Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 367 insertions, 0 deletions

diff --git a/src/expvar/expvar.go b/src/expvar/expvar.go
new file mode 100644
index 0000000..13b5c99
--- /dev/null
+++ b/src/expvar/expvar.go
@@ -0,0 +1,367 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package expvar provides a standardized interface to public variables, such
+// as operation counters in servers. It exposes these variables via HTTP at
+// /debug/vars in JSON format.
+//
+// Operations to set or modify these public variables are atomic.
+//
+// In addition to adding the HTTP handler, this package registers the
+// following variables:
+//
+//	cmdline   os.Args
+//	memstats  runtime.Memstats
+//
+// The package is sometimes only imported for the side effect of
+// registering its HTTP handler and the above variables. To use it
+// this way, link this package into your program:
+//	import _ "expvar"
+//
+package expvar
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"math"
+	"net/http"
+	"os"
+	"runtime"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+)
+
+// Var is an abstract type for all exported variables.
+type Var interface {
+	// String returns a valid JSON value for the variable.
+	// Types with String methods that do not return valid JSON
+	// (such as time.Time) must not be used as a Var.
+	String() string
+}
+
+// Int is a 64-bit integer variable that satisfies the Var interface.
+type Int struct {
+	i int64
+}
+
+func (v *Int) Value() int64 {
+	return atomic.LoadInt64(&v.i)
+}
+
+func (v *Int) String() string {
+	return strconv.FormatInt(atomic.LoadInt64(&v.i), 10)
+}
+
+func (v *Int) Add(delta int64) {
+	atomic.AddInt64(&v.i, delta)
+}
+
+func (v *Int) Set(value int64) {
+	atomic.StoreInt64(&v.i, value)
+}
+
+// Float is a 64-bit float variable that satisfies the Var interface.
+type Float struct {
+	f uint64
+}
+
+func (v *Float) Value() float64 {
+	return math.Float64frombits(atomic.LoadUint64(&v.f))
+}
+
+func (v *Float) String() string {
+	return strconv.FormatFloat(
+		math.Float64frombits(atomic.LoadUint64(&v.f)), 'g', -1, 64)
+}
+
+// Add adds delta to v.
+func (v *Float) Add(delta float64) {
+	for {
+		cur := atomic.LoadUint64(&v.f)
+		curVal := math.Float64frombits(cur)
+		nxtVal := curVal + delta
+		nxt := math.Float64bits(nxtVal)
+		if atomic.CompareAndSwapUint64(&v.f, cur, nxt) {
+			return
+		}
+	}
+}
+
+// Set sets v to value.
+func (v *Float) Set(value float64) {
+	atomic.StoreUint64(&v.f, math.Float64bits(value))
+}
+
+// Map is a string-to-Var map variable that satisfies the Var interface.
+type Map struct {
+	m      sync.Map // map[string]Var
+	keysMu sync.RWMutex
+	keys   []string // sorted
+}
+
+// KeyValue represents a single entry in a Map.
+type KeyValue struct {
+	Key   string
+	Value Var
+}
+
+func (v *Map) String() string {
+	var b strings.Builder
+	fmt.Fprintf(&b, "{")
+	first := true
+	v.Do(func(kv KeyValue) {
+		if !first {
+			fmt.Fprintf(&b, ", ")
+		}
+		fmt.Fprintf(&b, "%q: %v", kv.Key, kv.Value)
+		first = false
+	})
+	fmt.Fprintf(&b, "}")
+	return b.String()
+}
+
+// Init removes all keys from the map.
+func (v *Map) Init() *Map {
+	v.keysMu.Lock()
+	defer v.keysMu.Unlock()
+	v.keys = v.keys[:0]
+	v.m.Range(func(k, _ interface{}) bool {
+		v.m.Delete(k)
+		return true
+	})
+	return v
+}
+
+// addKey updates the sorted list of keys in v.keys.
+func (v *Map) addKey(key string) {
+	v.keysMu.Lock()
+	defer v.keysMu.Unlock()
+	// Using insertion sort to place key into the already-sorted v.keys.
+	if i := sort.SearchStrings(v.keys, key); i >= len(v.keys) {
+		v.keys = append(v.keys, key)
+	} else if v.keys[i] != key {
+		v.keys = append(v.keys, "")
+		copy(v.keys[i+1:], v.keys[i:])
+		v.keys[i] = key
+	}
+}
+
+func (v *Map) Get(key string) Var {
+	i, _ := v.m.Load(key)
+	av, _ := i.(Var)
+	return av
+}
+
+func (v *Map) Set(key string, av Var) {
+	// Before we store the value, check to see whether the key is new. Try a Load
+	// before LoadOrStore: LoadOrStore causes the key interface to escape even on
+	// the Load path.
+	if _, ok := v.m.Load(key); !ok {
+		if _, dup := v.m.LoadOrStore(key, av); !dup {
+			v.addKey(key)
+			return
+		}
+	}
+
+	v.m.Store(key, av)
+}
+
+// Add adds delta to the *Int value stored under the given map key.
+func (v *Map) Add(key string, delta int64) {
+	i, ok := v.m.Load(key)
+	if !ok {
+		var dup bool
+		i, dup = v.m.LoadOrStore(key, new(Int))
+		if !dup {
+			v.addKey(key)
+		}
+	}
+
+	// Add to Int; ignore otherwise.
+	if iv, ok := i.(*Int); ok {
+		iv.Add(delta)
+	}
+}
+
+// AddFloat adds delta to the *Float value stored under the given map key.
+func (v *Map) AddFloat(key string, delta float64) {
+	i, ok := v.m.Load(key)
+	if !ok {
+		var dup bool
+		i, dup = v.m.LoadOrStore(key, new(Float))
+		if !dup {
+			v.addKey(key)
+		}
+	}
+
+	// Add to Float; ignore otherwise.
+	if iv, ok := i.(*Float); ok {
+		iv.Add(delta)
+	}
+}
+
+// Delete deletes the given key from the map.
+func (v *Map) Delete(key string) {
+	v.keysMu.Lock()
+	defer v.keysMu.Unlock()
+	i := sort.SearchStrings(v.keys, key)
+	if i < len(v.keys) && key == v.keys[i] {
+		v.keys = append(v.keys[:i], v.keys[i+1:]...)
+		v.m.Delete(key)
+	}
+}
+
+// Do calls f for each entry in the map.
+// The map is locked during the iteration,
+// but existing entries may be concurrently updated.
+func (v *Map) Do(f func(KeyValue)) {
+	v.keysMu.RLock()
+	defer v.keysMu.RUnlock()
+	for _, k := range v.keys {
+		i, _ := v.m.Load(k)
+		f(KeyValue{k, i.(Var)})
+	}
+}
+
+// String is a string variable, and satisfies the Var interface.
+type String struct {
+	s atomic.Value // string
+}
+
+func (v *String) Value() string {
+	p, _ := v.s.Load().(string)
+	return p
+}
+
+// String implements the Var interface. To get the unquoted string
+// use Value.
+func (v *String) String() string {
+	s := v.Value()
+	b, _ := json.Marshal(s)
+	return string(b)
+}
+
+func (v *String) Set(value string) {
+	v.s.Store(value)
+}
+
+// Func implements Var by calling the function
+// and formatting the returned value using JSON.
+type Func func() interface{}
+
+func (f Func) Value() interface{} {
+	return f()
+}
+
+func (f Func) String() string {
+	v, _ := json.Marshal(f())
+	return string(v)
+}
+
+// All published variables.
+var (
+	vars      sync.Map // map[string]Var
+	varKeysMu sync.RWMutex
+	varKeys   []string // sorted
+)
+
+// Publish declares a named exported variable. This should be called from a
+// package's init function when it creates its Vars. If the name is already
+// registered then this will log.Panic.
+func Publish(name string, v Var) {
+	if _, dup := vars.LoadOrStore(name, v); dup {
+		log.Panicln("Reuse of exported var name:", name)
+	}
+	varKeysMu.Lock()
+	defer varKeysMu.Unlock()
+	varKeys = append(varKeys, name)
+	sort.Strings(varKeys)
+}
+
+// Get retrieves a named exported variable. It returns nil if the name has
+// not been registered.
+func Get(name string) Var {
+	i, _ := vars.Load(name)
+	v, _ := i.(Var)
+	return v
+}
+
+// Convenience functions for creating new exported variables.
+
+func NewInt(name string) *Int {
+	v := new(Int)
+	Publish(name, v)
+	return v
+}
+
+func NewFloat(name string) *Float {
+	v := new(Float)
+	Publish(name, v)
+	return v
+}
+
+func NewMap(name string) *Map {
+	v := new(Map).Init()
+	Publish(name, v)
+	return v
+}
+
+func NewString(name string) *String {
+	v := new(String)
+	Publish(name, v)
+	return v
+}
+
+// Do calls f for each exported variable.
+// The global variable map is locked during the iteration,
+// but existing entries may be concurrently updated.
+func Do(f func(KeyValue)) {
+	varKeysMu.RLock()
+	defer varKeysMu.RUnlock()
+	for _, k := range varKeys {
+		val, _ := vars.Load(k)
+		f(KeyValue{k, val.(Var)})
+	}
+}
+
+func expvarHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	fmt.Fprintf(w, "{\n")
+	first := true
+	Do(func(kv KeyValue) {
+		if !first {
+			fmt.Fprintf(w, ",\n")
+		}
+		first = false
+		fmt.Fprintf(w, "%q: %s", kv.Key, kv.Value)
+	})
+	fmt.Fprintf(w, "\n}\n")
+}
+
+// Handler returns the expvar HTTP Handler.
+//
+// This is only needed to install the handler in a non-standard location.
+func Handler() http.Handler {
+	return http.HandlerFunc(expvarHandler)
+}
+
+func cmdline() interface{} {
+	return os.Args
+}
+
+func memstats() interface{} {
+	stats := new(runtime.MemStats)
+	runtime.ReadMemStats(stats)
+	return *stats
+}
+
+func init() {
+	http.HandleFunc("/debug/vars", expvarHandler)
+	Publish("cmdline", Func(cmdline))
+	Publish("memstats", Func(memstats))
+}