When a node finds a change in the other replication cluster and applies
to itself will already notify other peers. No need for all nodes in a
given cluster to do site replication healing, only one node is
sufficient.
This PR changes the handling of bucket deletes for site
replicated setups to hold on to deleted bucket state until
it syncs to all the clusters participating in site replication.
It is observed in a local 8 drive system the CPU seems to be
bottlenecked at
```
(pprof) top
Showing nodes accounting for 1385.31s, 88.47% of 1565.88s total
Dropped 1304 nodes (cum <= 7.83s)
Showing top 10 nodes out of 159
flat flat% sum% cum cum%
724s 46.24% 46.24% 724s 46.24% crypto/sha256.block
219.04s 13.99% 60.22% 226.63s 14.47% syscall.Syscall
158.04s 10.09% 70.32% 158.04s 10.09% runtime.memmove
127.58s 8.15% 78.46% 127.58s 8.15% crypto/md5.block
58.67s 3.75% 82.21% 58.67s 3.75% github.com/minio/highwayhash.updateAVX2
40.07s 2.56% 84.77% 40.07s 2.56% runtime.epollwait
33.76s 2.16% 86.93% 33.76s 2.16% github.com/klauspost/reedsolomon._galMulAVX512Parallel84
8.88s 0.57% 87.49% 11.56s 0.74% runtime.step
7.84s 0.5% 87.99% 7.84s 0.5% runtime.memclrNoHeapPointers
7.43s 0.47% 88.47% 22.18s 1.42% runtime.pcvalue
```
Bonus changes:
- re-use transport for bucket replication clients, also site replication clients.
- use 32KiB buffer for all read and writes at transport layer seems to help
TLS read connections.
- Do not have 'MaxConnsPerHost' this is problematic to be used with net/http
connection pooling 'MaxIdleConnsPerHost' is enough.
site replication errors were printed at
various random locations, repeatedly - this
PR attempts to remove double logging and
capture all of them at a common place.
This PR also enhances the code to show
partial success and errors as well.
We need to make sure if we cannot read bucket metadata
for some reason, and bucket metadata is not missing and
returning corrupted information we should panic such
handlers to disallow I/O to protect the overall state
on the system.
In-case of such corruption we have a mechanism now
to force recreate the metadata on the bucket, using
`x-minio-force-create` header with `PUT /bucket` API
call.
Additionally fix the versioning config updated state
to be set properly for the site replication healing
to trigger correctly.
