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Table E-1 lists the cma exceptions and gives an explanation of each. It also contains the recommended action you should take if an exception occurs.
Exception Explanation and User Action
cma_e_alerted Thread execution was alerted
Explanation: A thread was requested to terminate
by either the cma_thread_alert or pthread_cancel
routine. DECthreads uses an alert to request that a
thread terminate after first performing cleanup and
shutdown operations.
User Action: If you do not want threads to
terminate at the point where this alert is being
delivered, you can use several routines (cma_alert_
disable_general, cma_alert_disable_asynch, cma_
alert_restore, pthread_setcancelstate, and pthread_
setcanceltype) to specify points in the thread
process where alerts cannot be delivered to the
thread.
cma_e_alert_ Improper nesting of alert scope
nesting
Explanation: An attempt was made to restore an
inner scope after an enclosing outer scope had
already been restored.
User Action: Examine the code to determine where
the incorrect alert state variable was passed to
the cma_alert_restore routine.
cma_e_badparam Parameter to DECthreads operation is invalid
Explanation: A parameter passed to a DECthreads
routine is improper; for example, the value is of
the wrong type or is out of range.
User Action: Determine which routine raised
the exception. Then consult the documentation
to determine the correct parameters and value
ranges. Update your code accordingly and retry
the operation.
If you continue to have problems, report it to
Digital, including a small test program that
reproduces the problem.
cma_e_existence Object referenced does not currently exist
Explanation: A DECthreads routine was requested to
operate on an object that does not exist.
User Action: Consult the documentation for the
DECthreads routine that issued this message to
determine the conditions that caused it. Also check
the program where the call is issued to determine
which object or objects that are being passed as
parameters do not currently exist.
cma_e_exit_ Current thread was requested to exit
thread
Explanation: The cma_thread_exit routine was
called to force the thread to shut down in an
orderly fashion. This message notifies all active
exception handlers to perform any necessary cleanup
activities.
User Action: None
cma_e_inialrpro DECthreads initialization is already in progress
Explanation: A call was made to the DECthreads
initialization routine cma_init while DECthreads
was still trying to initialize itself on a prior
call. DECthreads initialization must be complete
before any DECthreads routines are used. Once
DECthreads is fully initialized, all calls to cma_
init complete successfully.
User Action: Remove the offending concurrent call
to the cma_init routine or delay it until the first
call to cma_init has completed.
cma_e_in_use Object referenced is already in use
Explanation: The DECthreads operation cannot be
performed on the specified object because it
is already in use; for example, the routine is
attempting to delete a mutex that is locked.
User Action: Determine which routine caused the
error and make sure the object is in an appropriate
state before attempting the operation.
cma_e_ No space is currently available to create a new
nostackmem stack
Explanation: A call to cma_thread_create or another
DECthreads routine requires that a new stack be
created, but there is insufficient space to create
it.
User Action: Reduce the size of thread stacks
previously created, so that additional stacks may
be created. Alternatively, adjust system or user
quotas to allow the allocation of more virtual
memory.
cma_e_stackovf Attempted stack overflow was detected
Explanation: A thread overflowed its stack.
User Action: Recreate the thread with a larger
stack or redesign the code to require less stack
space; for example, nest your calls less deeply or
allocate less storage on the stack.
cma_e_unimp The specified DECthreads feature is not implemented
Explanation: You attempted to use a feature that
is not implemented in the version of DECthreads
that you are running. This error can occur when
a program developed on a system running a higher
version of DECthreads is executed on a system that
is running a lower version of DECthreads.
User Action: Use a higher version of DECthreads
that supports the feature or do not attempt to use
the feature with a lower version of DECthreads.
cma_e_uninitexc Uninitialized exception raised
Explanation: Code using the EXC_HANDLING.H package,
which provides portable exceptions for the C
language, attempted to raise an exception that
has not been initialized.
User Action: Check the error messages to determine
the program location where the uninitialized
exception is being raised. Use the EXCEPTION_INIT
macro defined in the EXC_HANDLING.H package to
initialize the exception.
cma_e_unkstatus Unknown exception reported
Explanation: A status exception was raised for
which DECthreads is unable to provide a meaningful
text translation.
User Action: Check the value of the status with
which the exception object was initialized to make
sure it has a proper text translation.
cma_e_use_error Requested operation is inappropriate for the
specified object
Explanation: The state or type of an object is
inappropriate for the operation; for example, the
operation attempts to unlock a mutex that is not
locked.
User Action: Determine which routine caused the
error and consult the documentation to learn which
object states are appropriate for the routine.
cma_e_ Wrong mutex specified in condition wait
wrongmutex
Explanation: A thread attempted to wait for a
condition variable that already has at least one
thread waiting and that thread has specified a
different mutex. DECthreads requires that all
threads concurrently waiting for a condition
variable specify the same mutex.
User Action: Design your code so that each
condition variable represents a particular state
of shared data that is protected by a given mutex.
See Table 5-1 for a list of pthread exceptions. Most pthread exceptions correspond directly to a cma interface exception.