diff options
Diffstat (limited to 'node/service.go')
-rw-r--r-- | node/service.go | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/node/service.go b/node/service.go new file mode 100644 index 000000000..bfeeb7ab9 --- /dev/null +++ b/node/service.go @@ -0,0 +1,80 @@ +// Copyright 2015 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. + +package node + +import ( + "path/filepath" + "reflect" + + "github.com/ethereum/go-ethereum/ethdb" + "github.com/ethereum/go-ethereum/event" + "github.com/ethereum/go-ethereum/p2p" +) + +// 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. +type ServiceContext struct { + datadir string // Data directory for protocol persistence + services map[reflect.Type]Service // Index of the already constructed services + EventMux *event.TypeMux // Event multiplexer used for decoupled notifications +} + +// 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 (ctx *ServiceContext) OpenDatabase(name string, cache int) (ethdb.Database, error) { + if ctx.datadir == "" { + return ethdb.NewMemDatabase() + } + return ethdb.NewLDBDatabase(filepath.Join(ctx.datadir, name), cache) +} + +// Service retrieves a currently running service registered of a specific type. +func (ctx *ServiceContext) Service(service interface{}) error { + element := reflect.ValueOf(service).Elem() + if running, ok := ctx.services[element.Type()]; ok { + element.Set(reflect.ValueOf(running)) + return nil + } + return ErrServiceUnknown +} + +// ServiceConstructor is the function signature of the constructors needed to be +// registered for service instantiation. +type ServiceConstructor func(ctx *ServiceContext) (Service, 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. +type Service interface { + // Protocol retrieves the P2P protocols the service wishes to start. + Protocols() []p2p.Protocol + + // 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 +} |