VictoriaMetrics/lib/protoparser/promremotewrite/streamparser.go
Aliaksandr Valialkin 9dfe00c962 lib/protoparser/promremotewrite: synchronously process Prometheus remote_write requests
There is no reason in processing these requests asynchronously in the face of https://github.com/VictoriaMetrics/VictoriaMetrics/issues/896
Synchronous processing code is easier to read and understand than the previous async code
2020-11-13 12:17:32 +02:00

140 lines
3.7 KiB
Go

package promremotewrite
import (
"bufio"
"fmt"
"io"
"net/http"
"runtime"
"sync"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompb"
"github.com/VictoriaMetrics/metrics"
"github.com/golang/snappy"
)
var maxInsertRequestSize = flagutil.NewBytes("maxInsertRequestSize", 32*1024*1024, "The maximum size in bytes of a single Prometheus remote_write API request")
// ParseStream parses Prometheus remote_write message req and calls callback for the parsed timeseries.
//
// callback shouldn't hold tss after returning.
func ParseStream(req *http.Request, callback func(tss []prompb.TimeSeries) error) error {
ctx := getPushCtx(req.Body)
defer putPushCtx(ctx)
if err := ctx.Read(); err != nil {
return err
}
// Synchronously process the request in order to properly return errors to ParseStream caller,
// so it could properly return HTTP 503 status code in response.
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/896
bb := bodyBufferPool.Get()
defer bodyBufferPool.Put(bb)
var err error
bb.B, err = snappy.Decode(bb.B[:cap(bb.B)], ctx.reqBuf.B)
if err != nil {
return fmt.Errorf("cannot decompress request with length %d: %w", len(ctx.reqBuf.B), err)
}
if len(bb.B) > maxInsertRequestSize.N {
return fmt.Errorf("too big unpacked request; mustn't exceed `-maxInsertRequestSize=%d` bytes; got %d bytes", maxInsertRequestSize.N, len(bb.B))
}
wr := getWriteRequest()
defer putWriteRequest(wr)
if err := wr.Unmarshal(bb.B); err != nil {
unmarshalErrors.Inc()
return fmt.Errorf("cannot unmarshal prompb.WriteRequest with size %d bytes: %w", len(bb.B), err)
}
rows := 0
tss := wr.Timeseries
for i := range tss {
rows += len(tss[i].Samples)
}
rowsRead.Add(rows)
if err := callback(tss); err != nil {
return fmt.Errorf("error when processing imported data: %w", err)
}
return nil
}
var bodyBufferPool bytesutil.ByteBufferPool
type pushCtx struct {
br *bufio.Reader
reqBuf bytesutil.ByteBuffer
}
func (ctx *pushCtx) reset() {
ctx.br.Reset(nil)
ctx.reqBuf.Reset()
}
func (ctx *pushCtx) Read() error {
readCalls.Inc()
lr := io.LimitReader(ctx.br, int64(maxInsertRequestSize.N)+1)
reqLen, err := ctx.reqBuf.ReadFrom(lr)
if err != nil {
readErrors.Inc()
return fmt.Errorf("cannot read compressed request: %w", err)
}
if reqLen > int64(maxInsertRequestSize.N) {
readErrors.Inc()
return fmt.Errorf("too big packed request; mustn't exceed `-maxInsertRequestSize=%d` bytes", maxInsertRequestSize.N)
}
return nil
}
var (
readCalls = metrics.NewCounter(`vm_protoparser_read_calls_total{type="promremotewrite"}`)
readErrors = metrics.NewCounter(`vm_protoparser_read_errors_total{type="promremotewrite"}`)
rowsRead = metrics.NewCounter(`vm_protoparser_rows_read_total{type="promremotewrite"}`)
unmarshalErrors = metrics.NewCounter(`vm_protoparser_unmarshal_errors_total{type="promremotewrite"}`)
)
func getPushCtx(r io.Reader) *pushCtx {
select {
case ctx := <-pushCtxPoolCh:
ctx.br.Reset(r)
return ctx
default:
if v := pushCtxPool.Get(); v != nil {
ctx := v.(*pushCtx)
ctx.br.Reset(r)
return ctx
}
return &pushCtx{
br: bufio.NewReaderSize(r, 64*1024),
}
}
}
func putPushCtx(ctx *pushCtx) {
ctx.reset()
select {
case pushCtxPoolCh <- ctx:
default:
pushCtxPool.Put(ctx)
}
}
var pushCtxPool sync.Pool
var pushCtxPoolCh = make(chan *pushCtx, runtime.GOMAXPROCS(-1))
func getWriteRequest() *prompb.WriteRequest {
v := writeRequestPool.Get()
if v == nil {
return &prompb.WriteRequest{}
}
return v.(*prompb.WriteRequest)
}
func putWriteRequest(wr *prompb.WriteRequest) {
wr.Reset()
writeRequestPool.Put(wr)
}
var writeRequestPool sync.Pool