Consolidate all hashing to the common/hashing package

And remove now unsued hashing funcs.

common/hashing/hashing.go

@@ -15,11 +15,15 @@
 package hashing
 
 import (
+	"crypto/md5"
 	"encoding/hex"
 	"io"
+	"strconv"
 	"sync"
 
 	"github.com/cespare/xxhash/v2"
+	"github.com/gohugoio/hashstructure"
+	"github.com/gohugoio/hugo/identity"
 )
 
 // XXHashFromReader calculates the xxHash for the given reader.
@@ -50,6 +54,82 @@ func XxHashFromStringHexEncoded(f string) string {
 	return hex.EncodeToString(hash)
 }
 
+// MD5FromStringHexEncoded returns the MD5 hash of the given string.
+func MD5FromStringHexEncoded(f string) string {
+	h := md5.New()
+	h.Write([]byte(f))
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+// HashString returns a hash from the given elements.
+// It will panic if the hash cannot be calculated.
+// Note that this hash should be used primarily for identity, not for change detection as
+// it in the more complex values (e.g. Page) will not hash the full content.
+func HashString(vs ...any) string {
+	hash := HashUint64(vs...)
+	return strconv.FormatUint(hash, 10)
+}
+
+var hashOptsPool = sync.Pool{
+	New: func() any {
+		return &hashstructure.HashOptions{
+			Hasher: xxhash.New(),
+		}
+	},
+}
+
+func getHashOpts() *hashstructure.HashOptions {
+	return hashOptsPool.Get().(*hashstructure.HashOptions)
+}
+
+func putHashOpts(opts *hashstructure.HashOptions) {
+	opts.Hasher.Reset()
+	hashOptsPool.Put(opts)
+}
+
+// HashUint64 returns a hash from the given elements.
+// It will panic if the hash cannot be calculated.
+// Note that this hash should be used primarily for identity, not for change detection as
+// it in the more complex values (e.g. Page) will not hash the full content.
+func HashUint64(vs ...any) uint64 {
+	var o any
+	if len(vs) == 1 {
+		o = toHashable(vs[0])
+	} else {
+		elements := make([]any, len(vs))
+		for i, e := range vs {
+			elements[i] = toHashable(e)
+		}
+		o = elements
+	}
+
+	hashOpts := getHashOpts()
+	defer putHashOpts(hashOpts)
+
+	hash, err := hashstructure.Hash(o, hashOpts)
+	if err != nil {
+		panic(err)
+	}
+	return hash
+}
+
+type keyer interface {
+	Key() string
+}
+
+// For structs, hashstructure.Hash only works on the exported fields,
+// so rewrite the input slice for known identity types.
+func toHashable(v any) any {
+	switch t := v.(type) {
+	case keyer:
+		return t.Key()
+	case identity.IdentityProvider:
+		return t.GetIdentity()
+	default:
+		return v
+	}
+}
+
 type xxhashReadFrom struct {
 	buff []byte
 	*xxhash.Digest

common/hashing/hashing_test.go

@@ -14,10 +14,11 @@
 package hashing
 
 import (
+	"fmt"
+	"math"
 	"strings"
 	"testing"
 
-	"github.com/cespare/xxhash/v2"
 	qt "github.com/frankban/quicktest"
 )
 
@@ -72,8 +73,47 @@ func BenchmarkXXHashFromStringHexEncoded(b *testing.B) {
 	}
 }
 
-func xxHashFromString(f string) uint64 {
-	h := xxhash.New()
-	h.WriteString(f)
-	return h.Sum64()
+func TestHashString(t *testing.T) {
+	c := qt.New(t)
+
+	c.Assert(HashString("a", "b"), qt.Equals, "3176555414984061461")
+	c.Assert(HashString("ab"), qt.Equals, "7347350983217793633")
+
+	var vals []any = []any{"a", "b", tstKeyer{"c"}}
+
+	c.Assert(HashString(vals...), qt.Equals, "4438730547989914315")
+	c.Assert(vals[2], qt.Equals, tstKeyer{"c"})
+}
+
+type tstKeyer struct {
+	key string
+}
+
+func (t tstKeyer) Key() string {
+	return t.key
+}
+
+func (t tstKeyer) String() string {
+	return "key: " + t.key
+}
+
+func BenchmarkHashString(b *testing.B) {
+	word := " hello "
+
+	var tests []string
+
+	for i := 1; i <= 5; i++ {
+		sentence := strings.Repeat(word, int(math.Pow(4, float64(i))))
+		tests = append(tests, sentence)
+	}
+
+	b.ResetTimer()
+
+	for _, test := range tests {
+		b.Run(fmt.Sprintf("n%d", len(test)), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				HashString(test)
+			}
+		})
+	}
 }

common/loggers/handlersmisc.go

@@ -21,7 +21,7 @@ import (
 	"sync"
 
 	"github.com/bep/logg"
-	"github.com/gohugoio/hugo/identity"
+	"github.com/gohugoio/hugo/common/hashing"
 )
 
 // PanicOnWarningHook panics on warnings.
@@ -85,7 +85,7 @@ func (h *logOnceHandler) HandleLog(e *logg.Entry) error {
 	}
 	h.mu.Lock()
 	defer h.mu.Unlock()
-	hash := identity.HashUint64(e.Level, e.Message, e.Fields)
+	hash := hashing.HashUint64(e.Level, e.Message, e.Fields)
 	if h.seen[hash] {
 		return errStop
 	}

config/namespace.go

@@ -16,13 +16,13 @@ package config
 import (
 	"encoding/json"
 
-	"github.com/gohugoio/hugo/identity"
+	"github.com/gohugoio/hugo/common/hashing"
 )
 
 func DecodeNamespace[S, C any](configSource any, buildConfig func(any) (C, any, error)) (*ConfigNamespace[S, C], error) {
 	// Calculate the hash of the input (not including any defaults applied later).
 	// This allows us to introduce new config options without breaking the hash.
-	h := identity.HashString(configSource)
+	h := hashing.HashString(configSource)
 
 	// Build the config
 	c, ext, err := buildConfig(configSource)

helpers/general.go

@@ -15,8 +15,6 @@ package helpers
 
 import (
 	"bytes"
-	"crypto/md5"
-	"encoding/hex"
 	"fmt"
 	"io"
 	"net"
@@ -257,66 +255,6 @@ func SliceToLower(s []string) []string {
 	return l
 }
 
-// XXHashFromReader creates a xxHash hash from the given reader.
-
-// MD5String takes a string and returns its MD5 hash.
-func MD5String(f string) string {
-	h := md5.New()
-	h.Write([]byte(f))
-	return hex.EncodeToString(h.Sum([]byte{}))
-}
-
-// MD5FromReaderFast creates a MD5 hash from the given file. It only reads parts of
-// the file for speed, so don't use it if the files are very subtly different.
-// It will not close the file.
-// It will return the MD5 hash and the size of r in bytes.
-func MD5FromReaderFast(r io.ReadSeeker) (string, int64, error) {
-	const (
-		// Do not change once set in stone!
-		maxChunks = 8
-		peekSize  = 64
-		seek      = 2048
-	)
-
-	h := md5.New()
-	buff := make([]byte, peekSize)
-
-	for i := 0; i < maxChunks; i++ {
-		if i > 0 {
-			_, err := r.Seek(seek, 0)
-			if err != nil {
-				if err == io.EOF {
-					break
-				}
-				return "", 0, err
-			}
-		}
-
-		_, err := io.ReadAtLeast(r, buff, peekSize)
-		if err != nil {
-			if err == io.EOF || err == io.ErrUnexpectedEOF {
-				h.Write(buff)
-				break
-			}
-			return "", 0, err
-		}
-		h.Write(buff)
-	}
-
-	size, _ := r.Seek(0, io.SeekEnd)
-
-	return hex.EncodeToString(h.Sum(nil)), size, nil
-}
-
-// MD5FromReader creates a MD5 hash from the given reader.
-func MD5FromReader(r io.Reader) (string, error) {
-	h := md5.New()
-	if _, err := io.Copy(h, r); err != nil {
-		return "", nil
-	}
-	return hex.EncodeToString(h.Sum(nil)), nil
-}
-
 // IsWhitespace determines if the given rune is whitespace.
 func IsWhitespace(r rune) bool {
 	return r == ' ' || r == '\t' || r == '\n' || r == '\r'

helpers/general_test.go

@@ -14,15 +14,13 @@
 package helpers_test
 
 import (
-	"fmt"
 	"reflect"
 	"strings"
 	"testing"
 
 	"github.com/gohugoio/hugo/helpers"
 
 	qt "github.com/frankban/quicktest"
-	"github.com/spf13/afero"
 )
 
 func TestResolveMarkup(t *testing.T) {
@@ -256,93 +254,6 @@ func TestUniqueStringsSorted(t *testing.T) {
 	c.Assert(helpers.UniqueStringsSorted(nil), qt.IsNil)
 }
 
-func TestFastMD5FromFile(t *testing.T) {
-	fs := afero.NewMemMapFs()
-
-	if err := afero.WriteFile(fs, "small.txt", []byte("abc"), 0o777); err != nil {
-		t.Fatal(err)
-	}
-
-	if err := afero.WriteFile(fs, "small2.txt", []byte("abd"), 0o777); err != nil {
-		t.Fatal(err)
-	}
-
-	if err := afero.WriteFile(fs, "bigger.txt", []byte(strings.Repeat("a bc d e", 100)), 0o777); err != nil {
-		t.Fatal(err)
-	}
-
-	if err := afero.WriteFile(fs, "bigger2.txt", []byte(strings.Repeat("c d e f g", 100)), 0o777); err != nil {
-		t.Fatal(err)
-	}
-
-	c := qt.New(t)
-
-	sf1, err := fs.Open("small.txt")
-	c.Assert(err, qt.IsNil)
-	sf2, err := fs.Open("small2.txt")
-	c.Assert(err, qt.IsNil)
-
-	bf1, err := fs.Open("bigger.txt")
-	c.Assert(err, qt.IsNil)
-	bf2, err := fs.Open("bigger2.txt")
-	c.Assert(err, qt.IsNil)
-
-	defer sf1.Close()
-	defer sf2.Close()
-	defer bf1.Close()
-	defer bf2.Close()
-
-	m1, _, err := helpers.MD5FromReaderFast(sf1)
-	c.Assert(err, qt.IsNil)
-	c.Assert(m1, qt.Equals, "e9c8989b64b71a88b4efb66ad05eea96")
-
-	m2, _, err := helpers.MD5FromReaderFast(sf2)
-	c.Assert(err, qt.IsNil)
-	c.Assert(m2, qt.Not(qt.Equals), m1)
-
-	m3, _, err := helpers.MD5FromReaderFast(bf1)
-	c.Assert(err, qt.IsNil)
-	c.Assert(m3, qt.Not(qt.Equals), m2)
-
-	m4, _, err := helpers.MD5FromReaderFast(bf2)
-	c.Assert(err, qt.IsNil)
-	c.Assert(m4, qt.Not(qt.Equals), m3)
-
-	m5, err := helpers.MD5FromReader(bf2)
-	c.Assert(err, qt.IsNil)
-	c.Assert(m5, qt.Not(qt.Equals), m4)
-}
-
-func BenchmarkMD5FromFileFast(b *testing.B) {
-	fs := afero.NewMemMapFs()
-
-	for _, full := range []bool{false, true} {
-		b.Run(fmt.Sprintf("full=%t", full), func(b *testing.B) {
-			for i := 0; i < b.N; i++ {
-				b.StopTimer()
-				if err := afero.WriteFile(fs, "file.txt", []byte(strings.Repeat("1234567890", 2000)), 0o777); err != nil {
-					b.Fatal(err)
-				}
-				f, err := fs.Open("file.txt")
-				if err != nil {
-					b.Fatal(err)
-				}
-				b.StartTimer()
-				if full {
-					if _, err := helpers.MD5FromReader(f); err != nil {
-						b.Fatal(err)
-					}
-				} else {
-					if _, _, err := helpers.MD5FromReaderFast(f); err != nil {
-						b.Fatal(err)
-					}
-				}
-				f.Close()
-			}
-		})
-	}
-}
-
 func BenchmarkUniqueStrings(b *testing.B) {
 	input := []string{"a", "b", "d", "e", "d", "h", "a", "i"}