Merging same-object - multiple versions from different pools would not always result in correct ordering.
When merging keep inputs separate.
```
λ mc ls --versions local/testbucket
------ before ------
[2024-03-05 20:17:19 CET] 228B STANDARD 1f163718-9bc5-4b01-bff7-5d8cf09caf10 v3 PUT hosts
[2024-03-05 20:19:56 CET] 19KiB STANDARD null v2 PUT hosts
[2024-03-05 20:17:15 CET] 228B STANDARD 73c9f651-f023-4566-b012-cc537fdb7ce2 v1 PUT hosts
------ after ------
λ mc ls --versions local/testbucket
[2024-03-05 20:19:56 CET] 19KiB STANDARD null v3 PUT hosts
[2024-03-05 20:17:19 CET] 228B STANDARD 1f163718-9bc5-4b01-bff7-5d8cf09caf10 v2 PUT hosts
[2024-03-05 20:17:15 CET] 228B STANDARD 73c9f651-f023-4566-b012-cc537fdb7ce2 v1 PUT hosts
```
* Do not use inline data size in xl.meta quorum calculation
Data shards of one object can different inline/not-inline decision
in multiple disks. This happens with outdated disks when inline
decision changes. For example, enabling bucket versioning configuration
will change the small file threshold.
When the parity of an object becomes low, GET object can return 503
because it is not unable to calculate the xl.meta quorum, just because
some xl.meta has inline data and other are not.
So this commit will be disable taking the size of the inline data into
consideration when calculating the xl.meta quorum.
* Add tests for simulatenous inline/notinline object
Co-authored-by: Anis Elleuch <anis@min.io>
```
tmp = buf[want:]
```
Would potentially crash when `buf` is truncated for some reason
and does not have the expected bytes, this is of course considered
not normal and is an odd situation. But we do not need to crash
here instead allow for errors to be returned and let callers handle
the errors.
When calculating signatures empty part ETags were not discarded, leading
to a different signature compared to freshly created ones.
This would mean that after a heal signature of the healed metadata would be
different. Fixing the calculation of signature will make these consistent.
Furthermore when inconsistent entries, with zero version ID, with the same
mod times but different signatures, the one with the lowest signature would
be picked for quorum check. Since this is 50/50, we fall back to a simple
quorum count on all signatures.
Each of these fixes by themselves will lead to quorum. Tests were added
for regressions and expected outcomes.
Existing:
```go
type xlMetaV2 struct {
Versions []xlMetaV2Version `json:"Versions" msg:"Versions"`
}
```
Serialized as regular MessagePack.
```go
//msgp:tuple xlMetaV2VersionHeader
type xlMetaV2VersionHeader struct {
VersionID [16]byte
ModTime int64
Type VersionType
Flags xlFlags
}
```
Serialize as streaming MessagePack, format:
```
int(headerVersion)
int(xlmetaVersion)
int(nVersions)
for each version {
binary blob, xlMetaV2VersionHeader, serialized
binary blob, xlMetaV2Version, serialized.
}
```
xlMetaV2VersionHeader is <= 30 bytes serialized. Deserialized struct
can easily be reused and does not contain pointers, so efficient as a
slice (single allocation)
This allows quickly parsing everything as slices of bytes (no copy).
Versions are always *saved* sorted by modTime, newest *first*.
No more need to sort on load.
* Allows checking if a version exists.
* Allows reading single version without unmarshal all.
* Allows reading latest version of type without unmarshal all.
* Allows reading latest version without unmarshal of all.
* Allows checking if the latest is deleteMarker by reading first entry.
* Allows adding/updating/deleting a version with only header deserialization.
* Reduces allocations on conversion to FileInfo(s).
`decryptObjectInfo` is a significant bottleneck when listing objects.
Reduce the allocations for a significant speedup.
https://github.com/minio/sio/pull/40
```
λ benchcmp before.txt after.txt
benchmark old ns/op new ns/op delta
Benchmark_decryptObjectInfo-32 24260928 808656 -96.67%
benchmark old MB/s new MB/s speedup
Benchmark_decryptObjectInfo-32 0.04 1.24 31.00x
benchmark old allocs new allocs delta
Benchmark_decryptObjectInfo-32 75112 48996 -34.77%
benchmark old bytes new bytes delta
Benchmark_decryptObjectInfo-32 287694772 4228076 -98.53%
```
Design: https://gist.github.com/klauspost/025c09b48ed4a1293c917cecfabdf21c
Gist of improvements:
* Cross-server caching and listing will use the same data across servers and requests.
* Lists can be arbitrarily resumed at a constant speed.
* Metadata for all files scanned is stored for streaming retrieval.
* The existing bloom filters controlled by the crawler is used for validating caches.
* Concurrent requests for the same data (or parts of it) will not spawn additional walkers.
* Listing a subdirectory of an existing recursive cache will use the cache.
* All listing operations are fully streamable so the number of objects in a bucket no
longer dictates the amount of memory.
* Listings can be handled by any server within the cluster.
* Caches are cleaned up when out of date or superseded by a more recent one.
