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manager.go
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manager.go
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// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.
package vms
import (
"fmt"
"sync"
"github.com/ava-labs/avalanchego/api/server"
"github.com/ava-labs/avalanchego/ids"
"github.com/ava-labs/avalanchego/snow"
"github.com/ava-labs/avalanchego/snow/engine/common"
"github.com/ava-labs/avalanchego/utils/constants"
"github.com/ava-labs/avalanchego/utils/logging"
)
// A Factory creates new instances of a VM
type Factory interface {
New(*snow.Context) (interface{}, error)
}
// Manager is a VM manager.
// It has the following functionality:
// 1) Register a VM factory. To register a VM is to associate its ID with a
// VMFactory which, when New() is called upon it, creates a new instance of that VM.
// 2) Get a VM factory. Given the ID of a VM that has been
// registered, return the factory that the ID is associated with.
// 3) Associate a VM with an alias
// 4) Get the ID of the VM by the VM's alias
// 5) Get the aliases of a VM
type Manager interface {
// Returns a factory that can create new instances of the VM
// with the given ID
GetFactory(ids.ID) (Factory, error)
// Associate an ID with the factory that creates new instances
// of the VM with the given ID
RegisterFactory(ids.ID, Factory) error
// Versions returns the versions of all the VMs that have been registered
Versions() (map[string]string, error)
// Given an alias, return the ID of the VM associated with that alias
Lookup(string) (ids.ID, error)
// Return the aliases associated with a VM
Aliases(ids.ID) []string
// Give an alias to a VM
Alias(ids.ID, string) error
}
// Implements Manager
type manager struct {
// Note: The string representation of a VM's ID is also considered to be an
// alias of the VM. That is, [VM].String() is an alias for the VM, too.
ids.Aliaser
// Key: A VM's ID
// Value: A factory that creates new instances of that VM
factories map[ids.ID]Factory
// Key: A VM's ID
// Value: version the VM returned
versions map[ids.ID]string
// The node's API server.
// [manager] adds routes to this server to expose new API endpoints/services
apiServer *server.Server
log logging.Logger
}
// NewManager returns an instance of a VM manager
func NewManager(apiServer *server.Server, log logging.Logger) Manager {
m := &manager{
factories: make(map[ids.ID]Factory),
versions: make(map[ids.ID]string),
apiServer: apiServer,
log: log,
}
m.Initialize()
return m
}
// Return a factory that can create new instances of the vm whose
// ID is [vmID]
func (m *manager) GetFactory(vmID ids.ID) (Factory, error) {
if factory, ok := m.factories[vmID]; ok {
return factory, nil
}
return nil, fmt.Errorf("%q was not registered as a vm", vmID)
}
// Map [vmID] to [factory]. [factory] creates new instances of the vm whose
// ID is [vmID]
func (m *manager) RegisterFactory(vmID ids.ID, factory Factory) error {
if _, exists := m.factories[vmID]; exists {
return fmt.Errorf("%q was already registered as a vm", vmID)
}
if err := m.Alias(vmID, vmID.String()); err != nil {
return err
}
m.factories[vmID] = factory
// VMs can expose a static API (one that does not depend on the state of a
// particular chain.) This adds to the node's API server the static API of
// the VM with ID [vmID]. This allows clients to call the VM's static API
// methods.
m.log.Debug("adding static API for vm %q", vmID)
vm, err := factory.New(nil)
if err != nil {
return err
}
commonVM, ok := vm.(common.VM)
if !ok {
return nil
}
version, err := commonVM.Version()
if err != nil {
m.log.Error("fetching version for %q errored with: %s", vmID, err)
if err := commonVM.Shutdown(); err != nil {
return fmt.Errorf("shutting down VM errored with: %s", err)
}
return nil
}
m.versions[vmID] = version
handlers, err := commonVM.CreateStaticHandlers()
if err != nil {
m.log.Error("creating static API endpoints for %q errored with: %s", vmID, err)
if err := commonVM.Shutdown(); err != nil {
return fmt.Errorf("shutting down VM errored with: %s", err)
}
return nil
}
// all static endpoints go to the vm endpoint, defaulting to the vm id
defaultEndpoint := constants.VMAliasPrefix + vmID.String()
// use a single lock for this entire vm
lock := new(sync.RWMutex)
// register the static endpoints
for extension, service := range handlers {
m.log.Verbo("adding static API endpoint: %s%s", defaultEndpoint, extension)
if err := m.apiServer.AddRoute(service, lock, defaultEndpoint, extension, m.log); err != nil {
return fmt.Errorf(
"failed to add static API endpoint %s%s: %s",
defaultEndpoint,
extension,
err,
)
}
}
return nil
}
// Versions returns the primary alias of the VM mapped to the reported version
// of the VM for all the registered VMs that reported versions.
func (m *manager) Versions() (map[string]string, error) {
versions := make(map[string]string, len(m.versions))
for vmID, version := range m.versions {
alias, err := m.PrimaryAlias(vmID)
if err != nil {
return nil, err
}
versions[alias] = version
}
return versions, nil
}