BR: add stream backup meta client

br/pkg/errors/errors.go

@@ -54,6 +54,9 @@ var (
 	ErrRestoreRTsConstrain = errors.Normalize("resolved ts constrain violation", errors.RFCCodeText("BR:Restore:ErrRestoreResolvedTsConstrain"))
 
 	ErrPiTRInvalidCDCLogFormat = errors.Normalize("invalid cdc log format", errors.RFCCodeText("BR:PiTR:ErrPiTRInvalidCDCLogFormat"))
+	ErrPiTRTaskNotFound        = errors.Normalize("task not found", errors.RFCCodeText("BR:PiTR:ErrTaskNotFound"))
+	ErrPiTRInvalidTaskInfo     = errors.Normalize("task info is invalid", errors.RFCCodeText("BR:PiTR:ErrInvalidTaskInfo"))
+	ErrPiTRMalformedMetadata   = errors.Normalize("malformed metadata", errors.RFCCodeText("BR:PiTR:ErrMalformedMetadata"))
 
 	ErrStorageUnknown           = errors.Normalize("unknown external storage error", errors.RFCCodeText("BR:ExternalStorage:ErrStorageUnknown"))
 	ErrStorageInvalidConfig     = errors.Normalize("invalid external storage config", errors.RFCCodeText("BR:ExternalStorage:ErrStorageInvalidConfig"))

br/pkg/stream/client.go

@@ -0,0 +1,172 @@
+// Copyright 2021 PingCAP, Inc. Licensed under Apache-2.0.
+package stream
+
+import (
+	"context"
+	"encoding/binary"
+	"math"
+
+	"github.com/gogo/protobuf/proto"
+	"github.com/pingcap/errors"
+
+	backuppb "github.com/pingcap/kvproto/pkg/brpb"
+	berrors "github.com/pingcap/tidb/br/pkg/errors"
+	"github.com/pingcap/tidb/br/pkg/redact"
+	"github.com/pingcap/tidb/kv"
+	"go.etcd.io/etcd/clientv3"
+)
+
+// MetaDataClient is the client for operations over metadata.
+type MetaDataClient struct {
+	*clientv3.Client
+}
+
+// PutTask put a task to the metadata storage.
+func (c *MetaDataClient) PutTask(ctx context.Context, task TaskInfo) error {
+	data, err := task.PBInfo.Marshal()
+	if err != nil {
+		return errors.Annotatef(err, "failed to marshal task %s", task.PBInfo.Name)
+	}
+
+	ops := make([]clientv3.Op, 0, 2+len(task.Ranges))
+	ops = append(ops, clientv3.OpPut(TaskOf(task.PBInfo.Name), string(data)))
+	for _, r := range task.Ranges {
+		ops = append(ops, clientv3.OpPut(RangeKeyOf(task.PBInfo.Name, r.StartKey), string(r.EndKey)))
+	}
+	if task.Pausing {
+		ops = append(ops, clientv3.OpPut(Pause(task.PBInfo.Name), ""))
+	}
+
+	txn := c.KV.Txn(ctx)
+	_, err = txn.Then(ops...).Commit()
+	if err != nil {
+		return errors.Annotatef(err, "failed to commit the change for task %s", task.PBInfo.Name)
+	}
+	return nil
+}
+
+// DeleteTask deletes a task, along with its metadata.
+func (c *MetaDataClient) DeleteTask(ctx context.Context, taskName string) error {
+	_, err := c.KV.Txn(ctx).
+		Then(clientv3.OpDelete(TaskOf(taskName)),
+			clientv3.OpDelete(RangesOf(taskName), clientv3.WithPrefix()),
+			clientv3.OpDelete(Pause(taskName))).
+		Commit()
+	if err != nil {
+		return errors.Annotatef(err, "failed to delete task itself %s", taskName)
+	}
+	return nil
+}
+
+func (c *MetaDataClient) PauseTask(ctx context.Context, taskName string) error {
+	_, err := c.KV.Put(ctx, Pause(taskName), "")
+	if err != nil {
+		return errors.Annotatef(err, "failed to pause task %s", taskName)
+	}
+	return nil
+}
+
+func (c *MetaDataClient) ResumeTask(ctx context.Context, taskName string) error {
+	_, err := c.KV.Delete(ctx, Pause(taskName))
+	if err != nil {
+		return errors.Annotatef(err, "failed to resume task %s", taskName)
+	}
+	return nil
+}
+
+// GetTask get the basic task handle from the metadata storage.
+func (c *MetaDataClient) GetTask(ctx context.Context, taskName string) (*Task, error) {
+	resp, err := c.Get(ctx, TaskOf(taskName))
+	if err != nil {
+		return nil, errors.Annotatef(err, "failed to fetch task %s", taskName)
+	}
+	if len(resp.Kvs) == 0 {
+		return nil, errors.Annotatef(berrors.ErrPiTRTaskNotFound, "no such task %s", taskName)
+	}
+	var taskInfo backuppb.StreamBackupTaskInfo
+	err = proto.Unmarshal(resp.Kvs[0].Value, &taskInfo)
+	if err != nil {
+		return nil, errors.Annotatef(err, "invalid binary presentation of task info (name = %s)", taskName)
+	}
+	task := &Task{
+		cli:  c,
+		Info: taskInfo,
+	}
+	return task, nil
+}
+
+// Task presents a remote "task" object.
+// returned by a query of task.
+// Associated to the client created it, hence be able to fetch remote fields like `ranges`.
+type Task struct {
+	cli  *MetaDataClient
+	Info backuppb.StreamBackupTaskInfo
+}
+
+// Pause is a shorthand for `metaCli.PauseTask`.
+func (t *Task) Pause(ctx context.Context) error {
+	return t.cli.PauseTask(ctx, t.Info.Name)
+}
+
+// Resume is a shorthand for `metaCli.ResumeTask`
+func (t *Task) Resume(ctx context.Context) error {
+	return t.cli.ResumeTask(ctx, t.Info.Name)
+}
+
+func (t *Task) Paused(ctx context.Context) (bool, error) {
+	resp, err := t.cli.KV.Get(ctx, Pause(t.Info.Name), clientv3.WithCountOnly())
+	if err != nil {
+		return false, errors.Annotatef(err, "failed to fetch the status of task %s", t.Info.Name)
+	}
+	return resp.Count > 0, nil
+}
+
+// Ranges tries to fetch the range from the metadata storage.
+func (t *Task) Ranges(ctx context.Context) (Ranges, error) {
+	ranges := make(Ranges, 0, 64)
+	kvs, err := scanEtcdPrefix(t.cli.Client, RangesOf(t.Info.Name)).AllPages(ctx, 64)
+	if err != nil {
+		return nil, errors.Annotatef(err, "failed to fetch ranges of task %s", t.Info.Name)
+	}
+	commonPrefix := []byte(RangesOf(t.Info.Name))
+	for _, kvp := range kvs {
+		// The prefix must matches.
+		startKey := kvp.Key[len(commonPrefix):]
+		ranges = append(ranges, kv.KeyRange{StartKey: startKey, EndKey: kvp.Value})
+	}
+	return ranges, nil
+}
+
+// MinNextBackupTS query the all next backup ts of a store, returning the minimal next backup ts of the store.
+func (t *Task) MinNextBackupTS(ctx context.Context, store uint64) (uint64, error) {
+	min := uint64(math.MaxUint64)
+	scanner := scanEtcdPrefix(t.cli.Client, CheckPointsOf(t.Info.Name, store))
+	kvs, err := scanner.AllPages(ctx, 1024)
+	if err != nil {
+		return 0, errors.Annotatef(err, "failed to get checkpoints of %s", t.Info.Name)
+	}
+	for _, kv := range kvs {
+		if len(kv.Value) != 8 {
+			return 0, errors.Annotatef(berrors.ErrPiTRMalformedMetadata,
+				"the next backup ts of store %d isn't 64bits (it is %d bytes, value = %s)",
+				store,
+				len(kv.Value),
+				redact.Key(kv.Value))
+		}
+		nextBackupTS := binary.BigEndian.Uint64(kv.Value)
+		if nextBackupTS < min {
+			min = nextBackupTS
+		}
+	}
+	return min, nil
+}
+
+// Step forwards the progress (next_backup_ts) of some region.
+// The task should be done by TiKV. This function should only be used for test cases.
+func (t *Task) Step(ctx context.Context, store uint64, region uint64, ts uint64) error {
+	_, err := t.cli.KV.Put(ctx, CheckpointOf(t.Info.Name, store, region), string(encodeUint64(ts)))
+	if err != nil {
+		return errors.Annotatef(err, "failed forward the progress of %s to %d", t.Info.Name, ts)
+	}
+	return nil
+}