Initial QSfera import

Server/vendor/google.golang.org/grpc/mem/buffer_pool.go

@@ -0,0 +1,96 @@
+/*
+ *
+ * Copyright 2024 gRPC 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 mem
+
+import (
+	"fmt"
+
+	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/mem"
+)
+
+// BufferPool is a pool of buffers that can be shared and reused, resulting in
+// decreased memory allocation.
+type BufferPool interface {
+	// Get returns a buffer with specified length from the pool.
+	Get(length int) *[]byte
+
+	// Put returns a buffer to the pool.
+	//
+	// The provided pointer must hold a prefix of the buffer obtained via
+	// BufferPool.Get to ensure the buffer's entire capacity can be re-used.
+	Put(*[]byte)
+}
+
+var (
+	defaultBufferPoolSizeExponents = []uint8{
+		8,
+		12, // Go page size, 4KB
+		14, // 16KB (max HTTP/2 frame size used by gRPC)
+		15, // 32KB (default buffer size for io.Copy)
+		20, // 1MB
+	}
+	defaultBufferPool BufferPool
+)
+
+func init() {
+	var err error
+	defaultBufferPool, err = NewBinaryTieredBufferPool(defaultBufferPoolSizeExponents...)
+	if err != nil {
+		panic(fmt.Sprintf("Failed to create default buffer pool: %v", err))
+	}
+
+	internal.SetDefaultBufferPool = func(pool BufferPool) {
+		defaultBufferPool = pool
+	}
+
+	internal.SetBufferPoolingThresholdForTesting = func(threshold int) {
+		bufferPoolingThreshold = threshold
+	}
+}
+
+// DefaultBufferPool returns the current default buffer pool. It is a BufferPool
+// created with NewBufferPool that uses a set of default sizes optimized for
+// expected workflows.
+func DefaultBufferPool() BufferPool {
+	return defaultBufferPool
+}
+
+// NewTieredBufferPool returns a BufferPool implementation that uses multiple
+// underlying pools of the given pool sizes.
+func NewTieredBufferPool(poolSizes ...int) BufferPool {
+	return mem.NewTieredBufferPool(poolSizes...)
+}
+
+// NewBinaryTieredBufferPool returns a BufferPool backed by multiple sub-pools.
+// This structure enables O(1) lookup time for Get and Put operations.
+//
+// The arguments provided are the exponents for the buffer capacities (powers
+// of 2), not the raw byte sizes. For example, to create a pool of 16KB buffers
+// (2^14 bytes), pass 14 as the argument.
+func NewBinaryTieredBufferPool(powerOfTwoExponents ...uint8) (BufferPool, error) {
+	return mem.NewBinaryTieredBufferPool(powerOfTwoExponents...)
+}
+
+// NopBufferPool is a buffer pool that returns new buffers without pooling.
+type NopBufferPool struct {
+	mem.NopBufferPool
+}
+
+var _ BufferPool = NopBufferPool{}