Add go.mod; build on buster with recent go

vendor/github.com/cespare/xxhash/v2/xxhash.go

+// Package xxhash implements the 64-bit variant of xxHash (XXH64) as described
+// at http://cyan4973.github.io/xxHash/.
+package xxhash
+
+import (
+	"encoding/binary"
+	"errors"
+	"math/bits"
+)
+
+const (
+	prime1 uint64 = 11400714785074694791
+	prime2 uint64 = 14029467366897019727
+	prime3 uint64 = 1609587929392839161
+	prime4 uint64 = 9650029242287828579
+	prime5 uint64 = 2870177450012600261
+)
+
+// NOTE(caleb): I'm using both consts and vars of the primes. Using consts where
+// possible in the Go code is worth a small (but measurable) performance boost
+// by avoiding some MOVQs. Vars are needed for the asm and also are useful for
+// convenience in the Go code in a few places where we need to intentionally
+// avoid constant arithmetic (e.g., v1 := prime1 + prime2 fails because the
+// result overflows a uint64).
+var (
+	prime1v = prime1
+	prime2v = prime2
+	prime3v = prime3
+	prime4v = prime4
+	prime5v = prime5
+)
+
+// Digest implements hash.Hash64.
+type Digest struct {
+	v1    uint64
+	v2    uint64
+	v3    uint64
+	v4    uint64
+	total uint64
+	mem   [32]byte
+	n     int // how much of mem is used
+}
+
+// New creates a new Digest that computes the 64-bit xxHash algorithm.
+func New() *Digest {
+	var d Digest
+	d.Reset()
+	return &d
+}
+
+// Reset clears the Digest's state so that it can be reused.
+func (d *Digest) Reset() {
+	d.v1 = prime1v + prime2
+	d.v2 = prime2
+	d.v3 = 0
+	d.v4 = -prime1v
+	d.total = 0
+	d.n = 0
+}
+
+// Size always returns 8 bytes.
+func (d *Digest) Size() int { return 8 }
+
+// BlockSize always returns 32 bytes.
+func (d *Digest) BlockSize() int { return 32 }
+
+// Write adds more data to d. It always returns len(b), nil.
+func (d *Digest) Write(b []byte) (n int, err error) {
+	n = len(b)
+	d.total += uint64(n)
+
+	if d.n+n < 32 {
+		// This new data doesn't even fill the current block.
+		copy(d.mem[d.n:], b)
+		d.n += n
+		return
+	}
+
+	if d.n > 0 {
+		// Finish off the partial block.
+		copy(d.mem[d.n:], b)
+		d.v1 = round(d.v1, u64(d.mem[0:8]))
+		d.v2 = round(d.v2, u64(d.mem[8:16]))
+		d.v3 = round(d.v3, u64(d.mem[16:24]))
+		d.v4 = round(d.v4, u64(d.mem[24:32]))
+		b = b[32-d.n:]
+		d.n = 0
+	}
+
+	if len(b) >= 32 {
+		// One or more full blocks left.
+		nw := writeBlocks(d, b)
+		b = b[nw:]
+	}
+
+	// Store any remaining partial block.
+	copy(d.mem[:], b)
+	d.n = len(b)
+
+	return
+}
+
+// Sum appends the current hash to b and returns the resulting slice.
+func (d *Digest) Sum(b []byte) []byte {
+	s := d.Sum64()
+	return append(
+		b,
+		byte(s>>56),
+		byte(s>>48),
+		byte(s>>40),
+		byte(s>>32),
+		byte(s>>24),
+		byte(s>>16),
+		byte(s>>8),
+		byte(s),
+	)
+}
+
+// Sum64 returns the current hash.
+func (d *Digest) Sum64() uint64 {
+	var h uint64
+
+	if d.total >= 32 {
+		v1, v2, v3, v4 := d.v1, d.v2, d.v3, d.v4
+		h = rol1(v1) + rol7(v2) + rol12(v3) + rol18(v4)
+		h = mergeRound(h, v1)
+		h = mergeRound(h, v2)
+		h = mergeRound(h, v3)
+		h = mergeRound(h, v4)
+	} else {
+		h = d.v3 + prime5
+	}
+
+	h += d.total
+
+	i, end := 0, d.n
+	for ; i+8 <= end; i += 8 {
+		k1 := round(0, u64(d.mem[i:i+8]))
+		h ^= k1
+		h = rol27(h)*prime1 + prime4
+	}
+	if i+4 <= end {
+		h ^= uint64(u32(d.mem[i:i+4])) * prime1
+		h = rol23(h)*prime2 + prime3
+		i += 4
+	}
+	for i < end {
+		h ^= uint64(d.mem[i]) * prime5
+		h = rol11(h) * prime1
+		i++
+	}
+
+	h ^= h >> 33
+	h *= prime2
+	h ^= h >> 29
+	h *= prime3
+	h ^= h >> 32
+
+	return h
+}
+
+const (
+	magic         = "xxh\x06"
+	marshaledSize = len(magic) + 8*5 + 32
+)
+
+// MarshalBinary implements the encoding.BinaryMarshaler interface.
+func (d *Digest) MarshalBinary() ([]byte, error) {
+	b := make([]byte, 0, marshaledSize)
+	b = append(b, magic...)
+	b = appendUint64(b, d.v1)
+	b = appendUint64(b, d.v2)
+	b = appendUint64(b, d.v3)
+	b = appendUint64(b, d.v4)
+	b = appendUint64(b, d.total)
+	b = append(b, d.mem[:d.n]...)
+	b = b[:len(b)+len(d.mem)-d.n]
+	return b, nil
+}
+
+// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
+func (d *Digest) UnmarshalBinary(b []byte) error {
+	if len(b) < len(magic) || string(b[:len(magic)]) != magic {
+		return errors.New("xxhash: invalid hash state identifier")
+	}
+	if len(b) != marshaledSize {
+		return errors.New("xxhash: invalid hash state size")
+	}
+	b = b[len(magic):]
+	b, d.v1 = consumeUint64(b)
+	b, d.v2 = consumeUint64(b)
+	b, d.v3 = consumeUint64(b)
+	b, d.v4 = consumeUint64(b)
+	b, d.total = consumeUint64(b)
+	copy(d.mem[:], b)
+	b = b[len(d.mem):]
+	d.n = int(d.total % uint64(len(d.mem)))
+	return nil
+}
+
+func appendUint64(b []byte, x uint64) []byte {
+	var a [8]byte
+	binary.LittleEndian.PutUint64(a[:], x)
+	return append(b, a[:]...)
+}
+
+func consumeUint64(b []byte) ([]byte, uint64) {
+	x := u64(b)
+	return b[8:], x
+}
+
+func u64(b []byte) uint64 { return binary.LittleEndian.Uint64(b) }
+func u32(b []byte) uint32 { return binary.LittleEndian.Uint32(b) }
+
+func round(acc, input uint64) uint64 {
+	acc += input * prime2
+	acc = rol31(acc)
+	acc *= prime1
+	return acc
+}
+
+func mergeRound(acc, val uint64) uint64 {
+	val = round(0, val)
+	acc ^= val
+	acc = acc*prime1 + prime4
+	return acc
+}
+
+func rol1(x uint64) uint64  { return bits.RotateLeft64(x, 1) }
+func rol7(x uint64) uint64  { return bits.RotateLeft64(x, 7) }
+func rol11(x uint64) uint64 { return bits.RotateLeft64(x, 11) }
+func rol12(x uint64) uint64 { return bits.RotateLeft64(x, 12) }
+func rol18(x uint64) uint64 { return bits.RotateLeft64(x, 18) }
+func rol23(x uint64) uint64 { return bits.RotateLeft64(x, 23) }
+func rol27(x uint64) uint64 { return bits.RotateLeft64(x, 27) }
+func rol31(x uint64) uint64 { return bits.RotateLeft64(x, 31) }

vendor/github.com/cespare/xxhash/v2/xxhash_amd64.go

+// +build !appengine
+// +build gc
+// +build !purego
+
+package xxhash
+
+// Sum64 computes the 64-bit xxHash digest of b.
+//
+//go:noescape
+func Sum64(b []byte) uint64
+
+//go:noescape
+func writeBlocks(d *Digest, b []byte) int

vendor/github.com/cespare/xxhash/v2/xxhash_amd64.s

+// +build !appengine
+// +build gc
+// +build !purego
+
+#include "textflag.h"
+
+// Register allocation:
+// AX	h
+// CX	pointer to advance through b
+// DX	n
+// BX	loop end
+// R8	v1, k1
+// R9	v2
+// R10	v3
+// R11	v4
+// R12	tmp
+// R13	prime1v
+// R14	prime2v
+// R15	prime4v
+
+// round reads from and advances the buffer pointer in CX.
+// It assumes that R13 has prime1v and R14 has prime2v.
+#define round(r) \
+	MOVQ  (CX), R12 \
+	ADDQ  $8, CX    \
+	IMULQ R14, R12  \
+	ADDQ  R12, r    \
+	ROLQ  $31, r    \
+	IMULQ R13, r
+
+// mergeRound applies a merge round on the two registers acc and val.
+// It assumes that R13 has prime1v, R14 has prime2v, and R15 has prime4v.
+#define mergeRound(acc, val) \
+	IMULQ R14, val \
+	ROLQ  $31, val \
+	IMULQ R13, val \
+	XORQ  val, acc \
+	IMULQ R13, acc \
+	ADDQ  R15, acc
+
+// func Sum64(b []byte) uint64
+TEXT ·Sum64(SB), NOSPLIT, $0-32
+	// Load fixed primes.
+	MOVQ ·prime1v(SB), R13
+	MOVQ ·prime2v(SB), R14
+	MOVQ ·prime4v(SB), R15
+
+	// Load slice.
+	MOVQ b_base+0(FP), CX
+	MOVQ b_len+8(FP), DX
+	LEAQ (CX)(DX*1), BX
+
+	// The first loop limit will be len(b)-32.
+	SUBQ $32, BX
+
+	// Check whether we have at least one block.
+	CMPQ DX, $32
+	JLT  noBlocks
+
+	// Set up initial state (v1, v2, v3, v4).
+	MOVQ R13, R8
+	ADDQ R14, R8
+	MOVQ R14, R9
+	XORQ R10, R10
+	XORQ R11, R11
+	SUBQ R13, R11
+
+	// Loop until CX > BX.
+blockLoop:
+	round(R8)
+	round(R9)
+	round(R10)
+	round(R11)
+
+	CMPQ CX, BX
+	JLE  blockLoop
+
+	MOVQ R8, AX
+	ROLQ $1, AX
+	MOVQ R9, R12
+	ROLQ $7, R12
+	ADDQ R12, AX
+	MOVQ R10, R12
+	ROLQ $12, R12
+	ADDQ R12, AX
+	MOVQ R11, R12
+	ROLQ $18, R12
+	ADDQ R12, AX
+
+	mergeRound(AX, R8)
+	mergeRound(AX, R9)
+	mergeRound(AX, R10)
+	mergeRound(AX, R11)
+
+	JMP afterBlocks
+
+noBlocks:
+	MOVQ ·prime5v(SB), AX
+
+afterBlocks:
+	ADDQ DX, AX
+
+	// Right now BX has len(b)-32, and we want to loop until CX > len(b)-8.
+	ADDQ $24, BX
+
+	CMPQ CX, BX
+	JG   fourByte
+
+wordLoop:
+	// Calculate k1.
+	MOVQ  (CX), R8
+	ADDQ  $8, CX
+	IMULQ R14, R8
+	ROLQ  $31, R8
+	IMULQ R13, R8
+
+	XORQ  R8, AX
+	ROLQ  $27, AX
+	IMULQ R13, AX
+	ADDQ  R15, AX
+
+	CMPQ CX, BX
+	JLE  wordLoop
+
+fourByte:
+	ADDQ $4, BX
+	CMPQ CX, BX
+	JG   singles
+
+	MOVL  (CX), R8
+	ADDQ  $4, CX
+	IMULQ R13, R8
+	XORQ  R8, AX
+
+	ROLQ  $23, AX
+	IMULQ R14, AX
+	ADDQ  ·prime3v(SB), AX
+
+singles:
+	ADDQ $4, BX
+	CMPQ CX, BX
+	JGE  finalize
+
+singlesLoop:
+	MOVBQZX (CX), R12
+	ADDQ    $1, CX
+	IMULQ   ·prime5v(SB), R12
+	XORQ    R12, AX
+
+	ROLQ  $11, AX
+	IMULQ R13, AX
+
+	CMPQ CX, BX
+	JL   singlesLoop
+
+finalize:
+	MOVQ  AX, R12
+	SHRQ  $33, R12
+	XORQ  R12, AX
+	IMULQ R14, AX
+	MOVQ  AX, R12
+	SHRQ  $29, R12
+	XORQ  R12, AX
+	IMULQ ·prime3v(SB), AX
+	MOVQ  AX, R12
+	SHRQ  $32, R12
+	XORQ  R12, AX
+
+	MOVQ AX, ret+24(FP)
+	RET
+
+// writeBlocks uses the same registers as above except that it uses AX to store
+// the d pointer.
+
+// func writeBlocks(d *Digest, b []byte) int
+TEXT ·writeBlocks(SB), NOSPLIT, $0-40
+	// Load fixed primes needed for round.
+	MOVQ ·prime1v(SB), R13
+	MOVQ ·prime2v(SB), R14
+
+	// Load slice.
+	MOVQ b_base+8(FP), CX
+	MOVQ b_len+16(FP), DX
+	LEAQ (CX)(DX*1), BX
+	SUBQ $32, BX
+
+	// Load vN from d.
+	MOVQ d+0(FP), AX
+	MOVQ 0(AX), R8   // v1
+	MOVQ 8(AX), R9   // v2
+	MOVQ 16(AX), R10 // v3
+	MOVQ 24(AX), R11 // v4
+
+	// We don't need to check the loop condition here; this function is
+	// always called with at least one block of data to process.
+blockLoop:
+	round(R8)
+	round(R9)
+	round(R10)
+	round(R11)
+
+	CMPQ CX, BX
+	JLE  blockLoop
+
+	// Copy vN back to d.
+	MOVQ R8, 0(AX)
+	MOVQ R9, 8(AX)
+	MOVQ R10, 16(AX)
+	MOVQ R11, 24(AX)
+
+	// The number of bytes written is CX minus the old base pointer.
+	SUBQ b_base+8(FP), CX
+	MOVQ CX, ret+32(FP)
+
+	RET

vendor/github.com/cespare/xxhash/v2/xxhash_other.go

+// +build !amd64 appengine !gc purego
+
+package xxhash
+
+// Sum64 computes the 64-bit xxHash digest of b.
+func Sum64(b []byte) uint64 {
+	// A simpler version would be
+	//   d := New()
+	//   d.Write(b)
+	//   return d.Sum64()
+	// but this is faster, particularly for small inputs.
+
+	n := len(b)
+	var h uint64
+
+	if n >= 32 {
+		v1 := prime1v + prime2
+		v2 := prime2
+		v3 := uint64(0)
+		v4 := -prime1v
+		for len(b) >= 32 {
+			v1 = round(v1, u64(b[0:8:len(b)]))
+			v2 = round(v2, u64(b[8:16:len(b)]))
+			v3 = round(v3, u64(b[16:24:len(b)]))
+			v4 = round(v4, u64(b[24:32:len(b)]))
+			b = b[32:len(b):len(b)]
+		}
+		h = rol1(v1) + rol7(v2) + rol12(v3) + rol18(v4)
+		h = mergeRound(h, v1)
+		h = mergeRound(h, v2)
+		h = mergeRound(h, v3)
+		h = mergeRound(h, v4)
+	} else {
+		h = prime5
+	}
+
+	h += uint64(n)
+
+	i, end := 0, len(b)
+	for ; i+8 <= end; i += 8 {
+		k1 := round(0, u64(b[i:i+8:len(b)]))
+		h ^= k1
+		h = rol27(h)*prime1 + prime4
+	}
+	if i+4 <= end {
+		h ^= uint64(u32(b[i:i+4:len(b)])) * prime1
+		h = rol23(h)*prime2 + prime3
+		i += 4
+	}
+	for ; i < end; i++ {
+		h ^= uint64(b[i]) * prime5
+		h = rol11(h) * prime1
+	}
+
+	h ^= h >> 33
+	h *= prime2
+	h ^= h >> 29
+	h *= prime3
+	h ^= h >> 32
+
+	return h
+}
+
+func writeBlocks(d *Digest, b []byte) int {
+	v1, v2, v3, v4 := d.v1, d.v2, d.v3, d.v4
+	n := len(b)
+	for len(b) >= 32 {
+		v1 = round(v1, u64(b[0:8:len(b)]))
+		v2 = round(v2, u64(b[8:16:len(b)]))
+		v3 = round(v3, u64(b[16:24:len(b)]))
+		v4 = round(v4, u64(b[24:32:len(b)]))
+		b = b[32:len(b):len(b)]
+	}
+	d.v1, d.v2, d.v3, d.v4 = v1, v2, v3, v4
+	return n - len(b)
+}

vendor/github.com/cespare/xxhash/v2/xxhash_safe.go

+// +build appengine
+
+// This file contains the safe implementations of otherwise unsafe-using code.
+
+package xxhash
+
+// Sum64String computes the 64-bit xxHash digest of s.
+func Sum64String(s string) uint64 {
+	return Sum64([]byte(s))
+}
+
+// WriteString adds more data to d. It always returns len(s), nil.
+func (d *Digest) WriteString(s string) (n int, err error) {
+	return d.Write([]byte(s))
+}

vendor/github.com/cespare/xxhash/v2/xxhash_unsafe.go

+// +build !appengine
+
+// This file encapsulates usage of unsafe.
+// xxhash_safe.go contains the safe implementations.
+
+package xxhash
+
+import (
+	"reflect"
+	"unsafe"
+)
+
+// Notes:
+//
+// See https://groups.google.com/d/msg/golang-nuts/dcjzJy-bSpw/tcZYBzQqAQAJ
+// for some discussion about these unsafe conversions.
+//
+// In the future it's possible that compiler optimizations will make these
+// unsafe operations unnecessary: https://golang.org/issue/2205.
+//
+// Both of these wrapper functions still incur function call overhead since they
+// will not be inlined. We could write Go/asm copies of Sum64 and Digest.Write
+// for strings to squeeze out a bit more speed. Mid-stack inlining should
+// eventually fix this.
+
+// Sum64String computes the 64-bit xxHash digest of s.
+// It may be faster than Sum64([]byte(s)) by avoiding a copy.
+func Sum64String(s string) uint64 {
+	var b []byte
+	bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
+	bh.Data = (*reflect.StringHeader)(unsafe.Pointer(&s)).Data
+	bh.Len = len(s)
+	bh.Cap = len(s)
+	return Sum64(b)
+}
+
+// WriteString adds more data to d. It always returns len(s), nil.
+// It may be faster than Write([]byte(s)) by avoiding a copy.
+func (d *Digest) WriteString(s string) (n int, err error) {
+	var b []byte
+	bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
+	bh.Data = (*reflect.StringHeader)(unsafe.Pointer(&s)).Data
+	bh.Len = len(s)
+	bh.Cap = len(s)
+	return d.Write(b)
+}

vendor/github.com/felixge/httpsnoop/.travis.yml

+language: go
+
+go:
+  - 1.6
+  - 1.7
+  - 1.8

vendor/github.com/felixge/httpsnoop/LICENSE.txt

+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.

vendor/github.com/felixge/httpsnoop/Makefile

+.PHONY: ci generate clean
+
+ci: clean generate
+	go test -v ./...
+
+generate:
+	go generate .
+
+clean:
+	rm -rf *_generated*.go

vendor/github.com/felixge/httpsnoop/README.md

+# 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.
+
+[![GoDoc](https://godoc.org/github.com/felixge/httpsnoop?status.svg)](https://godoc.org/github.com/felixge/httpsnoop)
+[![Build Status](https://travis-ci.org/felixge/httpsnoop.svg?branch=master)](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.
+
+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

vendor/github.com/felixge/httpsnoop/capture_metrics.go

+package httpsnoop
+
+import (
+	"io"
+	"net/http"
+	"sync"
+	"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 {
+	var (
+		start         = time.Now()
+		m             = Metrics{Code: http.StatusOK}
+		headerWritten bool
+		lock          sync.Mutex
+		hooks         = Hooks{
+			WriteHeader: func(next WriteHeaderFunc) WriteHeaderFunc {
+				return func(code int) {
+					next(code)
+					lock.Lock()
+					defer lock.Unlock()
+					if !headerWritten {
+						m.Code = code
+						headerWritten = true
+					}
+				}
+			},
+
+			Write: func(next WriteFunc) WriteFunc {
+				return func(p []byte) (int, error) {
+					n, err := next(p)
+					lock.Lock()
+					defer lock.Unlock()
+					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)
+					lock.Lock()
+					defer lock.Unlock()
+					headerWritten = true
+					m.Written += n
+					return n, err
+				}
+			},
+		}
+	)
+
+	fn(Wrap(w, hooks))
+	m.Duration = time.Since(start)
+	return m
+}

vendor/github.com/felixge/httpsnoop/docs.go

+// 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

vendor/github.com/felixge/httpsnoop/go.mod

+module github.com/felixge/httpsnoop
+
+go 1.13

vendor/github.com/felixge/httpsnoop/wrap_generated_gteq_1.8.go

+// +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 {
+			http.ResponseWriter
+		}{rw}
+	// combination 2/32
+	case !i0 && !i1 && !i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Pusher
+		}{rw, rw}
+	// combination 3/32
+	case !i0 && !i1 && !i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			io.ReaderFrom
+		}{rw, rw}
+	// combination 4/32
+	case !i0 && !i1 && !i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw}
+	// combination 5/32
+	case !i0 && !i1 && i2 && !i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Hijacker
+		}{rw, rw}
+	// combination 6/32
+	case !i0 && !i1 && i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Hijacker
+			http.Pusher
+		}{rw, rw, rw}
+	// combination 7/32
+	case !i0 && !i1 && i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Hijacker
+			io.ReaderFrom
+		}{rw, rw, rw}
+	// combination 8/32
+	case !i0 && !i1 && i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Hijacker
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw, rw}
+	// combination 9/32
+	case !i0 && i1 && !i2 && !i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+		}{rw, rw}
+	// combination 10/32
+	case !i0 && i1 && !i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+			http.Pusher
+		}{rw, rw, rw}
+	// combination 11/32
+	case !i0 && i1 && !i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+			io.ReaderFrom
+		}{rw, rw, rw}
+	// combination 12/32
+	case !i0 && i1 && !i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw, rw}
+	// combination 13/32
+	case !i0 && i1 && i2 && !i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+			http.Hijacker
+		}{rw, rw, rw}
+	// combination 14/32
+	case !i0 && i1 && i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+			http.Hijacker
+			http.Pusher
+		}{rw, rw, rw, rw}
+	// combination 15/32
+	case !i0 && i1 && i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+			http.Hijacker
+			io.ReaderFrom
+		}{rw, rw, rw, rw}
+	// combination 16/32
+	case !i0 && i1 && i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.CloseNotifier
+			http.Hijacker
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw, rw, rw}
+	// combination 17/32
+	case i0 && !i1 && !i2 && !i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+		}{rw, rw}
+	// combination 18/32
+	case i0 && !i1 && !i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.Pusher
+		}{rw, rw, rw}
+	// combination 19/32
+	case i0 && !i1 && !i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			io.ReaderFrom
+		}{rw, rw, rw}
+	// combination 20/32
+	case i0 && !i1 && !i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw, rw}
+	// combination 21/32
+	case i0 && !i1 && i2 && !i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.Hijacker
+		}{rw, rw, rw}
+	// combination 22/32
+	case i0 && !i1 && i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.Hijacker
+			http.Pusher
+		}{rw, rw, rw, rw}
+	// combination 23/32
+	case i0 && !i1 && i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.Hijacker
+			io.ReaderFrom
+		}{rw, rw, rw, rw}
+	// combination 24/32
+	case i0 && !i1 && i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.Hijacker
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw, rw, rw}
+	// combination 25/32
+	case i0 && i1 && !i2 && !i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+		}{rw, rw, rw}
+	// combination 26/32
+	case i0 && i1 && !i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+			http.Pusher
+		}{rw, rw, rw, rw}
+	// combination 27/32
+	case i0 && i1 && !i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+			io.ReaderFrom
+		}{rw, rw, rw, rw}
+	// combination 28/32
+	case i0 && i1 && !i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw, rw, rw}
+	// combination 29/32
+	case i0 && i1 && i2 && !i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+			http.Hijacker
+		}{rw, rw, rw, rw}
+	// combination 30/32
+	case i0 && i1 && i2 && !i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+			http.Hijacker
+			http.Pusher
+		}{rw, rw, rw, rw, rw}
+	// combination 31/32
+	case i0 && i1 && i2 && i3 && !i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+			http.Hijacker
+			io.ReaderFrom
+		}{rw, rw, rw, rw, rw}
+	// combination 32/32
+	case i0 && i1 && i2 && i3 && i4:
+		return struct {
+			http.ResponseWriter
+			http.Flusher
+			http.CloseNotifier
+			http.Hijacker
+			io.ReaderFrom
+			http.Pusher
+		}{rw, rw, rw, rw, rw, rw}
+	}
+	panic("unreachable")
+}
+
+type rw struct {
+	w http.ResponseWriter
+	h Hooks
+}
+
+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)
+}