Intercepting I/O multiplexing operations involving cross-domain file descriptor sets

• US 6,732,211 B1
• Filed: 09/18/2000
• Issued: 05/04/2004
• Est. Priority Date: 09/18/2000
• Status: Expired due to Fees

• Current Assignee: Cufer Asset Ltd LLC (Intellectual Ventures LLC)
• Original Assignee: Ensim Corporation (Techstep ASA)
• Inventors: Huang, Xun Wilson, Gylfason, Snorri, Sharma, Rosen, Goyal, Pawan, Keshav, Srinivasan
• Primary Examiner(s): Myers, Paul R.
• Application Number:
  US09/664,914
• Time in Patent Office: 1,324 Days
• Field of Search: 710/261, 710/266, 707/200, 707/1, 707/9, 707/10
• US Class Current: 710/261
• CPC Class Codes: G06F 2209/542 Intercept
• CPC Class Codes: G06F 9/468 Specific access rights for resources, e.g. using capability register
• CPC Class Codes: G06F 9/545 where tasks reside in different layers, e.g. user- and kernel-space

Abstract

An I/O multiplexing operation involving a cross-domain file descriptor set is intercepted. The cross-domain set is divided into a first subset corresponding to a first file type and a second subset corresponding to a second file type. System calls are initiated in parallel for performing separate I/O multiplexing operations on the first and second subsets of file descriptors. In response to one of the parallel system calls identifying at least one file descriptor ready for communication, the other parallel system call is unblocked. Sets of file descriptors identified as ready for communication by the parallel system calls are combined and returned to a calling process.

Claims

1. A method in a computer system for executing I/O multiplexing operations comprising:

intercepting a system call for performing an I/O multiplexing operation on a set of file descriptors;

initiating system calls in parallel for performing separate I/O multiplexing operations on a first subset and a second subset of the set of file descriptors;

in response to one of the parallel system calls identifying at least one file descriptor ready for communication, unblocking the other parallel system call; and

returning to a calling process an indication of the at least one file descriptor.

2. The method of claim 1, wherein initiating system calls comprises:

dividing the set of file descriptors into a first subset corresponding to a first file type and a second subset corresponding to a second file type.

3. The method of claim 2, wherein one of the file types identifies a communication channel.

4. The method of claim 3, wherein one of the file types identifies a file stored on media.

5. The method of claim 4, wherein one of the file types identifies a hardware device.

6. The method of claim 1, wherein intercepting a system call comprises:

loading a system call wrapper into an operating system;

saving a pointer to the system call; and

replacing the pointer to the system call with a pointer to the system call wrapper.

7. The method of claim 6, wherein the pointer to the system call comprises an interrupt vector.

8. The method of claim 1, wherein dividing the set of file descriptors comprises:

disambiguating the set of file descriptors according to file type.

9. The method of claim 8, wherein an association data structure stores associations between file descriptors and file types, and wherein disambiguating the set of file descriptors comprises:

identifying, for each file descriptor, a file type from an association therewith in the association data structure.

10. The method of claim 8, wherein disambiguating the set of file descriptors comprises:

intercepting system calls that establish a file descriptor; and

storing an association between an established file descriptor and a file type.

11. The method of claim 1, wherein initiating system calls comprises:

executing a first system call using a first process, the first system call for initiating an I/O multiplexing operation on the first subset of file descriptors; and

executing a second system call using a second process, the second system call for initiating an I/O multiplexing operation on the second subset of file descriptors.

12. The method of claim 11, wherein initiating system calls further comprises:

establishing a connection between the first and second processes.

13. The method of claim 12, wherein establishing a connection comprises:

opening a communication channel between the first and second processes, the communication channel identified by a virtual file descriptor.

14. The method of claim 13, wherein initiating system calls further comprises:

adding the virtual file descriptor to the first and second subsets of file descriptors.

15. The method of claim 14, wherein unblocking the other parallel system call comprises:

performing a read operation using the virtual file descriptor.

16. The method of claim 14, wherein unblocking the other parallel system call comprises:

performing a write operation using the virtual file descriptor.

17. The method of claim 1, wherein returning to a calling process comprises:

returning to a calling process an indication of at least one file descriptor identified by the other parallel system call as ready for communication.

18. An method in a computer system for executing I/O multiplexing operations comprising:

intercepting a system call by a system call wrapper, the system call for performing an I/O multiplexing operation on a set of file descriptors;

establishing a connection between the system call wrapper and a functional module;

dividing the set of file descriptors into a first subset corresponding to a first file type and a second subset corresponding to a second file type;

initiating a first system call by the system call wrapper for performing an I/O multiplexing operation on the first subset of file descriptors;

initiating in parallel a second system call by the functional module for performing an I/O multiplexing operation on the second subset of file descriptors;

combining sets of file descriptors identified by the first and second system calls as ready for communication into a third subset; and

returning to a calling process the third subset of file descriptors.

19. The method of claim 18, further comprising:

in response to the first system call identifying at least one file descriptor ready for communication, unblocking the second system call.

20. The method of claim 19, wherein unblocking the second system call comprises:

performing an I/O operation via the connection.

21. A computer program product for executing I/O multiplexing operations comprising:

program code for intercepting a system call for performing an I/O multiplexing operation on a set of file descriptors;

program code for initiating system calls in parallel for performing separate I/O multiplexing operations on a first subset and a second subset of the set of file descriptors;

program code for, in response to one of the parallel system calls identifying at least one file descriptor ready for communication, unblocking the other parallel system call; and

program code for returning to a calling process an indication of the at least one file descriptor.

22. The computer program product of claim 21, wherein program code for initiating system calls comprises:

program code for dividing the set of file descriptors into a first subset corresponding to a first file type and a second subset corresponding to a second file type.

23. The computer program product of claim 22, wherein one of the file types identifies a communication channel.

24. The computer program product of claim 23, wherein one of the file types identifies a file stored on media.

25. The computer program product of claim 24, wherein one of the file types identifies a hardware device.

26. The computer program product of claim 21, wherein program code for intercepting a system call comprises:

program code for loading a system call wrapper into an operating system;

program code for saving a pointer to the system call; and

program code for replacing the pointer to the system call with a pointer to the system call wrapper.

27. The computer program product of claim 26, wherein the pointer to the system call comprises an interrupt vector.

28. The computer program product of claim 21, wherein program code for dividing the set of file descriptors comprises:

program code for disambiguating the set of file descriptors according to file type.

29. The computer program product of claim 28, wherein an association data structure stores associations between file descriptors and file types, and wherein program code for disambiguating the set of file descriptors comprises:

program code for identifying, for each file descriptor, a file type from an association therewith in the association data structure.

30. The computer program product of claim 28, wherein program code for disambiguating the set of file descriptors comprises:

program code for intercepting system calls that establish a file descriptor; and

program code for storing an association between an established file descriptor and a file type.

31. The computer program product of claim 21, wherein program code for initiating system calls comprises:

program code for executing a first system call using a first process, the first system call for initiating an I/O multiplexing operation on the first subset of file descriptors; and

program code for executing a second system call using a second process, the second system call for initiating an I/O multiplexing operation on the second subset of file descriptors.

32. The computer program product of claim 31, wherein program code for initiating system calls further comprises:

program code for establishing a connection between the first and second processes.

33. The computer program product of claim 32, wherein program code for establishing a connection comprises:

program code for opening a communication channel between the first and second processes, the communication channel identified by a virtual file descriptor.

34. The computer program product of claim 33, wherein program code for initiating system calls further comprises:

program code for adding the virtual file descriptor to the first and second subsets of file descriptors.

35. The computer program product of claim 34, wherein program code for unblocking the other parallel system call comprises:

program code for performing a read operation using the virtual file descriptor.

36. The computer program product of claim 34, wherein program code for unblocking the other parallel system call comprises:

program code for performing a write operation using the virtual file descriptor.

37. The computer program product of claim 21, wherein program code for returning to a calling process comprises:

program code for returning to a calling process an indication of at least one file descriptor identified by the other parallel system call as ready for communication.

38. An computer program product for executing I/O multiplexing operations comprising:

program code for intercepting a system call by a system call wrapper, the system call for performing an I/O multiplexing operation on a set of file descriptors;

program code for establishing a connection between the system call wrapper and a functional module;

program code for dividing the set of file descriptors into a first subset corresponding to a first file type and a second subset corresponding to a second file type;

program code for initiating a first system call by the system call wrapper for performing an I/O multiplexing operation on the first subset of file descriptors;

program code for initiating in parallel a second system call by the functional module for performing an I/O multiplexing operation on the second subset of file descriptors;

program code for combining sets of file descriptors identified by the first and second system calls as ready for communication into a third subset; and

program code for returning to a calling process the third subset of file descriptors.

39. The computer program product of claim 38, further comprising:

program code for, in response to the first system call identifying at least one file descriptor ready for communication, unblocking the second system call.

40. The computer program product of claim 39, wherein program code for unblocking the second system call comprises:

program code for performing an I/O operation via the connection.

41. A system for executing I/O multiplexing operations comprising:

a system call wrapper configured to intercept a system call for performing an I/O multiplexing operation on a set of file descriptors and to initiate a first system call for performing an I/O multiplexing operation on a first subset of the set of file descriptors; and

a functional module, in communication with the system call wrapper, configured to initiate in parallel a second system call for performing a separate I/O multiplexing operation on a second subset of the set of file descriptors.

42. The system of claim 41, wherein at least one of the file types is selected from the group consisting of a file stored on media, a communication channel, and a hardware device.

43. The system of claim 41, wherein the system call wrapper and the functional module comprise separate processes.

44. The system of claim 41, wherein a private connection links the system call wrapper and the functional module, the private connection being identified by a virtual file descriptor.

45. The system of claim 44, wherein the first and second subsets of file descriptors include the virtual file descriptor.