Update pods to use file locks

Also includes misc other fixes - adding labels, fixing pod names

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #138
Approved by: rhatdan

4 files changed, 61 insertions, 16 deletions

diff --git a/libpod/options.go b/libpod/options.go
index 07c25faf9..8a12c61e4 100644
--- a/libpod/options.go
+++ b/libpod/options.go
@@ -401,3 +401,19 @@ func WithPodName(name string) PodCreateOption {
 		return nil
 	}
 }
+
+// WithPodLabels sets the labels of a pod
+func WithPodLabels(labels map[string]string) PodCreateOption {
+	return func(pod *Pod) error {
+		if pod.valid {
+			return ErrPodFinalized
+		}
+
+		pod.labels = make(map[string]string)
+		for key, value := range labels {
+			pod.labels[key] = value
+		}
+
+		return nil
+	}
+}
diff --git a/libpod/pod.go b/libpod/pod.go
index 48a761d57..b336c2677 100644
--- a/libpod/pod.go
+++ b/libpod/pod.go
@@ -1,21 +1,25 @@
 package libpod
 
 import (
-	"sync"
+	"os"
+	"path/filepath"
 
+	"github.com/containers/storage"
+	"github.com/docker/docker/pkg/namesgenerator"
 	"github.com/docker/docker/pkg/stringid"
 	"github.com/pkg/errors"
 )
 
 // Pod represents a group of containers that may share namespaces
 type Pod struct {
-	id   string
-	name string
+	id     string
+	name   string
+	labels map[string]string
 
 	containers map[string]*Container
 
 	valid bool
-	lock  sync.RWMutex
+	lock  storage.Locker
 }
 
 // ID retrieves the pod's ID
@@ -28,14 +32,43 @@ func (p *Pod) Name() string {
 	return p.name
 }
 
-// Creates a new pod
-func newPod() (*Pod, error) {
+// Labels returns the pod's labels
+func (p *Pod) Labels() map[string]string {
+	labels := make(map[string]string)
+	for key, value := range p.labels {
+		labels[key] = value
+	}
+
+	return labels
+}
+
+// Creates a new, empty pod
+func newPod(lockDir string) (*Pod, error) {
 	pod := new(Pod)
 	pod.id = stringid.GenerateNonCryptoID()
-	pod.name = pod.id // TODO generate human-readable name here
+	pod.name = namesgenerator.GetRandomName(0)
 
 	pod.containers = make(map[string]*Container)
 
+	// TODO: containers and pods share a locks folder, but not tables in the
+	// database
+	// As the locks are 256-bit pseudorandom integers, collision is unlikely
+	// But it's something worth looking into
+
+	// Path our lock file will reside at
+	lockPath := filepath.Join(lockDir, pod.id)
+	// Ensure there is no conflict - file does not exist
+	_, err := os.Stat(lockPath)
+	if err == nil || !os.IsNotExist(err) {
+		return nil, errors.Wrapf(ErrCtrExists, "lockfile for pod ID %s already exists", pod.id)
+	}
+	// Grab a lockfile at the given path
+	lock, err := storage.GetLockfile(lockPath)
+	if err != nil {
+		return nil, errors.Wrapf(err, "error creating lockfile for new pod")
+	}
+	pod.lock = lock
+
 	return pod, nil
 }
 
@@ -45,8 +78,6 @@ func newPod() (*Pod, error) {
 func (p *Pod) addContainer(ctr *Container) error {
 	p.lock.Lock()
 	defer p.lock.Unlock()
-	ctr.lock.Lock()
-	defer ctr.lock.Unlock()
 
 	if !p.valid {
 		return ErrPodRemoved
@@ -101,8 +132,8 @@ func (p *Pod) Kill(signal uint) error {
 
 // HasContainer checks if a container is present in the pod
 func (p *Pod) HasContainer(id string) (bool, error) {
-	p.lock.RLock()
-	defer p.lock.RUnlock()
+	p.lock.Lock()
+	defer p.lock.Unlock()
 
 	if !p.valid {
 		return false, ErrPodRemoved
@@ -115,8 +146,8 @@ func (p *Pod) HasContainer(id string) (bool, error) {
 
 // GetContainers retrieves the containers in the pod
 func (p *Pod) GetContainers() ([]*Container, error) {
-	p.lock.RLock()
-	defer p.lock.RUnlock()
+	p.lock.Lock()
+	defer p.lock.Unlock()
 
 	if !p.valid {
 		return nil, ErrPodRemoved
diff --git a/libpod/runtime_pod.go b/libpod/runtime_pod.go
index 162b353e6..35c7f0642 100644
--- a/libpod/runtime_pod.go
+++ b/libpod/runtime_pod.go
@@ -24,7 +24,7 @@ func (r *Runtime) NewPod(options ...PodCreateOption) (*Pod, error) {
 		return nil, ErrRuntimeStopped
 	}
 
-	pod, err := newPod()
+	pod, err := newPod(r.lockDir)
 	if err != nil {
 		return nil, errors.Wrapf(err, "error creating pod")
 	}
diff --git a/libpod/sql_state_internal.go b/libpod/sql_state_internal.go
index 515b5b6ad..12a7dbd10 100644
--- a/libpod/sql_state_internal.go
+++ b/libpod/sql_state_internal.go
@@ -154,8 +154,6 @@ func prepareDB(db *sql.DB) (err error) {
 	// TODO add Pod ID to CreateStaticContainer as a FOREIGN KEY referencing podStatic(Id)
 	// TODO add ctr shared namespaces information - A separate table, probably? So we can FOREIGN KEY the ID
 	// TODO schema migration might be necessary and should be handled here
-	// TODO add a table for the runtime, and refuse to load the database if the runtime configuration
-	// does not match the one in the database
 
 	// Enable foreign keys in SQLite
 	if _, err := db.Exec("PRAGMA foreign_keys = ON;"); err != nil {