forked from nytlabs/streamtools
/
toFile.go
79 lines (73 loc) · 1.82 KB
/
toFile.go
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package library
import (
"bufio"
"encoding/json"
"fmt"
"github.com/nytlabs/streamtools/st/blocks" // blocks
"github.com/nytlabs/streamtools/st/util"
"os"
)
// specify those channels we're going to use to communicate with streamtools
type ToFile struct {
blocks.Block
file *os.File
filename string
queryrule chan chan interface{}
inrule chan interface{}
in chan interface{}
out chan interface{}
quit chan interface{}
}
// we need to build a simple factory so that streamtools can make new blocks of this kind
func NewToFile() blocks.BlockInterface {
return &ToFile{}
}
// Setup is called once before running the block. We build up the channels and specify what kind of block this is.
func (b *ToFile) Setup() {
b.Kind = "ToFile"
b.Desc = "writes messages, separated by newlines, to a file on the local filesystem"
b.in = b.InRoute("in")
b.inrule = b.InRoute("rule")
b.queryrule = b.QueryRoute("rule")
b.quit = b.Quit()
b.out = b.Broadcast()
}
// Run is the block's main loop. Here we listen on the different channels we set up.
func (b *ToFile) Run() {
for {
select {
case msgI := <-b.inrule:
// set a parameter of the block
filename, _ := util.ParseString(msgI, "Filename")
fo, err := os.Create(filename)
if err != nil {
b.Error(err)
}
// set the new file
b.file = fo
// record the filename
b.filename = filename
case <-b.quit:
// quit the block
if b.file != nil {
b.file.Close()
}
return
case msg := <-b.in:
// deal with inbound data
w := bufio.NewWriter(b.file)
msgStr, err := json.Marshal(msg)
if err != nil {
b.Error(err)
continue
}
fmt.Fprintln(w, string(msgStr))
w.Flush()
case respChan := <-b.queryrule:
// deal with a query request
respChan <- map[string]interface{}{
"Filename": b.filename,
}
}
}
}