codec.go

// Copyright 2017 The Prometheus 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 main

import (
	"io"

	"github.com/golang/snappy"
	"github.com/prometheus/prometheus/prompb"
)

// decodeReadLimit is the maximum size of a read request body in bytes.
const decodeReadLimit = 32 * 1024 * 1024

// DecodeWriteRequest from an io.Reader into a prompb.WriteRequest, handling
// snappy decompression.
func DecodeWriteRequest(r io.Reader) (*prompb.WriteRequest, error) {
	compressed, err := io.ReadAll(r)
	if err != nil {
		return nil, err
	}

	reqBuf, err := snappy.Decode(nil, compressed)
	if err != nil {
		return nil, err
	}

	var req prompb.WriteRequest
	if err := req.Unmarshal(reqBuf); err != nil {
		return nil, err
	}

	return &req, nil
}

// DecodeReadRequest from an io.Reader into a prompb.ReadRequest, handling
// snappy decompression.
func DecodeReadRequest(r io.Reader) (*prompb.ReadRequest, error) {
	compressed, err := io.ReadAll(io.LimitReader(r, decodeReadLimit))
	if err != nil {
		return nil, err
	}

	reqBuf, err := snappy.Decode(nil, compressed)
	if err != nil {
		return nil, err
	}

	var req prompb.ReadRequest
	if err := req.Unmarshal(reqBuf); err != nil {
		return nil, err
	}

	return &req, nil
}

// EncodeReadResponse writes a remote.Response to an io.Writer.
func EncodeReadResponse(resp *prompb.ReadResponse, w io.Writer) error {
	data, err := resp.Marshal()
	if err != nil {
		return err
	}

	compressed := snappy.Encode(nil, data)
	_, err = w.Write(compressed)
	return err
}