plugeth/plugins/plugin_loader.go

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package plugins
import (
"plugin"
"github.com/ethereum/go-ethereum/log"
"gopkg.in/urfave/cli.v1"
"flag"
"io/ioutil"
"strings"
"path"
"fmt"
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"reflect"
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)
type Subcommand func(*cli.Context, []string) error
type PluginLoader struct{
Plugins []*plugin.Plugin
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Subcommands map[string]Subcommand
Flags []*flag.FlagSet
LookupCache map[string][]interface{}
}
func (pl *PluginLoader) Lookup(name string, validate func(interface{}) bool) []interface{} {
if v, ok := pl.LookupCache[name]; ok { return v }
results := []interface{}{}
for _, plugin := range pl.Plugins {
if v, err := plugin.Lookup(name); err == nil {
if validate(v) {
results = append(results, v)
}
}
}
pl.LookupCache[name] = results
return results
}
func Lookup(name string, validate func(interface{}) bool) []interface{} {
if DefaultPluginLoader == nil {
log.Warn("Lookup attempted, but PluginLoader is not initialized", "name", name)
return []interface{}{}
}
return DefaultPluginLoader.Lookup(name, validate)
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}
var DefaultPluginLoader *PluginLoader
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func NewPluginLoader(target string) (*PluginLoader, error) {
pl := &PluginLoader{
Plugins: []*plugin.Plugin{},
// RPCPlugins: []APILoader{},
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Subcommands: make(map[string]Subcommand),
Flags: []*flag.FlagSet{},
LookupCache: make(map[string][]interface{}),
// CreateConsensusEngine: ethconfig.CreateConsensusEngine,
// UpdateBlockchainVMConfig: func(cfg *vm.Config) {},
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}
files, err := ioutil.ReadDir(target)
if err != nil {
log.Warn("Could not load plugins directory. Skipping.", "path", target)
return pl, nil
}
for _, file := range files {
fpath := path.Join(target, file.Name())
if !strings.HasSuffix(file.Name(), ".so") {
log.Debug("File inplugin directory is not '.so' file. Skipping.", "file", fpath)
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continue
}
plug, err := plugin.Open(fpath)
if err != nil {
log.Warn("File in plugin directory could not be loaded: %v", "file", fpath, "error", err.Error())
continue
}
// Any type of plugin can potentially specify flags
f, err := plug.Lookup("Flags")
if err == nil {
flagset, ok := f.(*flag.FlagSet)
if !ok {
log.Warn("Found plugin.Flags, but it its not a *FlagSet", "file", fpath)
} else {
pl.Flags = append(pl.Flags, flagset)
}
}
sb, err := plug.Lookup("Subcommands")
if err == nil {
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subcommands, ok := sb.(*map[string]func(*cli.Context, []string) error)
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if !ok {
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log.Warn("Could not cast plugin.Subcommands to `map[string]func(*cli.Context, []string) error`", "file", fpath, "type", reflect.TypeOf(sb))
} else {
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for k, v := range *subcommands {
if _, ok := pl.Subcommands[k]; ok {
log.Warn("Subcommand redeclared", "file", fpath, "subcommand", k)
}
pl.Subcommands[k] = v
}
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}
}
pl.Plugins = append(pl.Plugins, plug)
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}
return pl, nil
}
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func Initialize(target string, ctx *cli.Context) (err error) {
DefaultPluginLoader, err = NewPluginLoader(target)
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if err != nil { return err }
DefaultPluginLoader.Initialize(ctx)
return nil
}
func (pl *PluginLoader) Initialize(ctx *cli.Context) {
fns := pl.Lookup("Initialize", func(i interface{}) bool {
_, ok := i.(func(*cli.Context) error)
return ok
})
for _, fni := range fns {
if fn, ok := fni.(func(*cli.Context)); ok {
fn(ctx)
}
}
}
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func (pl *PluginLoader) RunSubcommand(ctx *cli.Context) (bool, error) {
args := ctx.Args()
if len(args) == 0 { return false, fmt.Errorf("No subcommand arguments")}
subcommand, ok := pl.Subcommands[args[0]]
if !ok { return false, fmt.Errorf("Subcommand %v does not exist", args[0])}
return true, subcommand(ctx, args[1:])
}
func RunSubcommand(ctx *cli.Context) (bool, error) {
if DefaultPluginLoader == nil { return false, fmt.Errorf("Plugin loader not initialized") }
return DefaultPluginLoader.RunSubcommand(ctx)
}
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func (pl *PluginLoader) ParseFlags(args []string) bool {
for _, flagset := range pl.Flags {
flagset.Parse(args)
}
return len(pl.Flags) > 0
}
func ParseFlags(args []string) bool {
if DefaultPluginLoader == nil {
log.Warn("Attempting to parse flags, but default PluginLoader has not been initialized")
return false
}
return DefaultPluginLoader.ParseFlags(args)
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}