Thread-Specific Data and Thread Local Storage

The following are three implementations of the C library function dirname, which, given a path, returns the parent directory (e.g., dirname("/foo/bar") returns "/foo".

The first implementation, dirname.c, like libc's version, is not thread-safe.

The second, dirname_tsd.c, uses thread-specific data (via the C library functions pthread_key_create, pthread_setspecific, and pthread_getspecific ) to implement a thread-safe version of dirname.

The third implementation, dirname_tls.c, uses a simliar technique called thread-local storage to also implement a thread-safe version of the function.

To run any of these programs, enter: 


      ./PROGRAM PATH1 PATH2

The main function computes the dirname of PATH1, and a second thread computes the dirname of PATH2. Note that the non-thread safe version of dirname prints the same dirname for both paths.

dirname.c


      
dirname_tsd.c

      


      
dirname_tls.c

      


      

      Additional files: