- Implemented only for the structured cache initially.
- Records are stored as compact binary packages with payloads stored within the record if small enough.
- Records are stored in Records/{Bucket}/{01}/{23}/{456789abcdef0123456789abcdef01234567} based on the hash in the cache key.
- Content that exceeds the size allowed for storage within the record is stored in Content/{01}/{23}/{456789abcdef0123456789abcdef01234567} based on the hash of the content.
- Both records and content are written to disk with their hash as a suffix, and are always checked on load.
- Maximum size of compressed data stored in the package can be configured by MaxRecordSizeKB and MaxValueSizeKB.
- Maintenance of the cache, to delete unused files, has been rewritten and can now scan ~175k files/second on modern hardware, though is limited to 10k files/second in the config to avoid adding too much overhead.
#rb Zousar.Shaker
#preflight 618b75c14a0c609a29204032
#preflight 618bfb5ec717ba4e929b7ac0
#ROBOMERGE-AUTHOR: devin.doucette
#ROBOMERGE-SOURCE: CL 18133085 in //UE5/Release-5.0/... via CL 18133356
#ROBOMERGE-BOT: STARSHIP (Release-Engine-Staging -> Release-Engine-Test) (v889-18060218)
#ROBOMERGE[STARSHIP]: UE5-Main
[CL 18133430 by devin doucette in ue5-release-engine-test branch]
- ICacheStore::Put() has updated documentation to reflect the requirements of partial records.
- ICacheStore::Get() now takes a FCacheRecordPolicy, which is implicitly constructible from ECachePolicy, and allows setting the policy by payload.
- ICacheStore::GetPayload() is replaced by ICacheStore::GetChunks(), which allows loading parts of payloads.
- ICacheStore::CancelAll() is moved to ICache::CancelAll() because the cache can track requests at the top level and cancel them without exposing cancellation on individual cache stores.
- ECachePolicy::SkipLocalCopy has been removed because it is difficult to reason about.
- ECachePolicy::SkipData flags now have a documented meaning for put requests, to hint that record existence implies payload existence.
- The filesystem and memory cache stores have been updated to support partial records, filtering of payloads, and loading parts of payloads.
- Requesting part of a payload will decompress the entire payload for now, until compressed buffers expose a way to decompress only part.
- Fixed a bug in FTexturePlatformData::AreDerivedMipsAvailable() that caused it to return false for structured cache keys.
#rb Zousar.Shaker
#rnx
#preflight 615e03241ed62f0001b95454
#ROBOMERGE-OWNER: Devin.Doucette
#ROBOMERGE-AUTHOR: devin.doucette
#ROBOMERGE-SOURCE: CL 17748550 in //UE5/Release-5.0/... via CL 17748555
#ROBOMERGE-BOT: STARSHIP (Release-Engine-Staging -> Release-Engine-Test) (v879-17706426)
#ROBOMERGE-CONFLICT from-shelf
#ROBOMERGE[STARSHIP]: UE5-Main
[CL 17748602 by Devin Doucette in ue5-release-engine-test branch]
The new flags are meant to prevent a cache store from evicting the associated cache records for the duration of the session.
#rb Zousar.Shaker
#rnx
#preflight 614954b611925a00017c525f
#ROBOMERGE-AUTHOR: devin.doucette
#ROBOMERGE-SOURCE: CL 17579887 in //UE5/Main/...
#ROBOMERGE-BOT: STARSHIP (Main -> Release-Engine-Test) (v871-17566257)
[CL 17579899 by devin doucette in ue5-release-engine-test branch]
FCacheBucket is now always exposed as FAnsiStringView.
#rb Zousar.Shaker
#rnx
#ROBOMERGE-SOURCE: CL 17084521 in //UE5/Main/...
#ROBOMERGE-BOT: STARSHIP (Main -> Release-Engine-Test) (v853-17066230)
[CL 17084549 by devin doucette in ue5-release-engine-test branch]
The new API uses exported functions and cannot be included with the old API without compile errors in existing code that has an include-only dependency on DDC.
#rb Zousar.Shaker
#rnx
#preflight 610c01e3aeb05700011dc5ab
#ROBOMERGE-SOURCE: CL 17071263 in //UE5/Main/...
#ROBOMERGE-BOT: STARSHIP (Main -> Release-Engine-Test) (v853-17066230)
[CL 17071271 by devin doucette in ue5-release-engine-test branch]
Any function that may create a request now has a IRequestOwner& parameter, and uses the Begin and End functions on the owner to manage the lifetime of any requests that it creates, as well as using End to invoke the completion callback for any request which has one.
The new FRequestBarrier may be used to block a group from being considered complete in a scope where more requests may be added to it.
#rb Matt.Peters
#rnx
#preflight 6109b5c403d303000144cce5
#preflight 610acf7103d30300016fda94
#ROBOMERGE-SOURCE: CL 17060470 in //UE5/Main/...
#ROBOMERGE-BOT: STARSHIP (Main -> Release-Engine-Test) (v850-17047176)
[CL 17060649 by devin doucette in ue5-release-engine-test branch]
- Removed the "Cache" prefix from ECachePriority, FCacheRequest, ICacheRequest, FCachePayload, FCachePayloadId to allow reuse in the Build API.
- Added FCompressedBuffer as the starting point for the API for creating and accessing compressed buffers.
#rb Zousar.Shaker
#rnx
[CL 15511723 by Devin Doucette in ue5-main branch]
- FCacheRecord must now be created by FCacheRecordBuilder.
- FCacheRecord values are always an opaque buffer now, and ECacheRecordType has been removed.
- FCachePayload has been added as a common type for the cache record value and attachments.
- FCachePayloadId has been added as a 12-byte identifier for cache payloads.
- ICache::GetAttachments is now GetPayloads and can fetch both values and attachments.
- ECachePriority::Blocking has been added for requests that the caller will block on.
#rb Zousar.Shaker
#rnx
[CL 15471951 by Devin Doucette in ue5-main branch]
ICache will eventually replace the existing cache access functions on FDerivedDataCacheInterface. The notable differences relative to the existing interface are:
- It is asynchronous with completion callbacks by default, and allows waiting when necessary.
- It allows batch requests containing multiple cache records by default.
- It uses a structured cache key made up of a bucket name and a hash.
- It supports prioritization and cancellation of requests.
- It supports structured cache records with metadata.
- It supports attachments to allow multi-part cache records.
- It uses a typed request object instead of an opaque integer handle.
- It provides cache policy flags to control how to query and store cache records, and which parts of a cache record to fetch.
This initial implementation of ICache is totally synchronous and uses the existing cache backends for storage.
#rb Zousar.Shaker
[CL 15152247 by Devin Doucette in ue5-main branch]
