-- C954010.A -- -- Grant of Unlimited Rights -- -- Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687, -- F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained -- unlimited rights in the software and documentation contained herein. -- Unlimited rights are defined in DFAR 252.227-7013(a)(19). By making -- this public release, the Government intends to confer upon all -- recipients unlimited rights equal to those held by the Government. -- These rights include rights to use, duplicate, release or disclose the -- released technical data and computer software in whole or in part, in -- any manner and for any purpose whatsoever, and to have or permit others -- to do so. -- -- DISCLAIMER -- -- ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR -- DISCLOSED ARE AS IS. THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED -- WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE -- SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE -- OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A -- PARTICULAR PURPOSE OF SAID MATERIAL. --* -- -- OBJECTIVE: -- Check that a requeue within an accept statement does not block. -- This test uses: Requeue to an entry in a different task -- Parameterless call -- Requeue with abort -- -- TEST DESCRIPTION: -- In the Distributor task, requeue two successive calls on the entries -- of two separate target tasks. Verify that the target tasks are -- run in parallel proving that the first requeue does not block -- while the first target rendezvous takes place. -- -- This series of tests uses a simulation of a transaction driven -- processing system. Line Drivers accept input from an external source -- and build them into transaction records. These records are then -- encapsulated in message tasks which remain extant for the life of the -- transaction in the system. The message tasks put themselves on the -- input queue of a Distributor which, from information in the -- transaction and/or system load conditions forwards them to other -- operating tasks. These in turn might forward the transactions to yet -- other tasks for further action. The routing is, in real life, -- dynamic and unpredictable at the time of message generation. All -- rerouting in this model is done by means of requeues. -- -- This test is directed towards the BLOCKING of the REQUEUE only -- If the original caller does not block, the outcome of the test will -- not be affected. If the original caller does not continue after -- the return, the test will not pass. -- If the requeue gets placed on the wrong entry a failing test could -- pass (eg. if the first message is delivered to the second -- computation task and the second message to the first) - a check for -- this condition is made in other tests -- -- -- CHANGE HISTORY: -- 06 Dec 94 SAIC ACVC 2.0 -- --! with Report; with ImpDef; procedure C954010 is -- Mechanism to count the number of Message tasks completed protected TC_Tasks_Completed is procedure Increment; function Count return integer; private Number_Complete : integer := 0; end TC_Tasks_Completed; -- TC_Expected_To_Complete : constant integer := 2; task type Message_Task; type acc_Message_Task is access Message_Task; task Line_Driver is entry Start; end Line_Driver; task Distributor is entry Input; end Distributor; task Credit_Computation is entry Input; end Credit_Computation; task Debit_Computation is entry Input; entry TC_Artificial_Rendezvous_1; -- test purposes only entry TC_Artificial_Rendezvous_2; -- test purposes only end Debit_Computation; -- Mechanism to count the number of Message tasks completed protected body TC_Tasks_Completed is procedure Increment is begin Number_Complete := Number_Complete + 1; end Increment; function Count return integer is begin return Number_Complete; end Count; end TC_Tasks_Completed; -- Assemble messages received from an external source -- Creates a message task for each and sends this to a Distributor -- for appropriate disposal around the network of tasks -- Such a task would normally be designed to loop continuously -- creating the messages as input is received. Simulate this -- but limit it to two dummy messages for this test and allow it -- to terminate at that point -- task body Line_Driver is begin accept Start; -- Wait for trigger from main for i in 1..2 loop declare -- create a new message task N : acc_Message_Task := new Message_Task; begin -- preparation code null; -- stub end; -- declare end loop; exception when others => Report.Failed ("Unexpected exception in Line_Driver"); end Line_Driver; task body Message_Task is begin -- Queue up on Distributor's Input queue Distributor.Input; -- After the required computations have been performed -- return the message appropriately (probably to an output -- line driver null; -- stub -- Increment to show completion of this task TC_Tasks_Completed.Increment; exception when others => Report.Failed ("Unexpected exception in Message_Task"); end Message_Task; -- Dispose each input message to the appropriate computation tasks -- Normally this would be according to some parameters in the entry -- but this simple test is using parameterless entries. -- task body Distributor is Last_was_for_Credit_Computation : Boolean := false; -- switch begin loop select accept Input do -- Determine to which task the message should be -- distributed -- For this test arbitrarily send the first to -- Credit_Computation and the second to Debit_Computation if Last_was_for_Credit_Computation then requeue Debit_Computation.Input with abort; else Last_was_for_Credit_Computation := true; requeue Credit_Computation.Input with abort; end if; end Input; or terminate; end select; end loop; exception when others => Report.Failed ("Unexpected exception in Distributor"); end Distributor; -- Computation task. After the computation is performed the rendezvous -- in the original message task is completed. task body Credit_Computation is begin loop select accept Input do -- Perform the computations required for this message -- null; -- stub -- For the test: -- Artificially rendezvous with Debit_Computation. -- If the first requeue in Distributor has blocked -- waiting for the current rendezvous to complete then the -- second message will not be sent to Debit_Computation -- which will still be waiting on its Input accept. -- This task will HANG -- Debit_Computation.TC_Artificial_Rendezvous_1; -- end Input; or terminate; end select; end loop; exception when others => Report.Failed ("Unexpected exception in Credit_Computation"); end Credit_Computation; -- Computation task. After the computation is performed the rendezvous -- in the original message task is completed. task body Debit_Computation is Message_Count : integer := 0; TC_AR1_is_complete : Boolean := false; begin loop select accept Input do -- Perform the computations required for this message null; -- stub end Input; Message_Count := Message_Count + 1; or -- Guard until the rendezvous with the message for this task -- has completed when Message_Count > 0 => accept TC_Artificial_Rendezvous_1; -- see comments in -- Credit_Computation above TC_AR1_is_complete := true; or -- Completion rendezvous with the main procedure when TC_AR1_is_complete => accept TC_Artificial_Rendezvous_2; or terminate; end select; end loop; exception when others => Report.Failed ("Unexpected exception in Debit_Computation"); end Debit_Computation; begin -- c954010 Report.Test ("C954010", "Requeue in an accept body does not block"); Line_Driver.Start; -- Ensure that both messages were delivered to the computation tasks -- This shows that both requeues were effective. -- Debit_Computation.TC_Artificial_Rendezvous_2; -- Ensure that the message tasks completed while (TC_Tasks_Completed.Count < TC_Expected_To_Complete) loop delay ImpDef.Minimum_Task_Switch; end loop; Report.Result; end C954010;