1 files changed, 273 insertions, 0 deletions
diff --git a/libpod/in_memory_state.go b/libpod/in_memory_state.go
new file mode 100644
index 000000000..b8747d4e7
--- /dev/null
+++ b/libpod/in_memory_state.go
@@ -0,0 +1,273 @@
+package libpod
+
+import (
+	"github.com/docker/docker/pkg/truncindex"
+	"github.com/kubernetes-incubator/cri-o/pkg/registrar"
+	"github.com/pkg/errors"
+)
+
+// An InMemoryState is a purely in-memory state store
+type InMemoryState struct {
+	pods         map[string]*Pod
+	containers   map[string]*Container
+	podNameIndex *registrar.Registrar
+	podIDIndex   *truncindex.TruncIndex
+	ctrNameIndex *registrar.Registrar
+	ctrIDIndex   *truncindex.TruncIndex
+}
+
+// NewInMemoryState initializes a new, empty in-memory state
+func NewInMemoryState() (State, error) {
+	state := new(InMemoryState)
+
+	state.pods = make(map[string]*Pod)
+	state.containers = make(map[string]*Container)
+
+	state.podNameIndex = registrar.NewRegistrar()
+	state.ctrNameIndex = registrar.NewRegistrar()
+
+	state.podIDIndex = truncindex.NewTruncIndex([]string{})
+	state.ctrIDIndex = truncindex.NewTruncIndex([]string{})
+
+	return state, nil
+}
+
+// Container retrieves a container from its full ID
+func (s *InMemoryState) Container(id string) (*Container, error) {
+	if id == "" {
+		return nil, ErrEmptyID
+	}
+
+	ctr, ok := s.containers[id]
+	if !ok {
+		return nil, errors.Wrapf(ErrNoSuchCtr, "no container with ID %s found", id)
+	}
+
+	return ctr, nil
+}
+
+// LookupContainer retrieves a container by full ID, unique partial ID, or name
+func (s *InMemoryState) LookupContainer(idOrName string) (*Container, error) {
+	if idOrName == "" {
+		return nil, ErrEmptyID
+	}
+
+	fullID, err := s.ctrNameIndex.Get(idOrName)
+	if err != nil {
+		if err == registrar.ErrNameNotReserved {
+			// What was passed is not a name, assume it's an ID
+			fullID, err = s.ctrIDIndex.Get(idOrName)
+			if err != nil {
+				if err == truncindex.ErrNotExist {
+					return nil, errors.Wrapf(ErrNoSuchCtr, "no container found with name or ID %s", idOrName)
+				}
+				return nil, errors.Wrapf(err, "error performing truncindex lookup for ID %s", idOrName)
+			}
+		} else {
+			return nil, errors.Wrapf(err, "error performing registry lookup for ID %s", idOrName)
+		}
+	}
+
+	ctr, ok := s.containers[fullID]
+	if !ok {
+		// This should never happen
+		return nil, errors.Wrapf(ErrInternal, "mismatch in container ID registry and containers map for ID %s", fullID)
+	}
+
+	return ctr, nil
+}
+
+// HasContainer checks if a container with the given ID is present in the state
+func (s *InMemoryState) HasContainer(id string) (bool, error) {
+	if id == "" {
+		return false, ErrEmptyID
+	}
+
+	_, ok := s.containers[id]
+
+	return ok, nil
+}
+
+// AddContainer adds a container to the state
+// If the container belongs to a pod, the pod must already be present when the
+// container is added, and the container must be present in the pod
+func (s *InMemoryState) AddContainer(ctr *Container) error {
+	if !ctr.valid {
+		return errors.Wrapf(ErrCtrRemoved, "container with ID %s is not valid", ctr.ID())
+	}
+
+	_, ok := s.containers[ctr.ID()]
+	if ok {
+		return errors.Wrapf(ErrCtrExists, "container with ID %s already exists in state", ctr.ID())
+	}
+
+	if ctr.pod != nil {
+		if _, ok := s.pods[ctr.pod.ID()]; !ok {
+			return errors.Wrapf(ErrNoSuchPod, "pod %s does not exist, cannot add container %s", ctr.pod.ID(), ctr.ID())
+		}
+
+		hasCtr, err := ctr.pod.HasContainer(ctr.ID())
+		if err != nil {
+			return errors.Wrapf(err, "error checking if container %s is present in pod %s", ctr.ID(), ctr.pod.ID())
+		} else if !hasCtr {
+			return errors.Wrapf(ErrNoSuchCtr, "container %s is not present in pod %s", ctr.ID(), ctr.pod.ID())
+		}
+	}
+
+	if err := s.ctrNameIndex.Reserve(ctr.Name(), ctr.ID()); err != nil {
+		return errors.Wrapf(err, "error registering container name %s", ctr.Name())
+	}
+
+	if err := s.ctrIDIndex.Add(ctr.ID()); err != nil {
+		s.ctrNameIndex.Release(ctr.Name())
+		return errors.Wrapf(err, "error registering container ID %s", ctr.ID())
+	}
+
+	s.containers[ctr.ID()] = ctr
+
+	return nil
+}
+
+// RemoveContainer removes a container from the state
+// The container will only be removed from the state, not from the pod the container belongs to
+func (s *InMemoryState) RemoveContainer(ctr *Container) error {
+	// Almost no validity checks are performed, to ensure we can kick
+	// misbehaving containers out of the state
+
+	if _, ok := s.containers[ctr.ID()]; !ok {
+		return errors.Wrapf(ErrNoSuchCtr, "no container exists in state with ID %s", ctr.ID())
+	}
+
+	if err := s.ctrIDIndex.Delete(ctr.ID()); err != nil {
+		return errors.Wrapf(err, "error removing container ID from index")
+	}
+	delete(s.containers, ctr.ID())
+	s.ctrNameIndex.Release(ctr.Name())
+
+	return nil
+}
+
+// AllContainers retrieves all containers from the state
+func (s *InMemoryState) AllContainers() ([]*Container, error) {
+	ctrs := make([]*Container, 0, len(s.containers))
+	for _, ctr := range s.containers {
+		ctrs = append(ctrs, ctr)
+	}
+
+	return ctrs, nil
+}
+
+// Pod retrieves a pod from the state from its full ID
+func (s *InMemoryState) Pod(id string) (*Pod, error) {
+	if id == "" {
+		return nil, ErrEmptyID
+	}
+
+	pod, ok := s.pods[id]
+	if !ok {
+		return nil, errors.Wrapf(ErrNoSuchPod, "no pod with id %s found", id)
+	}
+
+	return pod, nil
+}
+
+// LookupPod retrieves a pod from the state from a full or unique partial ID or
+// a full name
+func (s *InMemoryState) LookupPod(idOrName string) (*Pod, error) {
+	if idOrName == "" {
+		return nil, ErrEmptyID
+	}
+
+	fullID, err := s.podNameIndex.Get(idOrName)
+	if err != nil {
+		if err == registrar.ErrNameNotReserved {
+			// What was passed is not a name, assume it's an ID
+			fullID, err = s.podIDIndex.Get(idOrName)
+			if err != nil {
+				if err == truncindex.ErrNotExist {
+					return nil, errors.Wrapf(ErrNoSuchPod, "no pod found with name or ID %s", idOrName)
+				}
+				return nil, errors.Wrapf(err, "error performing truncindex lookup for ID %s", idOrName)
+			}
+		} else {
+			return nil, errors.Wrapf(err, "error performing registry lookup for ID %s", idOrName)
+		}
+	}
+
+	pod, ok := s.pods[fullID]
+	if !ok {
+		// This should never happen
+		return nil, errors.Wrapf(ErrInternal, "mismatch in pod ID registry and pod map for ID %s", fullID)
+	}
+
+	return pod, nil
+}
+
+// HasPod checks if a pod with the given ID is present in the state
+func (s *InMemoryState) HasPod(id string) (bool, error) {
+	if id == "" {
+		return false, ErrEmptyID
+	}
+
+	_, ok := s.pods[id]
+
+	return ok, nil
+}
+
+// AddPod adds a given pod to the state
+// Only empty pods can be added to the state
+func (s *InMemoryState) AddPod(pod *Pod) error {
+	if !pod.valid {
+		return errors.Wrapf(ErrPodRemoved, "pod %s is not valid and cannot be added", pod.ID())
+	}
+
+	if _, ok := s.pods[pod.ID()]; ok {
+		return errors.Wrapf(ErrPodExists, "pod with ID %s already exists in state", pod.ID())
+	}
+
+	if len(pod.containers) != 0 {
+		return errors.Wrapf(ErrInternal, "only empty pods can be added to the state")
+	}
+
+	if err := s.podNameIndex.Reserve(pod.Name(), pod.ID()); err != nil {
+		return errors.Wrapf(err, "error registering pod name %s", pod.Name())
+	}
+
+	if err := s.podIDIndex.Add(pod.ID()); err != nil {
+		s.podNameIndex.Release(pod.Name())
+		return errors.Wrapf(err, "error registering pod ID %s", pod.ID())
+	}
+
+	s.pods[pod.ID()] = pod
+
+	return nil
+}
+
+// RemovePod removes a given pod from the state
+// Containers within the pod will not be removed or changed
+func (s *InMemoryState) RemovePod(pod *Pod) error {
+	// Don't make many validity checks to ensure we can kick badly formed
+	// pods out of the state
+
+	if _, ok := s.pods[pod.ID()]; !ok {
+		return errors.Wrapf(ErrNoSuchPod, "no pod exists in state with ID %s", pod.ID())
+	}
+
+	if err := s.podIDIndex.Delete(pod.ID()); err != nil {
+		return errors.Wrapf(err, "error removing pod ID %s from index", pod.ID())
+	}
+	delete(s.pods, pod.ID())
+	s.podNameIndex.Release(pod.Name())
+
+	return nil
+}
+
+// AllPods retrieves all pods currently in the state
+func (s *InMemoryState) AllPods() ([]*Pod, error) {
+	pods := make([]*Pod, 0, len(s.pods))
+	for _, pod := range s.pods {
+		pods = append(pods, pod)
+	}
+
+	return pods, nil
+}