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// Package awslogs provides the logdriver for forwarding container logs to Amazon CloudWatch Logs
package awslogs // import "github.com/docker/docker/daemon/logger/awslogs"
import (
"fmt"
"os"
"regexp"
"runtime"
"sort"
"strconv"
"strings"
"sync"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/credentials/endpointcreds"
"github.com/aws/aws-sdk-go/aws/ec2metadata"
"github.com/aws/aws-sdk-go/aws/request"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
"github.com/docker/docker/daemon/logger"
"github.com/docker/docker/daemon/logger/loggerutils"
"github.com/docker/docker/dockerversion"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
const (
name = "awslogs"
regionKey = "awslogs-region"
endpointKey = "awslogs-endpoint"
regionEnvKey = "AWS_REGION"
logGroupKey = "awslogs-group"
logStreamKey = "awslogs-stream"
logCreateGroupKey = "awslogs-create-group"
tagKey = "tag"
datetimeFormatKey = "awslogs-datetime-format"
multilinePatternKey = "awslogs-multiline-pattern"
credentialsEndpointKey = "awslogs-credentials-endpoint"
batchPublishFrequency = 5 * time.Second
// See: http://docs.aws.amazon.com/AmazonCloudWatchLogs/latest/APIReference/API_PutLogEvents.html
perEventBytes = 26
maximumBytesPerPut = 1048576
maximumLogEventsPerPut = 10000
// See: http://docs.aws.amazon.com/AmazonCloudWatch/latest/DeveloperGuide/cloudwatch_limits.html
maximumBytesPerEvent = 262144 - perEventBytes
resourceAlreadyExistsCode = "ResourceAlreadyExistsException"
dataAlreadyAcceptedCode = "DataAlreadyAcceptedException"
invalidSequenceTokenCode = "InvalidSequenceTokenException"
resourceNotFoundCode = "ResourceNotFoundException"
credentialsEndpoint = "http://169.254.170.2"
userAgentHeader = "User-Agent"
)
type logStream struct {
logStreamName string
logGroupName string
logCreateGroup bool
logNonBlocking bool
multilinePattern *regexp.Regexp
client api
messages chan *logger.Message
lock sync.RWMutex
closed bool
sequenceToken *string
}
var _ logger.SizedLogger = &logStream{}
type api interface {
CreateLogGroup(*cloudwatchlogs.CreateLogGroupInput) (*cloudwatchlogs.CreateLogGroupOutput, error)
CreateLogStream(*cloudwatchlogs.CreateLogStreamInput) (*cloudwatchlogs.CreateLogStreamOutput, error)
PutLogEvents(*cloudwatchlogs.PutLogEventsInput) (*cloudwatchlogs.PutLogEventsOutput, error)
}
type regionFinder interface {
Region() (string, error)
}
type wrappedEvent struct {
inputLogEvent *cloudwatchlogs.InputLogEvent
insertOrder int
}
type byTimestamp []wrappedEvent
// init registers the awslogs driver
func init() {
if err := logger.RegisterLogDriver(name, New); err != nil {
logrus.Fatal(err)
}
if err := logger.RegisterLogOptValidator(name, ValidateLogOpt); err != nil {
logrus.Fatal(err)
}
}
// eventBatch holds the events that are batched for submission and the
// associated data about it.
//
// Warning: this type is not threadsafe and must not be used
// concurrently. This type is expected to be consumed in a single go
// routine and never concurrently.
type eventBatch struct {
batch []wrappedEvent
bytes int
}
// New creates an awslogs logger using the configuration passed in on the
// context. Supported context configuration variables are awslogs-region,
// awslogs-endpoint, awslogs-group, awslogs-stream, awslogs-create-group,
// awslogs-multiline-pattern and awslogs-datetime-format.
// When available, configuration is also taken from environment variables
// AWS_REGION, AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, the shared credentials
// file (~/.aws/credentials), and the EC2 Instance Metadata Service.
func New(info logger.Info) (logger.Logger, error) {
logGroupName := info.Config[logGroupKey]
logStreamName, err := loggerutils.ParseLogTag(info, "{{.FullID}}")
if err != nil {
return nil, err
}
logCreateGroup := false
if info.Config[logCreateGroupKey] != "" {
logCreateGroup, err = strconv.ParseBool(info.Config[logCreateGroupKey])
if err != nil {
return nil, err
}
}
logNonBlocking := info.Config["mode"] == "non-blocking"
if info.Config[logStreamKey] != "" {
logStreamName = info.Config[logStreamKey]
}
multilinePattern, err := parseMultilineOptions(info)
if err != nil {
return nil, err
}
client, err := newAWSLogsClient(info)
if err != nil {
return nil, err
}
containerStream := &logStream{
logStreamName: logStreamName,
logGroupName: logGroupName,
logCreateGroup: logCreateGroup,
logNonBlocking: logNonBlocking,
multilinePattern: multilinePattern,
client: client,
messages: make(chan *logger.Message, 4096),
}
creationDone := make(chan bool)
if logNonBlocking {
go func() {
backoff := 1
maxBackoff := 32
for {
// If logger is closed we are done
containerStream.lock.RLock()
if containerStream.closed {
containerStream.lock.RUnlock()
break
}
containerStream.lock.RUnlock()
err := containerStream.create()
if err == nil {
break
}
time.Sleep(time.Duration(backoff) * time.Second)
if backoff < maxBackoff {
backoff *= 2
}
logrus.
WithError(err).
WithField("container-id", info.ContainerID).
WithField("container-name", info.ContainerName).
Error("Error while trying to initialize awslogs. Retrying in: ", backoff, " seconds")
}
close(creationDone)
}()
} else {
if err = containerStream.create(); err != nil {
return nil, err
}
close(creationDone)
}
go containerStream.collectBatch(creationDone)
return containerStream, nil
}
// Parses awslogs-multiline-pattern and awslogs-datetime-format options
// If awslogs-datetime-format is present, convert the format from strftime
// to regexp and return.
// If awslogs-multiline-pattern is present, compile regexp and return
func parseMultilineOptions(info logger.Info) (*regexp.Regexp, error) {
dateTimeFormat := info.Config[datetimeFormatKey]
multilinePatternKey := info.Config[multilinePatternKey]
// strftime input is parsed into a regular expression
if dateTimeFormat != "" {
// %. matches each strftime format sequence and ReplaceAllStringFunc
// looks up each format sequence in the conversion table strftimeToRegex
// to replace with a defined regular expression
r := regexp.MustCompile("%.")
multilinePatternKey = r.ReplaceAllStringFunc(dateTimeFormat, func(s string) string {
return strftimeToRegex[s]
})
}
if multilinePatternKey != "" {
multilinePattern, err := regexp.Compile(multilinePatternKey)
if err != nil {
return nil, errors.Wrapf(err, "awslogs could not parse multiline pattern key %q", multilinePatternKey)
}
return multilinePattern, nil
}
return nil, nil
}
// Maps strftime format strings to regex
var strftimeToRegex = map[string]string{
/*weekdayShort */ `%a`: `(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun)`,
/*weekdayFull */ `%A`: `(?:Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday)`,
/*weekdayZeroIndex */ `%w`: `[0-6]`,
/*dayZeroPadded */ `%d`: `(?:0[1-9]|[1,2][0-9]|3[0,1])`,
/*monthShort */ `%b`: `(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)`,
/*monthFull */ `%B`: `(?:January|February|March|April|May|June|July|August|September|October|November|December)`,
/*monthZeroPadded */ `%m`: `(?:0[1-9]|1[0-2])`,
/*yearCentury */ `%Y`: `\d{4}`,
/*yearZeroPadded */ `%y`: `\d{2}`,
/*hour24ZeroPadded */ `%H`: `(?:[0,1][0-9]|2[0-3])`,
/*hour12ZeroPadded */ `%I`: `(?:0[0-9]|1[0-2])`,
/*AM or PM */ `%p`: "[A,P]M",
/*minuteZeroPadded */ `%M`: `[0-5][0-9]`,
/*secondZeroPadded */ `%S`: `[0-5][0-9]`,
/*microsecondZeroPadded */ `%f`: `\d{6}`,
/*utcOffset */ `%z`: `[+-]\d{4}`,
/*tzName */ `%Z`: `[A-Z]{1,4}T`,
/*dayOfYearZeroPadded */ `%j`: `(?:0[0-9][1-9]|[1,2][0-9][0-9]|3[0-5][0-9]|36[0-6])`,
/*milliseconds */ `%L`: `\.\d{3}`,
}
// newRegionFinder is a variable such that the implementation
// can be swapped out for unit tests.
var newRegionFinder = func() regionFinder {
return ec2metadata.New(session.New())
}
// newSDKEndpoint is a variable such that the implementation
// can be swapped out for unit tests.
var newSDKEndpoint = credentialsEndpoint
// newAWSLogsClient creates the service client for Amazon CloudWatch Logs.
// Customizations to the default client from the SDK include a Docker-specific
// User-Agent string and automatic region detection using the EC2 Instance
// Metadata Service when region is otherwise unspecified.
func newAWSLogsClient(info logger.Info) (api, error) {
var region, endpoint *string
if os.Getenv(regionEnvKey) != "" {
region = aws.String(os.Getenv(regionEnvKey))
}
if info.Config[regionKey] != "" {
region = aws.String(info.Config[regionKey])
}
if info.Config[endpointKey] != "" {
endpoint = aws.String(info.Config[endpointKey])
}
if region == nil || *region == "" {
logrus.Info("Trying to get region from EC2 Metadata")
ec2MetadataClient := newRegionFinder()
r, err := ec2MetadataClient.Region()
if err != nil {
logrus.WithFields(logrus.Fields{
"error": err,
}).Error("Could not get region from EC2 metadata, environment, or log option")
return nil, errors.New("Cannot determine region for awslogs driver")
}
region = &r
}
sess, err := session.NewSession()
if err != nil {
return nil, errors.New("Failed to create a service client session for for awslogs driver")
}
// attach region to cloudwatchlogs config
sess.Config.Region = region
// attach endpoint to cloudwatchlogs config
if endpoint != nil {
sess.Config.Endpoint = endpoint
}
if uri, ok := info.Config[credentialsEndpointKey]; ok {
logrus.Debugf("Trying to get credentials from awslogs-credentials-endpoint")
endpoint := fmt.Sprintf("%s%s", newSDKEndpoint, uri)
creds := endpointcreds.NewCredentialsClient(*sess.Config, sess.Handlers, endpoint,
func(p *endpointcreds.Provider) {
p.ExpiryWindow = 5 * time.Minute
})
// attach credentials to cloudwatchlogs config
sess.Config.Credentials = creds
}
logrus.WithFields(logrus.Fields{
"region": *region,
}).Debug("Created awslogs client")
client := cloudwatchlogs.New(sess)
client.Handlers.Build.PushBackNamed(request.NamedHandler{
Name: "DockerUserAgentHandler",
Fn: func(r *request.Request) {
currentAgent := r.HTTPRequest.Header.Get(userAgentHeader)
r.HTTPRequest.Header.Set(userAgentHeader,
fmt.Sprintf("Docker %s (%s) %s",
dockerversion.Version, runtime.GOOS, currentAgent))
},
})
return client, nil
}
// Name returns the name of the awslogs logging driver
func (l *logStream) Name() string {
return name
}
func (l *logStream) BufSize() int {
return maximumBytesPerEvent
}
// Log submits messages for logging by an instance of the awslogs logging driver
func (l *logStream) Log(msg *logger.Message) error {
l.lock.RLock()
defer l.lock.RUnlock()
if l.closed {
return errors.New("awslogs is closed")
}
if l.logNonBlocking {
select {
case l.messages <- msg:
return nil
default:
return errors.New("awslogs buffer is full")
}
}
l.messages <- msg
return nil
}
// Close closes the instance of the awslogs logging driver
func (l *logStream) Close() error {
l.lock.Lock()
defer l.lock.Unlock()
if !l.closed {
close(l.messages)
}
l.closed = true
return nil
}
// create creates log group and log stream for the instance of the awslogs logging driver
func (l *logStream) create() error {
if err := l.createLogStream(); err != nil {
if l.logCreateGroup {
if awsErr, ok := err.(awserr.Error); ok && awsErr.Code() == resourceNotFoundCode {
if err := l.createLogGroup(); err != nil {
return err
}
return l.createLogStream()
}
}
if err != nil {
return err
}
}
return nil
}
// createLogGroup creates a log group for the instance of the awslogs logging driver
func (l *logStream) createLogGroup() error {
if _, err := l.client.CreateLogGroup(&cloudwatchlogs.CreateLogGroupInput{
LogGroupName: aws.String(l.logGroupName),
}); err != nil {
if awsErr, ok := err.(awserr.Error); ok {
fields := logrus.Fields{
"errorCode": awsErr.Code(),
"message": awsErr.Message(),
"origError": awsErr.OrigErr(),
"logGroupName": l.logGroupName,
"logCreateGroup": l.logCreateGroup,
}
if awsErr.Code() == resourceAlreadyExistsCode {
// Allow creation to succeed
logrus.WithFields(fields).Info("Log group already exists")
return nil
}
logrus.WithFields(fields).Error("Failed to create log group")
}
return err
}
return nil
}
// createLogStream creates a log stream for the instance of the awslogs logging driver
func (l *logStream) createLogStream() error {
input := &cloudwatchlogs.CreateLogStreamInput{
LogGroupName: aws.String(l.logGroupName),
LogStreamName: aws.String(l.logStreamName),
}
_, err := l.client.CreateLogStream(input)
if err != nil {
if awsErr, ok := err.(awserr.Error); ok {
fields := logrus.Fields{
"errorCode": awsErr.Code(),
"message": awsErr.Message(),
"origError": awsErr.OrigErr(),
"logGroupName": l.logGroupName,
"logStreamName": l.logStreamName,
}
if awsErr.Code() == resourceAlreadyExistsCode {
// Allow creation to succeed
logrus.WithFields(fields).Info("Log stream already exists")
return nil
}
logrus.WithFields(fields).Error("Failed to create log stream")
}
}
return err
}
// newTicker is used for time-based batching. newTicker is a variable such
// that the implementation can be swapped out for unit tests.
var newTicker = func(freq time.Duration) *time.Ticker {
return time.NewTicker(freq)
}
// collectBatch executes as a goroutine to perform batching of log events for
// submission to the log stream. If the awslogs-multiline-pattern or
// awslogs-datetime-format options have been configured, multiline processing
// is enabled, where log messages are stored in an event buffer until a multiline
// pattern match is found, at which point the messages in the event buffer are
// pushed to CloudWatch logs as a single log event. Multiline messages are processed
// according to the maximumBytesPerPut constraint, and the implementation only
// allows for messages to be buffered for a maximum of 2*batchPublishFrequency
// seconds. When events are ready to be processed for submission to CloudWatch
// Logs, the processEvents method is called. If a multiline pattern is not
// configured, log events are submitted to the processEvents method immediately.
func (l *logStream) collectBatch(created chan bool) {
// Wait for the logstream/group to be created
<-created
ticker := newTicker(batchPublishFrequency)
var eventBuffer []byte
var eventBufferTimestamp int64
var batch = newEventBatch()
for {
select {
case t := <-ticker.C:
// If event buffer is older than batch publish frequency flush the event buffer
if eventBufferTimestamp > 0 && len(eventBuffer) > 0 {
eventBufferAge := t.UnixNano()/int64(time.Millisecond) - eventBufferTimestamp
eventBufferExpired := eventBufferAge >= int64(batchPublishFrequency)/int64(time.Millisecond)
eventBufferNegative := eventBufferAge < 0
if eventBufferExpired || eventBufferNegative {
l.processEvent(batch, eventBuffer, eventBufferTimestamp)
eventBuffer = eventBuffer[:0]
}
}
l.publishBatch(batch)
batch.reset()
case msg, more := <-l.messages:
if !more {
// Flush event buffer and release resources
l.processEvent(batch, eventBuffer, eventBufferTimestamp)
eventBuffer = eventBuffer[:0]
l.publishBatch(batch)
batch.reset()
return
}
if eventBufferTimestamp == 0 {
eventBufferTimestamp = msg.Timestamp.UnixNano() / int64(time.Millisecond)
}
line := msg.Line
if l.multilinePattern != nil {
if l.multilinePattern.Match(line) || len(eventBuffer)+len(line) > maximumBytesPerEvent {
// This is a new log event or we will exceed max bytes per event
// so flush the current eventBuffer to events and reset timestamp
l.processEvent(batch, eventBuffer, eventBufferTimestamp)
eventBufferTimestamp = msg.Timestamp.UnixNano() / int64(time.Millisecond)
eventBuffer = eventBuffer[:0]
}
// Append new line if event is less than max event size
if len(line) < maximumBytesPerEvent {
line = append(line, "\n"...)
}
eventBuffer = append(eventBuffer, line...)
logger.PutMessage(msg)
} else {
l.processEvent(batch, line, msg.Timestamp.UnixNano()/int64(time.Millisecond))
logger.PutMessage(msg)
}
}
}
}
// processEvent processes log events that are ready for submission to CloudWatch
// logs. Batching is performed on time- and size-bases. Time-based batching
// occurs at a 5 second interval (defined in the batchPublishFrequency const).
// Size-based batching is performed on the maximum number of events per batch
// (defined in maximumLogEventsPerPut) and the maximum number of total bytes in a
// batch (defined in maximumBytesPerPut). Log messages are split by the maximum
// bytes per event (defined in maximumBytesPerEvent). There is a fixed per-event
// byte overhead (defined in perEventBytes) which is accounted for in split- and
// batch-calculations.
func (l *logStream) processEvent(batch *eventBatch, events []byte, timestamp int64) {
for len(events) > 0 {
// Split line length so it does not exceed the maximum
lineBytes := len(events)
if lineBytes > maximumBytesPerEvent {
lineBytes = maximumBytesPerEvent
}
line := events[:lineBytes]
event := wrappedEvent{
inputLogEvent: &cloudwatchlogs.InputLogEvent{
Message: aws.String(string(line)),
Timestamp: aws.Int64(timestamp),
},
insertOrder: batch.count(),
}
added := batch.add(event, lineBytes)
if added {
events = events[lineBytes:]
} else {
l.publishBatch(batch)
batch.reset()
}
}
}
// publishBatch calls PutLogEvents for a given set of InputLogEvents,
// accounting for sequencing requirements (each request must reference the
// sequence token returned by the previous request).
func (l *logStream) publishBatch(batch *eventBatch) {
if batch.isEmpty() {
return
}
cwEvents := unwrapEvents(batch.events())
nextSequenceToken, err := l.putLogEvents(cwEvents, l.sequenceToken)
if err != nil {
if awsErr, ok := err.(awserr.Error); ok {
if awsErr.Code() == dataAlreadyAcceptedCode {
// already submitted, just grab the correct sequence token
parts := strings.Split(awsErr.Message(), " ")
nextSequenceToken = &parts[len(parts)-1]
logrus.WithFields(logrus.Fields{
"errorCode": awsErr.Code(),
"message": awsErr.Message(),
"logGroupName": l.logGroupName,
"logStreamName": l.logStreamName,
}).Info("Data already accepted, ignoring error")
err = nil
} else if awsErr.Code() == invalidSequenceTokenCode {
// sequence code is bad, grab the correct one and retry
parts := strings.Split(awsErr.Message(), " ")
token := parts[len(parts)-1]
nextSequenceToken, err = l.putLogEvents(cwEvents, &token)
}
}
}
if err != nil {
logrus.Error(err)
} else {
l.sequenceToken = nextSequenceToken
}
}
// putLogEvents wraps the PutLogEvents API
func (l *logStream) putLogEvents(events []*cloudwatchlogs.InputLogEvent, sequenceToken *string) (*string, error) {
input := &cloudwatchlogs.PutLogEventsInput{
LogEvents: events,
SequenceToken: sequenceToken,
LogGroupName: aws.String(l.logGroupName),
LogStreamName: aws.String(l.logStreamName),
}
resp, err := l.client.PutLogEvents(input)
if err != nil {
if awsErr, ok := err.(awserr.Error); ok {
logrus.WithFields(logrus.Fields{
"errorCode": awsErr.Code(),
"message": awsErr.Message(),
"origError": awsErr.OrigErr(),
"logGroupName": l.logGroupName,
"logStreamName": l.logStreamName,
}).Error("Failed to put log events")
}
return nil, err
}
return resp.NextSequenceToken, nil
}
// ValidateLogOpt looks for awslogs-specific log options awslogs-region, awslogs-endpoint
// awslogs-group, awslogs-stream, awslogs-create-group, awslogs-datetime-format,
// awslogs-multiline-pattern
func ValidateLogOpt(cfg map[string]string) error {
for key := range cfg {
switch key {
case logGroupKey:
case logStreamKey:
case logCreateGroupKey:
case regionKey:
case endpointKey:
case tagKey:
case datetimeFormatKey:
case multilinePatternKey:
case credentialsEndpointKey:
default:
return fmt.Errorf("unknown log opt '%s' for %s log driver", key, name)
}
}
if cfg[logGroupKey] == "" {
return fmt.Errorf("must specify a value for log opt '%s'", logGroupKey)
}
if cfg[logCreateGroupKey] != "" {
if _, err := strconv.ParseBool(cfg[logCreateGroupKey]); err != nil {
return fmt.Errorf("must specify valid value for log opt '%s': %v", logCreateGroupKey, err)
}
}
_, datetimeFormatKeyExists := cfg[datetimeFormatKey]
_, multilinePatternKeyExists := cfg[multilinePatternKey]
if datetimeFormatKeyExists && multilinePatternKeyExists {
return fmt.Errorf("you cannot configure log opt '%s' and '%s' at the same time", datetimeFormatKey, multilinePatternKey)
}
return nil
}
// Len returns the length of a byTimestamp slice. Len is required by the
// sort.Interface interface.
func (slice byTimestamp) Len() int {
return len(slice)
}
// Less compares two values in a byTimestamp slice by Timestamp. Less is
// required by the sort.Interface interface.
func (slice byTimestamp) Less(i, j int) bool {
iTimestamp, jTimestamp := int64(0), int64(0)
if slice != nil && slice[i].inputLogEvent.Timestamp != nil {
iTimestamp = *slice[i].inputLogEvent.Timestamp
}
if slice != nil && slice[j].inputLogEvent.Timestamp != nil {
jTimestamp = *slice[j].inputLogEvent.Timestamp
}
if iTimestamp == jTimestamp {
return slice[i].insertOrder < slice[j].insertOrder
}
return iTimestamp < jTimestamp
}
// Swap swaps two values in a byTimestamp slice with each other. Swap is
// required by the sort.Interface interface.
func (slice byTimestamp) Swap(i, j int) {
slice[i], slice[j] = slice[j], slice[i]
}
func unwrapEvents(events []wrappedEvent) []*cloudwatchlogs.InputLogEvent {
cwEvents := make([]*cloudwatchlogs.InputLogEvent, len(events))
for i, input := range events {
cwEvents[i] = input.inputLogEvent
}
return cwEvents
}
func newEventBatch() *eventBatch {
return &eventBatch{
batch: make([]wrappedEvent, 0),
bytes: 0,
}
}
// events returns a slice of wrappedEvents sorted in order of their
// timestamps and then by their insertion order (see `byTimestamp`).
//
// Warning: this method is not threadsafe and must not be used
// concurrently.
func (b *eventBatch) events() []wrappedEvent {
sort.Sort(byTimestamp(b.batch))
return b.batch
}
// add adds an event to the batch of events accounting for the
// necessary overhead for an event to be logged. An error will be
// returned if the event cannot be added to the batch due to service
// limits.
//
// Warning: this method is not threadsafe and must not be used
// concurrently.
func (b *eventBatch) add(event wrappedEvent, size int) bool {
addBytes := size + perEventBytes
// verify we are still within service limits
switch {
case len(b.batch)+1 > maximumLogEventsPerPut:
return false
case b.bytes+addBytes > maximumBytesPerPut:
return false
}
b.bytes += addBytes
b.batch = append(b.batch, event)
return true
}
// count is the number of batched events. Warning: this method
// is not threadsafe and must not be used concurrently.
func (b *eventBatch) count() int {
return len(b.batch)
}
// size is the total number of bytes that the batch represents.
//
// Warning: this method is not threadsafe and must not be used
// concurrently.
func (b *eventBatch) size() int {
return b.bytes
}
func (b *eventBatch) isEmpty() bool {
zeroEvents := b.count() == 0
zeroSize := b.size() == 0
return zeroEvents && zeroSize
}
// reset prepares the batch for reuse.
func (b *eventBatch) reset() {
b.bytes = 0
b.batch = b.batch[:0]
}