> Hi,
>
> I am trying to lock a file ( using jni and fcntl( ) ) from java on Linux, and
> i am not able to do it.
>
> When I write pure C++ code to achieve the same functionality, the locking
> happens fine - ie, when i run the program it locks the file, and when I run
> the same instance of the program again ( when the file is already locked and
> one instance of the program is already running ), the program returns as
> expected, bcos the file is already locked.
>
> When I write a JNI wrapper ( at the end of this mail ) around this C++ code,
> and run the program in java - the first instance locks the file successfully;
> however the 2nd instance does not return!! ( It seems to be blocking waiting
> for the lock to be released !)
>
> Can someone tell me how to make the 2nd instance return without blocking ??
>
> Thanks in advance,
>
> Nandakumar.
>
>
> JNIEXPORT jint JNICALL Java_Lock_LockFile(JNIEnv *env, jobject obj, jstring
> filename) {
> int fd;
> const char *file_name ;
>
> struct flock lock_it;
>
> lock_it.l_start = 0; /* -"- */
> lock_it.l_whence = 0; /* from current point */
> lock_it.l_len = 0; /* until end of file */
> lock_it.l_type = F_WRLCK; /* set exclusive/write lock */
> lock_it.l_pid = 0; /* pid not actually interesting */
>
> file_name = env->GetStringUTFChars(filename,0);
>
> if((fd = open(file_name,O_WRONLY))<0)
> {
> cout<<"Cannot open the file "<<"["<<errno<<"]"<<endl;
> return -1;
> }
>
> cout<<"opened the file " << file_name <<endl;
>
> if (fcntl(fd,F_SETLK, &lock_it)<0)
> {
> cout<<"Cannot Lock the file"<<"["<<errno<<"]"<<endl;
> return -1;
> }
> cout<<"locked the file " << file_name <<endl;
> return 1;
>
> }
----------------------------------------------------------------------
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
