fix: replace static buffer allocation on growth

Use `slices.Grow` and follow whatever algorithm it uses internally to
pick the next size of the buffer.

So the growth might not be exactly what we asked for, but it should be
optimal from Go runtime point of view.

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

Author: smira

.github/renovate.json

@@ -0,0 +1,36 @@
+{
+    "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+    "description": "THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.",
+    "prHeader": "Update Request | Renovate Bot",
+    "extends": [
+        ":dependencyDashboard",
+        ":gitSignOff",
+        ":semanticCommitScopeDisabled",
+        "schedule:earlyMondays"
+    ],
+    "packageRules": [
+        {
+            "groupName": "dependencies",
+            "matchUpdateTypes": [
+                "major",
+                "minor",
+                "patch",
+                "pin",
+                "digest"
+            ]
+        },
+        {
+            "enabled": false,
+            "matchFileNames": [
+                "Dockerfile"
+            ]
+        },
+        {
+            "enabled": false,
+            "matchFileNames": [
+                ".github/workflows/*.yaml"
+            ]
+        }
+    ],
+    "separateMajorMinor": false
+}

.golangci.yml

@@ -1,6 +1,6 @@
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2024-11-26T17:07:18Z by kres 232fe63.
+# Generated on 2025-01-30T12:16:36Z by kres 987bf4d.
 
 # options for analysis running
 run:
@@ -17,7 +17,6 @@ output:
       path: stdout
   print-issued-lines: true
   print-linter-name: true
-  uniq-by-line: true
   path-prefix: ""
 
 # all available settings of specific linters
@@ -134,6 +133,7 @@ linters:
     - perfsprint # complains about us using fmt.Sprintf in non-performance critical code, updating just kres took too long
     - goimports # same as gci
     - musttag # seems to be broken - goes into imported libraries and reports issues there
+    - exportloopref # WARN The linter 'exportloopref' is deprecated (since v1.60.2) due to: Since Go1.22 (loopvar) this linter is no longer relevant. Replaced by copyloopvar.
 
 issues:
   exclude: [ ]
@@ -143,6 +143,7 @@ issues:
   max-issues-per-linter: 10
   max-same-issues: 3
   new: false
+  uniq-by-line: true
 
 severity:
   default-severity: error

Dockerfile

@@ -1,21 +1,21 @@
-# syntax = docker/dockerfile-upstream:1.11.1-labs
+# syntax = docker/dockerfile-upstream:1.12.1-labs
 
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2024-11-26T17:07:18Z by kres 232fe63.
+# Generated on 2025-01-30T12:16:36Z by kres 987bf4d.
 
 ARG TOOLCHAIN
 
 # cleaned up specs and compiled versions
 FROM scratch AS generate
 
 # runs markdownlint
-FROM docker.io/oven/bun:1.1.36-alpine AS lint-markdown
+FROM docker.io/oven/bun:1.1.43-alpine AS lint-markdown
 WORKDIR /src
-RUN bun i markdownlint-cli@0.43.0 sentences-per-line@0.2.1
+RUN bun i markdownlint-cli@0.43.0 sentences-per-line@0.3.0
 COPY .markdownlint.json .
 COPY ./README.md ./README.md
-RUN bunx markdownlint --ignore "CHANGELOG.md" --ignore "**/node_modules/**" --ignore '**/hack/chglog/**' --rules node_modules/sentences-per-line/index.js .
+RUN bunx markdownlint --ignore "CHANGELOG.md" --ignore "**/node_modules/**" --ignore '**/hack/chglog/**' --rules sentences-per-line .
 
 # base toolchain image
 FROM --platform=${BUILDPLATFORM} ${TOOLCHAIN} AS toolchain

Makefile

@@ -1,6 +1,6 @@
 # THIS FILE WAS AUTOMATICALLY GENERATED, PLEASE DO NOT EDIT.
 #
-# Generated on 2024-11-26T17:07:18Z by kres 232fe63.
+# Generated on 2025-01-30T12:16:36Z by kres 987bf4d.
 
 # common variables
 
@@ -17,15 +17,15 @@ WITH_RACE ?= false
 REGISTRY ?= ghcr.io
 USERNAME ?= siderolabs
 REGISTRY_AND_USERNAME ?= $(REGISTRY)/$(USERNAME)
-PROTOBUF_GO_VERSION ?= 1.35.2
+PROTOBUF_GO_VERSION ?= 1.36.2
 GRPC_GO_VERSION ?= 1.5.1
-GRPC_GATEWAY_VERSION ?= 2.24.0
+GRPC_GATEWAY_VERSION ?= 2.25.1
 VTPROTOBUF_VERSION ?= 0.6.0
-GOIMPORTS_VERSION ?= 0.27.0
+GOIMPORTS_VERSION ?= 0.29.0
 DEEPCOPY_VERSION ?= v0.5.6
-GOLANGCILINT_VERSION ?= v1.62.0
+GOLANGCILINT_VERSION ?= v1.63.4
 GOFUMPT_VERSION ?= v0.7.0
-GO_VERSION ?= 1.23.3
+GO_VERSION ?= 1.23.5
 GO_BUILDFLAGS ?=
 GO_LDFLAGS ?=
 CGO_ENABLED ?= 0
@@ -41,13 +41,13 @@ PLATFORM ?= linux/amd64
 PROGRESS ?= auto
 PUSH ?= false
 CI_ARGS ?=
-BUILDKIT_MULTI_PLATFORM ?= 1
+BUILDKIT_MULTI_PLATFORM ?=
 COMMON_ARGS = --file=Dockerfile
 COMMON_ARGS += --provenance=false
 COMMON_ARGS += --progress=$(PROGRESS)
 COMMON_ARGS += --platform=$(PLATFORM)
-COMMON_ARGS += --push=$(PUSH)
 COMMON_ARGS += --build-arg=BUILDKIT_MULTI_PLATFORM=$(BUILDKIT_MULTI_PLATFORM)
+COMMON_ARGS += --push=$(PUSH)
 COMMON_ARGS += --build-arg=ARTIFACTS="$(ARTIFACTS)"
 COMMON_ARGS += --build-arg=SHA="$(SHA)"
 COMMON_ARGS += --build-arg=TAG="$(TAG)"
@@ -145,14 +145,17 @@ clean:  ## Cleans up all artifacts.
 target-%:  ## Builds the specified target defined in the Dockerfile. The build result will only remain in the build cache.
 	@$(BUILD) --target=$* $(COMMON_ARGS) $(TARGET_ARGS) $(CI_ARGS) .
 
+registry-%:  ## Builds the specified target defined in the Dockerfile and the output is an image. The image is pushed to the registry if PUSH=true.
+	@$(MAKE) target-$* TARGET_ARGS="--tag=$(REGISTRY)/$(USERNAME)/$(IMAGE_NAME):$(IMAGE_TAG)" BUILDKIT_MULTI_PLATFORM=1
+
 local-%:  ## Builds the specified target defined in the Dockerfile using the local output type. The build result will be output to the specified local destination.
 	@$(MAKE) target-$* TARGET_ARGS="--output=type=local,dest=$(DEST) $(TARGET_ARGS)"
 	@PLATFORM=$(PLATFORM) DEST=$(DEST) bash -c '\
 	  for platform in $$(tr "," "\n" <<< "$$PLATFORM"); do \
-	    echo $$platform; \
 	    directory="$${platform//\//_}"; \
 	    if [[ -d "$$DEST/$$directory" ]]; then \
-	      mv "$$DEST/$$directory/"* $$DEST; \
+		  echo $$platform; \
+	      mv -f "$$DEST/$$directory/"* $$DEST; \
 	      rmdir "$$DEST/$$directory/"; \
 	    fi; \
 	  done'

circular.go

@@ -112,7 +112,7 @@ func (buf *Buffer) Write(p []byte) (int, error) {
 	defer buf.mu.Unlock()
 
 	if buf.off < int64(buf.opt.MaxCapacity) {
-		if buf.off+int64(l) > int64(cap(buf.data)) && cap(buf.data) < buf.opt.MaxCapacity {
+		if buf.off+int64(l) > int64(buf.capacity()) && buf.capacity() < buf.opt.MaxCapacity {
 			// grow buffer to ensure write fits, but limit with max capacity
 			size := cap(buf.data) * 2
 			for size < int(buf.off)+l {
@@ -123,9 +123,9 @@ func (buf *Buffer) Write(p []byte) (int, error) {
 				size = buf.opt.MaxCapacity
 			}
 
-			data := make([]byte, size)
-			copy(data, buf.data)
-			buf.data = data
+			// grow and adjust length to the desired capacity
+			data := slices.Grow(buf.data, size)
+			buf.data = data[:min(cap(data), buf.opt.MaxCapacity)]
 		}
 	}
 
@@ -193,12 +193,20 @@ func (buf *Buffer) Write(p []byte) (int, error) {
 	return n, nil
 }
 
+// capacity returns the current buffer capacity.
+func (buf *Buffer) capacity() int {
+	// we return length here, not capacity, as the buffer might be larger due to the way slices.Grow works
+	//
+	// this is the useable length of the buffer, we might grow it (and actual capacity might or might not grow, leave it to slices.Grow)
+	return len(buf.data)
+}
+
 // Capacity returns number of bytes allocated for the buffer.
 func (buf *Buffer) Capacity() int {
 	buf.mu.Lock()
 	defer buf.mu.Unlock()
 
-	return cap(buf.data)
+	return buf.capacity()
 }
 
 // MaxCapacity returns maximum number of (decompressed) bytes (including compressed chunks) that can be stored in the buffer.
@@ -225,7 +233,7 @@ func (buf *Buffer) TotalCompressedSize() int64 {
 		size += int64(len(c.compressed))
 	}
 
-	return size + int64(cap(buf.data))
+	return size + int64(buf.capacity())
 }
 
 // TotalSize reports overall number of bytes available for reading in the buffer.
@@ -237,11 +245,7 @@ func (buf *Buffer) TotalSize() int64 {
 	defer buf.mu.Unlock()
 
 	if len(buf.chunks) == 0 {
-		if buf.off < int64(cap(buf.data)) {
-			return buf.off
-		}
-
-		return int64(cap(buf.data))
+		return min(int64(buf.capacity()), buf.off)
 	}
 
 	return buf.off - buf.chunks[0].startOffset

circular_test.go

@@ -87,7 +87,11 @@ func TestWrites(t *testing.T) {
 			req.NoError(err)
 			req.Equal(5000, n)
 
-			req.Equal(8192, buf.Capacity())
+			// capacity might grow to a number specific to the way `slices.Grow` works,
+			// but it should be within reasonable bounds
+			req.GreaterOrEqual(buf.Capacity(), 8192)
+			req.LessOrEqual(buf.Capacity(), 16384)
+
 			req.EqualValues(6100, buf.Offset())
 
 			for i := range 20 {

persistence.go

@@ -19,7 +19,6 @@ import (
 	"go.uber.org/zap"
 )
 
-//nolint:gocognit
 func (buf *Buffer) load() error {
 	if buf.opt.PersistenceOptions.ChunkPath == "" {
 		// persistence is disabled
@@ -97,18 +96,14 @@ func (buf *Buffer) load() error {
 			if err != nil {
 				buf.opt.Logger.Error("failed to decompress zero chunk, skipping", zap.String("path", chunkPath.path), zap.Error(err))
 
-				buf.data = buf.data[:cap(buf.data)]
+				buf.data = buf.data[:min(cap(buf.data), buf.opt.MaxCapacity)]
 
 				continue
 			}
 
 			buf.off = int64(len(buf.data))
 
-			if cap(buf.data) > buf.opt.MaxCapacity {
-				buf.data = buf.data[:buf.opt.MaxCapacity:buf.opt.MaxCapacity]
-			} else {
-				buf.data = buf.data[:cap(buf.data)]
-			}
+			buf.data = buf.data[:min(cap(buf.data), buf.opt.MaxCapacity)]
 		} else {
 			decompressedSize, err := buf.opt.Compressor.DecompressedSize(data)
 			if err != nil {
@@ -276,7 +271,7 @@ func (buf *Buffer) persistCurrentChunk(currentOffset, lastPersistedOffset int64,
 	}
 
 	buf.mu.Lock()
-	data := slices.Clone(buf.data[:currentOffset%int64(cap(buf.data))])
+	data := slices.Clone(buf.data[:currentOffset%int64(buf.capacity())])
 	buf.mu.Unlock()
 
 	compressed, err := buf.opt.Compressor.Compress(data, nil)

reader.go

@@ -126,11 +126,11 @@ func (r *Reader) Read(p []byte) (n int, err error) {
 		n = int(r.endOff - r.off)
 	}
 
-	n = min(min(n, len(p)), cap(r.buf.data))
+	n = min(min(n, len(p)), r.buf.capacity())
 
 	i := int(r.off % int64(r.buf.opt.MaxCapacity))
 
-	if l := cap(r.buf.data) - i; l < n {
+	if l := r.buf.capacity() - i; l < n {
 		copy(p, r.buf.data[i:])
 		copy(p[l:], r.buf.data[:n-l])
 	} else {