diff options
Diffstat (limited to 'vendor/github.com/felixge/httpsnoop')
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/.gitignore | 0 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/.travis.yml | 6 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/LICENSE.txt | 19 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/Makefile | 10 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/README.md | 95 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/capture_metrics.go | 86 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/docs.go | 10 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/wrap_generated_gteq_1.8.go | 436 | ||||
| -rw-r--r-- | vendor/github.com/felixge/httpsnoop/wrap_generated_lt_1.8.go | 278 |
9 files changed, 940 insertions, 0 deletions
diff --git a/vendor/github.com/felixge/httpsnoop/.gitignore b/vendor/github.com/felixge/httpsnoop/.gitignore new file mode 100644 index 0000000..e69de29 --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/.gitignore diff --git a/vendor/github.com/felixge/httpsnoop/.travis.yml b/vendor/github.com/felixge/httpsnoop/.travis.yml new file mode 100644 index 0000000..bfc4212 --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/.travis.yml @@ -0,0 +1,6 @@ +language: go + +go: + - 1.6 + - 1.7 + - 1.8 diff --git a/vendor/github.com/felixge/httpsnoop/LICENSE.txt b/vendor/github.com/felixge/httpsnoop/LICENSE.txt new file mode 100644 index 0000000..e028b46 --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/LICENSE.txt @@ -0,0 +1,19 @@ +Copyright (c) 2016 Felix Geisendörfer (felix@debuggable.com) + + Permission is hereby granted, free of charge, to any person obtaining a copy + of this software and associated documentation files (the "Software"), to deal + in the Software without restriction, including without limitation the rights + to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + copies of the Software, and to permit persons to whom the Software is + furnished to do so, subject to the following conditions: + + The above copyright notice and this permission notice shall be included in + all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + THE SOFTWARE. diff --git a/vendor/github.com/felixge/httpsnoop/Makefile b/vendor/github.com/felixge/httpsnoop/Makefile new file mode 100644 index 0000000..2d84889 --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/Makefile @@ -0,0 +1,10 @@ +.PHONY: ci generate clean + +ci: clean generate + go test -v ./... + +generate: + go generate . + +clean: + rm -rf *_generated*.go diff --git a/vendor/github.com/felixge/httpsnoop/README.md b/vendor/github.com/felixge/httpsnoop/README.md new file mode 100644 index 0000000..ddcecd1 --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/README.md @@ -0,0 +1,95 @@ +# httpsnoop + +Package httpsnoop provides an easy way to capture http related metrics (i.e. +response time, bytes written, and http status code) from your application's +http.Handlers. + +Doing this requires non-trivial wrapping of the http.ResponseWriter interface, +which is also exposed for users interested in a more low-level API. + +[](https://godoc.org/github.com/felixge/httpsnoop) +[](https://travis-ci.org/felixge/httpsnoop) + +## Usage Example + +```go +// myH is your app's http handler, perhaps a http.ServeMux or similar. +var myH http.Handler +// wrappedH wraps myH in order to log every request. +wrappedH := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { + m := httpsnoop.CaptureMetrics(myH, w, r) + log.Printf( + "%s %s (code=%d dt=%s written=%d)", + r.Method, + r.URL, + m.Code, + m.Duration, + m.Written, + ) +}) +http.ListenAndServe(":8080", wrappedH) +``` + +## Why this package exists + +Instrumenting an application's http.Handler is surprisingly difficult. + +However if you google for e.g. "capture ResponseWriter status code" you'll find +lots of advise and code examples that suggest it to be a fairly trivial +undertaking. Unfortunately everything I've seen so far has a high chance of +breaking your application. + +The main problem is that a `http.ResponseWriter` often implements additional +interfaces such as `http.Flusher`, `http.CloseNotifier`, `http.Hijacker`, `http.Pusher`, and +`io.ReaderFrom`. So the naive approach of just wrapping `http.ResponseWriter` +in your own struct that also implements the `http.ResponseWriter` interface +will hide the additional interfaces mentioned above. This has a high change of +introducing subtle bugs into any non-trivial application. + +Another approach I've seen people take is to return a struct that implements +all of the interfaces above. However, that's also problematic, because it's +difficult to fake some of these interfaces behaviors when the underlying +`http.ResponseWriter` doesn't have an implementation. It's also dangerous, +because an application may choose to operate differently, merely because it +detects the presence of these additional interfaces. + +This package solves this problem by checking which additional interfaces a +`http.ResponseWriter` implements, returning a wrapped version implementing the +exact same set of interfaces. + +Additionally this package properly handles edge cases such as `WriteHeader` not +being called, or called more than once, as well as concurrent calls to +`http.ResponseWriter` methods, and even calls happening after the wrapped +`ServeHTTP` has already returned. + +Unfortunately this package is not perfect either. It's possible that it is +still missing some interfaces provided by the go core (let me know if you find +one), and it won't work for applications adding their own interfaces into the +mix. You can however use `httpsnoop.Unwrap(w)` to access the underlying +`http.ResponseWriter` and type-assert the result to its other interfaces. + +However, hopefully the explanation above has sufficiently scared you of rolling +your own solution to this problem. httpsnoop may still break your application, +but at least it tries to avoid it as much as possible. + +Anyway, the real problem here is that smuggling additional interfaces inside +`http.ResponseWriter` is a problematic design choice, but it probably goes as +deep as the Go language specification itself. But that's okay, I still prefer +Go over the alternatives ;). + +## Performance + +``` +BenchmarkBaseline-8 20000 94912 ns/op +BenchmarkCaptureMetrics-8 20000 95461 ns/op +``` + +As you can see, using `CaptureMetrics` on a vanilla http.Handler introduces an +overhead of ~500 ns per http request on my machine. However, the margin of +error appears to be larger than that, therefor it should be reasonable to +assume that the overhead introduced by `CaptureMetrics` is absolutely +negligible. + +## License + +MIT diff --git a/vendor/github.com/felixge/httpsnoop/capture_metrics.go b/vendor/github.com/felixge/httpsnoop/capture_metrics.go new file mode 100644 index 0000000..b77cc7c --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/capture_metrics.go @@ -0,0 +1,86 @@ +package httpsnoop + +import ( + "io" + "net/http" + "time" +) + +// Metrics holds metrics captured from CaptureMetrics. +type Metrics struct { + // Code is the first http response code passed to the WriteHeader func of + // the ResponseWriter. If no such call is made, a default code of 200 is + // assumed instead. + Code int + // Duration is the time it took to execute the handler. + Duration time.Duration + // Written is the number of bytes successfully written by the Write or + // ReadFrom function of the ResponseWriter. ResponseWriters may also write + // data to their underlaying connection directly (e.g. headers), but those + // are not tracked. Therefor the number of Written bytes will usually match + // the size of the response body. + Written int64 +} + +// CaptureMetrics wraps the given hnd, executes it with the given w and r, and +// returns the metrics it captured from it. +func CaptureMetrics(hnd http.Handler, w http.ResponseWriter, r *http.Request) Metrics { + return CaptureMetricsFn(w, func(ww http.ResponseWriter) { + hnd.ServeHTTP(ww, r) + }) +} + +// CaptureMetricsFn wraps w and calls fn with the wrapped w and returns the +// resulting metrics. This is very similar to CaptureMetrics (which is just +// sugar on top of this func), but is a more usable interface if your +// application doesn't use the Go http.Handler interface. +func CaptureMetricsFn(w http.ResponseWriter, fn func(http.ResponseWriter)) Metrics { + m := Metrics{Code: http.StatusOK} + m.CaptureMetrics(w, fn) + return m +} + +// CaptureMetrics wraps w and calls fn with the wrapped w and updates +// Metrics m with the resulting metrics. This is similar to CaptureMetricsFn, +// but allows one to customize starting Metrics object. +func (m *Metrics) CaptureMetrics(w http.ResponseWriter, fn func(http.ResponseWriter)) { + var ( + start = time.Now() + headerWritten bool + hooks = Hooks{ + WriteHeader: func(next WriteHeaderFunc) WriteHeaderFunc { + return func(code int) { + next(code) + + if !headerWritten { + m.Code = code + headerWritten = true + } + } + }, + + Write: func(next WriteFunc) WriteFunc { + return func(p []byte) (int, error) { + n, err := next(p) + + m.Written += int64(n) + headerWritten = true + return n, err + } + }, + + ReadFrom: func(next ReadFromFunc) ReadFromFunc { + return func(src io.Reader) (int64, error) { + n, err := next(src) + + headerWritten = true + m.Written += n + return n, err + } + }, + } + ) + + fn(Wrap(w, hooks)) + m.Duration += time.Since(start) +} diff --git a/vendor/github.com/felixge/httpsnoop/docs.go b/vendor/github.com/felixge/httpsnoop/docs.go new file mode 100644 index 0000000..203c35b --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/docs.go @@ -0,0 +1,10 @@ +// Package httpsnoop provides an easy way to capture http related metrics (i.e. +// response time, bytes written, and http status code) from your application's +// http.Handlers. +// +// Doing this requires non-trivial wrapping of the http.ResponseWriter +// interface, which is also exposed for users interested in a more low-level +// API. +package httpsnoop + +//go:generate go run codegen/main.go diff --git a/vendor/github.com/felixge/httpsnoop/wrap_generated_gteq_1.8.go b/vendor/github.com/felixge/httpsnoop/wrap_generated_gteq_1.8.go new file mode 100644 index 0000000..31cbdfb --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/wrap_generated_gteq_1.8.go @@ -0,0 +1,436 @@ +// +build go1.8 +// Code generated by "httpsnoop/codegen"; DO NOT EDIT + +package httpsnoop + +import ( + "bufio" + "io" + "net" + "net/http" +) + +// HeaderFunc is part of the http.ResponseWriter interface. +type HeaderFunc func() http.Header + +// WriteHeaderFunc is part of the http.ResponseWriter interface. +type WriteHeaderFunc func(code int) + +// WriteFunc is part of the http.ResponseWriter interface. +type WriteFunc func(b []byte) (int, error) + +// FlushFunc is part of the http.Flusher interface. +type FlushFunc func() + +// CloseNotifyFunc is part of the http.CloseNotifier interface. +type CloseNotifyFunc func() <-chan bool + +// HijackFunc is part of the http.Hijacker interface. +type HijackFunc func() (net.Conn, *bufio.ReadWriter, error) + +// ReadFromFunc is part of the io.ReaderFrom interface. +type ReadFromFunc func(src io.Reader) (int64, error) + +// PushFunc is part of the http.Pusher interface. +type PushFunc func(target string, opts *http.PushOptions) error + +// Hooks defines a set of method interceptors for methods included in +// http.ResponseWriter as well as some others. You can think of them as +// middleware for the function calls they target. See Wrap for more details. +type Hooks struct { + Header func(HeaderFunc) HeaderFunc + WriteHeader func(WriteHeaderFunc) WriteHeaderFunc + Write func(WriteFunc) WriteFunc + Flush func(FlushFunc) FlushFunc + CloseNotify func(CloseNotifyFunc) CloseNotifyFunc + Hijack func(HijackFunc) HijackFunc + ReadFrom func(ReadFromFunc) ReadFromFunc + Push func(PushFunc) PushFunc +} + +// Wrap returns a wrapped version of w that provides the exact same interface +// as w. Specifically if w implements any combination of: +// +// - http.Flusher +// - http.CloseNotifier +// - http.Hijacker +// - io.ReaderFrom +// - http.Pusher +// +// The wrapped version will implement the exact same combination. If no hooks +// are set, the wrapped version also behaves exactly as w. Hooks targeting +// methods not supported by w are ignored. Any other hooks will intercept the +// method they target and may modify the call's arguments and/or return values. +// The CaptureMetrics implementation serves as a working example for how the +// hooks can be used. +func Wrap(w http.ResponseWriter, hooks Hooks) http.ResponseWriter { + rw := &rw{w: w, h: hooks} + _, i0 := w.(http.Flusher) + _, i1 := w.(http.CloseNotifier) + _, i2 := w.(http.Hijacker) + _, i3 := w.(io.ReaderFrom) + _, i4 := w.(http.Pusher) + switch { + // combination 1/32 + case !i0 && !i1 && !i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + }{rw, rw} + // combination 2/32 + case !i0 && !i1 && !i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Pusher + }{rw, rw, rw} + // combination 3/32 + case !i0 && !i1 && !i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + io.ReaderFrom + }{rw, rw, rw} + // combination 4/32 + case !i0 && !i1 && !i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw} + // combination 5/32 + case !i0 && !i1 && i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Hijacker + }{rw, rw, rw} + // combination 6/32 + case !i0 && !i1 && i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Hijacker + http.Pusher + }{rw, rw, rw, rw} + // combination 7/32 + case !i0 && !i1 && i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw} + // combination 8/32 + case !i0 && !i1 && i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Hijacker + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw, rw} + // combination 9/32 + case !i0 && i1 && !i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + }{rw, rw, rw} + // combination 10/32 + case !i0 && i1 && !i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + http.Pusher + }{rw, rw, rw, rw} + // combination 11/32 + case !i0 && i1 && !i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + io.ReaderFrom + }{rw, rw, rw, rw} + // combination 12/32 + case !i0 && i1 && !i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw, rw} + // combination 13/32 + case !i0 && i1 && i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + http.Hijacker + }{rw, rw, rw, rw} + // combination 14/32 + case !i0 && i1 && i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + http.Hijacker + http.Pusher + }{rw, rw, rw, rw, rw} + // combination 15/32 + case !i0 && i1 && i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw, rw} + // combination 16/32 + case !i0 && i1 && i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + http.Hijacker + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw, rw, rw} + // combination 17/32 + case i0 && !i1 && !i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + }{rw, rw, rw} + // combination 18/32 + case i0 && !i1 && !i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.Pusher + }{rw, rw, rw, rw} + // combination 19/32 + case i0 && !i1 && !i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + io.ReaderFrom + }{rw, rw, rw, rw} + // combination 20/32 + case i0 && !i1 && !i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw, rw} + // combination 21/32 + case i0 && !i1 && i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.Hijacker + }{rw, rw, rw, rw} + // combination 22/32 + case i0 && !i1 && i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.Hijacker + http.Pusher + }{rw, rw, rw, rw, rw} + // combination 23/32 + case i0 && !i1 && i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw, rw} + // combination 24/32 + case i0 && !i1 && i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.Hijacker + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw, rw, rw} + // combination 25/32 + case i0 && i1 && !i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + }{rw, rw, rw, rw} + // combination 26/32 + case i0 && i1 && !i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + http.Pusher + }{rw, rw, rw, rw, rw} + // combination 27/32 + case i0 && i1 && !i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + io.ReaderFrom + }{rw, rw, rw, rw, rw} + // combination 28/32 + case i0 && i1 && !i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw, rw, rw} + // combination 29/32 + case i0 && i1 && i2 && !i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + http.Hijacker + }{rw, rw, rw, rw, rw} + // combination 30/32 + case i0 && i1 && i2 && !i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + http.Hijacker + http.Pusher + }{rw, rw, rw, rw, rw, rw} + // combination 31/32 + case i0 && i1 && i2 && i3 && !i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw, rw, rw} + // combination 32/32 + case i0 && i1 && i2 && i3 && i4: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + http.Hijacker + io.ReaderFrom + http.Pusher + }{rw, rw, rw, rw, rw, rw, rw} + } + panic("unreachable") +} + +type rw struct { + w http.ResponseWriter + h Hooks +} + +func (w *rw) Unwrap() http.ResponseWriter { + return w.w +} + +func (w *rw) Header() http.Header { + f := w.w.(http.ResponseWriter).Header + if w.h.Header != nil { + f = w.h.Header(f) + } + return f() +} + +func (w *rw) WriteHeader(code int) { + f := w.w.(http.ResponseWriter).WriteHeader + if w.h.WriteHeader != nil { + f = w.h.WriteHeader(f) + } + f(code) +} + +func (w *rw) Write(b []byte) (int, error) { + f := w.w.(http.ResponseWriter).Write + if w.h.Write != nil { + f = w.h.Write(f) + } + return f(b) +} + +func (w *rw) Flush() { + f := w.w.(http.Flusher).Flush + if w.h.Flush != nil { + f = w.h.Flush(f) + } + f() +} + +func (w *rw) CloseNotify() <-chan bool { + f := w.w.(http.CloseNotifier).CloseNotify + if w.h.CloseNotify != nil { + f = w.h.CloseNotify(f) + } + return f() +} + +func (w *rw) Hijack() (net.Conn, *bufio.ReadWriter, error) { + f := w.w.(http.Hijacker).Hijack + if w.h.Hijack != nil { + f = w.h.Hijack(f) + } + return f() +} + +func (w *rw) ReadFrom(src io.Reader) (int64, error) { + f := w.w.(io.ReaderFrom).ReadFrom + if w.h.ReadFrom != nil { + f = w.h.ReadFrom(f) + } + return f(src) +} + +func (w *rw) Push(target string, opts *http.PushOptions) error { + f := w.w.(http.Pusher).Push + if w.h.Push != nil { + f = w.h.Push(f) + } + return f(target, opts) +} + +type Unwrapper interface { + Unwrap() http.ResponseWriter +} + +// Unwrap returns the underlying http.ResponseWriter from within zero or more +// layers of httpsnoop wrappers. +func Unwrap(w http.ResponseWriter) http.ResponseWriter { + if rw, ok := w.(Unwrapper); ok { + // recurse until rw.Unwrap() returns a non-Unwrapper + return Unwrap(rw.Unwrap()) + } else { + return w + } +} diff --git a/vendor/github.com/felixge/httpsnoop/wrap_generated_lt_1.8.go b/vendor/github.com/felixge/httpsnoop/wrap_generated_lt_1.8.go new file mode 100644 index 0000000..ab99c07 --- /dev/null +++ b/vendor/github.com/felixge/httpsnoop/wrap_generated_lt_1.8.go @@ -0,0 +1,278 @@ +// +build !go1.8 +// Code generated by "httpsnoop/codegen"; DO NOT EDIT + +package httpsnoop + +import ( + "bufio" + "io" + "net" + "net/http" +) + +// HeaderFunc is part of the http.ResponseWriter interface. +type HeaderFunc func() http.Header + +// WriteHeaderFunc is part of the http.ResponseWriter interface. +type WriteHeaderFunc func(code int) + +// WriteFunc is part of the http.ResponseWriter interface. +type WriteFunc func(b []byte) (int, error) + +// FlushFunc is part of the http.Flusher interface. +type FlushFunc func() + +// CloseNotifyFunc is part of the http.CloseNotifier interface. +type CloseNotifyFunc func() <-chan bool + +// HijackFunc is part of the http.Hijacker interface. +type HijackFunc func() (net.Conn, *bufio.ReadWriter, error) + +// ReadFromFunc is part of the io.ReaderFrom interface. +type ReadFromFunc func(src io.Reader) (int64, error) + +// Hooks defines a set of method interceptors for methods included in +// http.ResponseWriter as well as some others. You can think of them as +// middleware for the function calls they target. See Wrap for more details. +type Hooks struct { + Header func(HeaderFunc) HeaderFunc + WriteHeader func(WriteHeaderFunc) WriteHeaderFunc + Write func(WriteFunc) WriteFunc + Flush func(FlushFunc) FlushFunc + CloseNotify func(CloseNotifyFunc) CloseNotifyFunc + Hijack func(HijackFunc) HijackFunc + ReadFrom func(ReadFromFunc) ReadFromFunc +} + +// Wrap returns a wrapped version of w that provides the exact same interface +// as w. Specifically if w implements any combination of: +// +// - http.Flusher +// - http.CloseNotifier +// - http.Hijacker +// - io.ReaderFrom +// +// The wrapped version will implement the exact same combination. If no hooks +// are set, the wrapped version also behaves exactly as w. Hooks targeting +// methods not supported by w are ignored. Any other hooks will intercept the +// method they target and may modify the call's arguments and/or return values. +// The CaptureMetrics implementation serves as a working example for how the +// hooks can be used. +func Wrap(w http.ResponseWriter, hooks Hooks) http.ResponseWriter { + rw := &rw{w: w, h: hooks} + _, i0 := w.(http.Flusher) + _, i1 := w.(http.CloseNotifier) + _, i2 := w.(http.Hijacker) + _, i3 := w.(io.ReaderFrom) + switch { + // combination 1/16 + case !i0 && !i1 && !i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + }{rw, rw} + // combination 2/16 + case !i0 && !i1 && !i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + io.ReaderFrom + }{rw, rw, rw} + // combination 3/16 + case !i0 && !i1 && i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + http.Hijacker + }{rw, rw, rw} + // combination 4/16 + case !i0 && !i1 && i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw} + // combination 5/16 + case !i0 && i1 && !i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + }{rw, rw, rw} + // combination 6/16 + case !i0 && i1 && !i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + io.ReaderFrom + }{rw, rw, rw, rw} + // combination 7/16 + case !i0 && i1 && i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + http.Hijacker + }{rw, rw, rw, rw} + // combination 8/16 + case !i0 && i1 && i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + http.CloseNotifier + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw, rw} + // combination 9/16 + case i0 && !i1 && !i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + }{rw, rw, rw} + // combination 10/16 + case i0 && !i1 && !i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + io.ReaderFrom + }{rw, rw, rw, rw} + // combination 11/16 + case i0 && !i1 && i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.Hijacker + }{rw, rw, rw, rw} + // combination 12/16 + case i0 && !i1 && i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw, rw} + // combination 13/16 + case i0 && i1 && !i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + }{rw, rw, rw, rw} + // combination 14/16 + case i0 && i1 && !i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + io.ReaderFrom + }{rw, rw, rw, rw, rw} + // combination 15/16 + case i0 && i1 && i2 && !i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + http.Hijacker + }{rw, rw, rw, rw, rw} + // combination 16/16 + case i0 && i1 && i2 && i3: + return struct { + Unwrapper + http.ResponseWriter + http.Flusher + http.CloseNotifier + http.Hijacker + io.ReaderFrom + }{rw, rw, rw, rw, rw, rw} + } + panic("unreachable") +} + +type rw struct { + w http.ResponseWriter + h Hooks +} + +func (w *rw) Unwrap() http.ResponseWriter { + return w.w +} + +func (w *rw) Header() http.Header { + f := w.w.(http.ResponseWriter).Header + if w.h.Header != nil { + f = w.h.Header(f) + } + return f() +} + +func (w *rw) WriteHeader(code int) { + f := w.w.(http.ResponseWriter).WriteHeader + if w.h.WriteHeader != nil { + f = w.h.WriteHeader(f) + } + f(code) +} + +func (w *rw) Write(b []byte) (int, error) { + f := w.w.(http.ResponseWriter).Write + if w.h.Write != nil { + f = w.h.Write(f) + } + return f(b) +} + +func (w *rw) Flush() { + f := w.w.(http.Flusher).Flush + if w.h.Flush != nil { + f = w.h.Flush(f) + } + f() +} + +func (w *rw) CloseNotify() <-chan bool { + f := w.w.(http.CloseNotifier).CloseNotify + if w.h.CloseNotify != nil { + f = w.h.CloseNotify(f) + } + return f() +} + +func (w *rw) Hijack() (net.Conn, *bufio.ReadWriter, error) { + f := w.w.(http.Hijacker).Hijack + if w.h.Hijack != nil { + f = w.h.Hijack(f) + } + return f() +} + +func (w *rw) ReadFrom(src io.Reader) (int64, error) { + f := w.w.(io.ReaderFrom).ReadFrom + if w.h.ReadFrom != nil { + f = w.h.ReadFrom(f) + } + return f(src) +} + +type Unwrapper interface { + Unwrap() http.ResponseWriter +} + +// Unwrap returns the underlying http.ResponseWriter from within zero or more +// layers of httpsnoop wrappers. +func Unwrap(w http.ResponseWriter) http.ResponseWriter { + if rw, ok := w.(Unwrapper); ok { + // recurse until rw.Unwrap() returns a non-Unwrapper + return Unwrap(rw.Unwrap()) + } else { + return w + } +} |
