runtime/tchannel_helpers.go

// Copyright (c) 2023 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package zanzibar

import (
	"bytes"
	"fmt"
	"io"
	"sync"

	"go.uber.org/thriftrw/protocol/binary"
	"go.uber.org/thriftrw/wire"
)

var bytesPool = sync.Pool{
	New: func() interface{} {
		b := make([]byte, 128)
		return &b
	},
}

// EnsureEmpty ensures that the specified reader is empty. If the reader is
// not empty, it returns an error with the specified stage in the message.
func EnsureEmpty(r io.Reader, stage string) error {
	buf := bytesPool.Get().(*[]byte)
	defer bytesPool.Put(buf)

	n, err := r.Read(*buf)
	if n > 0 {
		return fmt.Errorf("found unexpected bytes after %s, found (upto 128 bytes): %x", stage, (*buf)[:n])
	}
	if err == io.EOF {
		return nil
	}
	return err
}

var bufPool = sync.Pool{
	New: func() interface{} {
		return &bytes.Buffer{}
	},
}

// GetBuffer returns a new Byte Buffer from the buffer pool that has been reset
func GetBuffer() *bytes.Buffer {
	buf := bufPool.Get().(*bytes.Buffer)
	buf.Reset()
	return buf
}

// PutBuffer returns byte buffer to the buffer pool
func PutBuffer(buf *bytes.Buffer) {
	bufPool.Put(buf)
}

// ReadStruct reads the given Thriftrw struct.
func ReadStruct(reader io.Reader, s RWTStruct) error {
	readerAt, ok := reader.(io.ReaderAt)

	// do not read all to buffer if reader already is type of io.ReaderAt
	if !ok {
		buf := GetBuffer()
		defer PutBuffer(buf)

		if _, err := buf.ReadFrom(reader); err != nil {
			return err
		}
		readerAt = bytes.NewReader(buf.Bytes())
	}

	wireValue, err := binary.Default.Decode(readerAt, wire.TStruct)
	if err != nil {
		return err
	}
	err = s.FromWire(wireValue)
	return err
}