forked from Mirrors/jsonapi
130 lines
3.4 KiB
Go
130 lines
3.4 KiB
Go
package jsonapi
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import (
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"crypto/rand"
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"fmt"
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"io"
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"reflect"
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"time"
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)
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// Event represents a lifecycle event in the marshaling or unmarshalling
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// process.
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type Event int
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const (
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// UnmarshalStart is the Event that is sent when deserialization of a payload
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// begins.
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UnmarshalStart Event = iota
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// UnmarshalStop is the Event that is sent when deserialization of a payload
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// ends.
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UnmarshalStop
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// MarshalStart is the Event that is sent sent when serialization of a payload
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// begins.
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MarshalStart
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// MarshalStop is the Event that is sent sent when serialization of a payload
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// ends.
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MarshalStop
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)
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// Runtime has the same methods as jsonapi package for serialization and
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// deserialization but also has a ctx, a map[string]interface{} for storing
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// state, designed for instrumenting serialization timings.
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type Runtime struct {
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ctx map[string]interface{}
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}
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// Events is the func type that provides the callback for handling event timings.
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type Events func(*Runtime, Event, string, time.Duration)
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// Instrumentation is a a global Events variable. This is the handler for all
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// timing events.
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var Instrumentation Events
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// NewRuntime creates a Runtime for use in an application.
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func NewRuntime() *Runtime { return &Runtime{make(map[string]interface{})} }
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// WithValue adds custom state variables to the runtime context.
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func (r *Runtime) WithValue(key string, value interface{}) *Runtime {
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r.ctx[key] = value
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return r
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}
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// Value returns a state variable in the runtime context.
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func (r *Runtime) Value(key string) interface{} {
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return r.ctx[key]
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}
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// Instrument is deprecated.
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func (r *Runtime) Instrument(key string) *Runtime {
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return r.WithValue("instrument", key)
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}
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func (r *Runtime) shouldInstrument() bool {
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return Instrumentation != nil
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}
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// UnmarshalPayload has docs in request.go for UnmarshalPayload.
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func (r *Runtime) UnmarshalPayload(reader io.Reader, model interface{}) error {
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return r.instrumentCall(UnmarshalStart, UnmarshalStop, func() error {
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return UnmarshalPayload(reader, model)
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})
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}
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// UnmarshalManyPayload has docs in request.go for UnmarshalManyPayload.
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func (r *Runtime) UnmarshalManyPayload(reader io.Reader, kind reflect.Type) (elems []interface{}, err error) {
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r.instrumentCall(UnmarshalStart, UnmarshalStop, func() error {
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elems, err = UnmarshalManyPayload(reader, kind)
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return err
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})
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return
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}
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// MarshalPayload has docs in response.go for MarshalPayload.
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func (r *Runtime) MarshalPayload(w io.Writer, model interface{}) error {
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return r.instrumentCall(MarshalStart, MarshalStop, func() error {
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return MarshalPayload(w, model)
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})
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}
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func (r *Runtime) instrumentCall(start Event, stop Event, c func() error) error {
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if !r.shouldInstrument() {
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return c()
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}
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instrumentationGUID, err := newUUID()
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if err != nil {
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return err
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}
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begin := time.Now()
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Instrumentation(r, start, instrumentationGUID, time.Duration(0))
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if err := c(); err != nil {
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return err
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}
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diff := time.Duration(time.Now().UnixNano() - begin.UnixNano())
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Instrumentation(r, stop, instrumentationGUID, diff)
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return nil
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}
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// citation: http://play.golang.org/p/4FkNSiUDMg
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func newUUID() (string, error) {
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uuid := make([]byte, 16)
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if _, err := io.ReadFull(rand.Reader, uuid); err != nil {
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return "", err
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}
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// variant bits; see section 4.1.1
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uuid[8] = uuid[8]&^0xc0 | 0x80
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// version 4 (pseudo-random); see section 4.1.3
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uuid[6] = uuid[6]&^0xf0 | 0x40
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return fmt.Sprintf("%x-%x-%x-%x-%x", uuid[0:4], uuid[4:6], uuid[6:8], uuid[8:10], uuid[10:]), nil
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}
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