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-rw-r--r--runsc/container/BUILD1
-rw-r--r--runsc/container/container.go344
-rw-r--r--runsc/container/state_file.go185
3 files changed, 312 insertions, 218 deletions
diff --git a/runsc/container/BUILD b/runsc/container/BUILD
index 26d1cd5ab..2bd12120d 100644
--- a/runsc/container/BUILD
+++ b/runsc/container/BUILD
@@ -7,6 +7,7 @@ go_library(
srcs = [
"container.go",
"hook.go",
+ "state_file.go",
"status.go",
],
importpath = "gvisor.dev/gvisor/runsc/container",
diff --git a/runsc/container/container.go b/runsc/container/container.go
index 32510d427..68782c4be 100644
--- a/runsc/container/container.go
+++ b/runsc/container/container.go
@@ -17,13 +17,11 @@ package container
import (
"context"
- "encoding/json"
"fmt"
"io/ioutil"
"os"
"os/exec"
"os/signal"
- "path/filepath"
"regexp"
"strconv"
"strings"
@@ -31,7 +29,6 @@ import (
"time"
"github.com/cenkalti/backoff"
- "github.com/gofrs/flock"
specs "github.com/opencontainers/runtime-spec/specs-go"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sentry/control"
@@ -41,17 +38,6 @@ import (
"gvisor.dev/gvisor/runsc/specutils"
)
-const (
- // metadataFilename is the name of the metadata file relative to the
- // container root directory that holds sandbox metadata.
- metadataFilename = "meta.json"
-
- // metadataLockFilename is the name of a lock file in the container
- // root directory that is used to prevent concurrent modifications to
- // the container state and metadata.
- metadataLockFilename = "meta.lock"
-)
-
// validateID validates the container id.
func validateID(id string) error {
// See libcontainer/factory_linux.go.
@@ -99,11 +85,6 @@ type Container struct {
// BundleDir is the directory containing the container bundle.
BundleDir string `json:"bundleDir"`
- // Root is the directory containing the container metadata file. If this
- // container is the root container, Root and RootContainerDir will be the
- // same.
- Root string `json:"root"`
-
// CreatedAt is the time the container was created.
CreatedAt time.Time `json:"createdAt"`
@@ -121,21 +102,24 @@ type Container struct {
// be 0 if the gofer has been killed.
GoferPid int `json:"goferPid"`
+ // Sandbox is the sandbox this container is running in. It's set when the
+ // container is created and reset when the sandbox is destroyed.
+ Sandbox *sandbox.Sandbox `json:"sandbox"`
+
+ // Saver handles load from/save to the state file safely from multiple
+ // processes.
+ Saver StateFile `json:"saver"`
+
+ //
+ // Fields below this line are not saved in the state file and will not
+ // be preserved across commands.
+ //
+
// goferIsChild is set if a gofer process is a child of the current process.
//
// This field isn't saved to json, because only a creator of a gofer
// process will have it as a child process.
goferIsChild bool
-
- // Sandbox is the sandbox this container is running in. It's set when the
- // container is created and reset when the sandbox is destroyed.
- Sandbox *sandbox.Sandbox `json:"sandbox"`
-
- // RootContainerDir is the root directory containing the metadata file of the
- // sandbox root container. It's used to lock in order to serialize creating
- // and deleting this Container's metadata directory. If this container is the
- // root container, this is the same as Root.
- RootContainerDir string
}
// loadSandbox loads all containers that belong to the sandbox with the given
@@ -166,43 +150,35 @@ func loadSandbox(rootDir, id string) ([]*Container, error) {
return containers, nil
}
-// Load loads a container with the given id from a metadata file. id may be an
-// abbreviation of the full container id, in which case Load loads the
-// container to which id unambiguously refers to.
-// Returns ErrNotExist if container doesn't exist.
-func Load(rootDir, id string) (*Container, error) {
- log.Debugf("Load container %q %q", rootDir, id)
- if err := validateID(id); err != nil {
+// Load loads a container with the given id from a metadata file. partialID may
+// be an abbreviation of the full container id, in which case Load loads the
+// container to which id unambiguously refers to. Returns ErrNotExist if
+// container doesn't exist.
+func Load(rootDir, partialID string) (*Container, error) {
+ log.Debugf("Load container %q %q", rootDir, partialID)
+ if err := validateID(partialID); err != nil {
return nil, fmt.Errorf("validating id: %v", err)
}
- cRoot, err := findContainerRoot(rootDir, id)
+ id, err := findContainerID(rootDir, partialID)
if err != nil {
// Preserve error so that callers can distinguish 'not found' errors.
return nil, err
}
- // Lock the container metadata to prevent other runsc instances from
- // writing to it while we are reading it.
- unlock, err := lockContainerMetadata(cRoot)
- if err != nil {
- return nil, err
+ state := StateFile{
+ RootDir: rootDir,
+ ID: id,
}
- defer unlock()
+ defer state.close()
- // Read the container metadata file and create a new Container from it.
- metaFile := filepath.Join(cRoot, metadataFilename)
- metaBytes, err := ioutil.ReadFile(metaFile)
- if err != nil {
+ c := &Container{}
+ if err := state.load(c); err != nil {
if os.IsNotExist(err) {
// Preserve error so that callers can distinguish 'not found' errors.
return nil, err
}
- return nil, fmt.Errorf("reading container metadata file %q: %v", metaFile, err)
- }
- var c Container
- if err := json.Unmarshal(metaBytes, &c); err != nil {
- return nil, fmt.Errorf("unmarshaling container metadata from %q: %v", metaFile, err)
+ return nil, fmt.Errorf("reading container metadata file %q: %v", state.statePath(), err)
}
// If the status is "Running" or "Created", check that the sandbox
@@ -223,57 +199,37 @@ func Load(rootDir, id string) (*Container, error) {
}
}
- return &c, nil
+ return c, nil
}
-func findContainerRoot(rootDir, partialID string) (string, error) {
+func findContainerID(rootDir, partialID string) (string, error) {
// Check whether the id fully specifies an existing container.
- cRoot := filepath.Join(rootDir, partialID)
- if _, err := os.Stat(cRoot); err == nil {
- return cRoot, nil
+ stateFile := buildStatePath(rootDir, partialID)
+ if _, err := os.Stat(stateFile); err == nil {
+ return partialID, nil
}
// Now see whether id could be an abbreviation of exactly 1 of the
// container ids. If id is ambiguous (it could match more than 1
// container), it is an error.
- cRoot = ""
ids, err := List(rootDir)
if err != nil {
return "", err
}
+ rv := ""
for _, id := range ids {
if strings.HasPrefix(id, partialID) {
- if cRoot != "" {
- return "", fmt.Errorf("id %q is ambiguous and could refer to multiple containers: %q, %q", partialID, cRoot, id)
+ if rv != "" {
+ return "", fmt.Errorf("id %q is ambiguous and could refer to multiple containers: %q, %q", partialID, rv, id)
}
- cRoot = id
+ rv = id
}
}
- if cRoot == "" {
+ if rv == "" {
return "", os.ErrNotExist
}
- log.Debugf("abbreviated id %q resolves to full id %q", partialID, cRoot)
- return filepath.Join(rootDir, cRoot), nil
-}
-
-// List returns all container ids in the given root directory.
-func List(rootDir string) ([]string, error) {
- log.Debugf("List containers %q", rootDir)
- fs, err := ioutil.ReadDir(rootDir)
- if err != nil {
- return nil, fmt.Errorf("reading dir %q: %v", rootDir, err)
- }
- var out []string
- for _, f := range fs {
- // Filter out directories that do no belong to a container.
- cid := f.Name()
- if validateID(cid) == nil {
- if _, err := os.Stat(filepath.Join(rootDir, cid, metadataFilename)); err == nil {
- out = append(out, f.Name())
- }
- }
- }
- return out, nil
+ log.Debugf("abbreviated id %q resolves to full id %q", partialID, rv)
+ return rv, nil
}
// Args is used to configure a new container.
@@ -316,44 +272,34 @@ func New(conf *boot.Config, args Args) (*Container, error) {
return nil, err
}
- unlockRoot, err := maybeLockRootContainer(args.Spec, conf.RootDir)
- if err != nil {
- return nil, err
+ if err := os.MkdirAll(conf.RootDir, 0711); err != nil {
+ return nil, fmt.Errorf("creating container root directory: %v", err)
}
- defer unlockRoot()
+
+ c := &Container{
+ ID: args.ID,
+ Spec: args.Spec,
+ ConsoleSocket: args.ConsoleSocket,
+ BundleDir: args.BundleDir,
+ Status: Creating,
+ CreatedAt: time.Now(),
+ Owner: os.Getenv("USER"),
+ Saver: StateFile{
+ RootDir: conf.RootDir,
+ ID: args.ID,
+ },
+ }
+ // The Cleanup object cleans up partially created containers when an error
+ // occurs. Any errors occurring during cleanup itself are ignored.
+ cu := specutils.MakeCleanup(func() { _ = c.Destroy() })
+ defer cu.Clean()
// Lock the container metadata file to prevent concurrent creations of
// containers with the same id.
- containerRoot := filepath.Join(conf.RootDir, args.ID)
- unlock, err := lockContainerMetadata(containerRoot)
- if err != nil {
+ if err := c.Saver.lockForNew(); err != nil {
return nil, err
}
- defer unlock()
-
- // Check if the container already exists by looking for the metadata
- // file.
- if _, err := os.Stat(filepath.Join(containerRoot, metadataFilename)); err == nil {
- return nil, fmt.Errorf("container with id %q already exists", args.ID)
- } else if !os.IsNotExist(err) {
- return nil, fmt.Errorf("looking for existing container in %q: %v", containerRoot, err)
- }
-
- c := &Container{
- ID: args.ID,
- Spec: args.Spec,
- ConsoleSocket: args.ConsoleSocket,
- BundleDir: args.BundleDir,
- Root: containerRoot,
- Status: Creating,
- CreatedAt: time.Now(),
- Owner: os.Getenv("USER"),
- RootContainerDir: conf.RootDir,
- }
- // The Cleanup object cleans up partially created containers when an error occurs.
- // Any errors occuring during cleanup itself are ignored.
- cu := specutils.MakeCleanup(func() { _ = c.Destroy() })
- defer cu.Clean()
+ defer c.Saver.unlock()
// If the metadata annotations indicate that this container should be
// started in an existing sandbox, we must do so. The metadata will
@@ -431,7 +377,7 @@ func New(conf *boot.Config, args Args) (*Container, error) {
c.changeStatus(Created)
// Save the metadata file.
- if err := c.save(); err != nil {
+ if err := c.saveLocked(); err != nil {
return nil, err
}
@@ -451,17 +397,12 @@ func New(conf *boot.Config, args Args) (*Container, error) {
func (c *Container) Start(conf *boot.Config) error {
log.Debugf("Start container %q", c.ID)
- unlockRoot, err := maybeLockRootContainer(c.Spec, c.RootContainerDir)
- if err != nil {
+ if err := c.Saver.lock(); err != nil {
return err
}
- defer unlockRoot()
+ unlock := specutils.MakeCleanup(func() { c.Saver.unlock() })
+ defer unlock.Clean()
- unlock, err := c.lock()
- if err != nil {
- return err
- }
- defer unlock()
if err := c.requireStatus("start", Created); err != nil {
return err
}
@@ -509,14 +450,15 @@ func (c *Container) Start(conf *boot.Config) error {
}
c.changeStatus(Running)
- if err := c.save(); err != nil {
+ if err := c.saveLocked(); err != nil {
return err
}
- // Adjust the oom_score_adj for sandbox. This must be done after
- // save().
- err = adjustSandboxOOMScoreAdj(c.Sandbox, c.RootContainerDir, false)
- if err != nil {
+ // Release lock before adjusting OOM score because the lock is acquired there.
+ unlock.Clean()
+
+ // Adjust the oom_score_adj for sandbox. This must be done after saveLocked().
+ if err := adjustSandboxOOMScoreAdj(c.Sandbox, c.Saver.RootDir, false); err != nil {
return err
}
@@ -529,11 +471,10 @@ func (c *Container) Start(conf *boot.Config) error {
// to restore a container from its state file.
func (c *Container) Restore(spec *specs.Spec, conf *boot.Config, restoreFile string) error {
log.Debugf("Restore container %q", c.ID)
- unlock, err := c.lock()
- if err != nil {
+ if err := c.Saver.lock(); err != nil {
return err
}
- defer unlock()
+ defer c.Saver.unlock()
if err := c.requireStatus("restore", Created); err != nil {
return err
@@ -551,7 +492,7 @@ func (c *Container) Restore(spec *specs.Spec, conf *boot.Config, restoreFile str
return err
}
c.changeStatus(Running)
- return c.save()
+ return c.saveLocked()
}
// Run is a helper that calls Create + Start + Wait.
@@ -711,11 +652,10 @@ func (c *Container) Checkpoint(f *os.File) error {
// The call only succeeds if the container's status is created or running.
func (c *Container) Pause() error {
log.Debugf("Pausing container %q", c.ID)
- unlock, err := c.lock()
- if err != nil {
+ if err := c.Saver.lock(); err != nil {
return err
}
- defer unlock()
+ defer c.Saver.unlock()
if c.Status != Created && c.Status != Running {
return fmt.Errorf("cannot pause container %q in state %v", c.ID, c.Status)
@@ -725,18 +665,17 @@ func (c *Container) Pause() error {
return fmt.Errorf("pausing container: %v", err)
}
c.changeStatus(Paused)
- return c.save()
+ return c.saveLocked()
}
// Resume unpauses the container and its kernel.
// The call only succeeds if the container's status is paused.
func (c *Container) Resume() error {
log.Debugf("Resuming container %q", c.ID)
- unlock, err := c.lock()
- if err != nil {
+ if err := c.Saver.lock(); err != nil {
return err
}
- defer unlock()
+ defer c.Saver.unlock()
if c.Status != Paused {
return fmt.Errorf("cannot resume container %q in state %v", c.ID, c.Status)
@@ -745,7 +684,7 @@ func (c *Container) Resume() error {
return fmt.Errorf("resuming container: %v", err)
}
c.changeStatus(Running)
- return c.save()
+ return c.saveLocked()
}
// State returns the metadata of the container.
@@ -773,6 +712,17 @@ func (c *Container) Processes() ([]*control.Process, error) {
func (c *Container) Destroy() error {
log.Debugf("Destroy container %q", c.ID)
+ if err := c.Saver.lock(); err != nil {
+ return err
+ }
+ defer func() {
+ c.Saver.unlock()
+ c.Saver.close()
+ }()
+
+ // Stored for later use as stop() sets c.Sandbox to nil.
+ sb := c.Sandbox
+
// We must perform the following cleanup steps:
// * stop the container and gofer processes,
// * remove the container filesystem on the host, and
@@ -782,48 +732,43 @@ func (c *Container) Destroy() error {
// do our best to perform all of the cleanups. Hence, we keep a slice
// of errors return their concatenation.
var errs []string
-
- unlock, err := maybeLockRootContainer(c.Spec, c.RootContainerDir)
- if err != nil {
- return err
- }
- defer unlock()
-
- // Stored for later use as stop() sets c.Sandbox to nil.
- sb := c.Sandbox
-
if err := c.stop(); err != nil {
err = fmt.Errorf("stopping container: %v", err)
log.Warningf("%v", err)
errs = append(errs, err.Error())
}
- if err := os.RemoveAll(c.Root); err != nil && !os.IsNotExist(err) {
- err = fmt.Errorf("deleting container root directory %q: %v", c.Root, err)
+ if err := c.Saver.destroy(); err != nil {
+ err = fmt.Errorf("deleting container state files: %v", err)
log.Warningf("%v", err)
errs = append(errs, err.Error())
}
c.changeStatus(Stopped)
- // Adjust oom_score_adj for the sandbox. This must be done after the
- // container is stopped and the directory at c.Root is removed.
- // We must test if the sandbox is nil because Destroy should be
- // idempotent.
- if sb != nil {
- if err := adjustSandboxOOMScoreAdj(sb, c.RootContainerDir, true); err != nil {
+ // Adjust oom_score_adj for the sandbox. This must be done after the container
+ // is stopped and the directory at c.Root is removed. Adjustment can be
+ // skipped if the root container is exiting, because it brings down the entire
+ // sandbox.
+ //
+ // Use 'sb' to tell whether it has been executed before because Destroy must
+ // be idempotent.
+ if sb != nil && !isRoot(c.Spec) {
+ if err := adjustSandboxOOMScoreAdj(sb, c.Saver.RootDir, true); err != nil {
errs = append(errs, err.Error())
}
}
// "If any poststop hook fails, the runtime MUST log a warning, but the
- // remaining hooks and lifecycle continue as if the hook had succeeded" -OCI spec.
- // Based on the OCI, "The post-stop hooks MUST be called after the container is
- // deleted but before the delete operation returns"
+ // remaining hooks and lifecycle continue as if the hook had
+ // succeeded" - OCI spec.
+ //
+ // Based on the OCI, "The post-stop hooks MUST be called after the container
+ // is deleted but before the delete operation returns"
// Run it here to:
// 1) Conform to the OCI.
- // 2) Make sure it only runs once, because the root has been deleted, the container
- // can't be loaded again.
+ // 2) Make sure it only runs once, because the root has been deleted, the
+ // container can't be loaded again.
if c.Spec.Hooks != nil {
executeHooksBestEffort(c.Spec.Hooks.Poststop, c.State())
}
@@ -834,18 +779,13 @@ func (c *Container) Destroy() error {
return fmt.Errorf(strings.Join(errs, "\n"))
}
-// save saves the container metadata to a file.
+// saveLocked saves the container metadata to a file.
//
// Precondition: container must be locked with container.lock().
-func (c *Container) save() error {
+func (c *Container) saveLocked() error {
log.Debugf("Save container %q", c.ID)
- metaFile := filepath.Join(c.Root, metadataFilename)
- meta, err := json.Marshal(c)
- if err != nil {
- return fmt.Errorf("invalid container metadata: %v", err)
- }
- if err := ioutil.WriteFile(metaFile, meta, 0640); err != nil {
- return fmt.Errorf("writing container metadata: %v", err)
+ if err := c.Saver.saveLocked(c); err != nil {
+ return fmt.Errorf("saving container metadata: %v", err)
}
return nil
}
@@ -1106,48 +1046,6 @@ func (c *Container) requireStatus(action string, statuses ...Status) error {
return fmt.Errorf("cannot %s container %q in state %s", action, c.ID, c.Status)
}
-// lock takes a file lock on the container metadata lock file.
-func (c *Container) lock() (func() error, error) {
- return lockContainerMetadata(filepath.Join(c.Root, c.ID))
-}
-
-// lockContainerMetadata takes a file lock on the metadata lock file in the
-// given container root directory.
-func lockContainerMetadata(containerRootDir string) (func() error, error) {
- if err := os.MkdirAll(containerRootDir, 0711); err != nil {
- return nil, fmt.Errorf("creating container root directory %q: %v", containerRootDir, err)
- }
- f := filepath.Join(containerRootDir, metadataLockFilename)
- l := flock.NewFlock(f)
- if err := l.Lock(); err != nil {
- return nil, fmt.Errorf("acquiring lock on container lock file %q: %v", f, err)
- }
- return l.Unlock, nil
-}
-
-// maybeLockRootContainer locks the sandbox root container. It is used to
-// prevent races to create and delete child container sandboxes.
-func maybeLockRootContainer(spec *specs.Spec, rootDir string) (func() error, error) {
- if isRoot(spec) {
- return func() error { return nil }, nil
- }
-
- sbid, ok := specutils.SandboxID(spec)
- if !ok {
- return nil, fmt.Errorf("no sandbox ID found when locking root container")
- }
- sb, err := Load(rootDir, sbid)
- if err != nil {
- return nil, err
- }
-
- unlock, err := sb.lock()
- if err != nil {
- return nil, err
- }
- return unlock, nil
-}
-
func isRoot(spec *specs.Spec) bool {
return specutils.SpecContainerType(spec) != specutils.ContainerTypeContainer
}
@@ -1170,7 +1068,12 @@ func runInCgroup(cg *cgroup.Cgroup, fn func() error) error {
func (c *Container) adjustGoferOOMScoreAdj() error {
if c.GoferPid != 0 && c.Spec.Process.OOMScoreAdj != nil {
if err := setOOMScoreAdj(c.GoferPid, *c.Spec.Process.OOMScoreAdj); err != nil {
- return fmt.Errorf("setting gofer oom_score_adj for container %q: %v", c.ID, err)
+ // Ignore NotExist error because it can be returned when the sandbox
+ // exited while OOM score was being adjusted.
+ if !os.IsNotExist(err) {
+ return fmt.Errorf("setting gofer oom_score_adj for container %q: %v", c.ID, err)
+ }
+ log.Warningf("Gofer process (%d) not found setting oom_score_adj", c.GoferPid)
}
}
@@ -1252,7 +1155,12 @@ func adjustSandboxOOMScoreAdj(s *sandbox.Sandbox, rootDir string, destroy bool)
// Set the lowest of all containers oom_score_adj to the sandbox.
if err := setOOMScoreAdj(s.Pid, lowScore); err != nil {
- return fmt.Errorf("setting oom_score_adj for sandbox %q: %v", s.ID, err)
+ // Ignore NotExist error because it can be returned when the sandbox
+ // exited while OOM score was being adjusted.
+ if !os.IsNotExist(err) {
+ return fmt.Errorf("setting oom_score_adj for sandbox %q: %v", s.ID, err)
+ }
+ log.Warningf("Sandbox process (%d) not found setting oom_score_adj", s.Pid)
}
return nil
diff --git a/runsc/container/state_file.go b/runsc/container/state_file.go
new file mode 100644
index 000000000..d95151ea5
--- /dev/null
+++ b/runsc/container/state_file.go
@@ -0,0 +1,185 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package container
+
+import (
+ "encoding/json"
+ "fmt"
+ "io/ioutil"
+ "os"
+ "path/filepath"
+ "sync"
+
+ "github.com/gofrs/flock"
+ "gvisor.dev/gvisor/pkg/log"
+)
+
+const stateFileExtension = ".state"
+
+// StateFile handles load from/save to container state safely from multiple
+// processes. It uses a lock file to provide synchronization between operations.
+//
+// The lock file is located at: "${s.RootDir}/${s.ID}.lock".
+// The state file is located at: "${s.RootDir}/${s.ID}.state".
+type StateFile struct {
+ // RootDir is the directory containing the container metadata file.
+ RootDir string `json:"rootDir"`
+
+ // ID is the container ID.
+ ID string `json:"id"`
+
+ //
+ // Fields below this line are not saved in the state file and will not
+ // be preserved across commands.
+ //
+
+ once sync.Once
+ flock *flock.Flock
+}
+
+// List returns all container ids in the given root directory.
+func List(rootDir string) ([]string, error) {
+ log.Debugf("List containers %q", rootDir)
+ list, err := filepath.Glob(filepath.Join(rootDir, "*"+stateFileExtension))
+ if err != nil {
+ return nil, err
+ }
+ var out []string
+ for _, path := range list {
+ // Filter out files that do no belong to a container.
+ fileName := filepath.Base(path)
+ if len(fileName) < len(stateFileExtension) {
+ panic(fmt.Sprintf("invalid file match %q", path))
+ }
+ // Remove the extension.
+ cid := fileName[:len(fileName)-len(stateFileExtension)]
+ if validateID(cid) == nil {
+ out = append(out, cid)
+ }
+ }
+ return out, nil
+}
+
+// lock globally locks all locking operations for the container.
+func (s *StateFile) lock() error {
+ s.once.Do(func() {
+ s.flock = flock.NewFlock(s.lockPath())
+ })
+
+ if err := s.flock.Lock(); err != nil {
+ return fmt.Errorf("acquiring lock on %q: %v", s.flock, err)
+ }
+ return nil
+}
+
+// lockForNew acquires the lock and checks if the state file doesn't exist. This
+// is done to ensure that more than one creation didn't race to create
+// containers with the same ID.
+func (s *StateFile) lockForNew() error {
+ if err := s.lock(); err != nil {
+ return err
+ }
+
+ // Checks if the container already exists by looking for the metadata file.
+ if _, err := os.Stat(s.statePath()); err == nil {
+ s.unlock()
+ return fmt.Errorf("container already exists")
+ } else if !os.IsNotExist(err) {
+ s.unlock()
+ return fmt.Errorf("looking for existing container: %v", err)
+ }
+ return nil
+}
+
+// unlock globally unlocks all locking operations for the container.
+func (s *StateFile) unlock() error {
+ if !s.flock.Locked() {
+ panic("unlock called without lock held")
+ }
+
+ if err := s.flock.Unlock(); err != nil {
+ log.Warningf("Error to release lock on %q: %v", s.flock, err)
+ return fmt.Errorf("releasing lock on %q: %v", s.flock, err)
+ }
+ return nil
+}
+
+// saveLocked saves 'v' to the state file.
+//
+// Preconditions: lock() must been called before.
+func (s *StateFile) saveLocked(v interface{}) error {
+ if !s.flock.Locked() {
+ panic("saveLocked called without lock held")
+ }
+
+ meta, err := json.Marshal(v)
+ if err != nil {
+ return err
+ }
+ if err := ioutil.WriteFile(s.statePath(), meta, 0640); err != nil {
+ return fmt.Errorf("writing json file: %v", err)
+ }
+ return nil
+}
+
+func (s *StateFile) load(v interface{}) error {
+ if err := s.lock(); err != nil {
+ return err
+ }
+ defer s.unlock()
+
+ metaBytes, err := ioutil.ReadFile(s.statePath())
+ if err != nil {
+ return err
+ }
+ return json.Unmarshal(metaBytes, &v)
+}
+
+func (s *StateFile) close() error {
+ if s.flock == nil {
+ return nil
+ }
+ if s.flock.Locked() {
+ panic("Closing locked file")
+ }
+ return s.flock.Close()
+}
+
+func buildStatePath(rootDir, id string) string {
+ return filepath.Join(rootDir, id+stateFileExtension)
+}
+
+// statePath is the full path to the state file.
+func (s *StateFile) statePath() string {
+ return buildStatePath(s.RootDir, s.ID)
+}
+
+// lockPath is the full path to the lock file.
+func (s *StateFile) lockPath() string {
+ return filepath.Join(s.RootDir, s.ID+".lock")
+}
+
+// destroy deletes all state created by the stateFile. It may be called with the
+// lock file held. In that case, the lock file must still be unlocked and
+// properly closed after destroy returns.
+func (s *StateFile) destroy() error {
+ if err := os.Remove(s.statePath()); err != nil && !os.IsNotExist(err) {
+ return err
+ }
+ if err := os.Remove(s.lockPath()); err != nil && !os.IsNotExist(err) {
+ return err
+ }
+ return nil
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-15 23:28:20 +0000