Refer to: https://github.com/valkey-io/valkey/issues/1141
This update refactors the defrag code to:
* Make the overall code more readable and maintainable
* Reduce latencies incurred during defrag processing
With this update, the defrag cycle time is reduced to 500us, with more
frequent cycles. This results in much more predictable latencies, with a
dramatic reduction in tail latencies.
(See https://github.com/valkey-io/valkey/issues/1141 for more complete
details.)
This update is focused mostly on the high-level processing, and does NOT
address lower level functions which aren't currently timebound (e.g.
`activeDefragSdsDict()`, and `moduleDefragGlobals()`). These are out of
scope for this update and left for a future update.
I fixed `kvstoreDictLUTDefrag` because it was using up to 7ms on a CME
single shard. See original github issue for performance details.
---------
Signed-off-by: Jim Brunner <brunnerj@amazon.com>
Signed-off-by: Madelyn Olson <madelyneolson@gmail.com>
Co-authored-by: Madelyn Olson <madelyneolson@gmail.com>
This includes comments used for module API documentation.
* Strategy for replacement: Regex search: `(//|/\*| \*|#).* ("|\()?(r|R)edis( |\.
|'|\n|,|-|\)|")(?!nor the names of its contributors)(?!Ltd.)(?!Labs)(?!Contributors.)`
* Don't edit copyright comments
* Replace "Redis version X.X" -> "Redis OSS version X.X" to distinguish
from newly licensed repository
* Replace "Redis Object" -> "Object"
* Exclude markdown for now
* Don't edit Lua scripting comments referring to redis.X API
* Replace "Redis Protocol" -> "RESP"
* Replace redis-benchmark, -cli, -server, -check-aof/rdb with "valkey-"
prefix
* Most other places, I use best judgement to either remove "Redis", or
replace with "the server" or "server"
Fixes#148
---------
Signed-off-by: Jacob Murphy <jkmurphy@google.com>
Signed-off-by: Viktor Söderqvist <viktor.soderqvist@est.tech>
Additionally the older defrag tests are using an obsolete way to check
if the defragger is suuported (the error no longer contains "DISABLED").
this doesn't usually makes a difference since these tests are completely
skipped if the allocator is not jemalloc, but that would fail if the
allocator is a jemalloc that doesn't support defrag.
Add a new set of defrag functions that take a defrag context and allow
defragmenting memory blocks and RedisModuleStrings.
Modules can register a defrag callback which will be invoked when the
defrag process handles globals.
Modules with custom data types can also register a datatype-specific
defrag callback which is invoked for keys that require defragmentation.
The callback and associated functions support both one-step and
multi-step options, depending on the complexity of the key as exposed by
the free_effort callback.
