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package fs
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"
)
// The local context state.
type ltxState struct {
// Max state
maxCount int
processMaxCount bool
maxReached bool
// Before state
before int
processBefore bool
beforeBuf chan *bytes.Buffer
// After state
after int
processAfter bool
}
// We don't have any local grep context, which makes life much simpler and more efficient.
func (f *readFile) filterWithoutLContext(ctx context.Context, rawLines <-chan *bytes.Buffer,
lines chan<- *line.Line, re regex.Regex) {
for rawLine := range rawLines {
f.updatePosition()
if newLine, ok := f.transmittable(rawLine, len(lines), cap(lines), re); ok {
select {
case lines <- newLine:
case <-ctx.Done():
return
}
}
}
f.updatePosition()
}
// Filter log lines matching a given regular expression, however with local grep context.
func (f *readFile) filterWithLContext(ctx context.Context, ltx lcontext.LContext,
rawLines <-chan *bytes.Buffer, lines chan<- *line.Line, re regex.Regex) {
var ls ltxState
// The following 3 scenarios may also be used at once/any combination together.
// Scenario 1: Finish once maxCount hits found
ls.maxCount = ltx.MaxCount
ls.processMaxCount = ls.maxCount > 0
ls.maxReached = false
// Scenario 2: Print prev. N lines when current line matches.
ls.before = ltx.BeforeContext
ls.processBefore = ls.before > 0
if ls.processBefore {
ls.beforeBuf = make(chan *bytes.Buffer, ls.before)
}
// Screnario 3: Print next N lines when current line matches.
ls.after = 0
ls.processAfter = ltx.AfterContext > 0
// No go through all raw lines read to determine with they satisfy the local
// context or not. "Matching" lines will be sent to the lines channel.
for rawLine := range rawLines {
status := f.filterLineWithLContext(ctx, <x, &ls, rawLines, lines, &re, rawLine)
switch status {
case abortReading:
return
default:
}
}
}
// Filter log lines matching a given regular expression, however with local grep context.
func (f *readFile) filterLineWithLContext(ctx context.Context, ltx *lcontext.LContext,
ls *ltxState, rawLines <-chan *bytes.Buffer, lines chan<- *line.Line, re *regex.Regex,
rawLine *bytes.Buffer) readStatus {
f.updatePosition()
if !re.Match(rawLine.Bytes()) {
f.updateLineNotMatched()
status := f.lContextNotMatched(ctx, ls, lines, rawLine)
switch status {
case nothing:
default:
return status
}
}
f.updateLineMatched()
// If we have an "after" context to worry about...
if ls.processAfter {
if ls.maxReached {
// We have reached the "max" hits. Stop/abort reading.
return abortReading
}
// Reset the "after" context.
ls.after = ltx.AfterContext
}
// If we have a "before" context to worry about...
if ls.processBefore {
status := f.lContextProcessBefore(ctx, ls, lines, rawLine)
switch status {
case nothing:
default:
return status
}
}
line := line.New(rawLine, f.totalLineCount(), 100, f.globID)
select {
case lines <- line:
// If we have a "max" context to worry about...
if ls.processMaxCount {
status := f.lContextProcessMaxCount(ctx, ls)
switch status {
case nothing:
default:
return status
}
}
case <-ctx.Done():
return abortReading
}
return nothing
}
// Do some post-processing for the "after" and the "before" contexts in case the
// line didn't match the regex.
func (f *readFile) lContextNotMatched(ctx context.Context, ls *ltxState,
lines chan<- *line.Line, rawLine *bytes.Buffer) readStatus {
if ls.processAfter && ls.after > 0 {
ls.after--
myLine := line.New(rawLine, f.totalLineCount(), 100, f.globID)
select {
case lines <- myLine:
case <-ctx.Done():
return abortReading
}
} else if ls.processBefore {
// Keep last num BeforeContext raw messages.
select {
case ls.beforeBuf <- rawLine:
default:
pool.RecycleBytesBuffer(<-ls.beforeBuf)
ls.beforeBuf <- rawLine
}
}
return continueReading
}
// Do some processing for the "before" context.
func (f *readFile) lContextProcessBefore(ctx context.Context,
ls *ltxState, lines chan<- *line.Line, rawLine *bytes.Buffer) readStatus {
i := uint64(len(ls.beforeBuf))
for {
select {
case rawLine := <-ls.beforeBuf:
myLine := line.New(rawLine, f.totalLineCount()-i, 100, f.globID)
i--
select {
case lines <- myLine:
case <-ctx.Done():
return abortReading
}
default:
// beforeBuf is now empty.
}
if len(ls.beforeBuf) == 0 {
break
}
}
return nothing
}
// Do some processing for the "max" context.
func (f *readFile) lContextProcessMaxCount(ctx context.Context, ls *ltxState) readStatus {
ls.maxCount--
if ls.maxCount == 0 {
if !ls.processAfter || ls.after == 0 {
return abortReading
}
// Unfortunatley we have to continue filter, as there might be more lines to print
ls.maxReached = true
}
return nothing
}
|
