Upgrade module requirements

* add version.json file

* update .github/workflows/go-test.yml

* update .github/workflows/go-check.yml

* add .github/workflows/releaser.yml

* add .github/workflows/release-check.yml

* add .github/workflows/tagpush.yml

Co-authored-by: web3-bot <web3-bot@users.noreply.github.com>

.github/workflows/go-check.yml

@@ -27,7 +27,7 @@ jobs:
             echo "RUNGOGENERATE=true" >> $GITHUB_ENV
           fi
       - name: Install staticcheck
-        run: go install honnef.co/go/tools/cmd/staticcheck@df71e5d0e0ed317ebf43e6e59cf919430fa4b8f2 # 2021.1.1 (v0.2.1)
+        run: go install honnef.co/go/tools/cmd/staticcheck@c8caa92bad8c27ae734c6725b8a04932d54a147b # 2021.1.2 (v0.2.2)
       - name: Check that go.mod is tidy
         uses: protocol/multiple-go-modules@v1.2
         with:

.github/workflows/go-test.yml

@@ -26,13 +26,24 @@ jobs:
         run: |
           go version
           go env
+      - name: Use msys2 on windows
+        if: ${{ matrix.os == 'windows' }}
+        shell: bash
+        # The executable for msys2 is also called bash.cmd
+        #   https://github.com/actions/virtual-environments/blob/main/images/win/Windows2019-Readme.md#shells
+        # If we prepend its location to the PATH
+        #   subsequent 'shell: bash' steps will use msys2 instead of gitbash
+        run: echo "C:/msys64/usr/bin" >> $GITHUB_PATH
       - name: Run repo-specific setup
         uses: ./.github/actions/go-test-setup
         if: hashFiles('./.github/actions/go-test-setup') != ''
       - name: Run tests
         uses: protocol/multiple-go-modules@v1.2
         with:
-          run: go test -v -coverprofile module-coverage.txt ./...
+          # Use -coverpkg=./..., so that we include cross-package coverage.
+          # If package ./A imports ./B, and ./A's tests also cover ./B,
+          # this means ./B's coverage will be significantly higher than 0%.
+          run: go test -v -coverprofile=module-coverage.txt -coverpkg=./... ./...
       - name: Run tests (32 bit)
         if: ${{ matrix.os != 'macos' }} # can't run 32 bit tests on OSX.
         uses: protocol/multiple-go-modules@v1.2
@@ -49,7 +60,7 @@ jobs:
         shell: bash
         run: echo "COVERAGES=$(find . -type f -name 'module-coverage.txt' | tr -s '\n' ',' | sed 's/,$//')" >> $GITHUB_ENV
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@51d810878be5422784e86451c0e7c14e5860ec47 # v2.0.2
+        uses: codecov/codecov-action@f32b3a3741e1053eb607407145bc9619351dc93b # v2.1.0
         with:
           files: '${{ env.COVERAGES }}'
           env_vars: OS=${{ matrix.os }}, GO=${{ matrix.go }}

.github/workflows/release-check.yml

@@ -0,0 +1,11 @@
+# File managed by web3-bot. DO NOT EDIT.
+# See https://github.com/protocol/.github/ for details.
+
+name: Release Checker
+on:
+  pull_request:
+    paths: [ 'version.json' ]
+
+jobs:
+  release-check:
+    uses: protocol/.github/.github/workflows/release-check.yml@master

.github/workflows/releaser.yml

@@ -0,0 +1,11 @@
+# File managed by web3-bot. DO NOT EDIT.
+# See https://github.com/protocol/.github/ for details.
+
+name: Releaser
+on:
+  push:
+    paths: [ 'version.json' ]
+
+jobs:
+  releaser:
+    uses: protocol/.github/.github/workflows/releaser.yml@master

.github/workflows/tagpush.yml

@@ -0,0 +1,12 @@
+# File managed by web3-bot. DO NOT EDIT.
+# See https://github.com/protocol/.github/ for details.
+
+name: Tag Push Checker
+on:
+  push:
+    tags:
+      - v*
+
+jobs:
+  releaser:
+    uses: protocol/.github/.github/workflows/tagpush.yml@master

benchmark_test.go

@@ -0,0 +1,61 @@
+package cid_test
+
+import (
+	"math/rand"
+	"testing"
+
+	"github.com/ipfs/go-cid"
+	"github.com/multiformats/go-multihash"
+)
+
+// BenchmarkIdentityCheck benchmarks two ways of checking whether a CIDv1 has multihash.IDENTITY
+// code:
+//  1. Cid.Prefix(), and
+//  2. decoding the Cid.Hash().
+//
+// This benchmark illustrates that using Cid.Prefix is more efficient than multihash.Decode.
+// Users wishing to perform such a check should use Cid.Prefix.
+//
+// Consider that `Cid.Prefix` is already efficient enough and introducing a dedicated API for
+// performing this check will likely result in small gains.
+func BenchmarkIdentityCheck(b *testing.B) {
+	rng := rand.New(rand.NewSource(1413))
+
+	data := make([]byte, rng.Intn(100)+1024)
+	if _, err := rng.Read(data); err != nil {
+		b.Fatal(err)
+	}
+	mh, err := multihash.Sum(data, multihash.IDENTITY, -1)
+	if err != nil {
+		b.Fatal(err)
+	}
+	cv1 := cid.NewCidV1(cid.Raw, mh)
+
+	b.SetBytes(int64(cv1.ByteLen()))
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	b.Run("Prefix", func(b *testing.B) {
+		b.RunParallel(func(pb *testing.PB) {
+			for pb.Next() {
+				if cv1.Prefix().MhType != multihash.IDENTITY {
+					b.Fatal("expected IDENTITY CID")
+				}
+			}
+		})
+	})
+
+	b.Run("MultihashDecode", func(b *testing.B) {
+		b.RunParallel(func(pb *testing.PB) {
+			for pb.Next() {
+				dmh, err := multihash.Decode(cv1.Hash())
+				if err != nil {
+					b.Fatal(err)
+				}
+				if dmh.Code != multihash.IDENTITY {
+					b.Fatal("expected IDENTITY CID")
+				}
+			}
+		})
+	})
+}

cid.go

@@ -22,6 +22,7 @@ package cid
 import (
 	"bytes"
 	"encoding"
+	"encoding/binary"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -173,16 +174,24 @@ func NewCidV0(mhash mh.Multihash) Cid {
 // Panics if the multihash is invalid.
 func NewCidV1(codecType uint64, mhash mh.Multihash) Cid {
 	hashlen := len(mhash)
-	// two 8 bytes (max) numbers plus hash
-	buf := make([]byte, 1+varint.UvarintSize(codecType)+hashlen)
-	n := varint.PutUvarint(buf, 1)
-	n += varint.PutUvarint(buf[n:], codecType)
-	cn := copy(buf[n:], mhash)
+
+	// Two 8 bytes (max) numbers plus hash.
+	// We use strings.Builder to only allocate once.
+	var b strings.Builder
+	b.Grow(1 + varint.UvarintSize(codecType) + hashlen)
+
+	b.WriteByte(1)
+
+	var buf [binary.MaxVarintLen64]byte
+	n := varint.PutUvarint(buf[:], codecType)
+	b.Write(buf[:n])
+
+	cn, _ := b.Write(mhash)
 	if cn != hashlen {
 		panic("copy hash length is inconsistent")
 	}
 
-	return Cid{string(buf[:n+hashlen])}
+	return Cid{b.String()}
 }
 
 var (

go.mod

@@ -2,7 +2,7 @@ module github.com/ipfs/go-cid
 
 require (
 	github.com/multiformats/go-multibase v0.0.3
-	github.com/multiformats/go-multihash v0.0.15
+	github.com/multiformats/go-multihash v0.1.0
 	github.com/multiformats/go-varint v0.0.6
 	golang.org/x/crypto v0.0.0-20210506145944-38f3c27a63bf // indirect
 )

version.json

@@ -0,0 +1,3 @@
+{
+  "version": "v0.1.0"
+}