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util.go
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util.go
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// Copyright 2015 Comcast Cable Communications Management, LLC
//
// 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.
//
// End Copyright
package core
import (
"crypto/rand"
"encoding/json"
"fmt"
"log"
"net"
"os"
"reflect"
"runtime"
"runtime/pprof"
"strconv"
"strings"
"sync/atomic"
"time"
)
// ParseJSON parses a map from bytes.
func ParseJSON(ctx *Context, bs []byte) (map[string]interface{}, error) {
var pattern map[string]interface{}
err := json.Unmarshal(bs, &pattern)
if err != nil {
// convert golang error to rules specific one for proper error handling
err = NewSyntaxError(err.Error())
Log(UERR, ctx, "core.ParseJSON", "error", err, "bs", string(bs))
}
return pattern, err
}
// ParseJSONString parses a map from a string.
func ParseJSONString(ctx *Context, s string) (map[string]interface{}, error) {
m, err := ParseJSON(ctx, []byte(s))
return m, err
}
// StringSet represents a set of strings.
//
// A StringSet is not synchronized.
type StringSet map[string]struct{}
// NewStringSet does what you'd expect.
func NewStringSet(xs []string) StringSet {
ss := make(StringSet)
if xs != nil {
for _, x := range xs {
ss.Add(x)
}
}
return ss
}
// EmptyStringSet makes one of those.
func EmptyStringSet() StringSet {
ss := make(StringSet)
return ss
}
// Nothing really is nothing.
var Nothing = struct{}{}
// Add adds the given string to the set.
func (s StringSet) Add(x string) StringSet {
s[x] = Nothing
return s
}
// AddAll adds all elements of the given set to the set.
func (s StringSet) AddAll(more StringSet) StringSet {
for x := range more {
s.Add(x)
}
return s
}
func (s StringSet) AddStrings(xs ...string) StringSet {
for _, x := range xs {
s.Add(x)
}
return s
}
// Rem does what you'd think.
func (s StringSet) Rem(x string) StringSet {
delete(s, x)
return s
}
// Contains reports whether the given string is in the set
func (s StringSet) Contains(x string) bool {
_, have := s[x]
return have
}
// Insert removes elements not in the given set.
//
// The receiver is modified.
func (s StringSet) Intersect(t StringSet) {
for x := range s {
_, have := t[x]
if !have {
delete(s, x)
}
}
}
func (xs StringSet) json() string {
bs, err := json.Marshal(xs.Array())
if err != nil {
panic(err)
}
return string(bs)
}
// Array returns a pointer to an array of the set's elements.
func (xs StringSet) Array() []string {
acc := make([]string, 0, len(xs))
for x := range xs {
acc = append(acc, x)
}
return acc
}
// Difference returns a new set containing the elements in receiver
// that are not in the given set.
//
// No sets are harmed in this operation.
func (xs StringSet) Difference(ys StringSet) (StringSet, StringSet) {
left := make(StringSet)
right := make(StringSet)
for x := range xs {
if !ys.Contains(x) {
left.Add(x)
}
}
for y := range ys {
if !xs.Contains(y) {
right.Add(y)
}
}
return left, right
}
func (s StringSet) UnmarshalJSON(data []byte) error {
// Just a JSON array
var xs []string
if err := json.Unmarshal(data, &s); err != nil {
return err
}
s.AddStrings(xs...)
return nil
}
func (s StringSet) MarshalJSON() ([]byte, error) {
// Just a JSON array
return json.Marshal(s.Array())
}
// Now returns the current time in UTC nanoseconds.
func Now() int64 {
return time.Now().UTC().UnixNano()
}
// NowMicros returns the current time in UTC microseconds.
func NowMicros() int64 {
return int64(Now() / 1000)
}
// NowSecs returns the current time in UTC seconds.
func NowSecs() int64 {
return time.Now().UTC().Unix()
}
// Timestamp returns a string representing the given time in UTC in
// the 'RFC3339Nano' representation.
func Timestamp(t time.Time) string {
return t.UTC().Format(time.RFC3339Nano)
}
// GetTimestamp makes a timestamp from UNIX nanoseconds.
func GetTimestamp(ts int64) string {
return fmt.Sprintf("%s", time.Unix(ts/1000000, 0).Format(time.RFC3339Nano))
}
// NowString returns a string representing the current time in UTC in
// the 'RFC3339Nano' representation.
func NowString() string {
return Timestamp(time.Now())
}
// NanoStringToMilliString drops microseconds from the string, which
// should be in the 'RFC3339Nano' representation.
func NanoStringToMilliString(ns string) string {
if 24 > len(ns) {
return ns + "Z"
} else {
return ns[0:23] + "Z"
}
}
// IncCounter safely returns an increasing int.
func IncCounter() uint64 {
return atomic.AddUint64(&IncCounterBase, uint64(1))
}
// IncCounterBase is the state for IncCounter().
var IncCounterBase = uint64(0)
// CheckErr is a utility function to log an error if any.
//
// Useful in goroutines or in other places where there is no caller to
// bother but something inconvenient might have occurred. Ideally, we
// never use this function.
func CheckErr(ctx *Context, op string, err error) {
if err != nil {
Log(ERROR, ctx, op, "error", err)
}
}
// Inc atomically updates the given counter.
func Inc(p *uint64, d int64) {
atomic.AddUint64(p, uint64(d))
}
// UUID generates what is likely a v4 UUID using data from `crypto/Reader`.
// If crypto/Reader fails, returns the empty string instead.
// The implementation is platform-dependent; see
// https://golang.org/pkg/crypto/rand/ (random byte generation)
// https://groups.google.com/forum/#!topic/golang-nuts/Rn13T6BZpgE (uuid generation)
func UUID() string {
var b [16]byte
if _, err := rand.Reader.Read(b[:]); err != nil {
return ""
}
b[6] = (b[6] & 0x0f) | 0x40
b[8] = (b[8] & 0x3f) | 0x80
return fmt.Sprintf("%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
}
// Accumulator is sliding buffer.
//
// As it fills, older entries slide off the back.
//
// Not synchronized.
type Accumulator struct {
// sync.Mutex
// Acc is the buffer.
Acc []interface{}
// Limit is the capacity.
Limit int
// Dumped is the number of entries that have been dumped to
// make room for other entries.
Dumped int
}
// NewAccumulator returns an Accumulator with the given size.
func NewAccumulator(limit int) *Accumulator {
buf := make([]interface{}, 0, limit)
return &Accumulator{buf, limit, 0}
}
// Add adds the thing to the Accumulator.
//
// If there isn't room, then room.
func (acc *Accumulator) Add(x interface{}) {
// acc.Lock()
dump := len(acc.Acc) - acc.Limit
if 0 < dump {
acc.Acc = acc.Acc[dump:]
acc.Dumped += dump
}
if len(acc.Acc) < acc.Limit {
acc.Acc = append(acc.Acc, x)
} else {
acc.Dumped++
}
// acc.Unlock()
}
// Profile starts CPU and memory profiling and returns a function that will stop that.
//
//
// Writes "cpu" + filename and "mem" + filename.
//
// Usage:
//
// defer Profile("logfast.prof")()
//
func Profile(filename string) func() {
cpu, err := os.Create("cpu" + filename)
if err != nil {
panic(err)
}
mem, err := os.Create("mem" + filename)
if err != nil {
panic(err)
}
then := time.Now()
log.Printf("Profile starting %s\n", filename)
pprof.StartCPUProfile(cpu)
pprof.WriteHeapProfile(mem)
return func() {
elapsed := time.Now().Sub(then)
log.Printf("Profile stopping %s (elapsed %v)\n", filename, elapsed)
pprof.StopCPUProfile()
if err := mem.Close(); err != nil {
log.Printf("error closing mem profile (%v)", err)
}
}
}
// Gorep returns a string that represents the given thing in Go --
// except for plain strings.
//
// This function is used in logging generic data. All log records
// should have consistent types for a given property value. If
// property can actually have different values, use this function to
// homogenize the values. This function is slow and otherwise
// distasteful, but perhaps it's better than nothing.
func Gorep(x interface{}) string {
if s, ok := x.(string); ok {
return s
} else {
return fmt.Sprintf("%#v", x)
}
}
// UseCores will use all cores unless the environment variable
// 'GOMAXPROCS' is set.
//
// If 'silent', then do not make a 'Log()' call.
//
// There is a proposal for Go 1.5 to make GOMAXPROCS default to the
// number of available cores.
func UseCores(ctx *Context, silent bool) {
cores := os.Getenv("GOMAXPROCS")
if cores == "" {
n := runtime.NumCPU()
if !silent {
Log(INFO, ctx, "UseCores", "cores", n, "from", "NumCPU")
}
runtime.GOMAXPROCS(n)
cores = strconv.Itoa(n)
} else {
if !silent {
Log(INFO, ctx, "UseCores", "cores", cores, "from", "env")
}
}
}
// StructToMap converts a struct to a map.
func StructToMap(x interface{}) (map[string]interface{}, error) {
m := make(map[string]interface{})
v := reflect.ValueOf(x)
if v.Kind() == reflect.Ptr {
v = v.Elem()
}
if v.Kind() != reflect.Struct {
return nil, fmt.Errorf("not a struct (%T)", v)
}
t := v.Type()
for i := 0; i < v.NumField(); i++ {
p := t.Field(i).Name
m[p] = v.Field(i).Interface()
}
return m, nil
}
// TextContextWithLocation creates a location with indexed state on memory
// storage. Also returns a Context with its location se.
func TestContextWithLocation(name string) (*Context, error) {
ctx := TestContext(name)
store, err := NewMemStorage(ctx)
if err != nil {
return nil, err
}
state, err := NewIndexedState(ctx, name, store)
if err != nil {
return nil, err
}
loc, err := NewLocation(ctx, name, state, nil)
if err != nil {
return nil, err
}
ctx.SetLoc(loc)
return ctx, nil
}
// CoerceFakeFloats will make ints out of floats when possible.
//
// Since al JSON all numbers are floats, big "integers" can cause
// trouble. Example: millisecond timestamps get float representation:
// 1416505007395 becomes 1.416505007395e+12, which we don't want.
//
// Rather than using json.Decode with UseNumber, which results in
// numbers of the type json.Number (which could cause trouble with
// reflective code), we coerce what we can outbound.
//
// Inspirational code from Boris.
func CoerceFakeFloats(x interface{}) interface{} {
switch v := x.(type) {
case float64:
if v == float64(int(v)) {
x = int(v)
}
case map[string]interface{}:
for p, val := range v {
v[p] = CoerceFakeFloats(val)
}
}
return x
}
// IpAddresses tries to find a machine's (non-loopback) network
// interfaces.
//
// 127.0.0.1 and ::1 are not included in the results.
//
// Uses 'net.Interfaces()'.
func IpAddresses() ([]string, error) {
ifaces, err := net.Interfaces()
acc := make([]string, 0, 0)
if err != nil {
return acc, err
}
skip := func(s string) bool {
switch s {
case "127.0.0.1", "::1":
return true
default:
return false
}
}
for _, i := range ifaces {
addrs, err := i.Addrs()
if err != nil {
return acc, err
}
for _, addr := range addrs {
switch v := addr.(type) {
case *net.IPNet:
s := v.IP.String()
if !skip(s) {
acc = append(acc, s)
}
case *net.IPAddr:
s := v.IP.String()
if !skip(s) {
acc = append(acc, s)
}
}
}
}
return acc, nil
}
// IpAddress tries to return a (non-loopback) IP address for this machine.
//
// If it can't find one, it returns 127.0.0.1.
//
// Exactly what this function returns is not really defined. Don't
// rely on it for anything important.
func IpAddress() string {
ips, _ := IpAddresses()
if len(ips) == 0 {
return "127.0.0.1"
}
return ips[0]
}
// AnIpAddress is maybe an IP address for this machine.
//
// Will try to find a non-loopback interface. Failing that, it's
// 127.0.0.1.
var AnIpAddress = IpAddress()
// ISlice attempts to convert the given thing to an array of interface{}s.
//
// If the given thing isn't array, the thing is just returned.
//
// Uses reflection.
func ISlice(xs interface{}) (interface{}, bool) {
v := reflect.ValueOf(xs)
switch v.Kind() {
case reflect.Slice:
acc := make([]interface{}, v.Len())
for i := 0; i < v.Len(); i++ {
acc[i] = v.Index(i).Interface()
}
return acc, true
}
return v, false
}
// Map is a generic event, pattern, or fact.
//
// Kinda wants to be a transparent typedef.
type Map map[string]interface{}
// ParseMap tries to parse a Map from JSON.
func ParseMap(js string) (m Map, err error) {
err = json.Unmarshal([]byte(js), &m)
return m, nil
}
func MustMap(js string) Map {
m, err := ParseMap(js)
if err != nil {
panic(err)
}
return m
}
func (m Map) JSON() (string, error) {
bs, err := json.Marshal(&m)
if err != nil {
return "", err
}
return string(bs), nil
}
func Who(skip int) string {
_, file, line, ok := runtime.Caller(skip)
return fmt.Sprintf("who %s %d %v", file, line, ok)
}
// Copy mostly provides a deep copy of maps.
func Copy(x interface{}) interface{} {
switch vv := x.(type) {
case Map:
acc := make(Map, len(vv))
for k, v := range vv {
acc[k] = Copy(v)
}
return acc
case map[string]interface{}:
acc := make(map[string]interface{}, len(vv))
for k, v := range vv {
acc[k] = Copy(v)
}
return acc
case map[interface{}]interface{}:
acc := make(map[interface{}]interface{}, len(vv))
for k, v := range vv {
acc[k] = Copy(v)
}
return acc
default:
return x
}
}
func IsVariable(s string) bool {
return strings.HasPrefix(s, "?")
}
func IsConstant(s string) bool {
return !IsVariable(s)
}