Shared lease instruction support for transient blocking synchronization
View Patent ↗A computer system implementing transient blocking synchronization allows a memory location leased by a first process to be read-accessible to another process. In other words, more than one thread may have read-only type leases on a given memory location at a given time. Such “shared” leases expire when respective lease periods of the shared leases elapse.
1. A method of performing computer system operations, comprising:
obtaining a shared lease to a first memory location in a shared memory, wherein the shared lease is for a first predetermined period of time, and wherein an exclusive bit associated with the shared lease is not set;
extending the shared lease to the first memory location for a second predetermined amount of time;
setting the exclusive bit responsive to an attempt to obtain an exclusive lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
denying the attempt to obtain the exclusive lease;
attempting to extend the shared lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
denying the attempt to extend the shared lease when the exclusive bit associated with the shared lease is set; and
releasing the shared lease after the second predetermined amount of time.
2. A shared-memory multiprocessor computer system having instructions for synchronizing operations on memory, the instructions comprising instructions to:
obtain a shared lease to a first memory location in a shared memory, wherein the shared lease is for a first predetermined period of time, and wherein an exclusive bit associated with the shared lease is not set;
extend the shared lease to the first memory location for a second predetermined amount of time;
set the exclusive bit responsive to an attempt to obtain an exclusive lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
deny the attempt to obtain the exclusive lease;
attempt to extend the shared lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
deny the attempt to extend the shared lease when the exclusive bit associated with the shared lease is set; and
release the shared lease after the second predetermined amount of time.
3. A computer system, comprising:
at least one processor;
a shared memory operatively connected to the at least one processor and comprising at least a first memory location and a second memory location shared by a plurality of processes; and
a controller configured to:
obtain a shared lease to the first memory location for a first predetermined period of time,
wherein a first value in the first memory location is used to calculate a second value,
wherein the second value is stored in the second memory location, and
wherein an exclusive bit associated with the shared lease is not set;
extend the shared lease to the first memory location for a second predetermined amount of time;
set the exclusive bit responsive to an attempt to obtain an exclusive lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
deny the attempt to obtain the exclusive lease;
attempt to extend the shared lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
deny the attempt to extend the shared lease when the exclusive bit associated with the shared lease is set; and
release the shared lease after the second predetermined amount of time.