08-19-2008
C program
Can anyone tell me how to.....
program to create multiple threads (one master thread and rest worker threads) and using the threads write into and read from shared memory
Restrictions:
Only one thread should be able to read at any instant of time into shared memory region.
Only one thread should be able to write at any instant of time into shared memory region.
Worker threads should inform the master thread after every read and write operation.
Master thread inform the worker thread (which is waiting to acquire shared memory region) that read or write operation is successful and it can acquire the memory for either reading and writing operations.
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LEARN ABOUT HPUX
pthread_rwlock_trywrlock
pthread_rwlock_wrlock(3T) pthread_rwlock_wrlock(3T)
NAME
pthread_rwlock_wrlock(), pthread_rwlock_trywrlock() - lock or attempt to lock a read-write lock for writing
SYNOPSIS
PARAMETERS
rwlock Pointer to the read-write lock to be locked for writing.
DESCRIPTION
The function applies a write lock to the read-write lock object referenced by rwlock. The calling thread acquires the write lock if no
other thread (reader or writer) holds the read-write lock rwlock. Otherwise, the thread blocks (that is, it does not return from the call)
until it can acquire the lock. Results are undefined if the calling thread holds the read-write lock (whether a read or a write lock) at
the time the call is made.
The function applies a write lock as in the function with the exception that the function fails if any thread currently holds rwlock (for
reading or writing).
Results are undefined if any of these functions are called with an uninitialized read-write lock.
If a signal is delivered to a thread waiting for a read-write lock, upon return from the signal handler, the thread shall resume waiting
for the read-write lock as if it was not interrupted.
RETURN VALUE
Upon successful completion, and return zero. Otherwise, an error number is returned to indicate the error (the variable is not set).
ERRORS
If any of the following occur, the function returns the corresponding error number:
[EBUSY] The read-write lock rwlock could not be acquired for writing because it was already locked for reading or writing.
For each of the following conditions, if the condition is detected, the and functions return the corresponding error number:
[EINVAL] The value specified by rwlock does not refer to an initialized read-write lock.
[EDEADLK] The current thread already owns the read-write lock for reading or writing.
AUTHOR
and were developed by X/Open.
SEE ALSO
pthread_rwlock_init(3T), pthread_rwlock_destroy(3T), pthread_rwlock_tryrdlock(3T), pthread_rwlock_rdlock(3T), pthread_rwlock_unlock(3T).
STANDARDS CONFORMANCE
Pthread Library pthread_rwlock_wrlock(3T)