kubo/repo/fsrepo/fsrepo.go

package fsrepo

import (
	"errors"
	"fmt"
	"io"
	"os"
	"path"
	"strconv"
	"sync"

	ds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
	levelds "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/leveldb"
	ldbopts "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/opt"
	repo "github.com/jbenet/go-ipfs/repo"
	"github.com/jbenet/go-ipfs/repo/common"
	config "github.com/jbenet/go-ipfs/repo/config"
	counter "github.com/jbenet/go-ipfs/repo/fsrepo/counter"
	lockfile "github.com/jbenet/go-ipfs/repo/fsrepo/lock"
	serialize "github.com/jbenet/go-ipfs/repo/fsrepo/serialize"
	dir "github.com/jbenet/go-ipfs/thirdparty/dir"
	"github.com/jbenet/go-ipfs/thirdparty/eventlog"
	u "github.com/jbenet/go-ipfs/util"
	util "github.com/jbenet/go-ipfs/util"
	ds2 "github.com/jbenet/go-ipfs/util/datastore2"
	debugerror "github.com/jbenet/go-ipfs/util/debugerror"
)

const (
	defaultDataStoreDirectory = "datastore"
)

var (

	// packageLock must be held to while performing any operation that modifies an
	// FSRepo's state field. This includes Init, Open, Close, and Remove.
	packageLock sync.Mutex // protects openersCounter and lockfiles
	// lockfiles holds references to the Closers that ensure that repos are
	// only accessed by one process at a time.
	lockfiles map[string]io.Closer
	// openersCounter prevents the fsrepo from being removed while there exist open
	// FSRepo handles. It also ensures that the Init is atomic.
	//
	// packageLock also protects numOpenedRepos
	//
	// If an operation is used when repo is Open and the operation does not
	// change the repo's state, the package lock does not need to be acquired.
	openersCounter *counter.Openers

	// protects dsOpenersCounter and datastores
	dsLock           sync.Mutex
	dsOpenersCounter *counter.Openers
	datastores       map[string]ds2.ThreadSafeDatastoreCloser
)

func init() {
	openersCounter = counter.NewOpenersCounter()
	lockfiles = make(map[string]io.Closer)

	dsOpenersCounter = counter.NewOpenersCounter()
	datastores = make(map[string]ds2.ThreadSafeDatastoreCloser)
}

// FSRepo represents an IPFS FileSystem Repo. It is safe for use by multiple
// callers.
type FSRepo struct {
	// state is the FSRepo's state (unopened, opened, closed)
	state state
	// path is the file-system path
	path string
	// config is set on Open, guarded by packageLock
	config *config.Config
	// ds is set on Open
	ds ds2.ThreadSafeDatastoreCloser
}

var _ repo.Repo = (*FSRepo)(nil)

// At returns a handle to an FSRepo at the provided |path|.
func At(repoPath string) *FSRepo {
	// This method must not have side-effects.
	return &FSRepo{
		path:  path.Clean(repoPath),
		state: unopened, // explicitly set for clarity
	}
}

// ConfigAt returns an error if the FSRepo at the given path is not
// initialized. This function allows callers to read the config file even when
// another process is running and holding the lock.
func ConfigAt(repoPath string) (*config.Config, error) {

	// packageLock must be held to ensure that the Read is atomic.
	packageLock.Lock()
	defer packageLock.Unlock()

	configFilename, err := config.Filename(repoPath)
	if err != nil {
		return nil, err
	}
	return serialize.Load(configFilename)
}

// configIsInitialized returns true if the repo is initialized at
// provided |path|.
func configIsInitialized(path string) bool {
	configFilename, err := config.Filename(path)
	if err != nil {
		return false
	}
	if !util.FileExists(configFilename) {
		return false
	}
	return true
}

func initConfig(path string, conf *config.Config) error {
	if configIsInitialized(path) {
		return nil
	}
	configFilename, err := config.Filename(path)
	if err != nil {
		return err
	}
	// initialization is the one time when it's okay to write to the config
	// without reading the config from disk and merging any user-provided keys
	// that may exist.
	if err := serialize.WriteConfigFile(configFilename, conf); err != nil {
		return err
	}
	return nil
}

// Init initializes a new FSRepo at the given path with the provided config.
// TODO add support for custom datastores.
func Init(repoPath string, conf *config.Config) error {

	// packageLock must be held to ensure that the repo is not initialized more
	// than once.
	packageLock.Lock()
	defer packageLock.Unlock()

	if isInitializedUnsynced(repoPath) {
		return nil
	}

	if err := initConfig(repoPath, conf); err != nil {
		return err
	}

	// The actual datastore contents are initialized lazily when Opened.
	// During Init, we merely check that the directory is writeable.
	p := path.Join(repoPath, defaultDataStoreDirectory)
	if err := dir.Writable(p); err != nil {
		return debugerror.Errorf("datastore: %s", err)
	}

	if err := dir.Writable(path.Join(repoPath, "logs")); err != nil {
		return err
	}

	return nil
}

// Remove recursively removes the FSRepo at |path|.
func Remove(repoPath string) error {
	repoPath = path.Clean(repoPath)

	// packageLock must be held to ensure that the repo is not removed while
	// being accessed by others.
	packageLock.Lock()
	defer packageLock.Unlock()

	if openersCounter.NumOpeners(repoPath) != 0 {
		return errors.New("repo in use")
	}
	return os.RemoveAll(repoPath)
}

// LockedByOtherProcess returns true if the FSRepo is locked by another
// process. If true, then the repo cannot be opened by this process.
func LockedByOtherProcess(repoPath string) bool {
	repoPath = path.Clean(repoPath)

	// packageLock must be held to check the number of openers.
	packageLock.Lock()
	defer packageLock.Unlock()

	// NB: the lock is only held when repos are Open
	return lockfile.Locked(repoPath) && openersCounter.NumOpeners(repoPath) == 0
}

// openConfig returns an error if the config file is not present.
func (r *FSRepo) openConfig() error {
	configFilename, err := config.Filename(r.path)
	if err != nil {
		return err
	}
	conf, err := serialize.Load(configFilename)
	if err != nil {
		return err
	}
	r.config = conf
	return nil
}

// openDatastore returns an error if the config file is not present.
func (r *FSRepo) openDatastore() error {
	dsLock.Lock()
	defer dsLock.Unlock()

	dsPath := path.Join(r.path, defaultDataStoreDirectory)

	// if no other goroutines have the datastore Open, initialize it and assign
	// it to the package-scoped map for the goroutines that follow.
	if dsOpenersCounter.NumOpeners(dsPath) == 0 {
		ds, err := levelds.NewDatastore(dsPath, &levelds.Options{
			Compression: ldbopts.NoCompression,
		})
		if err != nil {
			return debugerror.New("unable to open leveldb datastore")
		}
		datastores[dsPath] = ds
	}

	// get the datastore from the package-scoped map and record self as an
	// opener.
	ds, dsIsPresent := datastores[dsPath]
	if !dsIsPresent {
		// This indicates a programmer error has occurred.
		return errors.New("datastore should be available, but it isn't")
	}
	r.ds = ds
	dsOpenersCounter.AddOpener(dsPath) // only after success
	return nil
}

func configureEventLoggerAtRepoPath(c *config.Config, repoPath string) {
	eventlog.Configure(eventlog.LevelInfo)
	eventlog.Configure(eventlog.LdJSONFormatter)
	rotateConf := eventlog.LogRotatorConfig{
		Filename:   path.Join(repoPath, "logs", "events.log"),
		MaxSizeMB:  c.Log.MaxSizeMB,
		MaxBackups: c.Log.MaxBackups,
		MaxAgeDays: c.Log.MaxAgeDays,
	}
	eventlog.Configure(eventlog.OutputRotatingLogFile(rotateConf))
}

// Open returns an error if the repo is not initialized.
func (r *FSRepo) Open() error {

	// packageLock must be held to make sure that the repo is not destroyed by
	// another caller. It must not be released until initialization is complete
	// and the number of openers is incremeneted.
	packageLock.Lock()
	defer packageLock.Unlock()

	expPath, err := u.TildeExpansion(r.path)
	if err != nil {
		return err
	}
	r.path = expPath

	if r.state != unopened {
		return debugerror.Errorf("repo is %s", r.state)
	}
	if !isInitializedUnsynced(r.path) {
		return debugerror.New("ipfs not initialized, please run 'ipfs init'")
	}
	// check repo path, then check all constituent parts.
	// TODO acquire repo lock
	// TODO if err := initCheckDir(logpath); err != nil { // }
	if err := dir.Writable(r.path); err != nil {
		return err
	}

	if err := r.openConfig(); err != nil {
		return err
	}

	if err := r.openDatastore(); err != nil {
		return err
	}

	// log.Debugf("writing eventlogs to ...", c.path)
	configureEventLoggerAtRepoPath(r.config, r.path)

	return r.transitionToOpened()
}

func (r *FSRepo) closeDatastore() error {
	dsLock.Lock()
	defer dsLock.Unlock()

	dsPath := path.Join(r.path, defaultDataStoreDirectory)

	// decrement the Opener count. if this goroutine is the last, also close
	// the underlying datastore (and remove its reference from the map)

	dsOpenersCounter.RemoveOpener(dsPath)

	if dsOpenersCounter.NumOpeners(dsPath) == 0 {
		delete(datastores, dsPath) // remove the reference
		return r.ds.Close()
	}
	return nil
}

// Close closes the FSRepo, releasing held resources.
func (r *FSRepo) Close() error {
	packageLock.Lock()
	defer packageLock.Unlock()

	if r.state != opened {
		return debugerror.Errorf("repo is %s", r.state)
	}

	if err := r.closeDatastore(); err != nil {
		return err
	}

	// This code existed in the previous versions, but
	// EventlogComponent.Close was never called. Preserving here
	// pending further discussion.
	//
	// TODO It isn't part of the current contract, but callers may like for us
	// to disable logging once the component is closed.
	// eventlog.Configure(eventlog.Output(os.Stderr))

	return r.transitionToClosed()
}

// Config returns the FSRepo's config. This method must not be called if the
// repo is not open.
//
// Result when not Open is undefined. The method may panic if it pleases.
func (r *FSRepo) Config() *config.Config {

	// It is not necessary to hold the package lock since the repo is in an
	// opened state. The package lock is _not_ meant to ensure that the repo is
	// thread-safe. The package lock is only meant to guard againt removal and
	// coordinate the lockfile. However, we provide thread-safety to keep
	// things simple.
	packageLock.Lock()
	defer packageLock.Unlock()

	if r.state != opened {
		panic(fmt.Sprintln("repo is", r.state))
	}
	return r.config
}

// setConfigUnsynced is for private use.
func (r *FSRepo) setConfigUnsynced(updated *config.Config) error {
	configFilename, err := config.Filename(r.path)
	if err != nil {
		return err
	}
	// to avoid clobbering user-provided keys, must read the config from disk
	// as a map, write the updated struct values to the map and write the map
	// to disk.
	var mapconf map[string]interface{}
	if err := serialize.ReadConfigFile(configFilename, &mapconf); err != nil {
		return err
	}
	m, err := config.ToMap(updated)
	if err != nil {
		return err
	}
	for k, v := range m {
		mapconf[k] = v
	}
	if err := serialize.WriteConfigFile(configFilename, mapconf); err != nil {
		return err
	}
	*r.config = *updated // copy so caller cannot modify this private config
	return nil
}

// SetConfig updates the FSRepo's config.
func (r *FSRepo) SetConfig(updated *config.Config) error {

	// packageLock is held to provide thread-safety.
	packageLock.Lock()
	defer packageLock.Unlock()

	return r.setConfigUnsynced(updated)
}

// GetConfigKey retrieves only the value of a particular key.
func (r *FSRepo) GetConfigKey(key string) (interface{}, error) {
	packageLock.Lock()
	defer packageLock.Unlock()

	if r.state != opened {
		return nil, debugerror.Errorf("repo is %s", r.state)
	}

	filename, err := config.Filename(r.path)
	if err != nil {
		return nil, err
	}
	var cfg map[string]interface{}
	if err := serialize.ReadConfigFile(filename, &cfg); err != nil {
		return nil, err
	}
	return common.MapGetKV(cfg, key)
}

// SetConfigKey writes the value of a particular key.
func (r *FSRepo) SetConfigKey(key string, value interface{}) error {
	packageLock.Lock()
	defer packageLock.Unlock()

	if r.state != opened {
		return debugerror.Errorf("repo is %s", r.state)
	}

	filename, err := config.Filename(r.path)
	if err != nil {
		return err
	}
	switch v := value.(type) {
	case string:
		if i, err := strconv.Atoi(v); err == nil {
			value = i
		}
	}
	var mapconf map[string]interface{}
	if err := serialize.ReadConfigFile(filename, &mapconf); err != nil {
		return err
	}
	if err := common.MapSetKV(mapconf, key, value); err != nil {
		return err
	}
	conf, err := config.FromMap(mapconf)
	if err != nil {
		return err
	}
	if err := serialize.WriteConfigFile(filename, mapconf); err != nil {
		return err
	}
	return r.setConfigUnsynced(conf) // TODO roll this into this method
}

// Datastore returns a repo-owned datastore. If FSRepo is Closed, return value
// is undefined.
func (r *FSRepo) Datastore() ds.ThreadSafeDatastore {
	packageLock.Lock()
	d := r.ds
	packageLock.Unlock()
	return d
}

var _ io.Closer = &FSRepo{}
var _ repo.Repo = &FSRepo{}

// IsInitialized returns true if the repo is initialized at provided |path|.
func IsInitialized(path string) bool {
	// packageLock is held to ensure that another caller doesn't attempt to
	// Init or Remove the repo while this call is in progress.
	packageLock.Lock()
	defer packageLock.Unlock()

	return isInitializedUnsynced(path)
}

// private methods below this point. NB: packageLock must held by caller.

// isInitializedUnsynced reports whether the repo is initialized. Caller must
// hold the packageLock.
func isInitializedUnsynced(repoPath string) bool {
	if !configIsInitialized(repoPath) {
		return false
	}
	if !util.FileExists(path.Join(repoPath, defaultDataStoreDirectory)) {
		return false
	}
	return true
}

// transitionToOpened manages the state transition to |opened|. Caller must hold
// the package mutex.
func (r *FSRepo) transitionToOpened() error {
	r.state = opened
	if countBefore := openersCounter.NumOpeners(r.path); countBefore == 0 { // #first
		closer, err := lockfile.Lock(r.path)
		if err != nil {
			return err
		}
		lockfiles[r.path] = closer
	}
	return openersCounter.AddOpener(r.path)
}

// transitionToClosed manages the state transition to |closed|. Caller must
// hold the package mutex.
func (r *FSRepo) transitionToClosed() error {
	r.state = closed
	if err := openersCounter.RemoveOpener(r.path); err != nil {
		return err
	}
	if countAfter := openersCounter.NumOpeners(r.path); countAfter == 0 {
		closer, ok := lockfiles[r.path]
		if !ok {
			return errors.New("package error: lockfile is not held")
		}
		if err := closer.Close(); err != nil {
			return err
		}
		delete(lockfiles, r.path)
	}
	return nil
}