github.com/haliliceylan/bsc@v1.1.10-0.20220501224556-eb78d644ebcb/node/node.go (about)

     1  // Copyright 2015 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package node
    18  
    19  import (
    20  	"errors"
    21  	"fmt"
    22  	"net/http"
    23  	"os"
    24  	"path"
    25  	"path/filepath"
    26  	"reflect"
    27  	"strings"
    28  	"sync"
    29  
    30  	"github.com/prometheus/tsdb/fileutil"
    31  
    32  	"github.com/ethereum/go-ethereum/accounts"
    33  	"github.com/ethereum/go-ethereum/core/rawdb"
    34  	"github.com/ethereum/go-ethereum/ethdb"
    35  	"github.com/ethereum/go-ethereum/ethdb/leveldb"
    36  	"github.com/ethereum/go-ethereum/event"
    37  	"github.com/ethereum/go-ethereum/log"
    38  	"github.com/ethereum/go-ethereum/p2p"
    39  	"github.com/ethereum/go-ethereum/rpc"
    40  )
    41  
    42  // Node is a container on which services can be registered.
    43  type Node struct {
    44  	eventmux      *event.TypeMux
    45  	config        *Config
    46  	accman        *accounts.Manager
    47  	log           log.Logger
    48  	ephemKeystore string            // if non-empty, the key directory that will be removed by Stop
    49  	dirLock       fileutil.Releaser // prevents concurrent use of instance directory
    50  	stop          chan struct{}     // Channel to wait for termination notifications
    51  	server        *p2p.Server       // Currently running P2P networking layer
    52  	startStopLock sync.Mutex        // Start/Stop are protected by an additional lock
    53  	state         int               // Tracks state of node lifecycle
    54  
    55  	lock          sync.Mutex
    56  	lifecycles    []Lifecycle // All registered backends, services, and auxiliary services that have a lifecycle
    57  	rpcAPIs       []rpc.API   // List of APIs currently provided by the node
    58  	http          *httpServer //
    59  	ws            *httpServer //
    60  	ipc           *ipcServer  // Stores information about the ipc http server
    61  	inprocHandler *rpc.Server // In-process RPC request handler to process the API requests
    62  
    63  	databases map[*closeTrackingDB]struct{} // All open databases
    64  }
    65  
    66  const (
    67  	initializingState = iota
    68  	runningState
    69  	closedState
    70  )
    71  
    72  const chainDataHandlesPercentage = 80
    73  
    74  // New creates a new P2P node, ready for protocol registration.
    75  func New(conf *Config) (*Node, error) {
    76  	// Copy config and resolve the datadir so future changes to the current
    77  	// working directory don't affect the node.
    78  	confCopy := *conf
    79  	conf = &confCopy
    80  	if conf.DataDir != "" {
    81  		absdatadir, err := filepath.Abs(conf.DataDir)
    82  		if err != nil {
    83  			return nil, err
    84  		}
    85  		conf.DataDir = absdatadir
    86  	}
    87  	if conf.LogConfig != nil {
    88  		logFilePath := ""
    89  		if conf.LogConfig.FileRoot == "" {
    90  			logFilePath = path.Join(conf.DataDir, conf.LogConfig.FilePath)
    91  		} else {
    92  			logFilePath = path.Join(conf.LogConfig.FileRoot, conf.LogConfig.FilePath)
    93  		}
    94  		log.Root().SetHandler(log.NewFileLvlHandler(logFilePath, conf.LogConfig.MaxBytesSize, conf.LogConfig.Level))
    95  	}
    96  	if conf.Logger == nil {
    97  		conf.Logger = log.New()
    98  	}
    99  
   100  	// Ensure that the instance name doesn't cause weird conflicts with
   101  	// other files in the data directory.
   102  	if strings.ContainsAny(conf.Name, `/\`) {
   103  		return nil, errors.New(`Config.Name must not contain '/' or '\'`)
   104  	}
   105  	if conf.Name == datadirDefaultKeyStore {
   106  		return nil, errors.New(`Config.Name cannot be "` + datadirDefaultKeyStore + `"`)
   107  	}
   108  	if strings.HasSuffix(conf.Name, ".ipc") {
   109  		return nil, errors.New(`Config.Name cannot end in ".ipc"`)
   110  	}
   111  
   112  	node := &Node{
   113  		config:        conf,
   114  		inprocHandler: rpc.NewServer(),
   115  		eventmux:      new(event.TypeMux),
   116  		log:           conf.Logger,
   117  		stop:          make(chan struct{}),
   118  		server:        &p2p.Server{Config: conf.P2P},
   119  		databases:     make(map[*closeTrackingDB]struct{}),
   120  	}
   121  
   122  	// Register built-in APIs.
   123  	node.rpcAPIs = append(node.rpcAPIs, node.apis()...)
   124  
   125  	// Acquire the instance directory lock.
   126  	if err := node.openDataDir(); err != nil {
   127  		return nil, err
   128  	}
   129  	// Ensure that the AccountManager method works before the node has started. We rely on
   130  	// this in cmd/geth.
   131  	am, ephemeralKeystore, err := makeAccountManager(conf)
   132  	if err != nil {
   133  		return nil, err
   134  	}
   135  	node.accman = am
   136  	node.ephemKeystore = ephemeralKeystore
   137  
   138  	// Initialize the p2p server. This creates the node key and discovery databases.
   139  	node.server.Config.PrivateKey = node.config.NodeKey()
   140  	node.server.Config.Name = node.config.NodeName()
   141  	node.server.Config.Logger = node.log
   142  	if node.server.Config.StaticNodes == nil {
   143  		node.server.Config.StaticNodes = node.config.StaticNodes()
   144  	}
   145  	if node.server.Config.TrustedNodes == nil {
   146  		node.server.Config.TrustedNodes = node.config.TrustedNodes()
   147  	}
   148  	if node.server.Config.NodeDatabase == "" {
   149  		node.server.Config.NodeDatabase = node.config.NodeDB()
   150  	}
   151  
   152  	// Check HTTP/WS prefixes are valid.
   153  	if err := validatePrefix("HTTP", conf.HTTPPathPrefix); err != nil {
   154  		return nil, err
   155  	}
   156  	if err := validatePrefix("WebSocket", conf.WSPathPrefix); err != nil {
   157  		return nil, err
   158  	}
   159  
   160  	// Configure RPC servers.
   161  	node.http = newHTTPServer(node.log, conf.HTTPTimeouts)
   162  	node.ws = newHTTPServer(node.log, rpc.DefaultHTTPTimeouts)
   163  	node.ipc = newIPCServer(node.log, conf.IPCEndpoint())
   164  
   165  	return node, nil
   166  }
   167  
   168  // Start starts all registered lifecycles, RPC services and p2p networking.
   169  // Node can only be started once.
   170  func (n *Node) Start() error {
   171  	n.startStopLock.Lock()
   172  	defer n.startStopLock.Unlock()
   173  
   174  	n.lock.Lock()
   175  	switch n.state {
   176  	case runningState:
   177  		n.lock.Unlock()
   178  		return ErrNodeRunning
   179  	case closedState:
   180  		n.lock.Unlock()
   181  		return ErrNodeStopped
   182  	}
   183  	n.state = runningState
   184  	// open networking and RPC endpoints
   185  	err := n.openEndpoints()
   186  	lifecycles := make([]Lifecycle, len(n.lifecycles))
   187  	copy(lifecycles, n.lifecycles)
   188  	n.lock.Unlock()
   189  
   190  	// Check if endpoint startup failed.
   191  	if err != nil {
   192  		n.doClose(nil)
   193  		return err
   194  	}
   195  	// Start all registered lifecycles.
   196  	var started []Lifecycle
   197  	for _, lifecycle := range lifecycles {
   198  		if err = lifecycle.Start(); err != nil {
   199  			break
   200  		}
   201  		started = append(started, lifecycle)
   202  	}
   203  	// Check if any lifecycle failed to start.
   204  	if err != nil {
   205  		n.stopServices(started)
   206  		n.doClose(nil)
   207  	}
   208  	return err
   209  }
   210  
   211  // Close stops the Node and releases resources acquired in
   212  // Node constructor New.
   213  func (n *Node) Close() error {
   214  	n.startStopLock.Lock()
   215  	defer n.startStopLock.Unlock()
   216  
   217  	n.lock.Lock()
   218  	state := n.state
   219  	n.lock.Unlock()
   220  	switch state {
   221  	case initializingState:
   222  		// The node was never started.
   223  		return n.doClose(nil)
   224  	case runningState:
   225  		// The node was started, release resources acquired by Start().
   226  		var errs []error
   227  		if err := n.stopServices(n.lifecycles); err != nil {
   228  			errs = append(errs, err)
   229  		}
   230  		return n.doClose(errs)
   231  	case closedState:
   232  		return ErrNodeStopped
   233  	default:
   234  		panic(fmt.Sprintf("node is in unknown state %d", state))
   235  	}
   236  }
   237  
   238  // doClose releases resources acquired by New(), collecting errors.
   239  func (n *Node) doClose(errs []error) error {
   240  	// Close databases. This needs the lock because it needs to
   241  	// synchronize with OpenDatabase*.
   242  	n.lock.Lock()
   243  	n.state = closedState
   244  	errs = append(errs, n.closeDatabases()...)
   245  	n.lock.Unlock()
   246  
   247  	if err := n.accman.Close(); err != nil {
   248  		errs = append(errs, err)
   249  	}
   250  	if n.ephemKeystore != "" {
   251  		if err := os.RemoveAll(n.ephemKeystore); err != nil {
   252  			errs = append(errs, err)
   253  		}
   254  	}
   255  
   256  	// Release instance directory lock.
   257  	n.closeDataDir()
   258  
   259  	// Unblock n.Wait.
   260  	close(n.stop)
   261  
   262  	// Report any errors that might have occurred.
   263  	switch len(errs) {
   264  	case 0:
   265  		return nil
   266  	case 1:
   267  		return errs[0]
   268  	default:
   269  		return fmt.Errorf("%v", errs)
   270  	}
   271  }
   272  
   273  // openEndpoints starts all network and RPC endpoints.
   274  func (n *Node) openEndpoints() error {
   275  	// start networking endpoints
   276  	n.log.Info("Starting peer-to-peer node", "instance", n.server.Name)
   277  	if err := n.server.Start(); err != nil {
   278  		return convertFileLockError(err)
   279  	}
   280  	// start RPC endpoints
   281  	err := n.startRPC()
   282  	if err != nil {
   283  		n.stopRPC()
   284  		n.server.Stop()
   285  	}
   286  	return err
   287  }
   288  
   289  // containsLifecycle checks if 'lfs' contains 'l'.
   290  func containsLifecycle(lfs []Lifecycle, l Lifecycle) bool {
   291  	for _, obj := range lfs {
   292  		if obj == l {
   293  			return true
   294  		}
   295  	}
   296  	return false
   297  }
   298  
   299  // stopServices terminates running services, RPC and p2p networking.
   300  // It is the inverse of Start.
   301  func (n *Node) stopServices(running []Lifecycle) error {
   302  	n.stopRPC()
   303  
   304  	// Stop running lifecycles in reverse order.
   305  	failure := &StopError{Services: make(map[reflect.Type]error)}
   306  	for i := len(running) - 1; i >= 0; i-- {
   307  		if err := running[i].Stop(); err != nil {
   308  			failure.Services[reflect.TypeOf(running[i])] = err
   309  		}
   310  	}
   311  
   312  	// Stop p2p networking.
   313  	n.server.Stop()
   314  
   315  	if len(failure.Services) > 0 {
   316  		return failure
   317  	}
   318  	return nil
   319  }
   320  
   321  func (n *Node) openDataDir() error {
   322  	if n.config.DataDir == "" {
   323  		return nil // ephemeral
   324  	}
   325  
   326  	instdir := filepath.Join(n.config.DataDir, n.config.name())
   327  	if err := os.MkdirAll(instdir, 0700); err != nil {
   328  		return err
   329  	}
   330  	// Lock the instance directory to prevent concurrent use by another instance as well as
   331  	// accidental use of the instance directory as a database.
   332  	release, _, err := fileutil.Flock(filepath.Join(instdir, "LOCK"))
   333  	if err != nil {
   334  		return convertFileLockError(err)
   335  	}
   336  	n.dirLock = release
   337  	return nil
   338  }
   339  
   340  func (n *Node) closeDataDir() {
   341  	// Release instance directory lock.
   342  	if n.dirLock != nil {
   343  		if err := n.dirLock.Release(); err != nil {
   344  			n.log.Error("Can't release datadir lock", "err", err)
   345  		}
   346  		n.dirLock = nil
   347  	}
   348  }
   349  
   350  // configureRPC is a helper method to configure all the various RPC endpoints during node
   351  // startup. It's not meant to be called at any time afterwards as it makes certain
   352  // assumptions about the state of the node.
   353  func (n *Node) startRPC() error {
   354  	if err := n.startInProc(); err != nil {
   355  		return err
   356  	}
   357  
   358  	// Configure IPC.
   359  	if n.ipc.endpoint != "" {
   360  		if err := n.ipc.start(n.rpcAPIs); err != nil {
   361  			return err
   362  		}
   363  	}
   364  
   365  	// Configure HTTP.
   366  	if n.config.HTTPHost != "" {
   367  		config := httpConfig{
   368  			CorsAllowedOrigins: n.config.HTTPCors,
   369  			Vhosts:             n.config.HTTPVirtualHosts,
   370  			Modules:            n.config.HTTPModules,
   371  			prefix:             n.config.HTTPPathPrefix,
   372  		}
   373  		if err := n.http.setListenAddr(n.config.HTTPHost, n.config.HTTPPort); err != nil {
   374  			return err
   375  		}
   376  		if err := n.http.enableRPC(n.rpcAPIs, config); err != nil {
   377  			return err
   378  		}
   379  	}
   380  
   381  	// Configure WebSocket.
   382  	if n.config.WSHost != "" {
   383  		server := n.wsServerForPort(n.config.WSPort)
   384  		config := wsConfig{
   385  			Modules: n.config.WSModules,
   386  			Origins: n.config.WSOrigins,
   387  			prefix:  n.config.WSPathPrefix,
   388  		}
   389  		if err := server.setListenAddr(n.config.WSHost, n.config.WSPort); err != nil {
   390  			return err
   391  		}
   392  		if err := server.enableWS(n.rpcAPIs, config); err != nil {
   393  			return err
   394  		}
   395  	}
   396  
   397  	if err := n.http.start(); err != nil {
   398  		return err
   399  	}
   400  	return n.ws.start()
   401  }
   402  
   403  func (n *Node) wsServerForPort(port int) *httpServer {
   404  	if n.config.HTTPHost == "" || n.http.port == port {
   405  		return n.http
   406  	}
   407  	return n.ws
   408  }
   409  
   410  func (n *Node) stopRPC() {
   411  	n.http.stop()
   412  	n.ws.stop()
   413  	n.ipc.stop()
   414  	n.stopInProc()
   415  }
   416  
   417  // startInProc registers all RPC APIs on the inproc server.
   418  func (n *Node) startInProc() error {
   419  	for _, api := range n.rpcAPIs {
   420  		if err := n.inprocHandler.RegisterName(api.Namespace, api.Service); err != nil {
   421  			return err
   422  		}
   423  	}
   424  	return nil
   425  }
   426  
   427  // stopInProc terminates the in-process RPC endpoint.
   428  func (n *Node) stopInProc() {
   429  	n.inprocHandler.Stop()
   430  }
   431  
   432  // Wait blocks until the node is closed.
   433  func (n *Node) Wait() {
   434  	<-n.stop
   435  }
   436  
   437  // RegisterLifecycle registers the given Lifecycle on the node.
   438  func (n *Node) RegisterLifecycle(lifecycle Lifecycle) {
   439  	n.lock.Lock()
   440  	defer n.lock.Unlock()
   441  
   442  	if n.state != initializingState {
   443  		panic("can't register lifecycle on running/stopped node")
   444  	}
   445  	if containsLifecycle(n.lifecycles, lifecycle) {
   446  		panic(fmt.Sprintf("attempt to register lifecycle %T more than once", lifecycle))
   447  	}
   448  	n.lifecycles = append(n.lifecycles, lifecycle)
   449  }
   450  
   451  // RegisterProtocols adds backend's protocols to the node's p2p server.
   452  func (n *Node) RegisterProtocols(protocols []p2p.Protocol) {
   453  	n.lock.Lock()
   454  	defer n.lock.Unlock()
   455  
   456  	if n.state != initializingState {
   457  		panic("can't register protocols on running/stopped node")
   458  	}
   459  	n.server.Protocols = append(n.server.Protocols, protocols...)
   460  }
   461  
   462  // RegisterAPIs registers the APIs a service provides on the node.
   463  func (n *Node) RegisterAPIs(apis []rpc.API) {
   464  	n.lock.Lock()
   465  	defer n.lock.Unlock()
   466  
   467  	if n.state != initializingState {
   468  		panic("can't register APIs on running/stopped node")
   469  	}
   470  	n.rpcAPIs = append(n.rpcAPIs, apis...)
   471  }
   472  
   473  // RegisterHandler mounts a handler on the given path on the canonical HTTP server.
   474  //
   475  // The name of the handler is shown in a log message when the HTTP server starts
   476  // and should be a descriptive term for the service provided by the handler.
   477  func (n *Node) RegisterHandler(name, path string, handler http.Handler) {
   478  	n.lock.Lock()
   479  	defer n.lock.Unlock()
   480  
   481  	if n.state != initializingState {
   482  		panic("can't register HTTP handler on running/stopped node")
   483  	}
   484  
   485  	n.http.mux.Handle(path, handler)
   486  	n.http.handlerNames[path] = name
   487  }
   488  
   489  // Attach creates an RPC client attached to an in-process API handler.
   490  func (n *Node) Attach() (*rpc.Client, error) {
   491  	return rpc.DialInProc(n.inprocHandler), nil
   492  }
   493  
   494  // RPCHandler returns the in-process RPC request handler.
   495  func (n *Node) RPCHandler() (*rpc.Server, error) {
   496  	n.lock.Lock()
   497  	defer n.lock.Unlock()
   498  
   499  	if n.state == closedState {
   500  		return nil, ErrNodeStopped
   501  	}
   502  	return n.inprocHandler, nil
   503  }
   504  
   505  // Config returns the configuration of node.
   506  func (n *Node) Config() *Config {
   507  	return n.config
   508  }
   509  
   510  // Server retrieves the currently running P2P network layer. This method is meant
   511  // only to inspect fields of the currently running server. Callers should not
   512  // start or stop the returned server.
   513  func (n *Node) Server() *p2p.Server {
   514  	n.lock.Lock()
   515  	defer n.lock.Unlock()
   516  
   517  	return n.server
   518  }
   519  
   520  // DataDir retrieves the current datadir used by the protocol stack.
   521  // Deprecated: No files should be stored in this directory, use InstanceDir instead.
   522  func (n *Node) DataDir() string {
   523  	return n.config.DataDir
   524  }
   525  
   526  // InstanceDir retrieves the instance directory used by the protocol stack.
   527  func (n *Node) InstanceDir() string {
   528  	return n.config.instanceDir()
   529  }
   530  
   531  // AccountManager retrieves the account manager used by the protocol stack.
   532  func (n *Node) AccountManager() *accounts.Manager {
   533  	return n.accman
   534  }
   535  
   536  // IPCEndpoint retrieves the current IPC endpoint used by the protocol stack.
   537  func (n *Node) IPCEndpoint() string {
   538  	return n.ipc.endpoint
   539  }
   540  
   541  // HTTPEndpoint returns the URL of the HTTP server. Note that this URL does not
   542  // contain the JSON-RPC path prefix set by HTTPPathPrefix.
   543  func (n *Node) HTTPEndpoint() string {
   544  	return "http://" + n.http.listenAddr()
   545  }
   546  
   547  // WSEndpoint returns the current JSON-RPC over WebSocket endpoint.
   548  func (n *Node) WSEndpoint() string {
   549  	if n.http.wsAllowed() {
   550  		return "ws://" + n.http.listenAddr() + n.http.wsConfig.prefix
   551  	}
   552  	return "ws://" + n.ws.listenAddr() + n.ws.wsConfig.prefix
   553  }
   554  
   555  // EventMux retrieves the event multiplexer used by all the network services in
   556  // the current protocol stack.
   557  func (n *Node) EventMux() *event.TypeMux {
   558  	return n.eventmux
   559  }
   560  
   561  // OpenDatabase opens an existing database with the given name (or creates one if no
   562  // previous can be found) from within the node's instance directory. If the node is
   563  // ephemeral, a memory database is returned.
   564  func (n *Node) OpenDatabase(name string, cache, handles int, namespace string, readonly bool) (ethdb.Database, error) {
   565  	n.lock.Lock()
   566  	defer n.lock.Unlock()
   567  	if n.state == closedState {
   568  		return nil, ErrNodeStopped
   569  	}
   570  
   571  	var db ethdb.Database
   572  	var err error
   573  	if n.config.DataDir == "" {
   574  		db = rawdb.NewMemoryDatabase()
   575  	} else {
   576  		db, err = rawdb.NewLevelDBDatabase(n.ResolvePath(name), cache, handles, namespace, readonly)
   577  	}
   578  
   579  	if err == nil {
   580  		db = n.wrapDatabase(db)
   581  	}
   582  	return db, err
   583  }
   584  
   585  func (n *Node) OpenAndMergeDatabase(name string, cache, handles int, freezer, diff, namespace string, readonly, persistDiff bool) (ethdb.Database, error) {
   586  	chainDataHandles := handles
   587  	if persistDiff {
   588  		chainDataHandles = handles * chainDataHandlesPercentage / 100
   589  	}
   590  	chainDB, err := n.OpenDatabaseWithFreezer(name, cache, chainDataHandles, freezer, namespace, readonly, false, false)
   591  	if err != nil {
   592  		return nil, err
   593  	}
   594  	if persistDiff {
   595  		diffStore, err := n.OpenDiffDatabase(name, handles-chainDataHandles, diff, namespace, readonly)
   596  		if err != nil {
   597  			chainDB.Close()
   598  			return nil, err
   599  		}
   600  		chainDB.SetDiffStore(diffStore)
   601  	}
   602  	return chainDB, nil
   603  }
   604  
   605  // OpenDatabaseWithFreezer opens an existing database with the given name (or
   606  // creates one if no previous can be found) from within the node's data directory,
   607  // also attaching a chain freezer to it that moves ancient chain data from the
   608  // database to immutable append-only files. If the node is an ephemeral one, a
   609  // memory database is returned.
   610  func (n *Node) OpenDatabaseWithFreezer(name string, cache, handles int, freezer, namespace string, readonly, disableFreeze, isLastOffset bool) (ethdb.Database, error) {
   611  	n.lock.Lock()
   612  	defer n.lock.Unlock()
   613  	if n.state == closedState {
   614  		return nil, ErrNodeStopped
   615  	}
   616  
   617  	var db ethdb.Database
   618  	var err error
   619  	if n.config.DataDir == "" {
   620  		db = rawdb.NewMemoryDatabase()
   621  	} else {
   622  		root := n.ResolvePath(name)
   623  		switch {
   624  		case freezer == "":
   625  			freezer = filepath.Join(root, "ancient")
   626  		case !filepath.IsAbs(freezer):
   627  			freezer = n.ResolvePath(freezer)
   628  		}
   629  		db, err = rawdb.NewLevelDBDatabaseWithFreezer(root, cache, handles, freezer, namespace, readonly, disableFreeze, isLastOffset)
   630  	}
   631  
   632  	if err == nil {
   633  		db = n.wrapDatabase(db)
   634  	}
   635  	return db, err
   636  }
   637  
   638  func (n *Node) OpenDiffDatabase(name string, handles int, diff, namespace string, readonly bool) (*leveldb.Database, error) {
   639  	n.lock.Lock()
   640  	defer n.lock.Unlock()
   641  	if n.state == closedState {
   642  		return nil, ErrNodeStopped
   643  	}
   644  
   645  	var db *leveldb.Database
   646  	var err error
   647  	if n.config.DataDir == "" {
   648  		panic("datadir is missing")
   649  	}
   650  	root := n.ResolvePath(name)
   651  	switch {
   652  	case diff == "":
   653  		diff = filepath.Join(root, "diff")
   654  	case !filepath.IsAbs(diff):
   655  		diff = n.ResolvePath(diff)
   656  	}
   657  	db, err = leveldb.New(diff, 0, handles, namespace, readonly)
   658  
   659  	return db, err
   660  }
   661  
   662  // ResolvePath returns the absolute path of a resource in the instance directory.
   663  func (n *Node) ResolvePath(x string) string {
   664  	return n.config.ResolvePath(x)
   665  }
   666  
   667  // closeTrackingDB wraps the Close method of a database. When the database is closed by the
   668  // service, the wrapper removes it from the node's database map. This ensures that Node
   669  // won't auto-close the database if it is closed by the service that opened it.
   670  type closeTrackingDB struct {
   671  	ethdb.Database
   672  	n *Node
   673  }
   674  
   675  func (db *closeTrackingDB) Close() error {
   676  	db.n.lock.Lock()
   677  	delete(db.n.databases, db)
   678  	db.n.lock.Unlock()
   679  	return db.Database.Close()
   680  }
   681  
   682  // wrapDatabase ensures the database will be auto-closed when Node is closed.
   683  func (n *Node) wrapDatabase(db ethdb.Database) ethdb.Database {
   684  	wrapper := &closeTrackingDB{db, n}
   685  	n.databases[wrapper] = struct{}{}
   686  	return wrapper
   687  }
   688  
   689  // closeDatabases closes all open databases.
   690  func (n *Node) closeDatabases() (errors []error) {
   691  	for db := range n.databases {
   692  		delete(n.databases, db)
   693  		if err := db.Database.Close(); err != nil {
   694  			errors = append(errors, err)
   695  		}
   696  	}
   697  	return errors
   698  }