Introduced fallback contract execution (#388)

examples/nodejs_contract/echo_contract.js

@@ -5,10 +5,10 @@ const exectsFile = "exects.txt";
 
 // HP smart contract is defined as a function which takes HP ExecutionContext as an argument.
 // HP considers execution as complete, when this function completes and all the NPL message callbacks are complete.
-const echoContract = async (ctx) => {
+const contract = async (ctx, readonly = false) => {
 
     // We just save execution timestamp as an example state file change.
-    if (!ctx.readonly) {
+    if (!readonly) {
         fs.appendFileSync(exectsFile, "ts:" + ctx.timestamp + "\n");
 
         const stats = fs.statSync(exectsFile);
@@ -56,7 +56,7 @@ const echoContract = async (ctx) => {
     // ctx.unl.find("<public key hex>");
 
     // NPL messages example.
-    // if (!ctx.readonly) {
+    // if (!readonly) {
     //     // Start listening to incoming NPL messages before we send ours.
     //     const promise = new Promise((resolve, reject) => {
     //         let timeout = setTimeout(() => {
@@ -84,5 +84,33 @@ const echoContract = async (ctx) => {
     // await ctx.updateConfig(config);
 }
 
+const fallback = async (ctx) => {
+    console.log(`Fallback mode: Non consensus execution count: ${ctx.nonConsensusRounds}`);
+    // NPL messages example.
+    // Start listening to incoming NPL messages before we send ours.
+    const promise = new Promise((resolve, reject) => {
+        let timeout = setTimeout(() => {
+            reject('NPL timeout.');
+        }, 2000);
+
+        let list = [];
+        ctx.unl.onMessage((node, msg) => {
+            console.log(`${node.publicKey} said ${msg} to me.`);
+            list.push(msg);
+            if (list.length == ctx.unl.list().length) {
+                clearTimeout(timeout);
+                resolve();
+            }
+        });
+    });
+
+    await ctx.unl.send("Hello");
+    await promise;
+}
+
 const hpc = new HotPocket.Contract();
-hpc.init(echoContract);
+hpc.init({
+    "consensus": async (ctx) => { await contract(ctx, false); },
+    "consensus_fallback": async (ctx) => { await fallback(ctx); },
+    "read_req": async (ctx) => { await contract(ctx, true); }
+});