also simplify readerLocks to be just like
writeLocks, DRWMutex() is never shared
and there are order guarantees that need
for such a thing to work for RLock's
it would seem like using `bufio.Scan()` is very
slow for heavy concurrent I/O, ie. when r.Body
is slow , instead use a proper
binary exchange format, to marshal and unmarshal
the LockArgs datastructure in a cleaner way.
this PR increases performance of the locking
sub-system for tiny repeated read lock requests
on same object.
```
BenchmarkLockArgs
BenchmarkLockArgs-4 6417609 185.7 ns/op 56 B/op 2 allocs/op
BenchmarkLockArgsOld
BenchmarkLockArgsOld-4 1187368 1015 ns/op 4096 B/op 1 allocs/op
```
This was a regression introduced in '14bb969782'
this has the potential to cause corruption when
there are concurrent overwrites attempting to update
the content on the namespace.
This PR adds a situation where PutObject(), CopyObject()
compete properly for the same locks with NewMultipartUpload()
however it ends up turning off competing locks for the actual
object with GetObject() and DeleteObject() - since they do not
compete due to concurrent I/O on a versioned bucket it can lead
to loss of versions.
This PR fixes this bug with multi-pool setup with replication
that causes corruption of inlined data due to lack of competing
locks in a multi-pool setup.
Instead CompleteMultipartUpload holds the necessary
locks when finishing the transaction, knowing the exact
location of an object to schedule the multipart upload
doesn't need to compete in this manner, a pool id location
for existing object.
A multi resources lock is a single lock UID with multiple associated
resources. This is created for example by multi objects delete
operation. This commit changes the behavior of Refresh() to iterate over
all locks having the same UID and refresh them.
Bonus: Fix showing top locks for multi delete objects
In the event when a lock is not refreshed in the cluster, this latter
will be automatically removed in the subsequent cleanup of non
refreshed locks routine, but it forgot to clean the local server,
hence having the same weird stale locks present.
This commit will remove the lock locally also in remote nodes, if
removing a lock from a remote node will fail, it will be anyway
removed later in the locks cleanup routine.
This is to ensure that there are no projects
that try to import `minio/minio/pkg` into
their own repo. Any such common packages should
go to `https://github.com/minio/pkg`
