DUAL-BUFFER SERIALIZATION AND CONSUMPTION OF VARIABLE-LENGTH DATA RECORDS PRODUCED BY MULTIPLE PARALLEL THREADS

• US 20140237145A1
• Filed: 02/20/2013
• Published: 08/21/2014
• Est. Priority Date: 02/20/2013
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Mints, Vitali
• Granted Patent: US 9,250,858 B2
• Time in Patent Office: Days
• US Class Current: 710/53
• CPC Class Codes: G06F 2205/106 Details of pointers, i.e. structure of the address generators
• CPC Class Codes: G06F 2205/126 Monitoring of intermediate fill level, i.e. with additional means for monitoring the fill level, e.g. half full flag, almost empty flag
• CPC Class Codes: G06F 5/10 having a sequence of storage locations each being individually accessible for both enqueue and dequeue operations, e.g. using random access memory G06F5/065 takes precedence
• CPC Class Codes: G06F 5/12 Means for monitoring the fill level; Means for resolving contention, i.e. conflicts between simultaneous enqueue and dequeue operations

Abstract

Under control of the consumer, it is determined that a first buffer is empty and that a second buffer contains data; a first compare-double-and-swap operation within a spin loop is executed to swap a double pointer of the first buffer and a double pointer of the second buffer, wherein responsive to the executing of the operation the consumer drains the second buffer, and wherein the executing of the operation directs the at least one producer to fill the first buffer; and it is determined that the first buffer and the second buffer are empty and the consumer waits for a notification from one of i) the at least one producer and ii) a timer. Under control of the at least one producer, a second compare-double-and-swap operation within a spin loop is executed to atomically locate the first buffer and update the double pointer of the first buffer.

Claims

1. A method, comprising:

under control of a consumer;

determining, with a processor of a computer, that a first buffer is empty and that a second buffer contains data, wherein the first buffer has a double-pointer, and wherein the second buffer has a double pointer;

executing a first compare-double-and-swap operation within a spin loop, wherein the executing includes swapping the double pointer of the first buffer and the double pointer of the second buffer, wherein responsive to the executing of the operation the consumer drains the second buffer, and wherein the executing of the operation directs at least one producer to fill the first buffer; and

determining that the first buffer and the second buffer are empty and responsively waiting for a notification from one of i) the at least one producer and ii) a timer; and

under control of the at least one producer;

executing a second compare-double-and-swap operation within a spin loop, wherein executing the second compare-double-and-swap operation includes atomically locating the first buffer and updating the double pointer of the first buffer to reserve a slot for a data record in the first buffer.

2. The method of claim 1, wherein the double pointer of the first buffer has one pointer containing an address of the first buffer and another pointer containing a size of filled area in the first buffer.

3. The method of claim 1, wherein the double pointer of the second buffer has one pointer containing an address of the second buffer and another pointer containing a size of filled area in the second buffer.

4. The method of claim 1, wherein the consumer and the at least one producer share the first buffer and the second buffer without using lock requests.

5. The method of claim 1, wherein the consumer sets an indicator to indicate that the second buffer is drained and further comprising:

executing a third compare-double-and-swap operation within a spin loop to swap the double pointer of the second buffer and the double pointer of the first buffer to direct the consumer to drain the first buffer and the at least one producer to fill the second buffer.

6. The method of claim 1, wherein the consumer is configured with a wait timer to become idle for a period of time.

7. The method of claim 1, wherein the at least one producer is configured with a condition controlling a frequency of issuing POST operations to the consumer to notify the consumer that one of the first buffer and the second buffer contains data.

8. A computer program product, the computer program product comprising:

a computer readable storage medium having computer readable program code embodied therein, the computer readable program code, when executed by a processor of a computer, is configured to perform;

under control of a consumer;

determining, with a processor of a computer, that a first buffer is empty and that a second buffer contains data, wherein the first buffer has a double-pointer, and wherein the second buffer has a double pointer;

executing a first compare-double-and-swap operation within a spin loop, wherein the executing includes swapping the double pointer of the first buffer and the double pointer of the second buffer, wherein responsive to the executing of the operation the consumer drains the second buffer, and wherein the executing of the operation directs at least one producer to fill the first buffer; and

determining that the first buffer and the second buffer are empty and responsively waiting for a notification from one of i) the at least one producer and ii) a timer; and

under control of the at least one producer;

executing a second compare-double-and-swap operation within a spin loop, wherein executing the second compare-double-and-swap operation includes atomically locating the first buffer and updating the double pointer of the first buffer to reserve a slot for a data record in the first buffer.

9. The computer program product of claim 8, wherein the double pointer of the first buffer has one pointer containing an address of the first buffer and another pointer containing a size of filled area in the first buffer.

10. The computer program product of claim 8, wherein the double pointer of the second buffer has one pointer containing an address of the second buffer and another pointer containing a size of filled area in the second buffer.

11. The computer program product of claim 8, wherein the consumer and the at least one producer share the first buffer and the second buffer without using lock requests.

12. The computer program product of claim 8, wherein the consumer sets an indicator to indicate that the second buffer is drained and the computer readable program code, when executed by the processor of the computer, is configured to perform:

executing a third compare-double-and-swap operation within a spin loop to swap the double pointer of the second buffer and the double pointer of the first buffer to direct the consumer to drain the first buffer and the at least one producer to fill the second buffer.

13. The computer program product of claim 8, wherein the consumer is configured with a wait timer to become idle for a period of time.

14. The computer program product of claim 8, wherein the at least one producer is configured with a condition controlling a frequency of issuing POST operations to the consumer to notify the consumer that one of the first buffer and the second buffer contains data.

15. A computer system, comprising:

a processor; and

a storage device coupled to the processor, wherein the storage device has stored thereon a program, and wherein the processor is configured to execute instructions of the program to perform operations, wherein the operations comprise;

under control of a consumer;

determining, with a processor of a computer, that a first buffer is empty and that a second buffer contains data, wherein the first buffer has a double-pointer, and wherein the second buffer has a double pointer;

executing a first compare-double-and-swap operation within a spin loop, wherein the executing includes swapping the double pointer of the first buffer and the double pointer of the second buffer, wherein responsive to the executing of the operation the consumer drains the second buffer, and wherein the executing of the operation directs at least one producer to fill the first buffer; and

determining that the first buffer and the second buffer are empty and responsively waiting for a notification from one of i) the at least one producer and ii) a timer; and

under control of the at least one producer;

executing a second compare-double-and-swap operation within a spin loop, wherein executing the second compare-double-and-swap operation includes atomically locating the first buffer and updating the double pointer of the first buffer to reserve a slot for a data record in the first buffer.

16. The computer system of claim 15, wherein the double pointer of the first buffer has one pointer containing an address of the first buffer and another pointer containing a size of filled area in the first buffer.

17. The computer system of claim 15, wherein the double pointer of the second buffer has one pointer containing an address of the second buffer and another pointer containing a size of filled area in the second buffer.

18. The computer system of claim 15, wherein the consumer and the at least one producer share the first buffer and the second buffer without using lock requests.

19. The computer system of claim 15, wherein the consumer sets an indicator to indicate that the second buffer is drained and wherein the operations further comprise:

executing a third compare-double-and-swap operation within a spin loop to swap the double pointer of the second buffer and the double pointer of the first buffer to direct the consumer to drain the first buffer and the at least one producer to fill the second buffer.

20. The computer system of claim 15, wherein the consumer is configured with a wait timer to become idle for a period of time.

21. The computer system of claim 15, wherein the at least one producer is configured with a condition controlling a frequency of issuing POST operations to the consumer to notify the consumer that one of the first buffer and the second buffer contains data.