Reduce SQL sanitizer allocations

internal/sanitize/benchmmark.sh

@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+current_branch=$(git rev-parse --abbrev-ref HEAD)
+if [ "$current_branch" == "HEAD" ]; then
+    current_branch=$(git rev-parse HEAD)
+fi
+
+restore_branch() {
+    echo "Restoring original branch/commit: $current_branch"
+    git checkout "$current_branch"
+}
+trap restore_branch EXIT
+
+# Check if there are uncommitted changes
+if ! git diff --quiet || ! git diff --cached --quiet; then
+    echo "There are uncommitted changes. Please commit or stash them before running this script."
+    exit 1
+fi
+
+# Ensure that at least one commit argument is passed
+if [ "$#" -lt 1 ]; then
+    echo "Usage: $0 <commit1> <commit2> ... <commitN>"
+    exit 1
+fi
+
+commits=("$@")
+benchmarks_dir=benchmarks
+
+if ! mkdir -p "${benchmarks_dir}"; then
+    echo "Unable to create dir for benchmarks data"
+    exit 1
+fi
+
+# Benchmark results
+bench_files=()
+
+# Run benchmark for each listed commit
+for i in "${!commits[@]}"; do
+    commit="${commits[i]}"
+    git checkout "$commit" || {
+        echo "Failed to checkout $commit"
+        exit 1
+    }
+
+    # Sanitized commmit message
+    commit_message=$(git log -1 --pretty=format:"%s" | tr ' ' '_')
+
+    # Benchmark data will go there
+    bench_file="${benchmarks_dir}/${i}_${commit_message}.bench"
+
+    if ! go test -bench=. -count=10 >"$bench_file"; then
+        echo "Benchmarking failed for commit $commit"
+        exit 1
+    fi
+
+    bench_files+=("$bench_file")
+done
+
+benchstat "${bench_files[@]}"

internal/sanitize/sanitize.go

@@ -4,8 +4,10 @@ import (
 	"bytes"
 	"encoding/hex"
 	"fmt"
+	"slices"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 	"unicode/utf8"
 )
@@ -24,53 +26,75 @@ type Query struct {
 // https://github.com/jackc/pgx/issues/1380
 const replacementcharacterwidth = 3
 
+const maxBufSize = 16384 // 16 Ki
+
+var bufPool = &pool[*bytes.Buffer]{
+	new: func() *bytes.Buffer {
+		return &bytes.Buffer{}
+	},
+	reset: func(b *bytes.Buffer) bool {
+		n := b.Len()
+		b.Reset()
+		return n < maxBufSize
+	},
+}
+
+var null = []byte("null")
+
 func (q *Query) Sanitize(args ...any) (string, error) {
 	argUse := make([]bool, len(args))
-	buf := &bytes.Buffer{}
+	buf := bufPool.get()
+	defer bufPool.put(buf)
 
 	for _, part := range q.Parts {
-		var str string
 		switch part := part.(type) {
 		case string:
-			str = part
+			buf.WriteString(part)
 		case int:
 			argIdx := part - 1
-
+			var p []byte
 			if argIdx < 0 {
 				return "", fmt.Errorf("first sql argument must be > 0")
 			}
 
 			if argIdx >= len(args) {
 				return "", fmt.Errorf("insufficient arguments")
 			}
+
+			// Prevent SQL injection via Line Comment Creation
+			// https://github.com/jackc/pgx/security/advisories/GHSA-m7wr-2xf7-cm9p
+			buf.WriteByte(' ')
+
 			arg := args[argIdx]
 			switch arg := arg.(type) {
 			case nil:
-				str = "null"
+				p = null
 			case int64:
-				str = strconv.FormatInt(arg, 10)
+				p = strconv.AppendInt(buf.AvailableBuffer(), arg, 10)
 			case float64:
-				str = strconv.FormatFloat(arg, 'f', -1, 64)
+				p = strconv.AppendFloat(buf.AvailableBuffer(), arg, 'f', -1, 64)
 			case bool:
-				str = strconv.FormatBool(arg)
+				p = strconv.AppendBool(buf.AvailableBuffer(), arg)
 			case []byte:
-				str = QuoteBytes(arg)
+				p = QuoteBytes(buf.AvailableBuffer(), arg)
 			case string:
-				str = QuoteString(arg)
+				p = QuoteString(buf.AvailableBuffer(), arg)
 			case time.Time:
-				str = arg.Truncate(time.Microsecond).Format("'2006-01-02 15:04:05.999999999Z07:00:00'")
+				p = arg.Truncate(time.Microsecond).
+					AppendFormat(buf.AvailableBuffer(), "'2006-01-02 15:04:05.999999999Z07:00:00'")
 			default:
 				return "", fmt.Errorf("invalid arg type: %T", arg)
 			}
 			argUse[argIdx] = true
 
+			buf.Write(p)
+
 			// Prevent SQL injection via Line Comment Creation
 			// https://github.com/jackc/pgx/security/advisories/GHSA-m7wr-2xf7-cm9p
-			str = " " + str + " "
+			buf.WriteByte(' ')
 		default:
 			return "", fmt.Errorf("invalid Part type: %T", part)
 		}
-		buf.WriteString(str)
 	}
 
 	for i, used := range argUse {
@@ -82,26 +106,81 @@ func (q *Query) Sanitize(args ...any) (string, error) {
 }
 
 func NewQuery(sql string) (*Query, error) {
-	l := &sqlLexer{
-		src:     sql,
-		stateFn: rawState,
+	query := &Query{}
+	query.init(sql)
+
+	return query, nil
+}
+
+var sqlLexerPool = &pool[*sqlLexer]{
+	new: func() *sqlLexer {
+		return &sqlLexer{}
+	},
+	reset: func(sl *sqlLexer) bool {
+		*sl = sqlLexer{}
+		return true
+	},
+}
+
+func (q *Query) init(sql string) {
+	parts := q.Parts[:0]
+	if parts == nil {
+		// dirty, but fast heuristic to preallocate for ~90% usecases
+		n := strings.Count(sql, "$") + strings.Count(sql, "--") + 1
+		parts = make([]Part, 0, n)
 	}
 
+	l := sqlLexerPool.get()
+	defer sqlLexerPool.put(l)
+
+	l.src = sql
+	l.stateFn = rawState
+	l.parts = parts
+
 	for l.stateFn != nil {
 		l.stateFn = l.stateFn(l)
 	}
 
-	query := &Query{Parts: l.parts}
-
-	return query, nil
+	q.Parts = l.parts
 }
 
-func QuoteString(str string) string {
-	return "'" + strings.ReplaceAll(str, "'", "''") + "'"
+func QuoteString(dst []byte, str string) []byte {
+	const quote = "'"
+
+	n := strings.Count(str, quote)
+
+	dst = append(dst, quote...)
+
+	p := slices.Grow(dst[len(dst):], 2*len(quote)+len(str)+2*n)
+
+	for len(str) > 0 {
+		i := strings.Index(str, quote)
+		if i < 0 {
+			p = append(p, str...)
+			break
+		}
+		p = append(p, str[:i]...)
+		p = append(p, "''"...)
+		str = str[i+1:]
+	}
+
+	dst = append(dst, p...)
+
+	dst = append(dst, quote...)
+
+	return dst
 }
 
-func QuoteBytes(buf []byte) string {
-	return `'\x` + hex.EncodeToString(buf) + "'"
+func QuoteBytes(dst, buf []byte) []byte {
+	dst = append(dst, `'\x`...)
+
+	n := hex.EncodedLen(len(buf))
+	p := slices.Grow(dst[len(dst):], n)[:n]
+	hex.Encode(p, buf)
+	dst = append(dst, p...)
+
+	dst = append(dst, `'`...)
+	return dst
 }
 
 type sqlLexer struct {
@@ -319,13 +398,45 @@ func multilineCommentState(l *sqlLexer) stateFn {
 	}
 }
 
+var queryPool = &pool[*Query]{
+	new: func() *Query {
+		return &Query{}
+	},
+	reset: func(q *Query) bool {
+		n := len(q.Parts)
+		q.Parts = q.Parts[:0]
+		return n < 64 // drop too large queries
+	},
+}
+
 // SanitizeSQL replaces placeholder values with args. It quotes and escapes args
 // as necessary. This function is only safe when standard_conforming_strings is
 // on.
 func SanitizeSQL(sql string, args ...any) (string, error) {
-	query, err := NewQuery(sql)
-	if err != nil {
-		return "", err
-	}
+	query := queryPool.get()
+	query.init(sql)
+	defer queryPool.put(query)
+
 	return query.Sanitize(args...)
 }
+
+type pool[E any] struct {
+	p     sync.Pool
+	new   func() E
+	reset func(E) bool
+}
+
+func (pool *pool[E]) get() E {
+	v, ok := pool.p.Get().(E)
+	if !ok {
+		v = pool.new()
+	}
+
+	return v
+}
+
+func (p *pool[E]) put(v E) {
+	if p.reset(v) {
+		p.p.Put(v)
+	}
+}

internal/sanitize/sanitize_bench_test.go

@@ -0,0 +1,62 @@
+// sanitize_benchmark_test.go
+package sanitize_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/jackc/pgx/v5/internal/sanitize"
+)
+
+var benchmarkSanitizeResult string
+
+const benchmarkQuery = "" +
+	`SELECT * 
+   FROM "water_containers" 
+   WHERE NOT "id" = $1			-- int64
+   AND "tags" NOT IN $2         -- nil
+   AND "volume" > $3            -- float64
+   AND "transportable" = $4     -- bool
+   AND position($5 IN "sign")   -- bytes
+   AND "label" LIKE $6          -- string
+   AND "created_at" > $7;       -- time.Time`
+
+var benchmarkArgs = []any{
+	int64(12345),
+	nil,
+	float64(500),
+	true,
+	[]byte("8BADF00D"),
+	"kombucha's han'dy awokowa",
+	time.Date(2015, 10, 1, 0, 0, 0, 0, time.UTC),
+}
+
+func BenchmarkSanitize(b *testing.B) {
+	query, err := sanitize.NewQuery(benchmarkQuery)
+	if err != nil {
+		b.Fatalf("failed to create query: %v", err)
+	}
+
+	b.ResetTimer()
+	b.ReportAllocs()
+
+	for i := 0; i < b.N; i++ {
+		benchmarkSanitizeResult, err = query.Sanitize(benchmarkArgs...)
+		if err != nil {
+			b.Fatalf("failed to sanitize query: %v", err)
+		}
+	}
+}
+
+var benchmarkNewSQLResult string
+
+func BenchmarkSanitizeSQL(b *testing.B) {
+	b.ReportAllocs()
+	var err error
+	for i := 0; i < b.N; i++ {
+		benchmarkNewSQLResult, err = sanitize.SanitizeSQL(benchmarkQuery, benchmarkArgs...)
+		if err != nil {
+			b.Fatalf("failed to sanitize SQL: %v", err)
+		}
+	}
+}