X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/a95f899d7ac84f29b3d019aa410d265bb40833e5..fd717a88835be62ae1b5c4b1ecd74c21cab0e744:/services/keepstore/volume.go

diff --git a/services/keepstore/volume.go b/services/keepstore/volume.go
index 8ae6660fd4..b72258d51a 100644
--- a/services/keepstore/volume.go
+++ b/services/keepstore/volume.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"io"
 	"sync/atomic"
 	"time"
@@ -10,6 +11,15 @@ import (
 // for example, a single mounted disk, a RAID array, an Amazon S3 volume,
 // etc.
 type Volume interface {
+	// Volume type as specified in config file. Examples: "S3",
+	// "Directory".
+	Type() string
+
+	// Do whatever private setup tasks and configuration checks
+	// are needed. Return non-nil if the volume is unusable (e.g.,
+	// invalid config).
+	Start() error
+
 	// Get a block: copy the block data into buf, and return the
 	// number of bytes copied.
 	//
@@ -38,14 +48,14 @@ type Volume interface {
 	// any of the data.
 	//
 	// len(buf) will not exceed BlockSize.
-	Get(loc string, buf []byte) (int, error)
+	Get(ctx context.Context, 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
 	// CollisionError or DiskHashError (depending on whether the
 	// data on disk matches the expected hash), or whatever error
 	// was encountered opening/reading the stored data.
-	Compare(loc string, data []byte) error
+	Compare(ctx context.Context, loc string, data []byte) error
 
 	// Put writes a block to an underlying storage device.
 	//
@@ -75,7 +85,7 @@ type Volume interface {
 	//
 	// Put should not verify that loc==hash(block): this is the
 	// caller's responsibility.
-	Put(loc string, block []byte) error
+	Put(ctx context.Context, loc string, block []byte) error
 
 	// Touch sets the timestamp for the given locator to the
 	// current time.
@@ -150,7 +160,7 @@ type Volume interface {
 	// loc is as described in Get.
 	//
 	// If the timestamp for the given locator is newer than
-	// blobSignatureTTL, Trash must not trash the data.
+	// BlobSignatureTTL, Trash must not trash the data.
 	//
 	// If a Trash operation overlaps with any Touch or Put
 	// operations on the same locator, the implementation must
@@ -171,7 +181,7 @@ type Volume interface {
 	// reliably or fail outright.
 	//
 	// Corollary: A successful Touch or Put guarantees a block
-	// will not be trashed for at least blobSignatureTTL
+	// will not be trashed for at least BlobSignatureTTL
 	// seconds.
 	Trash(loc string) error
 
@@ -204,11 +214,18 @@ type Volume interface {
 	// responses to PUT requests.
 	Replication() int
 
-	// EmptyTrash looks for trashed blocks that exceeded trashLifetime
+	// EmptyTrash looks for trashed blocks that exceeded TrashLifetime
 	// and deletes them from the volume.
 	EmptyTrash()
 }
 
+// A VolumeWithExamples provides example configs to display in the
+// -help message.
+type VolumeWithExamples interface {
+	Volume
+	Examples() []Volume
+}
+
 // A VolumeManager tells callers which volumes can read, which volumes
 // can write, and on which volume the next write should be attempted.
 type VolumeManager interface {
@@ -226,6 +243,10 @@ type VolumeManager interface {
 	// with more free space, etc.
 	NextWritable() Volume
 
+	// VolumeStats returns the ioStats used for tracking stats for
+	// the given Volume.
+	VolumeStats(Volume) *ioStats
+
 	// Close shuts down the volume manager cleanly.
 	Close()
 }
@@ -237,12 +258,16 @@ type RRVolumeManager struct {
 	readables []Volume
 	writables []Volume
 	counter   uint32
+	iostats   map[Volume]*ioStats
 }
 
 // MakeRRVolumeManager initializes RRVolumeManager
 func MakeRRVolumeManager(volumes []Volume) *RRVolumeManager {
-	vm := &RRVolumeManager{}
+	vm := &RRVolumeManager{
+		iostats: make(map[Volume]*ioStats),
+	}
 	for _, v := range volumes {
+		vm.iostats[v] = &ioStats{}
 		vm.readables = append(vm.readables, v)
 		if v.Writable() {
 			vm.writables = append(vm.writables, v)
@@ -270,18 +295,35 @@ func (vm *RRVolumeManager) NextWritable() Volume {
 	return vm.writables[i%uint32(len(vm.writables))]
 }
 
+// VolumeStats returns an ioStats for the given volume.
+func (vm *RRVolumeManager) VolumeStats(v Volume) *ioStats {
+	return vm.iostats[v]
+}
+
 // Close the RRVolumeManager
 func (vm *RRVolumeManager) Close() {
 }
 
-// VolumeStatus provides status information of the volume consisting of:
-//   * mount_point
-//   * device_num (an integer identifying the underlying storage system)
-//   * bytes_free
-//   * bytes_used
+// VolumeStatus describes the current condition of a volume
 type VolumeStatus struct {
-	MountPoint string `json:"mount_point"`
-	DeviceNum  uint64 `json:"device_num"`
-	BytesFree  uint64 `json:"bytes_free"`
-	BytesUsed  uint64 `json:"bytes_used"`
+	MountPoint string
+	DeviceNum  uint64
+	BytesFree  uint64
+	BytesUsed  uint64
+}
+
+// ioStats tracks I/O statistics for a volume or server
+type ioStats struct {
+	Errors     uint64
+	Ops        uint64
+	CompareOps uint64
+	GetOps     uint64
+	PutOps     uint64
+	TouchOps   uint64
+	InBytes    uint64
+	OutBytes   uint64
+}
+
+type InternalStatser interface {
+	InternalStats() interface{}
 }