Add build flags to make CGO optional

options.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/dgraph-io/badger/options"
 	"github.com/dgraph-io/badger/table"
+	"github.com/dgraph-io/badger/y"
 )
 
 // Note: If you add a new option X make sure you also add a WithX method on Options.
@@ -98,6 +99,11 @@ type Options struct {
 // DefaultOptions sets a list of recommended options for good performance.
 // Feel free to modify these to suit your needs with the WithX methods.
 func DefaultOptions(path string) Options {
+	defaultCompression := options.ZSTD
+	// Use snappy as default compression algorithm if badger is built without CGO.
+	if !y.CgoEnabled {
+		defaultCompression = options.Snappy
+	}
 	return Options{
 		Dir:                 path,
 		ValueDir:            path,
@@ -120,7 +126,7 @@ func DefaultOptions(path string) Options {
 		CompactL0OnClose:        true,
 		KeepL0InMemory:          true,
 		VerifyValueChecksum:     false,
-		Compression:             options.ZSTD,
+		Compression:             defaultCompression,
 		MaxCacheSize:            1 << 30, // 1 GB
 		// Nothing to read/write value log using standard File I/O
 		// MemoryMap to mmap() the value log files

table/builder.go

@@ -22,7 +22,6 @@ import (
 	"math"
 	"unsafe"
 
-	"github.com/DataDog/zstd"
 	"github.com/dgryski/go-farm"
 	"github.com/golang/protobuf/proto"
 	"github.com/golang/snappy"
@@ -347,7 +346,7 @@ func (b *Builder) compressData(data []byte) ([]byte, error) {
 	case options.Snappy:
 		return snappy.Encode(nil, data), nil
 	case options.ZSTD:
-		return zstd.Compress(nil, data)
+		return y.ZSTDCompress(nil, data)
 	}
 	return nil, errors.New("Unsupported compression type")
 }

table/table.go

@@ -30,7 +30,6 @@ import (
 	"sync/atomic"
 	"unsafe"
 
-	"github.com/DataDog/zstd"
 	"github.com/golang/protobuf/proto"
 	"github.com/golang/snappy"
 	"github.com/pkg/errors"
@@ -539,7 +538,7 @@ func (t *Table) decompressData(data []byte) ([]byte, error) {
 	case options.Snappy:
 		return snappy.Decode(nil, data)
 	case options.ZSTD:
-		return zstd.Decompress(nil, data)
+		return y.ZSTDDecompress(nil, data)
 	}
 	return nil, errors.New("Unsupported compression type")
 }

y/zstd_cgo.go

@@ -0,0 +1,36 @@
+// +build cgo
+
+/*
+ * Copyright 2019 Dgraph Labs, Inc. and Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package y
+
+import (
+	"github.com/DataDog/zstd"
+)
+
+// CgoEnabled is used to check if CGO is enabled while building badger.
+const CgoEnabled = true
+
+// ZSTDDecompress decompresses a block using ZSTD algorithm.
+func ZSTDDecompress(dst, src []byte) ([]byte, error) {
+	return zstd.Decompress(dst, src)
+}
+
+// ZSTDCompress compresses a block using ZSTD algorithm.
+func ZSTDCompress(dst, src []byte) ([]byte, error) {
+	return zstd.Compress(dst, src)
+}

y/zstd_nocgo.go

@@ -0,0 +1,38 @@
+// +build !cgo
+
+/*
+ * Copyright 2019 Dgraph Labs, Inc. and Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package y
+
+import (
+	"errors"
+)
+
+var errZstdCgo = errors.New("zstd compression requires building badger with cgo enabled")
+
+// CgoEnabled is used to check if CGO is enabled while building badger.
+const CgoEnabled = false
+
+// ZSTDDecompress decompresses a block using ZSTD algorithm.
+func ZSTDDecompress(dst, src []byte) ([]byte, error) {
+	return nil, errZstdCgo
+}
+
+// ZSTDCompress compresses a block using ZSTD algorithm.
+func ZSTDCompress(dst, src []byte) ([]byte, error) {
+	return nil, errZstdCgo
+}