OSF DCE Application Development Guide--Core Components

Using the DCE Threads Exception-Returning Interface

Note that a CATCH_ALL handler and RERAISE could be used to do this, but the

epilogue code would then have to be duplicated in two places, as follows:

TRY

try_block

CATCH_ALL

final_block

RERAISE;

ENDTRY

{ final_block }

A FINALLY statement has exactly this meaning, but avoids code duplication.

Note: The behavior of FINALLY along with the CATCH or CATCH_ALL

clauses is undeﬁned. Do not combine them for the same try_block.

Another example of the FINALLY statement is as follows:

pthread__mutex_lock (some_object.mutex);

some_object.num_waiters = some_object.num_waiters + 1;

TRY

while (! some_object.data_available)

pthread_cond_wait (some_object.condition);

/* The code to act on the data_available goes here */

FINALLY

some_object.num_waiters = some_object.num_waiters - 1;

pthread_mutex_unlock (some_object.mutex);

ENDTRY

In the preceding example, the call to pthread_cond_wait() could raise the

pthread_cancel_e exception. The ﬁnal_block ensures that the shared data associated

with the lock is correct for the next thread that acquires the mutex.

9.2 Invoking the Exception-Returning Interface

To use the exception-returning interface, replace the ﬁrst statement that follows with the

second:

#include <pthread.h>

#include <pthread_exc.h>

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