Reduce marshal and unmarshal overhead (#1044)

* Reduce marshal and unmarshal overhead

Targeted optimizations to reduce performance overhead introduced by
recent feature additions and the unsafe removal.

Unmarshal:
- parseKeyval: access the node directly in the builder's slice to set
  Raw, bypassing NodeAt which triggers a GC write barrier for the
  nodes-pointer on every key-value expression.
- Iterator.Next: cache the *nodes slice dereference in a local variable
  to avoid repeated pointer-to-slice indirection in the hot loop.

Marshal:
- Guard shouldOmitZero calls with an inlineable options.omitzero check.
  shouldOmitZero has inlining cost 1145 (budget 80), so avoiding the
  function call when omitzero is not set removes per-field overhead.
- Inline the isNil check in encodeMap. isNil has inlining cost 93
  (budget 80), so expanding it at the single hot call site avoids
  per-map-entry function call overhead.

Update README benchmarks.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/coverage.yml

@@ -15,6 +15,6 @@ jobs:
       - name: Setup go
         uses: actions/setup-go@v6
         with:
-          go-version: "1.25"
+          go-version: "1.26"
       - name: Run tests with coverage
         run: ./ci.sh coverage -d "${GITHUB_BASE_REF-HEAD}"

.github/workflows/go-versions-test.yml

@@ -20,7 +20,7 @@ jobs:
           fetch-depth: 0
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Run Go versions compatibility test
         run: |

.github/workflows/lint.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Setup go
         uses: actions/setup-go@v6
         with:
-          go-version: "1.24"
+          go-version: "1.26"
       - name: Run golangci-lint
         uses: golangci/golangci-lint-action@v9
         with:

.github/workflows/release.yml

@@ -22,9 +22,9 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v6
         with:
-          go-version: "1.25"
+          go-version: "1.26"
       - name: Login to GitHub Container Registry
-        uses: docker/login-action@v3
+        uses: docker/login-action@v4
         with:
           registry: ghcr.io
           username: ${{ github.actor }}

.github/workflows/workflow.yml

@@ -13,7 +13,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ 'ubuntu-latest', 'windows-latest', 'macos-latest', 'macos-14' ]
-        go: [ '1.24', '1.25' ]
+        go: [ '1.25', '1.26' ]
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.go }}/${{ matrix.os }}
     steps:

.goreleaser.yaml

@@ -22,7 +22,6 @@ builds:
       - linux_riscv64
       - windows_amd64
       - windows_arm64
-      - windows_arm
       - darwin_amd64
       - darwin_arm64
   - id: tomljson
@@ -42,7 +41,6 @@ builds:
       - linux_riscv64
       - windows_amd64
       - windows_arm64
-      - windows_arm
       - darwin_amd64
       - darwin_arm64
   - id: jsontoml
@@ -62,7 +60,6 @@ builds:
       - linux_arm
       - windows_amd64
       - windows_arm64
-      - windows_arm
       - darwin_amd64
       - darwin_arm64
 universal_binaries:

README.md

@@ -235,17 +235,17 @@ the AST level. See https://pkg.go.dev/github.com/pelletier/go-toml/v2/unstable.
 Execution time speedup compared to other Go TOML libraries:
 
 <table>
-	<thead>
-		<tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr>
-	</thead>
-	<tbody>
-		<tr><td>Marshal/HugoFrontMatter-2</td><td>1.9x</td><td>2.2x</td></tr>
-		<tr><td>Marshal/ReferenceFile/map-2</td><td>1.7x</td><td>2.1x</td></tr>
-		<tr><td>Marshal/ReferenceFile/struct-2</td><td>2.2x</td><td>3.0x</td></tr>
-		<tr><td>Unmarshal/HugoFrontMatter-2</td><td>2.9x</td><td>2.7x</td></tr>
-		<tr><td>Unmarshal/ReferenceFile/map-2</td><td>2.6x</td><td>2.7x</td></tr>
-		<tr><td>Unmarshal/ReferenceFile/struct-2</td><td>4.6x</td><td>5.1x</td></tr>
-	 </tbody>
+    <thead>
+        <tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr>
+    </thead>
+    <tbody>
+        <tr><td>Marshal/HugoFrontMatter-2</td><td>2.1x</td><td>2.0x</td></tr>
+        <tr><td>Marshal/ReferenceFile/map-2</td><td>2.0x</td><td>2.0x</td></tr>
+        <tr><td>Marshal/ReferenceFile/struct-2</td><td>2.3x</td><td>2.5x</td></tr>
+        <tr><td>Unmarshal/HugoFrontMatter-2</td><td>3.3x</td><td>2.8x</td></tr>
+        <tr><td>Unmarshal/ReferenceFile/map-2</td><td>2.9x</td><td>3.0x</td></tr>
+        <tr><td>Unmarshal/ReferenceFile/struct-2</td><td>4.8x</td><td>5.0x</td></tr>
+     </tbody>
 </table>
 <details><summary>See more</summary>
 <p>The table above has the results of the most common use-cases. The table below
@@ -253,22 +253,22 @@ contains the results of all benchmarks, including unrealistic ones. It is
 provided for completeness.</p>
 
 <table>
-	<thead>
-		<tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr>
-	</thead>
-	<tbody>
-		<tr><td>Marshal/SimpleDocument/map-2</td><td>1.8x</td><td>2.7x</td></tr>
-		<tr><td>Marshal/SimpleDocument/struct-2</td><td>2.7x</td><td>3.8x</td></tr>
-		<tr><td>Unmarshal/SimpleDocument/map-2</td><td>3.8x</td><td>3.0x</td></tr>
-		<tr><td>Unmarshal/SimpleDocument/struct-2</td><td>5.6x</td><td>4.1x</td></tr>
-		<tr><td>UnmarshalDataset/example-2</td><td>3.0x</td><td>3.2x</td></tr>
-		<tr><td>UnmarshalDataset/code-2</td><td>2.3x</td><td>2.9x</td></tr>
-		<tr><td>UnmarshalDataset/twitter-2</td><td>2.6x</td><td>2.7x</td></tr>
-		<tr><td>UnmarshalDataset/citm_catalog-2</td><td>2.2x</td><td>2.3x</td></tr>
-		<tr><td>UnmarshalDataset/canada-2</td><td>1.8x</td><td>1.5x</td></tr>
-		<tr><td>UnmarshalDataset/config-2</td><td>4.1x</td><td>2.9x</td></tr>
-		<tr><td>geomean</td><td>2.7x</td><td>2.8x</td></tr>
-	 </tbody>
+    <thead>
+        <tr><th>Benchmark</th><th>go-toml v1</th><th>BurntSushi/toml</th></tr>
+    </thead>
+    <tbody>
+        <tr><td>Marshal/SimpleDocument/map-2</td><td>2.0x</td><td>2.9x</td></tr>
+        <tr><td>Marshal/SimpleDocument/struct-2</td><td>2.5x</td><td>3.6x</td></tr>
+        <tr><td>Unmarshal/SimpleDocument/map-2</td><td>4.2x</td><td>3.4x</td></tr>
+        <tr><td>Unmarshal/SimpleDocument/struct-2</td><td>5.9x</td><td>4.4x</td></tr>
+        <tr><td>UnmarshalDataset/example-2</td><td>3.2x</td><td>2.9x</td></tr>
+        <tr><td>UnmarshalDataset/code-2</td><td>2.4x</td><td>2.8x</td></tr>
+        <tr><td>UnmarshalDataset/twitter-2</td><td>2.7x</td><td>2.5x</td></tr>
+        <tr><td>UnmarshalDataset/citm_catalog-2</td><td>2.3x</td><td>2.3x</td></tr>
+        <tr><td>UnmarshalDataset/canada-2</td><td>1.9x</td><td>1.5x</td></tr>
+        <tr><td>UnmarshalDataset/config-2</td><td>5.4x</td><td>3.0x</td></tr>
+        <tr><td>geomean</td><td>2.9x</td><td>2.8x</td></tr>
+     </tbody>
 </table>
 <p>This table can be generated with <code>./ci.sh benchmark -a -html</code>.</p>
 </details>

ci.sh

@@ -147,7 +147,7 @@ bench() {
     pushd "$dir"
 
     if [ "${replace}" != "" ]; then
-        find ./benchmark/ -iname '*.go' -exec sed -i -E "s|github.com/pelletier/go-toml/v2|${replace}|g" {} \;
+        find ./benchmark/ -iname '*.go' -exec sed -i -E "s|github.com/pelletier/go-toml/v2\"|${replace}\"|g" {} \;
         go get "${replace}"
     fi
 
@@ -195,6 +195,11 @@ for line in reversed(lines[2:]):
         "%.1fx" % (float(line[3])/v2),  # v1
         "%.1fx" % (float(line[7])/v2),  # bs
     ])
+
+if not results:
+    print("No benchmark results to display.", file=sys.stderr)
+    sys.exit(1)
+
 # move geomean to the end
 results.append(results[0])
 del results[0]

errors_test.go

@@ -259,6 +259,12 @@ func TestDecodeError_Position(t *testing.T) {
 			expectedRow: 3,
 			minCol:      5,
 		},
+		{
+			name:        "missing equals on last line without trailing newline",
+			doc:         "a = 1\nb = 2\nc",
+			expectedRow: 3,
+			minCol:      1,
+		},
 	}
 
 	for _, e := range examples {

marshaler.go

@@ -704,15 +704,18 @@ func (enc *Encoder) encodeMap(b []byte, ctx encoderCtx, v reflect.Value) ([]byte
 	for iter.Next() {
 		v := iter.Value()
 
-		if isNil(v) {
-			// For nil pointers, convert to zero value of the element type.
-			// This allows round-trip marshaling of maps with nil pointer values.
-			// For nil interfaces and nil maps, skip since we can't derive a type.
-			if v.Kind() == reflect.Ptr {
+		// Handle nil values: convert nil pointers to zero value,
+		// skip nil interfaces and nil maps.
+		switch v.Kind() {
+		case reflect.Ptr:
+			if v.IsNil() {
 				v = reflect.Zero(v.Type().Elem())
-			} else {
+			}
+		case reflect.Interface, reflect.Map:
+			if v.IsNil() {
 				continue
 			}
+		default:
 		}
 
 		k, err := enc.keyToString(iter.Key())
@@ -936,7 +939,7 @@ func (enc *Encoder) encodeTable(b []byte, ctx encoderCtx, t table) ([]byte, erro
 		if shouldOmitEmpty(kv.Options, kv.Value) {
 			continue
 		}
-		if shouldOmitZero(kv.Options, kv.Value) {
+		if kv.Options.omitzero && shouldOmitZero(kv.Options, kv.Value) {
 			continue
 		}
 		hasNonEmptyKV = true
@@ -958,7 +961,7 @@ func (enc *Encoder) encodeTable(b []byte, ctx encoderCtx, t table) ([]byte, erro
 		if shouldOmitEmpty(table.Options, table.Value) {
 			continue
 		}
-		if shouldOmitZero(table.Options, table.Value) {
+		if table.Options.omitzero && shouldOmitZero(table.Options, table.Value) {
 			continue
 		}
 		if first {
@@ -995,7 +998,7 @@ func (enc *Encoder) encodeTableInline(b []byte, ctx encoderCtx, t table) ([]byte
 		if shouldOmitEmpty(kv.Options, kv.Value) {
 			continue
 		}
-		if shouldOmitZero(kv.Options, kv.Value) {
+		if kv.Options.omitzero && shouldOmitZero(kv.Options, kv.Value) {
 			continue
 		}
 

test-go-versions.sh

@@ -9,7 +9,7 @@ YELLOW='\033[1;33m'
 BLUE='\033[0;34m'
 NC='\033[0m' # No Color
 
-# Go versions to test (1.11 through 1.25)
+# Go versions to test (1.11 through 1.26)
 GO_VERSIONS=(
     "1.11"
     "1.12"
@@ -26,6 +26,7 @@ GO_VERSIONS=(
     "1.23"
     "1.24"
     "1.25"
+    "1.26"
 )
 
 # Default values
@@ -64,7 +65,7 @@ EXAMPLES:
     $0                          # Test all Go versions in parallel
     $0 --sequential             # Test all Go versions sequentially
     $0 1.21 1.22 1.23          # Test specific versions
-    $0 --verbose --output ./results 1.24 1.25  # Verbose output to custom directory
+    $0 --verbose --output ./results 1.25 1.26  # Verbose output to custom directory
 
 EXIT CODES:
     0                   Recent Go versions pass (good compatibility)
@@ -136,8 +137,8 @@ fi
 
 # Validate Go versions
 for version in "${GO_VERSIONS[@]}"; do
-    if ! [[ "$version" =~ ^1\.(1[1-9]|2[0-5])$ ]]; then
-        log_error "Invalid Go version: $version. Supported versions: 1.11-1.25"
+    if ! [[ "$version" =~ ^1\.(1[1-9]|2[0-6])$ ]]; then
+        log_error "Invalid Go version: $version. Supported versions: 1.11-1.26"
         exit 1
     fi
 done

unstable/ast.go

@@ -28,12 +28,16 @@ func (c *Iterator) Next() bool {
 	if c.nodes == nil {
 		return false
 	}
+	nodes := *c.nodes
 	if !c.started {
 		c.started = true
-	} else if c.idx >= 0 {
-		c.idx = (*c.nodes)[c.idx].next
+	} else {
+		idx := c.idx
+		if idx >= 0 && int(idx) < len(nodes) {
+			c.idx = nodes[idx].next
+		}
 	}
-	return c.idx >= 0 && int(c.idx) < len(*c.nodes)
+	return c.idx >= 0 && int(c.idx) < len(nodes)
 }
 
 // IsLast returns true if the current node of the iterator is the last

unstable/parser.go

@@ -345,7 +345,7 @@ func (p *Parser) parseKeyval(b []byte) (reference, []byte, error) {
 	b = p.parseWhitespace(b)
 
 	if len(b) == 0 {
-		return invalidReference, nil, NewParserError(b, "expected = after a key, but the document ends there")
+		return invalidReference, nil, NewParserError(startB[:len(startB)-len(b)], "expected = after a key, but the document ends there")
 	}
 
 	b, err = expect('=', b)
@@ -363,9 +363,10 @@ func (p *Parser) parseKeyval(b []byte) (reference, []byte, error) {
 	p.builder.Chain(valRef, key)
 	p.builder.AttachChild(ref, valRef)
 
-	// Set Raw to span the entire key-value expression
-	node := p.builder.NodeAt(ref)
-	node.Raw = p.rangeOfToken(startB[:len(startB)-len(b)], b)
+	// Set Raw to span the entire key-value expression.
+	// Access the node directly in the slice to avoid the write barrier
+	// that NodeAt's nodes-pointer setup would trigger.
+	p.builder.tree.nodes[ref].Raw = p.rangeOfToken(startB[:len(startB)-len(b)], b)
 
 	return ref, b, err
 }