;
if(_timeout > 0){
prevtime = newtime;
                   }
} else { break; } } } return nread;


e&oe

regards
Mark


On 29/08/2016 10:58, Vyom Tewari wrote:
> gentle reminder, please review the below code change.
>
> Vyom
>
>
> On Monday 22 August 2016 05:12 PM, Vyom Tewari wrote:
>> Hi All,
>>
>> Please review the code changes for below issue.
>>
>> Bug         : https://bugs.openjdk.java.net/browse/JDK-8075484
>>
>> webrev    : 
>> http://cr.openjdk.java.net/~vtewari/8075484/webrev0.0/index.html 
>> <http://cr.openjdk.java.net/%7Evtewari/8075484/webrev0.0/index.html>
>>
>> This issue is SocketInputStream.socketread0() hangs even with 
>> "soTimeout" set.the implementation of 
>> Java_java_net_SocketInputStream_socketRead0 assumes that read() won't 
>> block after poll() reports that a read is possible.
>>
>> This assumption does not hold, as noted on the man page for select 
>> (referenced by the man page for poll): Under Linux, select() may 
>> report a socket file descriptor as "ready for reading", while 
>> nevertheless a subsequent read blocks. This could for example happen 
>> when data has arrived but upon examination has wrong checksum and is 
>> discarded.
>>
>> Thanks,
>>
>> Vyom
>>
>>
>

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