Merge pull request #369 from stevvooe/http-request-status-context-manager

context, registry/handlers: instantiate http context before dispatch
This commit is contained in:
Stephen Day 2015-04-15 23:23:40 -07:00
commit 10d875d50d
2 changed files with 81 additions and 34 deletions

View file

@ -273,6 +273,21 @@ func (app *App) configureRedis(configuration *configuration.Configuration) {
func (app *App) ServeHTTP(w http.ResponseWriter, r *http.Request) {
defer r.Body.Close() // ensure that request body is always closed.
// Instantiate an http context here so we can track the error codes
// returned by the request router.
ctx := defaultContextManager.context(app, w, r)
defer func() {
ctxu.GetResponseLogger(ctx).Infof("response completed")
}()
defer defaultContextManager.release(ctx)
// NOTE(stevvooe): Total hack to get instrumented responsewriter from context.
var err error
w, err = ctxu.GetResponseWriter(ctx)
if err != nil {
ctxu.GetLogger(ctx).Warnf("response writer not found in context")
}
// Set a header with the Docker Distribution API Version for all responses.
w.Header().Add("Docker-Distribution-API-Version", "registry/2.0")
app.router.ServeHTTP(w, r)
@ -287,38 +302,12 @@ type dispatchFunc func(ctx *Context, r *http.Request) http.Handler
// TODO(stevvooe): dispatchers should probably have some validation error
// chain with proper error reporting.
// singleStatusResponseWriter only allows the first status to be written to be
// the valid request status. The current use case of this class should be
// factored out.
type singleStatusResponseWriter struct {
http.ResponseWriter
status int
}
func (ssrw *singleStatusResponseWriter) WriteHeader(status int) {
if ssrw.status != 0 {
return
}
ssrw.status = status
ssrw.ResponseWriter.WriteHeader(status)
}
func (ssrw *singleStatusResponseWriter) Flush() {
if flusher, ok := ssrw.ResponseWriter.(http.Flusher); ok {
flusher.Flush()
}
}
// dispatcher returns a handler that constructs a request specific context and
// handler, using the dispatch factory function.
func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
context := app.context(w, r)
defer func() {
ctxu.GetResponseLogger(context).Infof("response completed")
}()
if err := app.authorized(w, r, context); err != nil {
ctxu.GetLogger(context).Errorf("error authorizing context: %v", err)
return
@ -360,16 +349,16 @@ func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
}
}
handler := dispatch(context, r)
ssrw := &singleStatusResponseWriter{ResponseWriter: w}
handler.ServeHTTP(ssrw, r)
dispatch(context, r).ServeHTTP(w, r)
// Automated error response handling here. Handlers may return their
// own errors if they need different behavior (such as range errors
// for layer upload).
if context.Errors.Len() > 0 {
if ssrw.status == 0 {
if context.Value("http.response.status") == 0 {
// TODO(stevvooe): Getting this value from the context is a
// bit of a hack. We can further address with some of our
// future refactoring.
w.WriteHeader(http.StatusBadRequest)
}
serveJSON(w, context.Errors)
@ -380,10 +369,8 @@ func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
// context constructs the context object for the application. This only be
// called once per request.
func (app *App) context(w http.ResponseWriter, r *http.Request) *Context {
ctx := ctxu.WithRequest(app, r)
ctx, w = ctxu.WithResponseWriter(ctx, w)
ctx := defaultContextManager.context(app, w, r)
ctx = ctxu.WithVars(ctx, r)
ctx = ctxu.WithLogger(ctx, ctxu.GetRequestLogger(ctx))
ctx = ctxu.WithLogger(ctx, ctxu.GetLogger(ctx,
"vars.name",
"vars.reference",

View file

@ -3,6 +3,7 @@ package handlers
import (
"fmt"
"net/http"
"sync"
"github.com/docker/distribution"
ctxu "github.com/docker/distribution/context"
@ -88,3 +89,62 @@ func getUserName(ctx context.Context, r *http.Request) string {
return username
}
// contextManager allows us to associate net/context.Context instances with a
// request, based on the memory identity of http.Request. This prepares http-
// level context, which is not application specific. If this is called,
// (*contextManager).release must be called on the context when the request is
// completed.
//
// Providing this circumvents a lot of necessity for dispatchers with the
// benefit of instantiating the request context much earlier.
//
// TODO(stevvooe): Consider making this facility a part of the context package.
type contextManager struct {
contexts map[*http.Request]context.Context
mu sync.Mutex
}
// defaultContextManager is just a global instance to register request contexts.
var defaultContextManager = newContextManager()
func newContextManager() *contextManager {
return &contextManager{
contexts: make(map[*http.Request]context.Context),
}
}
// context either returns a new context or looks it up in the manager.
func (cm *contextManager) context(parent context.Context, w http.ResponseWriter, r *http.Request) context.Context {
cm.mu.Lock()
defer cm.mu.Unlock()
ctx, ok := cm.contexts[r]
if ok {
return ctx
}
if parent == nil {
parent = ctxu.Background()
}
ctx = ctxu.WithRequest(parent, r)
ctx, w = ctxu.WithResponseWriter(ctx, w)
ctx = ctxu.WithLogger(ctx, ctxu.GetRequestLogger(ctx))
cm.contexts[r] = ctx
return ctx
}
// releases frees any associated with resources from request.
func (cm *contextManager) release(ctx context.Context) {
cm.mu.Lock()
defer cm.mu.Unlock()
r, err := ctxu.GetRequest(ctx)
if err != nil {
ctxu.GetLogger(ctx).Errorf("no request found in context during release")
return
}
delete(cm.contexts, r)
}