US 9,003,377 B2Granted

Efficient resumption of co-routines on a linear stack

AssigneeMicrosoft Technology Licensing, LLC

InventorsNeal M. Gafter, Mads Torgersen, Henricus Johannes Maria Meijer, Niklas Gustafsson

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Abstract

Unsuspended co-routines are handled by the machine call stack mechanism in which the stack grows and shrinks as recursive calls are made and returned from. When a co-routine is suspended, however, additional call stack processing is performed. A suspension message is issued, and the entire resume-able part of the call stack is removed, and is copied to the heap. A frame that returns control to a driver method (a resumer) is copied to the call stack so that resumption of the co-routine does not recursively reactivate the whole call stack. Instead the resumer reactivates only the topmost or most current frame called the leaf frame. When a co-routine is suspended, it does not return to its caller, but instead returns to the resumer that has reactivated it.

Claims20

Dependent claims

A system comprising:

a processor and a memory including a module configured to cause the processor to:
suspend and resume co-routines comprising a calling co-routine and a called co-routine in a computer environment utilizing a single linear machine call stack not inherently capable of suspending and resuming co-routines, wherein only in response to detecting suspension of the called co-routine, the module:
saves a resume-able portion of the single linear machine call stack not previously saved to a heap that emulates the single linear machine call stack but is separate from the single linear machine call stack such that the resume-able portion of the single linear machine call stack is only copied to the heap once, the resume-able portion of the single linear machine call stack comprising a stack frame for the calling co-routine, a stack frame for the called co-routine and a stack frame for a resumer;
removes the resume-able portion of the single linear machine call stack from the single linear machine call stack;
places a return address for a resumer that controls co-routine execution on the single linear machine call stack so that when the called co-routine is suspended it does not return to the calling co-routine but instead returns to the resumer;
and in response to detecting resumption of the called co-routine:
copies only the stack frame for the called co-routine onto the single linear machine call stack without copying all of the resume-able portion of the single linear machine call stack onto the single linear machine call stack.

4 more elements

A method comprising:

suspending and resuming co-routines comprising a calling co-routine and a called co-routine in a computer environment utilizing a single linear machine call stack not inherently capable of suspending and resuming co-routines, wherein only in response to detecting suspension of the called co-routine, the computer environment:
saving a resume-able portion of the single linear machine call stack not previously saved to a heap that emulates the single linear machine call stack but is separate from the single linear machine call stack such that the resume-able portion of the single linear machine call stack is only copied to the heap once, the resume-able portion of the single linear machine call stack comprising a stack frame for the calling co-routine, a stack frame for the called co-routine and a stack frame for a resumer;
removing the resume-able portion of the single linear machine call stack from the single linear machine call stack;
placing a return address for a resumer that controls co-routine execution on the single linear machine call stack so that when the called co-routine is suspended it does not return to the calling co-routine but instead returns to the resumer;
and in response to detecting resumption of the called co-routine:
copying only the stack frame for the called co-routine onto the single linear machine call stack without copying all of the resume-able portion of the single linear machine call stack onto the single linear machine call stack.

3 more elements

A hardware memory, comprising computer-executable instructions which when executed cause at least one processor to:

suspend and resume co-routines comprising a calling co-routine and a called co-routine in a computer environment utilizing a single linear machine call stack not inherently capable of suspending and resuming co-routines, wherein only in response to detecting suspension of the called co-routine, the processor:
saves a resume-able portion of the single linear machine call stack not previously saved to a heap that emulates the single linear machine call stack but is separate from the single linear machine call stack such that the resume-able portion of the single linear machine call stack is only copied to the heap once, the resume-able portion of the single linear machine call stack comprising a stack frame for the calling co-routine, a stack frame for the called co-routine and a stack frame for a resumer;
removes the resume-able portion of the single linear machine call stack from the single linear machine call stack;
places a return address for a resumer that controls co-routine execution on the single linear machine call stack so that when the called co-routine is suspended it does not return to the calling co-routine but instead returns to the resumer;
and in response to detecting resumption of the called co-routine:
copies only the stack frame for the called co-routine onto the single linear machine call stack without copying all of the resume-able portion of the single linear machine call stack onto the single linear machine call stack.

3 more elements

Dependencies are inferred from the claim text.