mirror of
https://github.com/anchore/grype
synced 2024-11-10 06:34:13 +00:00
98 lines
3.2 KiB
Go
98 lines
3.2 KiB
Go
package cmd
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import (
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"errors"
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"fmt"
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"os"
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"github.com/hashicorp/go-multierror"
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"github.com/wagoodman/go-partybus"
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"github.com/anchore/grype/internal/log"
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"github.com/anchore/grype/internal/ui"
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)
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// eventLoop listens to worker errors (from execution path), worker events (from a partybus subscription), and
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// signal interrupts. Is responsible for handling each event relative to a given UI an to coordinate eventing until
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// an eventual graceful exit.
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func eventLoop(workerErrs <-chan error, signals <-chan os.Signal, subscription *partybus.Subscription, cleanupFn func(), uxs ...ui.UI) error {
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defer cleanupFn()
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events := subscription.Events()
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var err error
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var ux ui.UI
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if ux, err = setupUI(subscription.Unsubscribe, uxs...); err != nil {
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return err
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}
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var retErr error
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var forceTeardown bool
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for {
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if workerErrs == nil && events == nil {
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break
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}
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select {
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case err, isOpen := <-workerErrs:
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if !isOpen {
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workerErrs = nil
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continue
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}
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if err != nil {
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// capture the error from the worker and unsubscribe to complete a graceful shutdown
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retErr = multierror.Append(retErr, err)
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_ = subscription.Unsubscribe()
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// the worker has exited, we may have been mid-handling events for the UI which should now be
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// ignored, in which case forcing a teardown of the UI irregardless of the state is required.
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forceTeardown = true
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}
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case e, isOpen := <-events:
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if !isOpen {
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events = nil
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continue
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}
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if err := ux.Handle(e); err != nil {
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if errors.Is(err, partybus.ErrUnsubscribe) {
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events = nil
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} else {
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retErr = multierror.Append(retErr, err)
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// TODO: should we unsubscribe? should we try to halt execution? or continue?
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}
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}
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case <-signals:
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// ignore further results from any event source and exit ASAP, but ensure that all cache is cleaned up.
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// we ignore further errors since cleaning up the tmp directories will affect running catalogers that are
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// reading/writing from/to their nested temp dirs. This is acceptable since we are bailing without result.
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// TODO: potential future improvement would be to pass context into workers with a cancel function that is
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// to the event loop. In this way we can have a more controlled shutdown even at the most nested levels
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// of processing.
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events = nil
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workerErrs = nil
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forceTeardown = true
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}
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}
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if err := ux.Teardown(forceTeardown); err != nil {
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retErr = multierror.Append(retErr, err)
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}
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return retErr
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}
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// setupUI takes one or more UIs that responds to events and takes a event bus unsubscribe function for use
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// during teardown. With the given UIs, the first UI which the ui.Setup() function does not return an error
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// will be utilized in execution. Providing a set of UIs allows for the caller to provide graceful fallbacks
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// when there are environmental problem (e.g. unable to setup a TUI with the current TTY).
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func setupUI(unsubscribe func() error, uis ...ui.UI) (ui.UI, error) {
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for _, ux := range uis {
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if err := ux.Setup(unsubscribe); err != nil {
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log.Warnf("unable to setup given UI, falling back to alternative UI: %+v", err)
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continue
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}
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return ux, nil
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}
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return nil, fmt.Errorf("unable to setup any UI")
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}
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