code of this form is always racy, when the
map itself is being written to as well
```
func (r Map) retMap() map[string]string {
.. lock ..
return r.internalMap
}
func (r Map) addMap(k, v string) {
.. lock ..
r.internalMap[k] = v
}
```
Anyone reading from `retMap()` is not protected
because of locking and we need to make sure
to avoid code in this manner. Always safe to
copy the map and return.
The measures are consolidated to the following metrics
- `disk_storage_used` : Disk space used by the disk.
- `disk_storage_available`: Available disk space left on the disk.
- `disk_storage_total`: Total disk space on the disk.
- `disks_offline`: Total number of offline disks in current MinIO instance.
- `disks_total`: Total number of disks in current MinIO instance.
- `s3_requests_total`: Total number of s3 requests in current MinIO instance.
- `s3_errors_total`: Total number of errors in s3 requests in current MinIO instance.
- `s3_requests_current`: Total number of active s3 requests in current MinIO instance.
- `internode_rx_bytes_total`: Total number of internode bytes received by current MinIO server instance.
- `internode_tx_bytes_total`: Total number of bytes sent to the other nodes by current MinIO server instance.
- `s3_rx_bytes_total`: Total number of s3 bytes received by current MinIO server instance.
- `s3_tx_bytes_total`: Total number of s3 bytes sent by current MinIO server instance.
- `minio_version_info`: Current MinIO version with commit-id.
- `s3_ttfb_seconds_bucket`: Histogram that holds the latency information of the requests.
And this PR also modifies the current StorageInfo queries
- Decouples StorageInfo from ServerInfo .
- StorageInfo is enhanced to give endpoint information.
NOTE: ADMIN API VERSION IS BUMPED UP IN THIS PR
Fixes#7873
Removed field minio_http_requests_total as it was redundant with
minio_http_requests_duration_seconds_count
Also removed field minio_server_start_time_seconds as it was
redundant with process_start_time_seconds
