plugeth/plugins/plugin_loader.go

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package plugins
import (
"flag"
"fmt"
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"io/ioutil"
"path"
"plugin"
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"reflect"
"strings"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/log"
"github.com/openrelayxyz/plugeth-utils/core"
"github.com/urfave/cli/v2"
)
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type Subcommand func(core.Context, []string) error
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type pluginDetails struct {
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p *plugin.Plugin
name string
}
type PluginLoader struct {
Plugins []pluginDetails
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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.p.Lookup(name); err == nil {
if validate(v) {
results = append(results, v)
} else {
log.Warn("Plugin matches hook but not signature", "plugin", plugin.name, "hook", name)
}
}
}
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: []pluginDetails{},
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Subcommands: make(map[string]Subcommand),
Flags: []*flag.FlagSet{},
LookupCache: make(map[string][]interface{}),
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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") {
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log.Debug("File in plugin directory is not '.so' file. Skipping.", "file", fpath)
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continue
}
plug, err := plugin.Open(fpath)
if err != nil {
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log.Warn("File in plugin directory could not be loaded", "file", fpath, "error", err)
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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 {
subcommands, ok := sb.(*map[string]func(core.Context, []string) error)
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if !ok {
log.Warn("Could not cast plugin.Subcommands to `map[string]func(core.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, pluginDetails{plug, fpath})
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}
return pl, nil
}
func Initialize(target string, ctx core.Context) (err error) {
DefaultPluginLoader, err = NewPluginLoader(target)
if err != nil {
return err
}
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DefaultPluginLoader.Initialize(ctx)
return nil
}
func (pl *PluginLoader) Initialize(ctx core.Context) {
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fns := pl.Lookup("Initialize", func(i interface{}) bool {
_, ok := i.(func(core.Context, core.PluginLoader, core.Logger))
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return ok
})
for _, fni := range fns {
if fn, ok := fni.(func(core.Context, core.PluginLoader, core.Logger)); ok {
fn(ctx, pl, log.Root())
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}
}
}
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func (pl *PluginLoader) RunSubcommand(ctx *cli.Context) (bool, error) {
args := ctx.Args().Slice()
if len(args) == 0 {
return false, fmt.Errorf("no subcommand arguments")
}
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subcommand, ok := pl.Subcommands[args[0]]
if !ok {
return false, fmt.Errorf("Subcommand %v does not exist", args[0])
}
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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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}
type feedWrapper struct {
feed *event.Feed
}
func (f *feedWrapper) Send(item interface{}) int {
return f.feed.Send(item)
}
func (f *feedWrapper) Subscribe(ch interface{}) core.Subscription {
return f.feed.Subscribe(ch)
}
func (pl *PluginLoader) GetFeed() core.Feed {
return &feedWrapper{&event.Feed{}}
}