status-go/vendor/github.com/raulk/go-watchdog/watchdog_linux.go

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2022-04-01 16:16:46 +00:00
package watchdog
import (
"fmt"
"os"
"time"
"github.com/containerd/cgroups"
)
var (
pid = os.Getpid()
memSubsystem = cgroups.SingleSubsystem(cgroups.V1, cgroups.Memory)
)
// CgroupDriven initializes a cgroups-driven watchdog. It will try to discover
// the memory limit from the cgroup of the process (derived from /proc/self/cgroup),
// or from the root cgroup path if the PID == 1 (which indicates that the process
// is running in a container).
//
// Memory usage is calculated by querying the cgroup stats.
//
// This function will return an error immediately if the OS does not support cgroups,
// or if another error occurs during initialization. The caller can then safely fall
// back to the system driven watchdog.
func CgroupDriven(frequency time.Duration, policyCtor PolicyCtor) (err error, stopFn func()) {
// use self path unless our PID is 1, in which case we're running inside
// a container and our limits are in the root path.
path := cgroups.NestedPath("")
if pid := os.Getpid(); pid == 1 {
path = cgroups.RootPath
}
cgroup, err := cgroups.Load(memSubsystem, path)
if err != nil {
return fmt.Errorf("failed to load cgroup for process: %w", err), nil
}
var limit uint64
if stat, err := cgroup.Stat(); err != nil {
return fmt.Errorf("failed to load memory cgroup stats: %w", err), nil
} else if stat.Memory == nil || stat.Memory.Usage == nil {
return fmt.Errorf("cgroup memory stats are nil; aborting"), nil
} else {
limit = stat.Memory.Usage.Limit
}
if limit == 0 {
return fmt.Errorf("cgroup limit is 0; refusing to start memory watchdog"), nil
}
policy, err := policyCtor(limit)
if err != nil {
return fmt.Errorf("failed to construct policy with limit %d: %w", limit, err), nil
}
if err := start(UtilizationProcess); err != nil {
return err, nil
}
_watchdog.wg.Add(1)
go pollingWatchdog(policy, frequency, limit, func() (uint64, error) {
stat, err := cgroup.Stat()
if err != nil {
return 0, err
} else if stat.Memory == nil || stat.Memory.Usage == nil {
return 0, fmt.Errorf("cgroup memory stats are nil; aborting")
}
return stat.Memory.Usage.Usage, nil
})
return nil, stop
}