feat: Go wasm - extracting common code without generics...

Author: ppedziwiatr

go/README.md

@@ -1,8 +1,7 @@
 # Go smartweave example contract
 
-Note: we're using `tinygo` compiler, as the default compiler produces huuuuge binaries 
-(`hello world` example - ~2MB)
-![img.png](img.png)
+## Install go 1.17
+https://go.dev/doc/install
 
 ## How to use (default Go compiler)
 - [Install easyjson](https://github.com/mailru/easyjson#install)
@@ -17,5 +16,16 @@ Note: we're using `tinygo` compiler, as the default compiler produces huuuuge bi
 - Build wasm contract file: `bash build-tiny.sh` (it should create `out` folder)
 - Run wasm contract simulation: `node run-tiny.js`
 
-Size comparison for PST contract:  
-![img_1.png](img_1.png)
+### Size comparison for PST contract (default go compiler vs `tinygo` compiler):  
+![img_1.png](img_1.png)
+
+### Folder structure
+- `common` - package for commons code, that will be reused between contracts (
+handles the low-level WASM-JS communication for Go). Contains `SwContract` interface
+that has to implemented by contract developers.
+- `common_types` - package for commons structs. Have to be a separate package, 
+otherwise easyjson throws error during code generation
+- `impl` - package that contains implementation of the given contract (i.e. implementation of the `SwContract`
+interface)
+- `types` - package that contains types specific to the contract that needs to be generated with easyjson
+- `main.go` - main file - entry point to the wasm library.

go/common/imports/console/imports.go

@@ -5,7 +5,7 @@ import (
 )
 
 func Log(args ...interface{}) {
-	importConsole().Call("log", args)
+	importConsole().Call("log", args[0], args[1:])
 }
 
 func importConsole() js.Value {

go/wasm/wasm.go renamed to go/common/wasm.go

@@ -1,13 +1,12 @@
-package wasm
+package common
 
 import (
 	"encoding/json"
 	"github.com/redstone-finance/redstone-contracts-wasm/go/common_types"
-	"github.com/redstone-finance/redstone-contracts-wasm/go/impl"
 	"syscall/js"
 )
 
-func Run(contract *impl.PstContract) {
+func Run(contract common_types.SwContract) {
 	// the Go way of defining WASM exports...
 	// standard "exports" from the wasm module do not work here...
 	// that's kinda ugly TBH
@@ -22,7 +21,7 @@ func Run(contract *impl.PstContract) {
 	<-make(chan bool)
 }
 
-func handle(contract *impl.PstContract) js.Func {
+func handle(contract common_types.SwContract) js.Func {
 	// note: each 'exported' function has to be wrapped into
 	// js.FuncOf(func(this js.Value, args []js.Value) interface{}
 	// - that's kinda ugly too...
@@ -80,14 +79,14 @@ func lang() interface{} {
 	})
 }
 
-func currentState(contract *impl.PstContract) interface{} {
+func currentState(contract common_types.SwContract) interface{} {
 	return js.FuncOf(func(this js.Value, args []js.Value) interface{} {
 		data, _ := json.Marshal(contract.CurrentState())
 		return string(data)
 	})
 }
 
-func initState(contract *impl.PstContract) interface{} {
+func initState(contract common_types.SwContract) interface{} {
 	return js.FuncOf(func(this js.Value, args []js.Value) interface{} {
 		contract.InitState(args[0].String())
 		return nil

go/common_types/types.go

@@ -6,6 +6,15 @@ type Action struct {
 
 type ActionResult = interface{}
 
+// SwContract We need to use "any" (interface{}) type here for the state - as this is
+// a common interface for all contracts implemented in Go WASM.
+// Version with generics is available on branch ppe/go-generics (but to use it real life
+// we need to wait for the official release of Go 1.18 and tinygo compiler with generics
+// support added - https://github.com/tinygo-org/tinygo/issues/2158)
 //easyjson:skip
 type SwContract interface {
+	Handle(action Action, actionBytes []byte) (interface{}, ActionResult, error)
+	InitState(stateJson string)
+	UpdateState(newState interface{})
+	CurrentState() interface{}
 }

go/img.png

@@ -13,7 +13,7 @@ type PstContract struct {
 }
 
 // Handle the function that contract developers actually need to implement
-func (c *PstContract) Handle(action common_types.Action, actionBytes []byte) (*types.PstState, common_types.ActionResult, error) {
+func (c *PstContract) Handle(action common_types.Action, actionBytes []byte) (interface{}, common_types.ActionResult, error) {
 	fn := action.Function
 
 	console.Log("Calling", fn)
@@ -22,6 +22,8 @@ func (c *PstContract) Handle(action common_types.Action, actionBytes []byte) (*t
 	console.Log("Block indep_hash", block.IndepHash())
 	console.Log("Block timestamp", block.Timestamp())
 
+	clonedState := c.CloneState().(types.PstState)
+
 	switch fn {
 	case "transfer":
 		// not sure how to "automatically" handle casting to concrete action impl in Go.
@@ -32,23 +34,23 @@ func (c *PstContract) Handle(action common_types.Action, actionBytes []byte) (*t
 		if err != nil {
 			return nil, nil, err
 		}
-		state, err := Transfer(c.CloneState(), transfer)
+		state, err := Transfer(clonedState, transfer)
 		return state, nil, err
 	case "balance":
 		var balance types.BalanceAction
 		err := balance.UnmarshalJSON(actionBytes)
 		if err != nil {
 			return nil, nil, err
 		}
-		result, err := Balance(c.CloneState(), balance)
+		result, err := Balance(clonedState, balance)
 		return nil, result, err
 	case "foreignCall":
 		var foreignCall types.ForeignCallAction
 		err := foreignCall.UnmarshalJSON(actionBytes)
 		if err != nil {
 			return nil, nil, err
 		}
-		result, err := ForeignCall(c.CloneState(), foreignCall)
+		result, err := ForeignCall(clonedState, foreignCall)
 		return nil, result, err
 	default:
 		return nil, nil, errors.New("[RE:WTF] unknown function: " + fn)
@@ -64,18 +66,20 @@ func (c *PstContract) InitState(stateJson string) {
 	c.UpdateState(&state)
 }
 
-func (c *PstContract) UpdateState(newState *types.PstState) {
-	c.state = *newState
+func (c *PstContract) UpdateState(newState interface{}) {
+	// note: we're first type asserting here to the pointer to types.PstState
+	// - and the retrieving value from the pointer
+	c.state = *(newState.(*types.PstState))
 }
 
-func (c *PstContract) CurrentState() types.PstState {
+func (c *PstContract) CurrentState() interface{} {
 	return c.state
 }
 
 // CloneState TODO: discuss whether it is necessary
 // it allows to make the given action transactional, but
 // at the cost of performance
-func (c *PstContract) CloneState() types.PstState {
+func (c *PstContract) CloneState() interface{} {
 	json, _ := c.state.MarshalJSON()
 	state := types.PstState{}
 	err := state.UnmarshalJSON(json)

go/impl/pst-contract.go

@@ -1,14 +1,14 @@
 package main
 
 import (
+	"github.com/redstone-finance/redstone-contracts-wasm/go/common"
 	"github.com/redstone-finance/redstone-contracts-wasm/go/impl"
-	"github.com/redstone-finance/redstone-contracts-wasm/go/wasm"
 )
 
-// the current state of the contract that contract developers have to define
+// contract - implementation of the SwContract interface
 var contract = impl.PstContract{}
 
 // handles all the WASM-JS related trickery...
 func main() {
-	wasm.Run(&contract)
+	common.Run(&contract)
 }

go/main.go

@@ -26,7 +26,7 @@ async function main() {
     global.redstone.go = {
         console: {
             log: function (...args) {
-                console.log(args[0], args.slice(1));
+                console.log(`[WASM] ${args[0]}`, ...args.slice(1));
             }
         },
         Transaction: {
@@ -102,7 +102,7 @@ async function main() {
             }
         }
     )));
-    console.log('\ncurrentState()', currentState());
+    console.log('\ncurrentState()', JSON.parse(currentState()));
 
     console.log("\nCalling async handle - transfer");
 
@@ -117,7 +117,7 @@ async function main() {
     console.log('Result from transfer:', resultTransfer);
     console.log('Gas used', usedGas);
 
-    console.log('\ncurrentState()', currentState());
+    console.log('\ncurrentState()', JSON.parse(currentState()));
 
     console.log("\nCalling async handle - balance");
     const resultBalance = await handle(JSON.stringify({

go/run-tiny.js

@@ -26,7 +26,7 @@ async function main() {
     global.redstone.go = {
         console: {
             log: function (...args) {
-                console.log(args[0], args.slice(1));
+                console.log(args[0], ...args.slice(1));
             }
         },
         Transaction: {