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//go:build linux
package journal
import (
"bytes"
"context"
"github.com/mimecast/dtail/internal/io/line"
"github.com/mimecast/dtail/internal/io/pool"
"github.com/mimecast/dtail/internal/lcontext"
"github.com/mimecast/dtail/internal/regex"
)
type journalSink interface {
Emit(context.Context, *bytes.Buffer, uint64, int, string) error
Full() bool
}
type processorSink struct {
processor line.Processor
}
func (s processorSink) Emit(_ context.Context, rawLine *bytes.Buffer, count uint64,
_ int, sourceID string) error {
// Per the line.Processor contract, ownership of rawLine transfers to the
// processor: it is responsible for recycling the buffer on every return path,
// success or error (the journal-path processors installed via makeProcessor
// — DirectLineProcessor and AggregateProcessor — recycle unconditionally
// before returning a write error, for example). Recycling here
// on error would return the same buffer to the shared pool a second time; the
// pool would then hand one object to two Get callers and their concurrent
// writes would corrupt data and race. So do not recycle rawLine here.
return s.processor.ProcessLine(rawLine, count, sourceID)
}
func (s processorSink) Full() bool {
return false
}
type journalFilter struct {
ltx lcontext.LContext
sink journalSink
re regex.Regex
sourceID string
stats journalStats
before []bufferedLine
after int
maxCount int
maxHit int
maxClosed bool
}
type bufferedLine struct {
content *bytes.Buffer
count uint64
}
func newJournalFilter(ltx lcontext.LContext, sink journalSink, re regex.Regex,
sourceID string) *journalFilter {
return &journalFilter{
ltx: ltx,
sink: sink,
re: re,
sourceID: sourceID,
maxCount: ltx.MaxCount,
}
}
func (f *journalFilter) Process(ctx context.Context, rawLine *bytes.Buffer) error {
f.stats.updatePosition()
if !f.ltx.Has() {
return f.processWithoutContext(ctx, rawLine)
}
return f.processWithContext(ctx, rawLine)
}
func (f *journalFilter) Close() {
for _, line := range f.before {
pool.RecycleBytesBuffer(line.content)
}
f.before = nil
}
func (f *journalFilter) processWithoutContext(ctx context.Context, rawLine *bytes.Buffer) error {
if !f.re.Match(rawLine.Bytes()) {
f.stats.updateLineNotMatched()
f.stats.updateLineNotTransmitted()
pool.RecycleBytesBuffer(rawLine)
return nil
}
f.stats.updateLineMatched()
if f.sink.Full() {
f.stats.updateLineNotTransmitted()
pool.RecycleBytesBuffer(rawLine)
return nil
}
f.stats.updateLineTransmitted()
return f.sink.Emit(ctx, rawLine, f.stats.totalLineCount(), f.stats.transmittedPerc(), f.sourceID)
}
func (f *journalFilter) processWithContext(ctx context.Context, rawLine *bytes.Buffer) error {
if !f.re.Match(rawLine.Bytes()) {
return f.processContextMiss(ctx, rawLine)
}
f.stats.updateLineMatched()
if f.maxClosed {
pool.RecycleBytesBuffer(rawLine)
return errStopReading
}
if err := f.emitBefore(ctx); err != nil {
pool.RecycleBytesBuffer(rawLine)
return err
}
f.stats.updateLineTransmitted()
if err := f.sink.Emit(ctx, rawLine, f.stats.totalLineCount(), 100, f.sourceID); err != nil {
return err
}
if f.maxCount > 0 {
f.maxHit++
if f.maxHit >= f.maxCount {
if f.ltx.AfterContext == 0 {
return errStopReading
}
f.maxClosed = true
}
}
if f.ltx.AfterContext > 0 {
f.after = f.ltx.AfterContext
}
return nil
}
func (f *journalFilter) processContextMiss(ctx context.Context, rawLine *bytes.Buffer) error {
f.stats.updateLineNotMatched()
if f.maxClosed && f.after == 0 {
pool.RecycleBytesBuffer(rawLine)
return errStopReading
}
if f.after > 0 {
f.after--
f.stats.updateLineTransmitted()
err := f.sink.Emit(ctx, rawLine, f.stats.totalLineCount(), 100, f.sourceID)
if err == nil && f.maxClosed && f.after == 0 {
return errStopReading
}
return err
}
if f.ltx.BeforeContext > 0 {
f.rememberBefore(rawLine)
f.stats.updateLineNotTransmitted()
return nil
}
f.stats.updateLineNotTransmitted()
pool.RecycleBytesBuffer(rawLine)
return nil
}
func (f *journalFilter) rememberBefore(rawLine *bytes.Buffer) {
if len(f.before) >= f.ltx.BeforeContext {
pool.RecycleBytesBuffer(f.before[0].content)
copy(f.before, f.before[1:])
f.before = f.before[:len(f.before)-1]
}
f.before = append(f.before, bufferedLine{
content: rawLine,
count: f.stats.totalLineCount(),
})
}
func (f *journalFilter) emitBefore(ctx context.Context) error {
for i, line := range f.before {
f.stats.updateLineTransmitted()
if err := f.sink.Emit(ctx, line.content, line.count, 100, f.sourceID); err != nil {
f.discardBeforeFrom(i + 1)
return err
}
}
f.before = f.before[:0]
return nil
}
func (f *journalFilter) discardBeforeFrom(index int) {
for _, line := range f.before[index:] {
pool.RecycleBytesBuffer(line.content)
}
f.before = f.before[:0]
}
type journalStats struct {
pos int
lineCount uint64
matched [100]bool
matchCount uint64
transmitted [100]bool
transmitCount int
}
func (s *journalStats) totalLineCount() uint64 {
return s.lineCount
}
func (s *journalStats) transmittedPerc() int {
return int(percentOf(float64(s.matchCount), float64(s.transmitCount)))
}
func (s *journalStats) updatePosition() {
s.pos = (s.pos + 1) % 100
s.lineCount++
}
func (s *journalStats) updateLineMatched() {
if !s.matched[s.pos] {
s.matchCount++
s.matched[s.pos] = true
}
}
func (s *journalStats) updateLineTransmitted() {
if !s.transmitted[s.pos] {
s.transmitCount++
s.transmitted[s.pos] = true
}
}
func (s *journalStats) updateLineNotMatched() {
if s.matched[s.pos] {
s.matchCount--
s.matched[s.pos] = false
}
}
func (s *journalStats) updateLineNotTransmitted() {
if s.transmitted[s.pos] {
s.transmitCount--
s.transmitted[s.pos] = false
}
}
func percentOf(total float64, value float64) float64 {
if total == 0 || total == value {
return 100
}
return value / (total / 100.0)
}
|
