file.go

/*
Copyright (c) 2014 Ashley Jeffs

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 input

import (
	"bufio"
	"os"
	"sync/atomic"
	"time"

	"github.com/jeffail/benthos/lib/types"
	"github.com/jeffail/util/log"
	"github.com/jeffail/util/metrics"
)

//--------------------------------------------------------------------------------------------------

func init() {
	constructors["file"] = typeSpec{
		constructor: NewFile,
		description: `
The 'file' type reads input from a file. If multipart is set to false each line
is read as a separate message. If multipart is set to true each line is read as
a message part, and an empty line indicates the end of a message.`,
	}
}

//--------------------------------------------------------------------------------------------------

// FileConfig - Configuration values for the File input type.
type FileConfig struct {
	Path      string `json:"path" yaml:"path"`
	Multipart bool   `json:"multipart" yaml:"multipart"`
	MaxBuffer int    `json:"max_buffer" yaml:"max_buffer"`
}

// NewFileConfig - Creates a new FileConfig with default values.
func NewFileConfig() FileConfig {
	return FileConfig{
		Path:      "",
		Multipart: false,
		MaxBuffer: bufio.MaxScanTokenSize,
	}
}

//--------------------------------------------------------------------------------------------------

// File - An input type that reads lines from a file, creating a message per line.
type File struct {
	running int32

	conf Config
	log  log.Modular

	messages  chan types.Message
	responses <-chan types.Response

	closeChan  chan struct{}
	closedChan chan struct{}
}

// NewFile - Create a new File input type.
func NewFile(conf Config, log log.Modular, stats metrics.Type) (Type, error) {
	f := File{
		running:    1,
		conf:       conf,
		log:        log.NewModule(".input.file"),
		messages:   make(chan types.Message),
		responses:  nil,
		closeChan:  make(chan struct{}),
		closedChan: make(chan struct{}),
	}
	return &f, nil
}

//--------------------------------------------------------------------------------------------------

// loop - Internal loop brokers incoming messages to output pipe.
func (f *File) loop() {
	defer func() {
		atomic.StoreInt32(&f.running, 0)

		close(f.messages)
		close(f.closedChan)
	}()

	file, err := os.Open(f.conf.File.Path)
	if err != nil {
		f.log.Errorf("Read %v error: %v\n", f.conf.File.Path, err)
		return
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	if f.conf.File.MaxBuffer != bufio.MaxScanTokenSize {
		scanner.Buffer([]byte{}, f.conf.File.MaxBuffer)
	}

	f.log.Infof("Reading messages from: %v\n", f.conf.File.Path)

	var partsToSend, parts [][]byte

	for atomic.LoadInt32(&f.running) == 1 {
		if len(partsToSend) == 0 {
			if !scanner.Scan() {
				if err = scanner.Err(); err != nil {
					f.log.Errorf("File read error: %v\n", err)
				}
				return
			}
			data := make([]byte, len(scanner.Bytes()))
			copy(data, scanner.Bytes())
			if len(data) > 0 {
				if f.conf.File.Multipart {
					parts = append(parts, data)
				} else {
					partsToSend = append(partsToSend, data)
				}
			} else if f.conf.File.Multipart {
				partsToSend = parts
				parts = nil
			}
		}
		if len(partsToSend) > 0 {
			select {
			case f.messages <- types.Message{Parts: partsToSend}:
			case <-f.closeChan:
				return
			}
			res, open := <-f.responses
			if !open {
				return
			}
			if res.Error() == nil {
				partsToSend = nil
			}
		}
	}
}

// StartListening - Sets the channel used by the input to validate message receipt.
func (f *File) StartListening(responses <-chan types.Response) error {
	if f.responses != nil {
		return types.ErrAlreadyStarted
	}
	f.responses = responses
	go f.loop()
	return nil
}

// MessageChan - Returns the messages channel.
func (f *File) MessageChan() <-chan types.Message {
	return f.messages
}

// CloseAsync - Shuts down the File input and stops processing requests.
func (f *File) CloseAsync() {
	if atomic.CompareAndSwapInt32(&f.running, 1, 0) {
		close(f.closeChan)
	}
}

// WaitForClose - Blocks until the File input has closed down.
func (f *File) WaitForClose(timeout time.Duration) error {
	select {
	case <-f.closedChan:
	case <-time.After(timeout):
		return types.ErrTimeout
	}
	return nil
}

//--------------------------------------------------------------------------------------------------