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|
package jsonapi
import (
"crypto/rand"
"fmt"
"io"
"reflect"
"time"
)
type Event int
const (
UnmarshalStart Event = iota
UnmarshalStop
MarshalStart
MarshalStop
)
type Runtime struct {
ctx map[string]interface{}
}
type Events func(*Runtime, Event, string, time.Duration)
var Instrumentation Events
func NewRuntime() *Runtime { return &Runtime{make(map[string]interface{})} }
func (r *Runtime) WithValue(key string, value interface{}) *Runtime {
r.ctx[key] = value
return r
}
func (r *Runtime) Value(key string) interface{} {
return r.ctx[key]
}
func (r *Runtime) Instrument(key string) *Runtime {
return r.WithValue("instrument", key)
}
func (r *Runtime) shouldInstrument() bool {
return Instrumentation != nil
}
func (r *Runtime) UnmarshalPayload(reader io.Reader, model interface{}) error {
return r.instrumentCall(UnmarshalStart, UnmarshalStop, func() error {
return UnmarshalPayload(reader, model)
})
}
func (r *Runtime) UnmarshalManyPayload(reader io.Reader, kind reflect.Type) (elems []interface{}, err error) {
r.instrumentCall(UnmarshalStart, UnmarshalStop, func() error {
elems, err = UnmarshalManyPayload(reader, kind)
return err
})
return
}
func (r *Runtime) MarshalPayload(w io.Writer, model interface{}) error {
return r.instrumentCall(MarshalStart, MarshalStop, func() error {
return MarshalPayload(w, model)
})
}
func (r *Runtime) instrumentCall(start Event, stop Event, c func() error) error {
if !r.shouldInstrument() {
return c()
}
instrumentationGUID, err := newUUID()
if err != nil {
return err
}
begin := time.Now()
Instrumentation(r, start, instrumentationGUID, time.Duration(0))
if err := c(); err != nil {
return err
}
diff := time.Duration(time.Now().UnixNano() - begin.UnixNano())
Instrumentation(r, stop, instrumentationGUID, diff)
return nil
}
// citation: http://play.golang.org/p/4FkNSiUDMg
func newUUID() (string, error) {
uuid := make([]byte, 16)
if _, err := io.ReadFull(rand.Reader, uuid); err != nil {
return "", err
}
// variant bits; see section 4.1.1
uuid[8] = uuid[8]&^0xc0 | 0x80
// version 4 (pseudo-random); see section 4.1.3
uuid[6] = uuid[6]&^0xf0 | 0x40
return fmt.Sprintf("%x-%x-%x-%x-%x", uuid[0:4], uuid[4:6], uuid[6:8], uuid[8:10], uuid[10:]), nil
}
|
