Introduce the HTTP client

Signed-off-by: JmPotato <ghzpotato@gmail.com>

client/client.go

@@ -74,7 +74,7 @@ type GlobalConfigItem struct {
 	PayLoad   []byte
 }
 
-// Client is a PD (Placement Driver) client.
+// Client is a PD (Placement Driver) RPC client.
 // It should not be used after calling Close().
 type Client interface {
 	// GetClusterID gets the cluster ID from PD.
@@ -1062,7 +1062,7 @@ func (c *client) ScanRegions(ctx context.Context, key, endKey []byte, limit int)
 		defer span.Finish()
 	}
 	start := time.Now()
-	defer cmdDurationScanRegions.Observe(time.Since(start).Seconds())
+	defer func() { cmdDurationScanRegions.Observe(time.Since(start).Seconds()) }()
 
 	var cancel context.CancelFunc
 	scanCtx := ctx

client/http/api.go

@@ -0,0 +1,54 @@
+// 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 http
+
+import (
+	"fmt"
+	"net/url"
+)
+
+// The following constants are the paths of PD HTTP APIs.
+const (
+	HotRead             = "/pd/api/v1/hotspot/regions/read"
+	HotWrite            = "/pd/api/v1/hotspot/regions/write"
+	Regions             = "/pd/api/v1/regions"
+	regionByID          = "/pd/api/v1/region/id"
+	regionByKey         = "/pd/api/v1/region/key"
+	regionsByKey        = "/pd/api/v1/regions/key"
+	regionsByStoreID    = "/pd/api/v1/regions/store"
+	Stores              = "/pd/api/v1/stores"
+	MinResolvedTSPrefix = "/pd/api/v1/min-resolved-ts"
+)
+
+// RegionByID returns the path of PD HTTP API to get region by ID.
+func RegionByID(regionID uint64) string {
+	return fmt.Sprintf("%s/%d", regionByID, regionID)
+}
+
+// RegionByKey returns the path of PD HTTP API to get region by key.
+func RegionByKey(key []byte) string {
+	return fmt.Sprintf("%s/%s", regionByKey, url.QueryEscape(string(key)))
+}
+
+// RegionsByKey returns the path of PD HTTP API to scan regions with given start key, end key and limit parameters.
+func RegionsByKey(startKey, endKey []byte, limit int) string {
+	return fmt.Sprintf("%s?start_key=%s&end_key=%s&limit=%d",
+		regionsByKey, url.QueryEscape(string(startKey)), url.QueryEscape(string(endKey)), limit)
+}
+
+// RegionsByStoreID returns the path of PD HTTP API to get regions by store ID.
+func RegionsByStoreID(storeID uint64) string {
+	return fmt.Sprintf("%s/%d", regionsByStoreID, storeID)
+}

client/http/client.go

@@ -0,0 +1,276 @@
+// 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 http
+
+import (
+	"context"
+	"crypto/tls"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/pingcap/errors"
+	"github.com/pingcap/log"
+	"go.uber.org/zap"
+)
+
+const defaultTimeout = 30 * time.Second
+
+// HTTPClient is a PD (Placement Driver) HTTP client.
+type HTTPClient interface {
+	GetRegionByID(context.Context, uint64) (*RegionInfo, error)
+	GetRegionByKey(context.Context, []byte) (*RegionInfo, error)
+	GetRegions(context.Context) (*RegionsInfo, error)
+	GetRegionsByKey(context.Context, []byte, []byte, int) (*RegionsInfo, error)
+	GetRegionsByStoreID(context.Context, uint64) (*RegionsInfo, error)
+	GetHotReadRegions(context.Context) (*StoreHotPeersInfos, error)
+	GetHotWriteRegions(context.Context) (*StoreHotPeersInfos, error)
+	GetStores(context.Context) (*StoresInfo, error)
+	GetMinResolvedTSByStoresIDs(context.Context, []string) (uint64, map[uint64]uint64, error)
+	Close()
+}
+
+var _ HTTPClient = (*httpClient)(nil)
+
+type httpClient struct {
+	pdAddrs []string
+	tlsConf *tls.Config
+	cli     *http.Client
+}
+
+// HTTPClientOption configures the HTTP client.
+type HTTPClientOption func(hc *httpClient)
+
+// WithHTTPClient configures the client with the given initialized HTTP client.
+func WithHTTPClient(cli *http.Client) HTTPClientOption {
+	return func(hc *httpClient) {
+		hc.cli = cli
+	}
+}
+
+// WithTLSConfig configures the client with the given TLS config.
+// This option won't work if the client is configured with WithHTTPClient.
+func WithTLSConfig(tlsConf *tls.Config) HTTPClientOption {
+	return func(hc *httpClient) {
+		hc.tlsConf = tlsConf
+	}
+}
+
+// NewHTTPClient creates a PD HTTP client with the given PD addresses and TLS config.
+func NewHTTPClient(
+	pdAddrs []string,
+	opts ...HTTPClientOption,
+) HTTPClient {
+	hc := &httpClient{}
+	// Apply the options first.
+	for _, opt := range opts {
+		opt(hc)
+	}
+	// Normalize the addresses with correct scheme prefix.
+	for i, addr := range pdAddrs {
+		if !strings.HasPrefix(addr, "http") {
+			if hc.tlsConf != nil {
+				addr = "https://" + addr
+			} else {
+				addr = "http://" + addr
+			}
+			pdAddrs[i] = addr
+		}
+	}
+	hc.pdAddrs = pdAddrs
+	// Init the HTTP client.
+	if hc.cli != nil {
+		cli := &http.Client{Timeout: defaultTimeout}
+		if hc.tlsConf != nil {
+			transport := http.DefaultTransport.(*http.Transport).Clone()
+			transport.TLSClientConfig = hc.tlsConf
+			cli.Transport = transport
+		}
+	}
+
+	return hc
+}
+
+// Close closes the HTTP client.
+func (hc *httpClient) Close() {
+	if hc.cli != nil {
+		hc.cli.CloseIdleConnections()
+	}
+	log.Info("[pd] http client closed")
+}
+
+func (hc *httpClient) pdAddr() string {
+	// TODO: support the customized PD address selection strategy.
+	return hc.pdAddrs[0]
+}
+
+func (hc *httpClient) request(
+	ctx context.Context,
+	name, uri string,
+	res interface{},
+) error {
+	reqURL := fmt.Sprintf("%s%s", hc.pdAddr(), uri)
+	logFields := []zap.Field{
+		zap.String("name", name),
+		zap.String("url", reqURL),
+	}
+	log.Debug("[pd] request the http url", logFields...)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, reqURL, nil)
+	if err != nil {
+		log.Error("[pd] create http request failed", append(logFields, zap.Error(err))...)
+		return errors.Trace(err)
+	}
+	// TODO: integrate the metrics.
+	resp, err := hc.cli.Do(req)
+	if err != nil {
+		log.Error("[pd] do http request failed", append(logFields, zap.Error(err))...)
+		return errors.Trace(err)
+	}
+	defer func() {
+		err = resp.Body.Close()
+		if err != nil {
+			log.Warn("[pd] close http response body failed", append(logFields, zap.Error(err))...)
+		}
+	}()
+
+	if resp.StatusCode != http.StatusOK {
+		logFields = append(logFields, zap.String("status", resp.Status))
+
+		bs, readErr := io.ReadAll(resp.Body)
+		if readErr != nil {
+			logFields = append(logFields, zap.NamedError("read-body-error", err))
+		} else {
+			logFields = append(logFields, zap.ByteString("body", bs))
+		}
+
+		log.Error("[pd] request failed with a non-200 status", logFields...)
+		return errors.Errorf("request pd http api failed with status: '%s'", resp.Status)
+	}
+
+	err = json.NewDecoder(resp.Body).Decode(res)
+	if err != nil {
+		return errors.Trace(err)
+	}
+	return nil
+}
+
+// GetRegionByID gets the region info by ID.
+func (hc *httpClient) GetRegionByID(ctx context.Context, regionID uint64) (*RegionInfo, error) {
+	var region RegionInfo
+	err := hc.request(ctx, "GetRegionByID", RegionByID(regionID), &region)
+	if err != nil {
+		return nil, err
+	}
+	return &region, nil
+}
+
+// GetRegionByKey gets the region info by key.
+func (hc *httpClient) GetRegionByKey(ctx context.Context, key []byte) (*RegionInfo, error) {
+	var region RegionInfo
+	err := hc.request(ctx, "GetRegionByKey", RegionByKey(key), &region)
+	if err != nil {
+		return nil, err
+	}
+	return &region, nil
+}
+
+// GetRegions gets the regions info.
+func (hc *httpClient) GetRegions(ctx context.Context) (*RegionsInfo, error) {
+	var regions RegionsInfo
+	err := hc.request(ctx, "GetRegions", Regions, &regions)
+	if err != nil {
+		return nil, err
+	}
+	return &regions, nil
+}
+
+// GetRegionsByKey gets the regions info by key range. If the limit is -1, it will return all regions within the range.
+func (hc *httpClient) GetRegionsByKey(ctx context.Context, startKey, endKey []byte, limit int) (*RegionsInfo, error) {
+	var regions RegionsInfo
+	err := hc.request(ctx, "GetRegionsByKey", RegionsByKey(startKey, endKey, limit), &regions)
+	if err != nil {
+		return nil, err
+	}
+	return &regions, nil
+}
+
+// GetRegionsByStoreID gets the regions info by store ID.
+func (hc *httpClient) GetRegionsByStoreID(ctx context.Context, storeID uint64) (*RegionsInfo, error) {
+	var regions RegionsInfo
+	err := hc.request(ctx, "GetRegionsByStoreID", RegionsByStoreID(storeID), &regions)
+	if err != nil {
+		return nil, err
+	}
+	return &regions, nil
+}
+
+// GetHotReadRegions gets the hot read region statistics info.
+func (hc *httpClient) GetHotReadRegions(ctx context.Context) (*StoreHotPeersInfos, error) {
+	var hotReadRegions StoreHotPeersInfos
+	err := hc.request(ctx, "GetHotReadRegions", HotRead, &hotReadRegions)
+	if err != nil {
+		return nil, err
+	}
+	return &hotReadRegions, nil
+}
+
+// GetHotWriteRegions gets the hot write region statistics info.
+func (hc *httpClient) GetHotWriteRegions(ctx context.Context) (*StoreHotPeersInfos, error) {
+	var hotWriteRegions StoreHotPeersInfos
+	err := hc.request(ctx, "GetHotWriteRegions", HotWrite, &hotWriteRegions)
+	if err != nil {
+		return nil, err
+	}
+	return &hotWriteRegions, nil
+}
+
+// GetStores gets the stores info.
+func (hc *httpClient) GetStores(ctx context.Context) (*StoresInfo, error) {
+	var stores StoresInfo
+	err := hc.request(ctx, "GetStores", Stores, &stores)
+	if err != nil {
+		return nil, err
+	}
+	return &stores, nil
+}
+
+// GetMinResolvedTSByStoresIDs get min-resolved-ts by stores IDs.
+func (hc *httpClient) GetMinResolvedTSByStoresIDs(ctx context.Context, storeIDs []string) (uint64, map[uint64]uint64, error) {
+	uri := MinResolvedTSPrefix
+	// scope is an optional parameter, it can be `cluster` or specified store IDs.
+	// - When no scope is given, cluster-level's min_resolved_ts will be returned and storesMinResolvedTS will be nil.
+	// - When scope is `cluster`, cluster-level's min_resolved_ts will be returned and storesMinResolvedTS will be filled.
+	// - When scope given a list of stores, min_resolved_ts will be provided for each store
+	//      and the scope-specific min_resolved_ts will be returned.
+	if len(storeIDs) != 0 {
+		uri = fmt.Sprintf("%s?scope=%s", uri, strings.Join(storeIDs, ","))
+	}
+	resp := struct {
+		MinResolvedTS       uint64            `json:"min_resolved_ts"`
+		IsRealTime          bool              `json:"is_real_time,omitempty"`
+		StoresMinResolvedTS map[uint64]uint64 `json:"stores_min_resolved_ts"`
+	}{}
+	err := hc.request(ctx, "GetMinResolvedTSByStoresIDs", uri, &resp)
+	if err != nil {
+		return 0, nil, err
+	}
+	if !resp.IsRealTime {
+		return 0, nil, errors.Trace(errors.New("min resolved ts is not enabled"))
+	}
+	return resp.MinResolvedTS, resp.StoresMinResolvedTS, nil
+}