refactor(compress): using compression pool (#209)

###  refactor(compress): using compression pool to reduce GC


### Change 
 add compression pool 
 resue compression pool for reader

---------

Signed-off-by: kaixuan xu <[email protected]>

lib/pool/compression_cache_pool.go

@@ -0,0 +1,97 @@
+// Copyright 2024 openGemini Authors
+//
+// 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 pool
+
+import (
+	"bytes"
+	"compress/gzip"
+	"errors"
+	"runtime"
+
+	"github.com/golang/snappy"
+	"github.com/klauspost/compress/zstd"
+)
+
+var (
+	gzipReaderPool = NewCachePool[*gzip.Reader](func() *gzip.Reader {
+		return new(gzip.Reader)
+	}, 2*runtime.NumCPU())
+
+	snappyReaderPool = NewCachePool[*snappy.Reader](func() *snappy.Reader {
+		return snappy.NewReader(nil)
+	}, 2*runtime.NumCPU())
+
+	zstdDecoderPool = NewCachePool[*zstd.Decoder](func() *zstd.Decoder {
+		decoder, error := zstd.NewReader(nil)
+		if error != nil {
+			return nil
+		}
+		return decoder
+	}, 2*runtime.NumCPU())
+)
+
+func GetGzipReader(body []byte) (*gzip.Reader, error) {
+	gzipReader := gzipReaderPool.Get()
+	if gzipReader == nil {
+		return nil, errors.New("failed to get gzip reader")
+	}
+	err := gzipReader.Reset(bytes.NewReader(body))
+	if err != nil {
+		gzipReaderPool.Put(gzipReader) // Return the reader to the pool if reset fails
+		return nil, err
+	}
+	return gzipReader, nil
+}
+
+func PutGzipReader(reader *gzip.Reader) {
+	gzipReaderPool.Put(reader)
+}
+
+func GetSnappyReader(body []byte) (*snappy.Reader, error) {
+	snappyReader := snappyReaderPool.Get()
+	if snappyReader == nil {
+		return nil, errors.New("failed to get snappy reader")
+	}
+
+	snappyReader.Reset(bytes.NewReader(body))
+	return snappyReader, nil
+}
+
+func PutSnappyReader(reader *snappy.Reader) {
+	reader.Reset(nil)
+	snappyReaderPool.Put(reader)
+}
+
+func GetZstdDecoder(body []byte) (*zstd.Decoder, error) {
+	decoder := zstdDecoderPool.Get()
+	if decoder == nil {
+		return nil, errors.New("failed to get zstd decoder")
+	}
+
+	err := decoder.Reset(bytes.NewReader(body))
+	if err != nil {
+		zstdDecoderPool.Put(decoder) // Return the decoder to the pool if reset fails
+		return nil, err
+	}
+	return decoder, nil
+}
+
+func PutZstdDecoder(decoder *zstd.Decoder) {
+	err := decoder.Reset(nil)
+	if err != nil {
+		return
+	}
+	zstdDecoderPool.Put(decoder)
+}

lib/pool/compression_cache_pool_test.go

@@ -0,0 +1,109 @@
+// Copyright 2024 openGemini Authors
+//
+// 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 pool
+
+import (
+	"bytes"
+	"compress/gzip"
+	"io"
+	"testing"
+
+	"github.com/golang/snappy"
+	"github.com/klauspost/compress/zstd"
+)
+
+func TestGzipReaderPool(t *testing.T) {
+	data := []byte("test data")
+	var buf bytes.Buffer
+	writer := gzip.NewWriter(&buf)
+	_, err := writer.Write(data)
+	if err != nil {
+		t.Fatalf("failed to write gzip data: %v", err)
+	}
+	writer.Close()
+
+	compressedData := buf.Bytes()
+
+	reader, err := GetGzipReader(compressedData)
+	if err != nil {
+		t.Fatalf("failed to get gzip reader: %v", err)
+	}
+
+	decompressedData, err := io.ReadAll(reader)
+	if err != nil {
+		t.Fatalf("failed to read gzip data: %v", err)
+	}
+
+	if !bytes.Equal(decompressedData, data) {
+		t.Errorf("expected %v, got %v", data, decompressedData)
+	}
+
+	PutGzipReader(reader)
+}
+
+func TestSnappyReaderPool(t *testing.T) {
+	data := []byte("test data")
+	var buf bytes.Buffer
+
+	// Write data to buffer
+	writer := snappy.NewBufferedWriter(&buf)
+	_, err := writer.Write(data)
+	if err != nil {
+		t.Fatalf("failed to write snappy data: %v", err)
+	}
+	writer.Close()
+
+	compressedData := buf.Bytes()
+
+	reader, err := GetSnappyReader(compressedData)
+	if err != nil {
+		t.Fatalf("failed to get snappy reader: %v", err)
+	}
+
+	decompressedData, err := io.ReadAll(reader)
+	if err != nil {
+		t.Fatalf("failed to read snappy data: %v", err)
+	}
+
+	if !bytes.Equal(decompressedData, data) {
+		t.Errorf("expected %v, got %v", data, decompressedData)
+	}
+
+	PutSnappyReader(reader)
+
+}
+
+func TestZstdDecoderPool(t *testing.T) {
+	data := []byte("test data")
+	encoder, _ := zstd.NewWriter(nil)
+	compressedData := encoder.EncodeAll(data, nil)
+	encoder.Close()
+
+	decoder, err := GetZstdDecoder(compressedData)
+	if err != nil {
+		t.Fatalf("failed to get zstd decoder: %v", err)
+	}
+
+	decompressedData, err := decoder.DecodeAll(compressedData, nil)
+	if err != nil {
+		t.Fatalf("failed to read zstd data: %v", err)
+	}
+
+	if !bytes.Equal(decompressedData, data) {
+		t.Errorf("expected %v, got %v", data, decompressedData)
+	}
+
+	PutZstdDecoder(decoder)
+}

lib/pool/pool.go

@@ -0,0 +1,57 @@
+// Copyright 2024 openGemini Authors
+//
+// 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 pool
+
+import (
+	"sync"
+)
+
+type CachePool[T any] struct {
+	pool         sync.Pool
+	capacityChan chan struct{}
+	newFunc      func() T
+}
+
+func NewCachePool[T any](newFunc func() T, maxSize int) *CachePool[T] {
+	return &CachePool[T]{
+		pool: sync.Pool{
+			New: func() interface{} {
+				return newFunc()
+			},
+		},
+		capacityChan: make(chan struct{}, maxSize),
+		newFunc:      newFunc,
+	}
+}
+
+func (c *CachePool[T]) Get() T {
+	select {
+	case <-c.capacityChan:
+		item := c.pool.Get()
+
+		return item.(T)
+	default:
+		return c.newFunc()
+	}
+}
+
+func (c *CachePool[T]) Put(x T) {
+	select {
+	case c.capacityChan <- struct{}{}:
+		c.pool.Put(x)
+	default:
+		// Pool is full, discard the item
+	}
+}

lib/pool/pool_test.go

@@ -0,0 +1,77 @@
+// Copyright 2024 openGemini Authors
+//
+// 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 pool
+
+import (
+	"testing"
+)
+
+func TestCachePool(t *testing.T) {
+	// Create a new CachePool with a max size of 2
+	pool := NewCachePool(func() interface{} {
+		return new(struct{})
+	}, 2)
+
+	// Get an item from the pool
+	item1 := pool.Get().(*struct{})
+	if item1 == nil {
+		t.Errorf("expected non-nil item, got nil")
+	}
+
+	// Put the item back into the pool
+	pool.Put(item1)
+
+	// Get another item from the pool
+	item2 := pool.Get().(*struct{})
+	if item2 == nil {
+		t.Errorf("expected non-nil item, got nil")
+	}
+
+	// Ensure the item is the same as the first one
+	if item1 != item2 {
+		t.Errorf("expected the same item, got different items")
+	}
+
+}
+
+func TestPoolDiscardWhenFull(t *testing.T) {
+	// Create a pool with a capacity of 1
+	pool := NewCachePool(func() interface{} {
+		return 1
+	}, 1)
+
+	// Get an item from the pool
+	item1 := pool.Get().(int)
+
+	// Put the item back into the pool
+	pool.Put(item1)
+
+	// Try to put another item into the pool, which should be discarded
+	item2 := 2
+	pool.Put(item2)
+
+	// Get an item from the pool
+	item3 := pool.Get().(int)
+
+	// Ensure the item is the same as the first one, meaning the second item was discarded
+	if item1 != item3 {
+		t.Errorf("expected the same item, got different items")
+	}
+
+	// Ensure the discarded item is not the same as the one in the pool
+	if item2 == item3 {
+		t.Errorf("expected different items, got the same item")
+	}
+}