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streamparser.go
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streamparser.go
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package stream
import (
"bufio"
"fmt"
"io"
"sync"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/common"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/protoparser/prometheus"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/writeconcurrencylimiter"
"github.com/VictoriaMetrics/metrics"
)
// Parse parses lines with Prometheus exposition format from r and calls callback for the parsed rows.
//
// The callback can be called concurrently multiple times for streamed data from r.
//
// callback shouldn't hold rows after returning.
//
// limitConcurrency defines whether to control the number of concurrent calls to this function.
// It is recommended setting limitConcurrency=true if the caller doesn't have concurrency limits set,
// like /api/v1/write calls.
func Parse(r io.Reader, defaultTimestamp int64, isGzipped, limitConcurrency bool, callback func(rows []prometheus.Row) error, errLogger func(string)) error {
if limitConcurrency {
wcr := writeconcurrencylimiter.GetReader(r)
defer writeconcurrencylimiter.PutReader(wcr)
r = wcr
}
if isGzipped {
zr, err := common.GetGzipReader(r)
if err != nil {
return fmt.Errorf("cannot read gzipped lines with Prometheus exposition format: %w", err)
}
defer common.PutGzipReader(zr)
r = zr
}
ctx := getStreamContext(r)
defer putStreamContext(ctx)
for ctx.Read() {
uw := getUnmarshalWork()
uw.errLogger = errLogger
uw.ctx = ctx
uw.callback = callback
uw.defaultTimestamp = defaultTimestamp
uw.reqBuf, ctx.reqBuf = ctx.reqBuf, uw.reqBuf
ctx.wg.Add(1)
common.ScheduleUnmarshalWork(uw)
if wcr, ok := r.(*writeconcurrencylimiter.Reader); ok {
wcr.DecConcurrency()
}
}
ctx.wg.Wait()
if err := ctx.Error(); err != nil {
return err
}
return ctx.callbackErr
}
func (ctx *streamContext) Read() bool {
readCalls.Inc()
if ctx.err != nil || ctx.hasCallbackError() {
return false
}
ctx.reqBuf, ctx.tailBuf, ctx.err = common.ReadLinesBlock(ctx.br, ctx.reqBuf, ctx.tailBuf)
if ctx.err != nil {
if ctx.err != io.EOF {
readErrors.Inc()
ctx.err = fmt.Errorf("cannot read Prometheus exposition data: %w", ctx.err)
}
return false
}
return true
}
type streamContext struct {
br *bufio.Reader
reqBuf []byte
tailBuf []byte
err error
wg sync.WaitGroup
callbackErrLock sync.Mutex
callbackErr error
}
func (ctx *streamContext) Error() error {
if ctx.err == io.EOF {
return nil
}
return ctx.err
}
func (ctx *streamContext) hasCallbackError() bool {
ctx.callbackErrLock.Lock()
ok := ctx.callbackErr != nil
ctx.callbackErrLock.Unlock()
return ok
}
func (ctx *streamContext) reset() {
ctx.br.Reset(nil)
ctx.reqBuf = ctx.reqBuf[:0]
ctx.tailBuf = ctx.tailBuf[:0]
ctx.err = nil
ctx.callbackErr = nil
}
var (
readCalls = metrics.NewCounter(`vm_protoparser_read_calls_total{type="prometheus"}`)
readErrors = metrics.NewCounter(`vm_protoparser_read_errors_total{type="prometheus"}`)
rowsRead = metrics.NewCounter(`vm_protoparser_rows_read_total{type="prometheus"}`)
)
func getStreamContext(r io.Reader) *streamContext {
if v := streamContextPool.Get(); v != nil {
ctx := v.(*streamContext)
ctx.br.Reset(r)
return ctx
}
return &streamContext{
br: bufio.NewReaderSize(r, 64*1024),
}
}
func putStreamContext(ctx *streamContext) {
ctx.reset()
streamContextPool.Put(ctx)
}
var streamContextPool sync.Pool
type unmarshalWork struct {
rows prometheus.Rows
ctx *streamContext
callback func(rows []prometheus.Row) error
errLogger func(string)
defaultTimestamp int64
reqBuf []byte
}
func (uw *unmarshalWork) reset() {
uw.rows.Reset()
uw.ctx = nil
uw.callback = nil
uw.errLogger = nil
uw.defaultTimestamp = 0
uw.reqBuf = uw.reqBuf[:0]
}
func (uw *unmarshalWork) runCallback(rows []prometheus.Row) {
ctx := uw.ctx
if err := uw.callback(rows); err != nil {
ctx.callbackErrLock.Lock()
if ctx.callbackErr == nil {
ctx.callbackErr = fmt.Errorf("error when processing imported data: %w", err)
}
ctx.callbackErrLock.Unlock()
}
ctx.wg.Done()
}
// Unmarshal implements common.UnmarshalWork
func (uw *unmarshalWork) Unmarshal() {
if uw.errLogger != nil {
uw.rows.UnmarshalWithErrLogger(bytesutil.ToUnsafeString(uw.reqBuf), uw.errLogger)
} else {
uw.rows.Unmarshal(bytesutil.ToUnsafeString(uw.reqBuf))
}
rows := uw.rows.Rows
rowsRead.Add(len(rows))
// Fill missing timestamps with the current timestamp.
defaultTimestamp := uw.defaultTimestamp
if defaultTimestamp <= 0 {
defaultTimestamp = time.Now().UnixNano() / 1e6
}
for i := range rows {
r := &rows[i]
if r.Timestamp == 0 {
r.Timestamp = defaultTimestamp
}
}
uw.runCallback(rows)
putUnmarshalWork(uw)
}
func getUnmarshalWork() *unmarshalWork {
v := unmarshalWorkPool.Get()
if v == nil {
return &unmarshalWork{}
}
return v.(*unmarshalWork)
}
func putUnmarshalWork(uw *unmarshalWork) {
uw.reset()
unmarshalWorkPool.Put(uw)
}
var unmarshalWorkPool sync.Pool