-// A Volume is an interface representing a Keep back-end storage unit:
-// for example, a single mounted disk, a RAID array, an Amazon S3 volume,
-// etc.
-
package main
import (
"time"
)
+// A Volume is an interface representing a Keep back-end storage unit:
+// for example, a single mounted disk, a RAID array, an Amazon S3 volume,
+// etc.
type Volume interface {
- // Get a block. IFF the returned error is nil, the caller must
- // put the returned slice back into the buffer pool when it's
- // finished with it. (Otherwise, the buffer pool will be
- // depleted and eventually -- when all available buffers are
- // used and not returned -- operations will reach deadlock.)
+ // Get a block: copy the block data into buf, and return the
+ // number of bytes copied.
//
// loc is guaranteed to consist of 32 or more lowercase hex
// digits.
//
- // Get should not verify the integrity of the returned data:
- // it should just return whatever was found in its backing
+ // Get should not verify the integrity of the data: it should
+ // just return whatever was found in its backing
// store. (Integrity checking is the caller's responsibility.)
//
// If an error is encountered that prevents it from
// access log if the block is not found on any other volumes
// either).
//
- // If the data in the backing store is bigger than BLOCKSIZE,
- // Get is permitted to return an error without reading any of
- // the data.
- Get(loc string) ([]byte, error)
+ // If the data in the backing store is bigger than len(buf),
+ // then Get is permitted to return an error without reading
+ // any of the data.
+ //
+ // len(buf) will not exceed BlockSize.
+ Get(loc string, buf []byte) (int, error)
// Compare the given data with the stored data (i.e., what Get
// would return). If equal, return nil. If not, return
//
// loc is as described in Get.
//
- // len(block) is guaranteed to be between 0 and BLOCKSIZE.
+ // len(block) is guaranteed to be between 0 and BlockSize.
//
// If a block is already stored under the same name (loc) with
// different content, Put must either overwrite the existing
// particular order.
IndexTo(prefix string, writer io.Writer) error
- // Delete deletes the block data from the underlying storage
- // device.
+ // Trash moves the block data from the underlying storage
+ // device to trash area. The block then stays in trash for
+ // -trash-lifetime interval before it is actually deleted.
//
// loc is as described in Get.
//
// If the timestamp for the given locator is newer than
- // blob_signature_ttl, Delete must not delete the data.
+ // blobSignatureTTL, Trash must not trash the data.
//
- // If a Delete operation overlaps with any Touch or Put
+ // If a Trash operation overlaps with any Touch or Put
// operations on the same locator, the implementation must
// ensure one of the following outcomes:
//
// - Touch and Put return a non-nil error, or
- // - Delete does not delete the block, or
+ // - Trash does not trash the block, or
// - Both of the above.
//
// If it is possible for the storage device to be accessed by
// reliably or fail outright.
//
// Corollary: A successful Touch or Put guarantees a block
- // will not be deleted for at least blob_signature_ttl
+ // will not be trashed for at least blobSignatureTTL
// seconds.
- Delete(loc string) error
+ Trash(loc string) error
+
+ // Untrash moves block from trash back into store
+ Untrash(loc string) error
// Status returns a *VolumeStatus representing the current
// in-use and available storage capacity and an
// will fail because it is full, but Mtime or Delete can
// succeed -- then Writable should return false.
Writable() bool
+
+ // Replication returns the storage redundancy of the
+ // underlying device. It will be passed on to clients in
+ // responses to PUT requests.
+ Replication() int
+
+ // EmptyTrash looks for trashed blocks that exceeded trashLifetime
+ // and deletes them from the volume.
+ EmptyTrash()
}
// A VolumeManager tells callers which volumes can read, which volumes
counter uint32
}
+// MakeRRVolumeManager initializes RRVolumeManager
func MakeRRVolumeManager(volumes []Volume) *RRVolumeManager {
vm := &RRVolumeManager{}
for _, v := range volumes {
return vm
}
+// AllReadable returns an array of all readable volumes
func (vm *RRVolumeManager) AllReadable() []Volume {
return vm.readables
}
+// AllWritable returns an array of all writable volumes
func (vm *RRVolumeManager) AllWritable() []Volume {
return vm.writables
}
+// NextWritable returns the next writable
func (vm *RRVolumeManager) NextWritable() Volume {
if len(vm.writables) == 0 {
return nil
return vm.writables[i%uint32(len(vm.writables))]
}
+// Close the RRVolumeManager
func (vm *RRVolumeManager) Close() {
}
-// VolumeStatus
+// VolumeStatus provides status information of the volume consisting of:
// * mount_point
// * device_num (an integer identifying the underlying storage system)
// * bytes_free
projects / arvados.git / blobdiff