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moby--moby/daemon/logger/loggerutils/cache/local_cache.go
Brian Goff e2ceb83a53 Support reads for all log drivers.
This supplements any log driver which does not support reads with a
custom read implementation that uses a local file cache.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit d675e2bf2b75865915c7a4552e00802feeb0847f)
Signed-off-by: Madhu Venugopal <madhu@docker.com>
2020-02-19 17:01:44 -05:00

63 lines
1.7 KiB
Go

package cache // import "github.com/docker/docker/daemon/logger/loggerutils/cache"
import (
"github.com/docker/docker/daemon/logger"
"github.com/docker/docker/daemon/logger/local"
"github.com/sirupsen/logrus"
)
// WithLocalCache wraps the passed in logger with a logger caches all writes locally
// in addition to writing to the passed in logger.
func WithLocalCache(l logger.Logger, logInfo logger.Info) (logger.Logger, error) {
localLogger, err := local.New(logInfo)
if err != nil {
return nil, err
}
return &loggerWithCache{
l: l,
// TODO(@cpuguy83): Should this be configurable?
cache: logger.NewRingLogger(localLogger, logInfo, -1),
}, nil
}
type loggerWithCache struct {
l logger.Logger
cache logger.Logger
}
func (l *loggerWithCache) Log(msg *logger.Message) error {
// copy the message since the underlying logger will return the passed in message to the message pool
dup := logger.NewMessage()
dumbCopyMessage(dup, msg)
if err := l.l.Log(msg); err != nil {
return err
}
return l.cache.Log(dup)
}
func (l *loggerWithCache) Name() string {
return l.l.Name()
}
func (l *loggerWithCache) ReadLogs(config logger.ReadConfig) *logger.LogWatcher {
return l.cache.(logger.LogReader).ReadLogs(config)
}
func (l *loggerWithCache) Close() error {
err := l.l.Close()
if err := l.cache.Close(); err != nil {
logrus.WithError(err).Warn("error while shutting cache logger")
}
return err
}
// dumbCopyMessage is a bit of a fake copy but avoids extra allocations which
// are not necessary for this use case.
func dumbCopyMessage(dst, src *logger.Message) {
dst.Source = src.Source
dst.Timestamp = src.Timestamp
dst.PLogMetaData = src.PLogMetaData
dst.Err = src.Err
dst.Attrs = src.Attrs
dst.Line = src.Line
}