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.

client/http/api.go

@@ -0,0 +1,21 @@
+// 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
+
+// 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"
+)

client/http/backoff.go

@@ -0,0 +1,17 @@
+// 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
+
+// TODO: support the customized backoff strategy.

client/http/client.go

@@ -0,0 +1,152 @@
+// 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 {
+	GetHotReadRegions(context.Context) (*StoreHotPeersInfos, error)
+	GetHotWriteRegions(context.Context) (*StoreHotPeersInfos, error)
+}
+
+var _ HTTPClient = (*httpClient)(nil)
+
+type httpClient struct {
+	pdAddrs []string
+	cli     *http.Client
+}
+
+// NewHTTPClient creates a PD HTTP client with the given PD addresses and TLS config.
+func NewHTTPClient(
+	pdAddrs []string,
+	tlsConf *tls.Config,
+) HTTPClient {
+	// Normalize the addresses with correct scheme prefix.
+	for i, addr := range pdAddrs {
+		if !strings.HasPrefix(addr, "http") {
+			if tlsConf != nil {
+				addr = "https://" + addr
+			} else {
+				addr = "http://" + addr
+			}
+			pdAddrs[i] = addr
+		}
+	}
+	// Init the HTTP client.
+	// TODO: do we need to make the HTTP client a singleton?
+	cli := &http.Client{Timeout: defaultTimeout}
+	if tlsConf != nil {
+		transport := http.DefaultTransport.(*http.Transport).Clone()
+		transport.TLSClientConfig = tlsConf
+		cli.Transport = transport
+	}
+
+	return &httpClient{
+		pdAddrs: pdAddrs,
+		cli:     cli,
+	}
+}
+
+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, method, uri string,
+	res interface{},
+) error {
+	reqURL := fmt.Sprintf("%s%s", hc.pdAddr(), uri)
+	logFields := []zap.Field{
+		zap.String("name", name),
+		zap.String("url", reqURL),
+		zap.String("method", method),
+	}
+	log.Debug("[pd] request the http url", logFields...)
+	req, err := http.NewRequestWithContext(ctx, method, 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
+}
+
+// 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", http.MethodGet, 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", http.MethodGet, HotWrite, &hotWriteRegions)
+	if err != nil {
+		return nil, err
+	}
+	return &hotWriteRegions, nil
+}

client/http/types.go

@@ -0,0 +1,56 @@
+// 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 "time"
+
+// NOTICE: the structures below are copied from the PD API definitions.
+// Please make sure the consistency if any change happens to the PD API.
+
+// StoreHotPeersInfos is used to get human-readable description for hot regions.
+type StoreHotPeersInfos struct {
+	AsPeer   StoreHotPeersStat `json:"as_peer"`
+	AsLeader StoreHotPeersStat `json:"as_leader"`
+}
+
+// StoreHotPeersStat is used to record the hot region statistics group by store.
+type StoreHotPeersStat map[uint64]*HotPeersStat
+
+// HotPeersStat records all hot regions statistics
+type HotPeersStat struct {
+	StoreByteRate  float64           `json:"store_bytes"`
+	StoreKeyRate   float64           `json:"store_keys"`
+	StoreQueryRate float64           `json:"store_query"`
+	TotalBytesRate float64           `json:"total_flow_bytes"`
+	TotalKeysRate  float64           `json:"total_flow_keys"`
+	TotalQueryRate float64           `json:"total_flow_query"`
+	Count          int               `json:"regions_count"`
+	Stats          []HotPeerStatShow `json:"statistics"`
+}
+
+// HotPeerStatShow records the hot region statistics for output
+type HotPeerStatShow struct {
+	StoreID        uint64    `json:"store_id"`
+	Stores         []uint64  `json:"stores"`
+	IsLeader       bool      `json:"is_leader"`
+	IsLearner      bool      `json:"is_learner"`
+	RegionID       uint64    `json:"region_id"`
+	HotDegree      int       `json:"hot_degree"`
+	ByteRate       float64   `json:"flow_bytes"`
+	KeyRate        float64   `json:"flow_keys"`
+	QueryRate      float64   `json:"flow_query"`
+	AntiCount      int       `json:"anti_count"`
+	LastUpdateTime time.Time `json:"last_update_time,omitempty"`
+}