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https://github.com/wendiGo/Go-bind-plugin
go-bind-plugin generates API for exported plugin symbols (-buildmode=plugin) - go1.8+ only (http://golang.org/pkg/plugin)
https://github.com/wendiGo/Go-bind-plugin
Last synced: 20 days ago
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go-bind-plugin generates API for exported plugin symbols (-buildmode=plugin) - go1.8+ only (http://golang.org/pkg/plugin)
- Host: GitHub
- URL: https://github.com/wendiGo/Go-bind-plugin
- Owner: wendigo
- License: apache-2.0
- Created: 2016-11-08T14:40:26.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2019-08-29T11:59:32.000Z (about 5 years ago)
- Last Synced: 2024-07-31T01:29:36.988Z (4 months ago)
- Language: Go
- Homepage:
- Size: 2.22 MB
- Stars: 184
- Watchers: 6
- Forks: 11
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# go-bind-plugin [](https://travis-ci.org/wendigo/go-bind-plugin) [](https://coveralls.io/github/wendigo/go-bind-plugin?branch=master) [](https://godoc.org/github.com/wendigo/go-bind-plugin/cli) [](https://goreportcard.com/report/github.com/wendigo/go-bind-plugin) [](https://saythanks.io/to/wendigo)
> TL;DR: See end-to-end example in [go-bind-plugin-example](https://github.com/wendigo/go-bind-plugin-example).
**go-bind-plugin** is `go:generate` tool for building [golang 1.8 plugins](https://tip.golang.org/pkg/plugin) and generating wrappers around exported symbols (functions and variables).
## What is it?
**go-bind-plugin** generates neat API around symbols exported by a `*.so` plugin built with `go build -buildmode=plugin` in upcoming go 1.8. [plugin.Plugin](https://tip.golang.org/pkg/plugin/#Plugin) holds information about exported symbols as `map[string]interface{}`.
**go-bind-plugins** uses reflection to find out actual types of symbols and generates typed API wrapping plugin with additional functionalities (like dereferencing exported variables and checking SHA256 sum).
*Note: Basic usage does not require plugin sources as wrapper can be generated using only* `*.so` *file.*
## Why should I use it?
In example if plugin exports `func AddTwoInts(a, b int) int` and `var BuildVersion string` instead of using [Plugin.Lookup](https://tip.golang.org/pkg/plugin/#Plugin.Lookup) directly:
```go
plug, err := plugin.Open("plugin.so")
if err != nil {
panic(err)
}
symbol, err := plug.Lookup("AddTwoInts")
if err != nil {
panic("AddTwoInts was not found in a plugin")
}
if typed, ok := symbol.(func(int, int) int); ok {
result := typed(10, 20)
} else {
panic("AddTwoInts has different type than exported by plugin")
}
symbol, err := plug.Lookup("BuildVersion")
if err != nil {
panic("BuildVersion was not found in a plugin")
}
if typed, ok := symbol.(*string); ok {
fmt.Println(*typed)
} else {
panic("BuildVersion is not a string reference")
}
```
you can just simply do:
```go
plug, err := pluginapi.BindPluginAPI("plugin.so") // plug is *plugin_api.PluginAPI
if err != nil {
panic(err)
}
result := plug.AddTwoInts(10, 20)
fmt.Println(plug.BuildVersion) // or fmt.Println(*plug.BuildVersion) if -dereference-vars is not used
```
`pluginapi.BindPluginAPI()` ensures that plugin exports required symbols and their types are correct.
## Usage
```go
go get -u github.com/wendigo/go-bind-plugin
go-bind-plugin -help
Usage of go-bind-plugin:
-dereference-vars
Dereference plugin variables
-format
Format generated output file with gofmt (default true)
-hide-vars
Do not export plugin variables
-interface
Generate and return interface instead of struct (turns on -hide-vars)
-output-name string
Output struct name (default "PluginAPI")
-output-package string
Output package (can be derived from output-path) (default "main")
-output-path string
Output file path (default "plugin_api.go")
-plugin-package string
Plugin package url (as accepted by go get)
-plugin-path string
Path to plugin (.so file)
-rebuild
Rebuild plugin on every run
-sha256
Write plugin's sha256 checksum to wrapper and validate it when loading it
```
### Example
`
//go:generate go-bind-plugin -format -plugin-package github.com/plugin_test/plug -rebuild -sha256 -dereference-vars -output-name TestPlugin -output-path tmp/plugin.go -plugin-path tmp/plugin.so -output-package pluginapi
`
**go-bind-plugin** will do following things on invocation:
- build plugin to `tmp/plugin.so` (even if plugin exists it will be rebuilded) from `github.com/plugin_test/plug` source (must exist in $GOPATH or vendor/)
- generate wrapper struct `wrapper.TestPlugin` in `tmp/plugin.go`
- dereference variables in the generated wrapper
- format generated wrapper with `gofmt -s -w`
- write sha256 checksum to `tmp/plugin.go` that will be checked when loading plugin with `pluginapi.BindTestPlugin(path string) (*TestPlugin, error)`
### Wrapper API example (for -output-name "PluginAPI")
`BindPluginAPI(path string) (*PluginAPI, error)` - loads plugin from `path` and wraps it with `type PluginAPI struct`:
- all functions exported by the plugin are exposed as methods on struct `PluginAPI`
- all variables exported by the plugin are exposed as fields on struct `PluginAPI` (if `-dereference-vars` is used fields are not references to plugin's variables)
`func (*PluginAPI) String() string` - provides nice textual representation of the wrapper
### Wrapper as interface
When `-interface` is used instead of generating and returning `struct` interface containing all exported symbols is generated. This eases mocking and working with multiple plugins exporting the same API.
**Note** that `-interface` effectively enables `-hide-vars` so variables won't be exported from the plugin.
### Generated code quality
Generated code passes both `go vet` and `golint` and can be formatted using `gofmt -s -w`. Exported symbols names are not changed in any way so names not following [go naming convention](https://golang.org/doc/effective_go.html) will still be reported by `golint` as invalid.
### Example generated wrapper information
```go
Wrapper info:
- Generated on: 2016-11-08 16:15:07.513150982 +0100 CET
- Command: go-bind-plugin -plugin-path ./internal/test_fixtures/generated/basic_plugin/plugin.so -plugin-package ./internal/test_fixtures/basic_plugin -output-name TestWrapper -output-path ./internal/test_fixtures/generated/basic_plugin/plugin.go -output-package main -sha256 true -format true -rebuild true
Plugin info:
- package: github.com/wendigo/go-bind-plugin/internal/test_fixtures/basic_plugin
- sha256 sum: 55aa13402686f3200f5067604c04ce8d365e7cf2095d8278b2ff52ae26df7e6d
- size: 1232572 bytes
Exported functions (3):
- ReturningInt32 func() (int32)
- ReturningStringSlice func() ([]string)
- ReturningIntArray func() ([3]int32)
```
## Plugin call overhead
Using `-buildmode=plugin` with generated wrapper seems not to add overhead when calling methods on a wrapper (creating plugin instance and loading `*.so` file is constant cost).
```go
BenchmarkCallOverhead/plugin-8 30000000 58.0 ns/op 0 B/op 0 allocs/op
BenchmarkCallOverhead/plugin-8 30000000 59.3 ns/op 0 B/op 0 allocs/op
BenchmarkCallOverhead/plugin-8 30000000 54.8 ns/op 0 B/op 0 allocs/op
BenchmarkCallOverhead/native-8 20000000 59.3 ns/op 0 B/op 0 allocs/op
BenchmarkCallOverhead/native-8 20000000 59.8 ns/op 0 B/op 0 allocs/op
BenchmarkCallOverhead/native-8 20000000 59.7 ns/op 0 B/op 0 allocs/op
```