Each obj.Stat() call adds another request to the S3 endpoint
for some commands a lot of ReadAt calls are made for the same
object in S3. This patch essentially cuts the number of calls
to S3 in this case in half. Speeding up the progress and lowering
costs to S3.
This makes the following changes, before:
type backend interface {
// Test a boolean value whether a File with the name and type exists.
Test(t FileType, name string) (bool, error)
// Remove removes a File with type t and name.
Remove(t FileType, name string) error
}
After:
type backend interface {
// Test a boolean value whether a File with the name and type exists.
Test(h Handle) (bool, error)
// Remove removes a File with type t and name.
Remove(h Handle) error
}
Since client.BucketExists was changed to return a separate 'found' value, instead of reporting an error when the bucket doesn't exist, the error code path does no longer imply a call to client.MakeBucket. So the second part of the debug message, "...trying to create the bucket" doesn't apply any more.
Also, changed the name of the return value from 'ok' to 'found', matching the API documentation at https://docs.minio.io/docs/golang-client-api-reference#BucketExists.