-- C954001.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 statement within an entry_body with parameters -- may requeue the entry call to a protected entry with a subtype- -- conformant parameter profile. Check that, if the call is queued on the -- new entry's queue, the original caller remains blocked after the -- requeue, but the entry_body containing the requeue is completed. -- -- TEST DESCRIPTION: -- Declare a protected object which simulates a disk device. Declare an -- entry that requeues the caller to a second entry if the disk head is -- not in the proper location, but first sets the second entry's barrier -- to false. Declare a procedure which sets the second entry's barrier -- to true. -- -- Declare a task which calls the first entry such that the requeue is -- called. This task should be queued on the second entry and remain -- blocked, and the first entry should be complete. Call the procedure -- which releases the second entry's queue. The second entry should -- complete, after which the task should complete. -- -- -- CHANGE HISTORY: -- 06 Dec 94 SAIC ACVC 2.0 -- --! package C954001_0 is -- Disk management abstraction. -- Simulate a read-only disk device with a head that may be moved to -- different tracks. If a read request is issued for the current -- track, the request can be satisfied immediately. Otherwise, the head -- must be moved to the correct track, during which time the calling task -- is blocked. When the head reaches the correct track, the disk generates -- an interrupt, after which the request can be satisfied, and the -- calling task can proceed. Buffer_Size : constant := 100; type Disk_Buffer is new String (1 .. Buffer_Size); type Disk_Track is new Natural; type Disk_Address is record Track : Disk_Track; -- Additional components. end record; Initial_Track : constant Disk_Track := 0; New_Track : constant Disk_Track := 5; --==============================================-- protected Disk_Device is entry Read (Where : Disk_Address; -- Read data from disk Data : out Disk_Buffer); -- track. procedure Disk_Interrupt; -- Handle interrupt -- from disk. function TC_Track return Disk_Track; -- Return current track. function TC_Pending_Queued return Boolean; -- True when there is -- an entry in queue private entry Pending_Read (Where : Disk_Address; -- Wait for head to Data : out Disk_Buffer); -- move then read data. Current_Track : Disk_Track := Initial_Track; -- Current disk track. Operation_Pending : Boolean := False; -- Vis. entry barrier. Disk_Interrupted : Boolean := False; -- Priv. entry barrier. end Disk_Device; end C954001_0; --==================================================================-- package body C954001_0 is -- Disk management abstraction. protected body Disk_Device is entry Read (Where : Disk_Address; Data : out Disk_Buffer) when not Operation_Pending is begin if (Where.Track = Current_Track) then -- If the head is over the -- Read data from disk... -- requested track, read null; -- the data. else -- Otherwise, defer read Operation_Pending := True; -- while head is moved to -- correct track (signaled -- -- -- by a disk interrupt). -- Requeue is tested here -- -- -- requeue Pending_Read; end if; end Read; procedure Disk_Interrupt is -- Called when the disk begin -- interrupts, indicating Disk_Interrupted := True; -- that the head is over end Disk_Interrupt; -- the correct track. function TC_Track return Disk_Track is -- Artifice required for begin -- testing purposes. return (Current_Track); end TC_Track; entry Pending_Read (Where : Disk_Address; Data : out Disk_Buffer) when Disk_Interrupted is begin Current_Track := Where.Track; -- Head is now over the -- Read data from disk... -- correct track; read Operation_Pending := False; -- the data. Disk_Interrupted := False; end Pending_Read; function TC_Pending_Queued return Boolean is begin -- Return true when there is something on the Pending_Read queue return (Pending_Read'Count /=0); end TC_Pending_Queued; end Disk_Device; end C954001_0; --==================================================================-- with Report; with ImpDef; with C954001_0; -- Disk management abstraction. use C954001_0; procedure C954001 is task type Read_Task is -- an unusual (but legal) declaration end Read_Task; -- -- task body Read_Task is Location : constant Disk_Address := (Track => New_Track); Data : Disk_Buffer := (others => ' '); begin Disk_Device.Read (Location, Data); -- Invoke requeue statement. exception when others => Report.Failed ("Exception raised in task"); end Read_Task; --==============================================-- begin -- Main program. Report.Test ("C954001", "Requeue from an entry within a P.O. " & "to a private entry within the same P.O."); declare IO_Request : Read_Task; -- Request a read from other -- than the current track. -- IO_Request will be requeued -- from Read to Pending_Read. begin -- To pass this test, the following must be true: -- -- (A) The Read entry call made by the task IO_Request must be -- completed by the requeue. -- (B) IO_Request must remain blocked following the requeue. -- (C) IO_Request must be queued on the Pending_Read entry queue. -- (D) IO_Request must continue execution after the Pending_Read -- entry completes. -- -- First, verify (A): that the Read entry call is complete. -- -- Call a protected operation (Disk_Device.TC_Track). Since no two -- protected actions may proceed concurrently unless both are protected -- function calls, a call to a protected operation at this point can -- proceed only if the Read entry call is already complete. -- -- Note that if Read is NOT complete, the test will likely hang here. -- -- Next, verify (B): that IO_Request remains blocked following the -- requeue. Also verify that Pending_Read (the entry to which -- IO_Request should have been queued) has not yet executed. -- Wait until the task had made the call and the requeue has been -- effected. while not Disk_Device.TC_Pending_Queued loop delay ImpDef.Minimum_Task_Switch; end loop; if Disk_Device.TC_Track /= Initial_Track then Report.Failed ("Target entry of requeue executed prematurely"); elsif IO_Request'Terminated then Report.Failed ("Caller did not remain blocked after " & "the requeue or was never requeued"); else -- Verify (C): that IO_Request is queued on the -- Pending_Read entry queue. -- -- Set the barrier for Pending_Read to true. Check that the -- current track is updated and that IO_Request terminates. Disk_Device.Disk_Interrupt; -- Simulate a disk interrupt, -- signaling that the head is -- over the correct track. -- The Pending_Read entry body will complete before the next -- protected action is called (Disk_Device.TC_Track). if Disk_Device.TC_Track /= New_Track then Report.Failed ("Caller was not requeued on target entry"); end if; -- Finally, verify (D): that Read_Task continues after Pending_Read -- completes. -- -- Note that the test will hang here if Read_Task does not continue -- executing following the completion of the requeued entry call. end if; end; -- We will not exit the declare block until the task completes Report.Result; end C954001;