node

package
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 Go to latest Published: Feb 13, 2022 License: GPL-3.0 Imports: 33 Imported by: 1

Documentation

Overview

Package node sets up multi-protocol Core nodes.

In the model exposed by this package, a node is a collection of services which use shared resources to provide RPC APIs. Services can also offer devp2p protocols, which are wired up to the devp2p network when the node instance is started.

Resources Managed By Node

All file-system resources used by a node instance are located in a directory called the data directory. The location of each resource can be overridden through additional node configuration. The data directory is optional. If it is not set and the location of a resource is otherwise unspecified, package node will create the resource in memory.

To access to the devp2p network, Node configures and starts p2p.Server. Each host on the devp2p network has a unique identifier, the node key. The Node instance persists this key across restarts. Node also loads static and trusted node lists and ensures that knowledge about other hosts is persisted.

JSON-RPC servers which run HTTP, WebSocket or IPC can be started on a Node. RPC modules offered by registered services will be offered on those endpoints. Users can restrict any endpoint to a subset of RPC modules. Node itself offers the "debug", "admin" and "web3" modules.

Service implementations can open LevelDB databases through the service context. Package node chooses the file system location of each database. If the node is configured to run without a data directory, databases are opened in memory instead.

Node also creates the shared store of encrypted Core account keys. Services can access the account manager through the service context.

Sharing Data Directory Among Instances

Multiple node instances can share a single data directory if they have distinct instance names (set through the Name config option). Sharing behaviour depends on the type of resource.

devp2p-related resources (node key, static/trusted node lists, known hosts database) are stored in a directory with the same name as the instance. Thus, multiple node instances using the same data directory will store this information in different subdirectories of the data directory.

LevelDB databases are also stored within the instance subdirectory. If multiple node instances use the same data directory, opening the databases with identical names will create one database for each instance.

The account key store is shared among all node instances using the same data directory unless its location is changed through the KeyStoreDir configuration option.

Data Directory Sharing Example

In this example, two node instances named A and B are started with the same data directory. Node instance A opens the database "db", node instance B opens the databases "db" and "db-2". The following files will be created in the data directory: 

data-directory/
     A/
         nodekey            -- devp2p node key of instance A
         nodes/             -- devp2p discovery knowledge database of instance A
         db/                -- LevelDB content for "db"
     A.ipc                  -- JSON-RPC UNIX domain socket endpoint of instance A
     B/
         nodekey            -- devp2p node key of node B
         nodes/             -- devp2p discovery knowledge database of instance B
         static-nodes.json  -- devp2p static node list of instance B
         db/                -- LevelDB content for "db"
         db-2/              -- LevelDB content for "db-2"
     B.ipc                  -- JSON-RPC UNIX domain socket endpoint of instance B
     keystore/              -- account key store, used by both instances

Index

Examples

Constants

View Source 
const (
	DefaultHTTPHost    = "localhost" // Default host interface for the HTTP RPC server
	DefaultHTTPPort    = 8545        // Default TCP port for the HTTP RPC server
	DefaultWSHost      = "localhost" // Default host interface for the websocket RPC server
	DefaultWSPort      = 8546        // Default TCP port for the websocket RPC server
	DefaultGraphQLHost = "localhost" // Default host interface for the GraphQL server
	DefaultGraphQLPort = 8547        // Default TCP port for the GraphQL server
)

Variables

View Source 
var (
	ErrDatadirUsed    = errors.New("datadir already used by another process")
	ErrNodeStopped    = errors.New("node not started")
	ErrNodeRunning    = errors.New("node already running")
	ErrServiceUnknown = errors.New("unknown service")
)
View Source 
var DefaultConfig = Config{
	DataDir:             DefaultDataDir(),
	HTTPPort:            DefaultHTTPPort,
	HTTPModules:         []string{"net", "web3"},
	HTTPVirtualHosts:    []string{"localhost"},
	HTTPTimeouts:        rpc.DefaultHTTPTimeouts,
	WSPort:              DefaultWSPort,
	WSModules:           []string{"net", "web3"},
	GraphQLPort:         DefaultGraphQLPort,
	GraphQLVirtualHosts: []string{"localhost"},
	P2P: p2p.Config{
		ListenAddr: ":30300",
		MaxPeers:   50,
		NAT:        nat.Any(),
	},
}

DefaultConfig contains reasonable default settings.

Functions

func DefaultDataDir 

func DefaultDataDir() string

DefaultDataDir is the default data directory to use for the databases and other persistence requirements.

func DefaultHTTPEndpoint 

func DefaultHTTPEndpoint() string

DefaultHTTPEndpoint returns the HTTP endpoint used by default.

func DefaultIPCEndpoint 

func DefaultIPCEndpoint(clientIdentifier string) string

DefaultIPCEndpoint returns the IPC path used by default.

func DefaultWSEndpoint 

func DefaultWSEndpoint() string

DefaultWSEndpoint returns the websocket endpoint used by default.

Types

type Config 

type Config struct {
	// Name sets the instance name of the node. It must not contain the / character and is
	// used in the devp2p node identifier. The instance name of gocore is "gocore". If no
	// value is specified, the basename of the current executable is used.
	Name string `toml:"-"`

	// UserIdent, if set, is used as an additional component in the devp2p node identifier.
	UserIdent string `toml:",omitempty"`

	// Version should be set to the version number of the program. It is used
	// in the devp2p node identifier.
	Version string `toml:"-"`

	// DataDir is the file system folder the node should use for any data storage
	// requirements. The configured data directory will not be directly shared with
	// registered services, instead those can use utility methods to create/access
	// databases or flat files. This enables ephemeral nodes which can fully reside
	// in memory.
	DataDir string

	// Configuration of peer-to-peer networking.
	P2P p2p.Config

	// KeyStoreDir is the file system folder that contains private keys. The directory can
	// be specified as a relative path, in which case it is resolved relative to the
	// current directory.
	//
	// If KeyStoreDir is empty, the default location is the "keystore" subdirectory of
	// DataDir. If DataDir is unspecified and KeyStoreDir is empty, an ephemeral directory
	// is created by New and destroyed when the node is stopped.
	KeyStoreDir string `toml:",omitempty"`

	// ExternalSigner specifies an external URI for a clef-type signer
	ExternalSigner string `toml:"omitempty"`

	// UseLightweightKDF lowers the memory and CPU requirements of the key store
	// scrypt KDF at the expense of security.
	UseLightweightKDF bool `toml:",omitempty"`

	// InsecureUnlockAllowed allows user to unlock accounts in unsafe http environment.
	InsecureUnlockAllowed bool `toml:",omitempty"`

	// NoUSB disables hardware wallet monitoring and connectivity.
	NoUSB bool `toml:",omitempty"`

	// SmartCardDaemonPath is the path to the smartcard daemon's socket
	SmartCardDaemonPath string `toml:",omitempty"`

	// IPCPath is the requested location to place the IPC endpoint. If the path is
	// a simple file name, it is placed inside the data directory (or on the root
	// pipe path on Windows), whereas if it's a resolvable path name (absolute or
	// relative), then that specific path is enforced. An empty path disables IPC.
	IPCPath string

	// HTTPHost is the host interface on which to start the HTTP RPC server. If this
	// field is empty, no HTTP API endpoint will be started.
	HTTPHost string

	// HTTPPort is the TCP port number on which to start the HTTP RPC server. The
	// default zero value is/ valid and will pick a port number randomly (useful
	// for ephemeral nodes).
	HTTPPort int `toml:",omitempty"`

	// HTTPCors is the Cross-Origin Resource Sharing header to send to requesting
	// clients. Please be aware that CORS is a browser enforced security, it's fully
	// useless for custom HTTP clients.
	HTTPCors []string `toml:",omitempty"`

	// HTTPVirtualHosts is the list of virtual hostnames which are allowed on incoming requests.
	// This is by default {'localhost'}. Using this prevents attacks like
	// DNS rebinding, which bypasses SOP by simply masquerading as being within the same
	// origin. These attacks do not utilize CORS, since they are not cross-domain.
	// By explicitly checking the Host-header, the server will not allow requests
	// made against the server with a malicious host domain.
	// Requests using ip address directly are not affected
	HTTPVirtualHosts []string `toml:",omitempty"`

	// HTTPModules is a list of API modules to expose via the HTTP RPC interface.
	// If the module list is empty, all RPC API endpoints designated public will be
	// exposed.
	HTTPModules []string

	// HTTPTimeouts allows for customization of the timeout values used by the HTTP RPC
	// interface.
	HTTPTimeouts rpc.HTTPTimeouts

	// WSHost is the host interface on which to start the websocket RPC server. If
	// this field is empty, no websocket API endpoint will be started.
	WSHost string

	// WSPort is the TCP port number on which to start the websocket RPC server. The
	// default zero value is/ valid and will pick a port number randomly (useful for
	// ephemeral nodes).
	WSPort int `toml:",omitempty"`

	// WSOrigins is the list of domain to accept websocket requests from. Please be
	// aware that the server can only act upon the HTTP request the client sends and
	// cannot verify the validity of the request header.
	WSOrigins []string `toml:",omitempty"`

	// WSModules is a list of API modules to expose via the websocket RPC interface.
	// If the module list is empty, all RPC API endpoints designated public will be
	// exposed.
	WSModules []string

	// WSExposeAll exposes all API modules via the WebSocket RPC interface rather
	// than just the public ones.
	//
	// *WARNING* Only set this if the node is running in a trusted network, exposing
	// private APIs to untrusted users is a major security risk.
	WSExposeAll bool `toml:",omitempty"`

	// GraphQLHost is the host interface on which to start the GraphQL server. If this
	// field is empty, no GraphQL API endpoint will be started.
	GraphQLHost string

	// GraphQLPort is the TCP port number on which to start the GraphQL server. The
	// default zero value is/ valid and will pick a port number randomly (useful
	// for ephemeral nodes).
	GraphQLPort int `toml:",omitempty"`

	// GraphQLCors is the Cross-Origin Resource Sharing header to send to requesting
	// clients. Please be aware that CORS is a browser enforced security, it's fully
	// useless for custom HTTP clients.
	GraphQLCors []string `toml:",omitempty"`

	// GraphQLVirtualHosts is the list of virtual hostnames which are allowed on incoming requests.
	// This is by default {'localhost'}. Using this prevents attacks like
	// DNS rebinding, which bypasses SOP by simply masquerading as being within the same
	// origin. These attacks do not utilize CORS, since they are not cross-domain.
	// By explicitly checking the Host-header, the server will not allow requests
	// made against the server with a malicious host domain.
	// Requests using ip address directly are not affected
	GraphQLVirtualHosts []string `toml:",omitempty"`

	// Logger is a custom logger to use with the p2p.Server.
	Logger log.Logger `toml:",omitempty"`
	// contains filtered or unexported fields
}

Config represents a small collection of configuration values to fine tune the P2P network layer of a protocol stack. These values can be further extended by all registered services.

func (*Config) AccountConfig 

func (c *Config) AccountConfig() (int, int, string, error)

AccountConfig determines the settings for scrypt and keydirectory

func (*Config) ExtRPCEnabled 

func (c *Config) ExtRPCEnabled() bool

ExtRPCEnabled returns the indicator whether node enables the external RPC(http, ws or graphql).

func (*Config) GraphQLEndpoint 

func (c *Config) GraphQLEndpoint() string

GraphQLEndpoint resolves a GraphQL endpoint based on the configured host interface and port parameters.

func (*Config) HTTPEndpoint 

func (c *Config) HTTPEndpoint() string

HTTPEndpoint resolves an HTTP endpoint based on the configured host interface and port parameters.

func (*Config) IPCEndpoint 

func (c *Config) IPCEndpoint() string

IPCEndpoint resolves an IPC endpoint based on a configured value, taking into account the set data folders as well as the designated platform we're currently running on.

func (*Config) NodeDB 

func (c *Config) NodeDB() string

NodeDB returns the path to the discovery node database.

func (*Config) NodeKey 

func (c *Config) NodeKey() *eddsa.PrivateKey

NodeKey retrieves the currently configured private key of the node, checking first any manually set key, falling back to the one found in the configured data folder. If no key can be found, a new one is generated.

func (*Config) NodeName 

func (c *Config) NodeName() string

NodeName returns the devp2p node identifier.

func (*Config) ResolvePath 

func (c *Config) ResolvePath(path string) string

ResolvePath resolves path in the instance directory.

func (*Config) StaticNodes 

func (c *Config) StaticNodes() []*enode.Node

StaticNodes returns a list of node enode URLs configured as static nodes.

func (*Config) TrustedNodes 

func (c *Config) TrustedNodes() []*enode.Node

TrustedNodes returns a list of node enode URLs configured as trusted nodes.

func (*Config) WSEndpoint 

func (c *Config) WSEndpoint() string

WSEndpoint resolves a websocket endpoint based on the configured host interface and port parameters.

type DuplicateServiceError 

type DuplicateServiceError struct {
	Kind reflect.Type
}

DuplicateServiceError is returned during Node startup if a registered service constructor returns a service of the same type that was already started.

func (*DuplicateServiceError) Error 

func (e *DuplicateServiceError) Error() string

Error generates a textual representation of the duplicate service error.

type Node 

type Node struct {
	// contains filtered or unexported fields
}

Node is a container on which services can be registered.

func New 

func New(conf *Config) (*Node, error)

New creates a new P2P node, ready for protocol registration.

func (*Node) AccountManager 

func (n *Node) AccountManager() *accounts.Manager

AccountManager retrieves the account manager used by the protocol stack.

func (*Node) Attach 

func (n *Node) Attach() (*rpc.Client, error)

Attach creates an RPC client attached to an in-process API handler.

func (*Node) Close 

func (n *Node) Close() error

Close stops the Node and releases resources acquired in Node constructor New.

func (*Node) Config 

func (n *Node) Config() *Config

Config returns the configuration of node.

func (*Node) DataDir 

func (n *Node) DataDir() string

DataDir retrieves the current datadir used by the protocol stack. Deprecated: No files should be stored in this directory, use InstanceDir instead.

func (*Node) EventMux 

func (n *Node) EventMux() *event.TypeMux

EventMux retrieves the event multiplexer used by all the network services in the current protocol stack.

func (*Node) HTTPEndpoint 

func (n *Node) HTTPEndpoint() string

HTTPEndpoint retrieves the current HTTP endpoint used by the protocol stack.

func (*Node) IPCEndpoint 

func (n *Node) IPCEndpoint() string

IPCEndpoint retrieves the current IPC endpoint used by the protocol stack.

func (*Node) InstanceDir 

func (n *Node) InstanceDir() string

InstanceDir retrieves the instance directory used by the protocol stack.

func (*Node) OpenDatabase 

func (n *Node) OpenDatabase(name string, cache, handles int, namespace string) (xcbdb.Database, error)

OpenDatabase opens an existing database with the given name (or creates one if no previous can be found) from within the node's instance directory. If the node is ephemeral, a memory database is returned.

func (*Node) OpenDatabaseWithFreezer 

func (n *Node) OpenDatabaseWithFreezer(name string, cache, handles int, freezer, namespace string) (xcbdb.Database, error)

OpenDatabaseWithFreezer opens an existing database with the given name (or creates one if no previous can be found) from within the node's data directory, also attaching a chain freezer to it that moves ancient chain data from the database to immutable append-only files. If the node is an ephemeral one, a memory database is returned.

func (*Node) RPCHandler 

func (n *Node) RPCHandler() (*rpc.Server, error)

RPCHandler returns the in-process RPC request handler.

func (*Node) Register 

func (n *Node) Register(constructor ServiceConstructor) error

Register injects a new service into the node's stack. The service created by the passed constructor must be unique in its type with regard to sibling ones.

func (*Node) ResolvePath 

func (n *Node) ResolvePath(x string) string

ResolvePath returns the absolute path of a resource in the instance directory.

func (*Node) Restart 

func (n *Node) Restart() error

Restart terminates a running node and boots up a new one in its place. If the node isn't running, an error is returned.

func (*Node) Server 

func (n *Node) Server() *p2p.Server

Server retrieves the currently running P2P network layer. This method is meant only to inspect fields of the currently running server, life cycle management should be left to this Node entity.

func (*Node) Service 

func (n *Node) Service(service interface{}) error

Service retrieves a currently running service registered of a specific type.

func (*Node) Start 

func (n *Node) Start() error

Start creates a live P2P node and starts running it.

func (*Node) Stop 

func (n *Node) Stop() error

Stop terminates a running node along with all it's services. In the node was not started, an error is returned.

func (*Node) WSEndpoint 

func (n *Node) WSEndpoint() string

WSEndpoint retrieves the current WS endpoint used by the protocol stack.

func (*Node) Wait 

func (n *Node) Wait()

Wait blocks the thread until the node is stopped. If the node is not running at the time of invocation, the method immediately returns.

type PrivateAdminAPI 

type PrivateAdminAPI struct {
	// contains filtered or unexported fields
}

PrivateAdminAPI is the collection of administrative API methods exposed only over a secure RPC channel.

func NewPrivateAdminAPI 

func NewPrivateAdminAPI(node *Node) *PrivateAdminAPI

NewPrivateAdminAPI creates a new API definition for the private admin methods of the node itself.

func (*PrivateAdminAPI) AddPeer 

func (api *PrivateAdminAPI) AddPeer(url string) (bool, error)

AddPeer requests connecting to a remote node, and also maintaining the new connection at all times, even reconnecting if it is lost.

func (*PrivateAdminAPI) AddTrustedPeer 

func (api *PrivateAdminAPI) AddTrustedPeer(url string) (bool, error)

AddTrustedPeer allows a remote node to always connect, even if slots are full

func (*PrivateAdminAPI) PeerEvents 

func (api *PrivateAdminAPI) PeerEvents(ctx context.Context) (*rpc.Subscription, error)

PeerEvents creates an RPC subscription which receives peer events from the node's p2p.Server

func (*PrivateAdminAPI) RemovePeer 

func (api *PrivateAdminAPI) RemovePeer(url string) (bool, error)

RemovePeer disconnects from a remote node if the connection exists

func (*PrivateAdminAPI) RemoveTrustedPeer 

func (api *PrivateAdminAPI) RemoveTrustedPeer(url string) (bool, error)

RemoveTrustedPeer removes a remote node from the trusted peer set, but it does not disconnect it automatically.

func (*PrivateAdminAPI) StartRPC 

func (api *PrivateAdminAPI) StartRPC(host *string, port *int, cors *string, apis *string, vhosts *string) (bool, error)

StartRPC starts the HTTP RPC API server.

func (*PrivateAdminAPI) StartWS 

func (api *PrivateAdminAPI) StartWS(host *string, port *int, allowedOrigins *string, apis *string) (bool, error)

StartWS starts the websocket RPC API server.

func (*PrivateAdminAPI) StopRPC 

func (api *PrivateAdminAPI) StopRPC() (bool, error)

StopRPC terminates an already running HTTP RPC API endpoint.

func (*PrivateAdminAPI) StopWS 

func (api *PrivateAdminAPI) StopWS() (bool, error)

StopWS terminates an already running websocket RPC API endpoint.

type PublicAdminAPI 

type PublicAdminAPI struct {
	// contains filtered or unexported fields
}

PublicAdminAPI is the collection of administrative API methods exposed over both secure and unsecure RPC channels.

func NewPublicAdminAPI 

func NewPublicAdminAPI(node *Node) *PublicAdminAPI

NewPublicAdminAPI creates a new API definition for the public admin methods of the node itself.

func (*PublicAdminAPI) Datadir 

func (api *PublicAdminAPI) Datadir() string

Datadir retrieves the current data directory the node is using.

func (*PublicAdminAPI) NodeInfo 

func (api *PublicAdminAPI) NodeInfo() (*p2p.NodeInfo, error)

NodeInfo retrieves all the information we know about the host node at the protocol granularity.

func (*PublicAdminAPI) Peers 

func (api *PublicAdminAPI) Peers() ([]*p2p.PeerInfo, error)

Peers retrieves all the information we know about each individual peer at the protocol granularity.

type PublicWeb3API 

type PublicWeb3API struct {
	// contains filtered or unexported fields
}

PublicWeb3API offers helper utils

func NewPublicWeb3API 

func NewPublicWeb3API(stack *Node) *PublicWeb3API

NewPublicWeb3API creates a new Web3Service instance

func (*PublicWeb3API) ClientVersion 

func (s *PublicWeb3API) ClientVersion() string

ClientVersion returns the node name

func (*PublicWeb3API) Sha3 

func (s *PublicWeb3API) Sha3(input hexutil.Bytes) hexutil.Bytes

Sha3 applies the core sha3 implementation on the input. It assumes the input is hex encoded.

type Service 

type Service interface {
	// Protocols retrieves the P2P protocols the service wishes to start.
	Protocols() []p2p.Protocol

	// APIs retrieves the list of RPC descriptors the service provides
	APIs() []rpc.API

	// Start is called after all services have been constructed and the networking
	// layer was also initialized to spawn any goroutines required by the service.
	Start(server *p2p.Server) error

	// Stop terminates all goroutines belonging to the service, blocking until they
	// are all terminated.
	Stop() error
}

Service is an individual protocol that can be registered into a node.

Notes:

• Service life-cycle management is delegated to the node. The service is allowed to initialize itself upon creation, but no goroutines should be spun up outside of the Start method.

• Restart logic is not required as the node will create a fresh instance every time a service is started.

Example 
package main

import (
	"fmt"
	"log"

	"github.com/core-coin/go-core/node"
	"github.com/core-coin/go-core/p2p"
	"github.com/core-coin/go-core/rpc"
)

// SampleService is a trivial network service that can be attached to a node for
// life cycle management.
//
// The following methods are needed to implement a node.Service:
//   - Protocols() []p2p.Protocol - devp2p protocols the service can communicate on
//   - APIs() []rpc.API           - api methods the service wants to expose on rpc channels
//   - Start() error              - method invoked when the node is ready to start the service
//   - Stop() error               - method invoked when the node terminates the service
type SampleService struct{}

func (s *SampleService) Protocols() []p2p.Protocol { return nil }
func (s *SampleService) APIs() []rpc.API           { return nil }
func (s *SampleService) Start(*p2p.Server) error   { fmt.Println("Service starting..."); return nil }
func (s *SampleService) Stop() error               { fmt.Println("Service stopping..."); return nil }

func main() {
	// Create a network node to run protocols with the default values.
	stack, err := node.New(&node.Config{})
	if err != nil {
		log.Fatalf("Failed to create network node: %v", err)
	}
	defer stack.Close()

	// Create and register a simple network service. This is done through the definition
	// of a node.ServiceConstructor that will instantiate a node.Service. The reason for
	// the factory method approach is to support service restarts without relying on the
	// individual implementations' support for such operations.
	constructor := func(context *node.ServiceContext) (node.Service, error) {
		return new(SampleService), nil
	}
	if err := stack.Register(constructor); err != nil {
		log.Fatalf("Failed to register service: %v", err)
	}
	// Boot up the entire protocol stack, do a restart and terminate
	if err := stack.Start(); err != nil {
		log.Fatalf("Failed to start the protocol stack: %v", err)
	}
	if err := stack.Restart(); err != nil {
		log.Fatalf("Failed to restart the protocol stack: %v", err)
	}
	if err := stack.Stop(); err != nil {
		log.Fatalf("Failed to stop the protocol stack: %v", err)
	}
}

Output:

Service starting...
Service stopping...
Service starting...
Service stopping...

type ServiceConstructor 

type ServiceConstructor func(ctx *ServiceContext) (Service, error)

ServiceConstructor is the function signature of the constructors needed to be registered for service instantiation.

type ServiceContext 

type ServiceContext struct {
	Config         Config
	EventMux       *event.TypeMux    // Event multiplexer used for decoupled notifications
	AccountManager *accounts.Manager // Account manager created by the node.
	// contains filtered or unexported fields
}

ServiceContext is a collection of service independent options inherited from the protocol stack, that is passed to all constructors to be optionally used; as well as utility methods to operate on the service environment.

func (*ServiceContext) ExtRPCEnabled 

func (ctx *ServiceContext) ExtRPCEnabled() bool

ExtRPCEnabled returns the indicator whether node enables the external RPC(http, ws or graphql).

func (*ServiceContext) OpenDatabase 

func (ctx *ServiceContext) OpenDatabase(name string, cache int, handles int, namespace string) (xcbdb.Database, error)

OpenDatabase opens an existing database with the given name (or creates one if no previous can be found) from within the node's data directory. If the node is an ephemeral one, a memory database is returned.

func (*ServiceContext) OpenDatabaseWithFreezer 

func (ctx *ServiceContext) OpenDatabaseWithFreezer(name string, cache int, handles int, freezer string, namespace string) (xcbdb.Database, error)

OpenDatabaseWithFreezer opens an existing database with the given name (or creates one if no previous can be found) from within the node's data directory, also attaching a chain freezer to it that moves ancient chain data from the database to immutable append-only files. If the node is an ephemeral one, a memory database is returned.

func (*ServiceContext) ResolvePath 

func (ctx *ServiceContext) ResolvePath(path string) string

ResolvePath resolves a user path into the data directory if that was relative and if the user actually uses persistent storage. It will return an empty string for emphemeral storage and the user's own input for absolute paths.

func (*ServiceContext) Service 

func (ctx *ServiceContext) Service(service interface{}) error

Service retrieves a currently running service registered of a specific type.

type StopError 

type StopError struct {
	Server   error
	Services map[reflect.Type]error
}

StopError is returned if a Node fails to stop either any of its registered services or itself.

func (*StopError) Error 

func (e *StopError) Error() string

Error generates a textual representation of the stop error.

Source Files

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