vitess.io/vitess@v0.16.2/go/vt/vttablet/tabletserver/debugenv.go

/*
Copyright 2020 The Vitess 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 tabletserver

import (
	"encoding/json"
	"fmt"
	"html"
	"net/http"
	"strconv"
	"text/template"
	"time"

	"vitess.io/vitess/go/acl"
	"vitess.io/vitess/go/vt/log"
)

var (
	debugEnvHeader = []byte(`
	<thead><tr>
		<th>Variable Name</th>
		<th>Value</th>
		<th>Action</th>
	</tr></thead>
	`)
	debugEnvRow = template.Must(template.New("debugenv").Parse(`
	<tr><form method="POST">
		<td>{{.Name}}</td>
		<td>
			<input type="hidden" name="varname" value="{{.Name}}"></input>
			<input type="text" name="value" value="{{.Value}}"></input>
		</td>
		<td><input type="submit" name="Action" value="Modify"></input></td>
	</form></tr>
	`))
)

type envValue struct {
	Name  string
	Value string
}

// this cannot be an anonymous function within debugEnvHandler because those kinds
// of functions cannot (currently) have type params.
func addVar[T any](vars []envValue, name string, f func() T) []envValue {
	return append(vars, envValue{
		Name:  name,
		Value: fmt.Sprintf("%v", f()),
	})
}

func debugEnvHandler(tsv *TabletServer, w http.ResponseWriter, r *http.Request) {
	if err := acl.CheckAccessHTTP(r, acl.ADMIN); err != nil {
		acl.SendError(w, err)
		return
	}

	var msg string
	if r.Method == "POST" {
		varname := r.FormValue("varname")
		value := r.FormValue("value")
		setIntVal := func(f func(int)) {
			ival, err := strconv.Atoi(value)
			if err != nil {
				msg = fmt.Sprintf("Failed setting value for %v: %v", varname, err)
				return
			}
			f(ival)
			msg = fmt.Sprintf("Setting %v to: %v", varname, value)
		}
		setInt64Val := func(f func(int64)) {
			ival, err := strconv.ParseInt(value, 10, 64)
			if err != nil {
				msg = fmt.Sprintf("Failed setting value for %v: %v", varname, err)
				return
			}
			f(ival)
			msg = fmt.Sprintf("Setting %v to: %v", varname, value)
		}
		setDurationVal := func(f func(time.Duration)) {
			durationVal, err := time.ParseDuration(value)
			if err != nil {
				msg = fmt.Sprintf("Failed setting value for %v: %v", varname, err)
				return
			}
			f(durationVal)
			msg = fmt.Sprintf("Setting %v to: %v", varname, value)
		}
		setFloat64Val := func(f func(float64)) {
			fval, err := strconv.ParseFloat(value, 64)
			if err != nil {
				msg = fmt.Sprintf("Failed setting value for %v: %v", varname, err)
				return
			}
			f(fval)
			msg = fmt.Sprintf("Setting %v to: %v", varname, value)
		}
		switch varname {
		case "PoolSize":
			setIntVal(tsv.SetPoolSize)
		case "StreamPoolSize":
			setIntVal(tsv.SetStreamPoolSize)
		case "TxPoolSize":
			setIntVal(tsv.SetTxPoolSize)
		case "QueryCacheCapacity":
			setIntVal(tsv.SetQueryPlanCacheCap)
		case "MaxResultSize":
			setIntVal(tsv.SetMaxResultSize)
		case "WarnResultSize":
			setIntVal(tsv.SetWarnResultSize)
		case "RowStreamerMaxInnoDBTrxHistLen":
			setInt64Val(func(val int64) { tsv.Config().RowStreamer.MaxInnoDBTrxHistLen = val })
		case "RowStreamerMaxMySQLReplLagSecs":
			setInt64Val(func(val int64) { tsv.Config().RowStreamer.MaxMySQLReplLagSecs = val })
		case "UnhealthyThreshold":
			setDurationVal(tsv.Config().Healthcheck.UnhealthyThresholdSeconds.Set)
			setDurationVal(tsv.hs.SetUnhealthyThreshold)
			setDurationVal(tsv.sm.SetUnhealthyThreshold)
		case "ThrottleMetricThreshold":
			setFloat64Val(tsv.SetThrottleMetricThreshold)
		case "Consolidator":
			tsv.SetConsolidatorMode(value)
			msg = fmt.Sprintf("Setting %v to: %v", varname, value)
		}
	}

	var vars []envValue
	vars = addVar(vars, "PoolSize", tsv.PoolSize)
	vars = addVar(vars, "StreamPoolSize", tsv.StreamPoolSize)
	vars = addVar(vars, "TxPoolSize", tsv.TxPoolSize)
	vars = addVar(vars, "QueryCacheCapacity", tsv.QueryPlanCacheCap)
	vars = addVar(vars, "MaxResultSize", tsv.MaxResultSize)
	vars = addVar(vars, "WarnResultSize", tsv.WarnResultSize)
	vars = addVar(vars, "RowStreamerMaxInnoDBTrxHistLen", func() int64 { return tsv.Config().RowStreamer.MaxInnoDBTrxHistLen })
	vars = addVar(vars, "RowStreamerMaxMySQLReplLagSecs", func() int64 { return tsv.Config().RowStreamer.MaxMySQLReplLagSecs })
	vars = addVar(vars, "UnhealthyThreshold", tsv.Config().Healthcheck.UnhealthyThresholdSeconds.Get)
	vars = addVar(vars, "ThrottleMetricThreshold", tsv.ThrottleMetricThreshold)
	vars = append(vars, envValue{
		Name:  "Consolidator",
		Value: tsv.ConsolidatorMode(),
	})

	format := r.FormValue("format")
	if format == "json" {
		mvars := make(map[string]string)
		for _, v := range vars {
			mvars[v.Name] = v.Value
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(mvars)
		return
	}

	// gridTable is reused from twopcz.go.
	w.Write(gridTable)
	w.Write([]byte("<h3>Internal Variables</h3>\n"))
	if msg != "" {
		fmt.Fprintf(w, "<b>%s</b><br /><br />\n", html.EscapeString(msg))
	}
	w.Write(startTable)
	w.Write(debugEnvHeader)
	for _, v := range vars {
		if err := debugEnvRow.Execute(w, v); err != nil {
			log.Errorf("debugenv: couldn't execute template: %v", err)
		}
	}
	w.Write(endTable)
}