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.
A huge number of goroutines would build up from various monitors
When creating test filesystems provide a context so they can shut down when no longer needed.
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.
this allows for customers to use `mc admin service restart`
directly even when performing RPM, DEB upgrades. Upon such 'restart'
after upgrade MinIO will re-read the /etc/default/minio for any
newer environment variables.
As long as `MINIO_CONFIG_ENV_FILE=/etc/default/minio` is set, this
is honored.
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.
Main motivation is move towards a common backend format
for all different types of modes in MinIO, allowing for
a simpler code and predictable behavior across all features.
This PR also brings features such as versioning, replication,
transitioning to single drive setups.
