Extract Sent Cache to an interface for future expansion #561
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kentquirk
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type: enhancement
MikeGoldsmith
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Nov 14, 2022
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Looks great @kentquirk 👍🏻
I've left a couple of suggestions for updating the new interface but none are essential as they are for internal use only.
kentquirk
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Nov 22, 2022
## Which problem is this PR solving? Before this change, Refinery used a circular LRU cache to retain a record for every trace; this cache is hardcoded to 5x the configured cache size, and does not change when the cache is resized. This is a relatively small number, and for long-lived traces, it might mean that late spans look like new traces, and therefore might get a different sampling decision -- which would result in missing spans in Honeycomb. #561 abstracted the SampleCache interface to prepare for other implementations. This uses it to provide a new cache design. ## Short description of the changes This design implements a "cuckoo filter" cache for dropped traces, which can store the dropped trace information much more efficiently (about 4 bytes per trace as compared to about 200 bytes for kept traces). - Adds a CuckooTraceChecker type that implements a 2-stage cuckoo filter for tracking recently-used trace IDs over time. - Implements the SampleCache interface with a CuckooSentCache, which uses the existing LRU for kept traces, and a CuckooTraceChecker for dropped traces. - Implements a new configuration block for caches to allow users to opt into the cuckoo cache and control it for their needs, but is still backwards compatible. - Adds documentation to the config_complete file. - Adds additional metrics for tracking the cuckoo cache size
ghost
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Jul 5, 2024
) ## Which problem is this PR solving? This is a prep PR for further work on the sent trace cache. For improved scalability, we want to be able to store trace decision records for a longer time. The best way to implement this in a backwards-compatible way is to pull the mechanisms for managing decision records into an interface, and then implement the interface with the legacy logic. That's what this does. There are no expected changes in behavior, and all tests still pass. ## Short description of the changes - Define interfaces for a TraceSentCache and a TraceSentRecord - Implement code for those that duplicates the existing legacy logic - Refactor the places the code is used to use the new interfaces - Tweak span count data type so that it's not an int64 any more - Rename SpanCount to DescendantCount because now that we have links and events, they're not all Spans anymore, and future PRs will add additional counting functions. I haven't renamed the corresponding Get and Add functions because that's pretty messy.
ghost
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that referenced
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Jul 5, 2024
## Which problem is this PR solving? Before this change, Refinery used a circular LRU cache to retain a record for every trace; this cache is hardcoded to 5x the configured cache size, and does not change when the cache is resized. This is a relatively small number, and for long-lived traces, it might mean that late spans look like new traces, and therefore might get a different sampling decision -- which would result in missing spans in Honeycomb. honeycombio#561 abstracted the SampleCache interface to prepare for other implementations. This uses it to provide a new cache design. ## Short description of the changes This design implements a "cuckoo filter" cache for dropped traces, which can store the dropped trace information much more efficiently (about 4 bytes per trace as compared to about 200 bytes for kept traces). - Adds a CuckooTraceChecker type that implements a 2-stage cuckoo filter for tracking recently-used trace IDs over time. - Implements the SampleCache interface with a CuckooSentCache, which uses the existing LRU for kept traces, and a CuckooTraceChecker for dropped traces. - Implements a new configuration block for caches to allow users to opt into the cuckoo cache and control it for their needs, but is still backwards compatible. - Adds documentation to the config_complete file. - Adds additional metrics for tracking the cuckoo cache size
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Which problem is this PR solving?
This is a prep PR for further work on the sent trace cache. For improved scalability, we want to be able to store trace decision records for a longer time. The best way to implement this in a backwards-compatible way is to pull the mechanisms for managing decision records into an interface, and then implement the interface with the legacy logic. That's what this does. There are no expected changes in behavior, and all tests still pass.
Short description of the changes