Method and system for synchronizing the execution of a critical code section

• US 20100011372A1
• Filed: 12/12/2008
• Published: 01/14/2010
• Est. Priority Date: 07/09/2008
• Status: Abandoned Application

• Current Assignee: Software AG
• Original Assignee: Software AG
• Inventors: Trensch, Guido
• Application Number:
  US12/314,608
• Publication Number:
  US 20100011372A1
• Time in Patent Office: Days
• US Class Current: 718/107
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

The invention concerns a method for synchronizing the execution of at least one critical code section (C1) by at least one of a plurality of concurrent tasks (S1, Sn) of an application (4), the application (4) running on an operating system (5) providing cooperative multitasking, the critical code section (C1) being restricted to execution by only a limited number of the plurality of tasks (S1, Sn), the method comprising at least the following steps performed by at least one of the tasks (S1, Sn):

• • a. testing (F11) at least one variable (Mx) associated to the at least one critical code section (C1) and setting (F12) the variable (Mx) and entering the associated critical code section (C1), if the variable (Mx) is not set by another task (S1, Sn), or, waiting (F13) for a release (F22) by another task (S1, Sn) and releasing the CPU, if the variable (Mx) is already set by another task (S1, Sn); and
  • b. resetting (F21) the variable (Mx) and releasing (F22) at least one of the other waiting tasks (S1, Sn) when leaving the critical code section (C1);
  • c. wherein step a. is performed as an atomic function (F1).

Claims

1. A method for synchronizing the execution of at least one critical code section (C1) by at least one of a plurality of concurrent tasks (S1, Sn) of an application (4), the application (4) running on an operating system (5) providing cooperative multitasking, the critical code section (C1) being restricted to execution by only a limited number of the plurality of tasks (S1, Sn), the method comprising at least the following steps performed by at least one of the tasks (S1, Sn):

a. testing (F11) at least one variable (Mx) associated to the at least one critical code section (C1) and setting (F12) the variable (Mx) and entering the associated critical code section (C1), if the variable (Mx) is not set by another task (S1, Sn), or, waiting (F13) for a release (F22) by another task (S1, Sn) and releasing a CPU, if the variable (Mx) is already set by another task (S1, Sn); and

b. resetting (F21) the variable (Mx) and releasing (F22) at least one of 20 the other waiting tasks (S1, Sn) when leaving the critical code section (C1);

c. wherein step a. is performed as an atomic function (F1).

2. The method of claim 1, wherein the step of releasing (F22) at least one of the other waiting tasks (S1, Sn) comprises the step of informing the operating system (5) that the critical code section (C1) is available for other tasks (S1, Sn).

3. The method of claim 1, wherein a plurality of variables (M0, M1, Mx) is associated to the at least one critical code section (C1) and the method further comprises the step of:

c. testing (F31) each of the plurality of variables (M0, M1, Mx) and, if one of the variables (M0, M1, Mx) is not set by another task (S1, Sn), performing the atomic step a. on this variable, or, if all of the variables (M0, M1, Mx) are already set by other tasks (S1, Sn), performing the atomic step a. on any (F32) of the plurality of variables (M0, M1, Mx).

4. The method of claim 1, wherein the operating system (5) comprises a runtime environment adapted for running only one task of the application (4), and wherein each of the tasks (S1, Sn) is attached to an instance of the runtime environment (51, 51′

).

5. The method of claim 1, wherein the application (4) is programmed in C and the operating system (5) is adapted for running C-programs.

6. The method of claim 1, wherein the operating system (5) is z/VSE, wherein the variables (M0, M1, Mx) are mapped onto resource control blocks and wherein step a. is performed by the assembler macro ENQ of the z/VSE system.

7. The method of claim 1, wherein step b. is performed by the assembler macro DEQ of the z/VSE system.

8. A computer program comprising instructions adapted for implementing a method according to claim 1.

9. A system for synchronizing the execution of at least one critical code section (C1) by at least one of a plurality of concurrent tasks (S1, Sn) of an application (4), the application (4) running on an operating system (5) providing cooperative multitasking of a CPU, the critical code section (C1) being restricted to execution by only a limited number of the plurality of tasks (S1, Sn), the system comprising:

a. a first function (F1) adapted for being called by at least one of the tasks (S1, Sn), the first atomic function (F1) being further adapted for testing (F11) at least one variable (Mx) associated to the at least one critical code section (C1) and, if the variable (Mx) is not set, setting (F12) the variable (Mx) and granting access for the task (S1, Sn) to the associated critical code section (C1), or, if the variable (Mx) is already set by another task (S1, Sn), forcing the calling task (S1, Sn) to wait (F13) for being released (F22) by another task (S1, Sn) and to release the CPU; and

b. a second function (F2) adapted for being called by at least one of the tasks (S1, Sn), the second atomic function (F2) being further adapted for resetting (F21) the variable (Mx) and releasing (F22) at least one other waiting task (S1, Sn) when the calling task (S1, Sn) is leaving the critical code section (C1);

c. wherein the first function is atomic.

10. The system of claim 9, wherein the second atomic function (F2) is further adapted for informing the operating system (5) that the critical code section (C1) is available for other tasks (S1, Sn).

11. The system of claim 9, wherein a plurality of variables (M0, M1, Mx) is associated to the at least one critical code section (C1) and the system further comprises a function adapted for testing (F31) each of the plurality of variables (M0, M1, Mx) and, if one of the variables (M0, M1, Mx) is not set, performing the first atomic function (F1) on this variable, or if all of the variables (M0, M1, Mx) are already set, performing the first atomic function (F1) on any (F32) of the plurality of variables (M0, M1, Mx).

12. The system of claim 9, wherein the operating system (5) comprises a runtime environment adapted for running only one task of the application (4), and wherein each of the tasks (S1, Sn) is attached to an instance of the runtime environment (51, 51′

).

13. The system of claim 9, wherein the application (4) is programmed in C and the operating system (5) is adapted for running C-programs.

14. The system of claim 9, wherein the operating system (5) is z/VSE, wherein the variables (M0, M1, Mx) are mapped onto resource control blocks and wherein the first atomic function (F1) is adapted for calling the assembler macro ENQ of the z/VSE system.

15. The system of claim 14, wherein the second function (F2) is adapted for calling the assembler macro DEQ of the z/VSE system.