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package hcs
import (
"context"
"github.com/Microsoft/hcsshim/internal/logfields"
"github.com/Microsoft/hcsshim/internal/timeout"
"github.com/sirupsen/logrus"
)
// syscallWatcher is used as a very simple goroutine around calls into
// the platform. In some cases, we have seen HCS APIs not returning due to
// various bugs, and the goroutine making the syscall ends up not returning,
// prior to its async callback. By spinning up a syscallWatcher, it allows
// us to at least log a warning if a syscall doesn't complete in a reasonable
// amount of time.
//
// Usage is:
//
// syscallWatcher(logContext, func() {
// err = <syscall>(args...)
// })
//
func syscallWatcher(logContext logrus.Fields, syscallLambda func()) {
ctx, cancel := context.WithTimeout(context.Background(), timeout.SyscallWatcher)
defer cancel()
go watchFunc(ctx, logContext)
syscallLambda()
}
func watchFunc(ctx context.Context, logContext logrus.Fields) {
select {
case <-ctx.Done():
if ctx.Err() != context.Canceled {
logrus.WithFields(logContext).
WithField(logfields.Timeout, timeout.SyscallWatcher).
Warning("Syscall did not complete within operation timeout. This may indicate a platform issue. If it appears to be making no forward progress, obtain the stacks and see if there is a syscall stuck in the platform API for a significant length of time.")
}
}
}
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