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meta_storage_client.go
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/
meta_storage_client.go
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// Copyright 2023 TiKV Project Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pd
import (
"context"
"time"
"github.com/opentracing/opentracing-go"
"github.com/pingcap/errors"
"github.com/pingcap/failpoint"
"github.com/pingcap/kvproto/pkg/meta_storagepb"
"github.com/prometheus/client_golang/prometheus"
"github.com/tikv/pd/client/errs"
"github.com/tikv/pd/client/grpcutil"
)
// MetaStorageClient is the interface for meta storage client.
type MetaStorageClient interface {
// Watch watches on a key or prefix.
Watch(ctx context.Context, key []byte, opts ...OpOption) (chan []*meta_storagepb.Event, error)
// Get gets the value for a key.
Get(ctx context.Context, key []byte, opts ...OpOption) (*meta_storagepb.GetResponse, error)
// Put puts a key-value pair into meta storage.
Put(ctx context.Context, key []byte, value []byte, opts ...OpOption) (*meta_storagepb.PutResponse, error)
}
// metaStorageClient gets the meta storage client from current PD leader.
func (c *client) metaStorageClient() meta_storagepb.MetaStorageClient {
if client := c.pdSvcDiscovery.GetServingEndpointClientConn(); client != nil {
return meta_storagepb.NewMetaStorageClient(client)
}
return nil
}
// Op represents available options when using meta storage client.
type Op struct {
rangeEnd []byte
revision int64
prevKv bool
lease int64
limit int64
isOptsWithPrefix bool
}
// OpOption configures etcd Op.
type OpOption func(*Op)
// WithLimit specifies the limit of the key.
func WithLimit(limit int64) OpOption {
return func(op *Op) { op.limit = limit }
}
// WithRangeEnd specifies the range end of the key.
func WithRangeEnd(rangeEnd []byte) OpOption {
return func(op *Op) { op.rangeEnd = rangeEnd }
}
// WithRev specifies the start revision of the key.
func WithRev(revision int64) OpOption {
return func(op *Op) { op.revision = revision }
}
// WithPrevKV specifies the previous key-value pair of the key.
func WithPrevKV() OpOption {
return func(op *Op) { op.prevKv = true }
}
// WithLease specifies the lease of the key.
func WithLease(lease int64) OpOption {
return func(op *Op) { op.lease = lease }
}
// WithPrefix specifies the prefix of the key.
func WithPrefix() OpOption {
return func(op *Op) {
op.isOptsWithPrefix = true
}
}
// See https://github.com/etcd-io/etcd/blob/da4bf0f76fb708e0b57763edb46ba523447b9510/client/v3/op.go#L372-L385
func getPrefix(key []byte) []byte {
end := make([]byte, len(key))
copy(end, key)
for i := len(end) - 1; i >= 0; i-- {
if end[i] < 0xff {
end[i]++
end = end[:i+1]
return end
}
}
return []byte{0}
}
func (c *client) Put(ctx context.Context, key, value []byte, opts ...OpOption) (*meta_storagepb.PutResponse, error) {
options := &Op{}
for _, opt := range opts {
opt(options)
}
if span := opentracing.SpanFromContext(ctx); span != nil && span.Tracer() != nil {
span = span.Tracer().StartSpan("pdclient.Put", opentracing.ChildOf(span.Context()))
defer span.Finish()
}
start := time.Now()
defer func() { cmdDurationPut.Observe(time.Since(start).Seconds()) }()
ctx, cancel := context.WithTimeout(ctx, c.option.timeout)
req := &meta_storagepb.PutRequest{
Key: key,
Value: value,
Lease: options.lease,
PrevKv: options.prevKv,
}
ctx = grpcutil.BuildForwardContext(ctx, c.GetLeaderURL())
cli := c.metaStorageClient()
if cli == nil {
cancel()
return nil, errs.ErrClientGetMetaStorageClient
}
resp, err := cli.Put(ctx, req)
cancel()
if err = c.respForMetaStorageErr(cmdFailedDurationPut, start, err, resp.GetHeader()); err != nil {
return nil, err
}
return resp, nil
}
func (c *client) Get(ctx context.Context, key []byte, opts ...OpOption) (*meta_storagepb.GetResponse, error) {
options := &Op{}
for _, opt := range opts {
opt(options)
}
if options.isOptsWithPrefix {
options.rangeEnd = getPrefix(key)
}
if span := opentracing.SpanFromContext(ctx); span != nil && span.Tracer() != nil {
span = span.Tracer().StartSpan("pdclient.Get", opentracing.ChildOf(span.Context()))
defer span.Finish()
}
start := time.Now()
defer func() { cmdDurationGet.Observe(time.Since(start).Seconds()) }()
ctx, cancel := context.WithTimeout(ctx, c.option.timeout)
req := &meta_storagepb.GetRequest{
Key: key,
RangeEnd: options.rangeEnd,
Limit: options.limit,
Revision: options.revision,
}
ctx = grpcutil.BuildForwardContext(ctx, c.GetLeaderURL())
cli := c.metaStorageClient()
if cli == nil {
cancel()
return nil, errs.ErrClientGetMetaStorageClient
}
resp, err := cli.Get(ctx, req)
cancel()
if err = c.respForMetaStorageErr(cmdFailedDurationGet, start, err, resp.GetHeader()); err != nil {
return nil, err
}
return resp, nil
}
func (c *client) Watch(ctx context.Context, key []byte, opts ...OpOption) (chan []*meta_storagepb.Event, error) {
eventCh := make(chan []*meta_storagepb.Event, 100)
options := &Op{}
for _, opt := range opts {
opt(options)
}
if options.isOptsWithPrefix {
options.rangeEnd = getPrefix(key)
}
cli := c.metaStorageClient()
if cli == nil {
return nil, errs.ErrClientGetMetaStorageClient
}
res, err := cli.Watch(ctx, &meta_storagepb.WatchRequest{
Key: key,
RangeEnd: options.rangeEnd,
StartRevision: options.revision,
PrevKv: options.prevKv,
})
if err != nil {
close(eventCh)
return nil, err
}
go func() {
defer func() {
close(eventCh)
}()
for {
resp, err := res.Recv()
failpoint.Inject("watchStreamError", func() {
err = errors.Errorf("fake error")
})
if err != nil {
return
}
select {
case <-ctx.Done():
return
case eventCh <- resp.GetEvents():
}
}
}()
return eventCh, err
}
func (c *client) respForMetaStorageErr(observer prometheus.Observer, start time.Time, err error, header *meta_storagepb.ResponseHeader) error {
if err != nil || header.GetError() != nil {
observer.Observe(time.Since(start).Seconds())
if err != nil {
c.pdSvcDiscovery.ScheduleCheckMemberChanged()
return errors.WithStack(err)
}
return errors.WithStack(errors.New(header.GetError().String()))
}
return nil
}