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log API: add context to allow for cancelling

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Add a `context.Context` to the log APIs to allow for cancelling
streaming (e.g., via `podman logs -f`).  This fixes issues for
the remote API where some go routines of the server will continue
writing and produce nothing but heat and waste CPU cycles.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>
This commit is contained in:
Valentin Rothberg
2020-07-09 13:32:20 +02:00
parent edf5fe8b17
commit 09dc77aedf
7 changed files with 73 additions and 52 deletions
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23
libpod/container_log.go
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@ -1,6 +1,7 @@
package libpod
import (
"context"
"fmt"
"os"
"time"
@ -13,9 +14,9 @@ import (
)
// Log is a runtime function that can read one or more container logs.
func (r *Runtime) Log(containers []*Container, options *logs.LogOptions, logChannel chan *logs.LogLine) error {
func (r *Runtime) Log(ctx context.Context, containers []*Container, options *logs.LogOptions, logChannel chan *logs.LogLine) error {
for _, ctr := range containers {
if err := ctr.ReadLog(options, logChannel); err != nil {
if err := ctr.ReadLog(ctx, options, logChannel); err != nil {
return err
}
}
@ -23,25 +24,25 @@ func (r *Runtime) Log(containers []*Container, options *logs.LogOptions, logChan
}
// ReadLog reads a containers log based on the input options and returns loglines over a channel.
func (c *Container) ReadLog(options *logs.LogOptions, logChannel chan *logs.LogLine) error {
func (c *Container) ReadLog(ctx context.Context, options *logs.LogOptions, logChannel chan *logs.LogLine) error {
switch c.LogDriver() {
case define.NoLogging:
return errors.Wrapf(define.ErrNoLogs, "this container is using the 'none' log driver, cannot read logs")
case define.JournaldLogging:
// TODO Skip sending logs until journald logs can be read
return c.readFromJournal(options, logChannel)
return c.readFromJournal(ctx, options, logChannel)
case define.JSONLogging:
// TODO provide a separate implementation of this when Conmon
// has support.
fallthrough
case define.KubernetesLogging, "":
return c.readFromLogFile(options, logChannel)
return c.readFromLogFile(ctx, options, logChannel)
default:
return errors.Wrapf(define.ErrInternal, "unrecognized log driver %q, cannot read logs", c.LogDriver())
}
}
func (c *Container) readFromLogFile(options *logs.LogOptions, logChannel chan *logs.LogLine) error {
func (c *Container) readFromLogFile(ctx context.Context, options *logs.LogOptions, logChannel chan *logs.LogLine) error {
t, tailLog, err := logs.GetLogFile(c.LogPath(), options)
if err != nil {
// If the log file does not exist, this is not fatal.
@ -62,8 +63,17 @@ func (c *Container) readFromLogFile(options *logs.LogOptions, logChannel chan *l
}
go func() {
defer options.WaitGroup.Done()
var partial string
for line := range t.Lines {
select {
case <-ctx.Done():
// the consumer has cancelled
return
default:
// fallthrough
}
nll, err := logs.NewLogLine(line.Text)
if err != nil {
logrus.Error(err)
@ -82,7 +92,6 @@ func (c *Container) readFromLogFile(options *logs.LogOptions, logChannel chan *l
logChannel <- nll
}
}
options.WaitGroup.Done()
}()
// Check if container is still running or paused
if options.Follow {