Coherence protocol for distributed caches
The disclosure provides for a reactive cache coherence protocol that has efficiencies over proactive approaches. Rather than proactively performing remediation when a data item is invalidated, a destination endpoint checks cache coherence upon receiving an indication of a cache hit, and based at least on detecting a lack of coherence, performs a reactive remediation process. For example, the incoherence may be fixed by replacing, as a cached data item, a data block indicated by the cache hit with a replacement data block that triggered the cache hit.
1. A method for maintaining cache coherence, the method comprising:
receiving, at a destination endpoint, an indication of a cache hit from a teleporter;
based at least on receiving the indication of the cache hit, checking cache coherence; and
based at least on detecting a lack of coherence, performing a reactive remediation process using a data block in a first destination storage location.
2. The method of claim 1 , wherein the reactive remediation process comprises:
replacing, as a cached data item, a data block indicated by the cache hit with a replacement data block that triggered the cache hit.
3. The method of claim 1 , wherein receiving, at the destination endpoint, the indication of the cache hit from the teleporter comprises:
receiving, from the teleporter, a data hash value and a matching block location; and
wherein checking cache coherence comprises:
generating a check hash value for a data block found at the matching block location; and
comparing the check hash value with the data hash value.
4. The method of claim 3 , wherein the data hash value comprises a 256-bit hash.
5. The method of claim 3 , wherein the check hash value comprises a 256-bit hash.
6. The method of claim 3 , further comprising:
based at least on the check hash value matching the data hash value, copying the data block found at the matching block location to a second destination storage location; and
based at least on the check hash value not matching the data hash value, copying a data block received from a source endpoint to the second destination storage location.
7. The method of claim 3 , wherein the remediation process comprises:
promoting the data hash value from a short-term cache to a long-term cache.
8. A computer system for maintaining cache coherence, the computer system comprising:
a teleporter configured to indicate a cache hit;
a first destination storage location; and
a destination endpoint coupled to the teleporter and the first destination storage location, the destination endpoint configured to:
based at least on receiving an indication of the cache hit from the teleporter, check cache coherence; and
based at least on detecting a lack of coherence, perform a reactive remediation process using a data block in the first destination storage location.
9. The computer system of claim 8 , wherein the remediation process comprises:
replacing, as a cached data item, a data block indicated by the cache hit with a replacement data block that triggered the cache hit.
10. The computer system of claim 8 , wherein receiving, at the destination endpoint, the indication of the cache hit from the teleporter comprises:
receiving, from the teleporter, a data hash value and a matching block location; and
wherein checking cache coherence comprises:
generating a check hash value for a data block found at the matching block location; and
comparing the check hash value with the data hash value.
11. The computer system of claim 10 , wherein the data hash value comprises a 256-bit hash.
12. The computer system of claim 10 , wherein the check hash value comprises a 256-bit hash.
13. The computer system of claim 10 , wherein the destination endpoint is further configured to:
based at least on the check hash value matching the data hash value, copy the data block found at the matching block location to a second destination storage location; and
based at least on the check hash value not matching the data hash value, copy a data block received from a source endpoint to the second destination storage location.
14. The computer system of claim 10 , wherein the remediation process comprises:
promoting the data hash value from a short-term cache to a long-term cache.
15. A non-transitory computer storage medium having computer-executable instructions that, upon execution by a processor, cause the processor to at least perform operations to maintain cache coherence, the operations comprising:
receiving, at a destination endpoint, an indication of a cache hit from a teleporter;
based at least on receiving the indication of the cache hit, checking cache coherence; and
based at least on detecting a lack of coherence, performing a reactive remediation process using a data block in a first destination storage location.
16. The non-transitory computer storage medium of claim 15 , wherein the remediation process comprises:
replacing, as a cached data item, a data block indicated by the cache hit with a replacement data block that triggered the cache hit.
17. The non-transitory computer storage medium of claim 15 , wherein receiving, at the destination endpoint, the indication of the cache hit from the teleporter comprises:
receiving, from the teleporter, a data hash value and a matching block location; and
wherein checking cache coherence comprises:
generating a check hash value for a data block found at the matching block location; and
comparing the check hash value with the data hash value.
18. The non-transitory computer storage medium of claim 17 , wherein the data hash value comprises a 256-bit hash, and wherein the check hash value comprises a 256-bit hash.
19. The non-transitory computer storage medium of claim 17 , wherein the computer-executable instructions further cause the processor to perform operations comprising:
based at least on the check hash value matching the data hash value, copying the data block found at the matching block location to a second destination storage location; and
based at least on the check hash value not matching the data hash value, copying a data block received from a source endpoint to the second destination storage location.
20. The non-transitory computer storage medium of claim 17 , wherein the remediation process comprises:
promoting the data hash value from a short-term cache to a long-term cache.