Merge pull request #322 from keyhash/feature/send-email-on-rpc-error

Send an email when the worker cannot get the last block header

lib/worker.js

@@ -504,20 +504,42 @@ function updateWalletStats() {
 
 }
 
+let lastBlockCheckIsOk = true;
 function monitorNodes() {
-    global.mysql.query("SELECT blockID, hostname, ip FROM pools WHERE last_checkin > date_sub(now(), interval 30 minute)").then(function (rows) {
-        global.coinFuncs.getLastBlockHeader(function (err, block) {
-            if (err !== null){
-                console.error("Issue in getting block header.  Skipping node monitor");
-                return;
+    global.coinFuncs.getLastBlockHeader((err, block) => {
+        if (err !== null) {
+            if (lastBlockCheckIsOk) {
+                lastBlockCheckIsOk = false;
+                global.support.sendEmail(
+                    global.config.general.adminEmail,
+                    'Failed to query daemon for last block header',
+                    `The worker failed to return last block header. Please verify if the daemon is running properly.`
+                );
             }
-            rows.forEach(function (row) {
-                    if (row.blockID < block.height - 3) {
-                        global.support.sendEmail(global.config.general.adminEmail, "Pool server behind in blocks", "The pool server: "+row.hostname+" with IP: "+row.ip+" is "+(block.height - row.blockID)+ " blocks behind");
-                    }
-                }
+            return
+        }
+        if (!lastBlockCheckIsOk) {
+            lastBlockCheckIsOk = true;
+            global.support.sendEmail(
+                global.config.general.adminEmail,
+                'Quering daemon for last block header is back to normal',
+                `An warning was sent to you indicating that the the worker failed to return the last block header.
+                 The issue seems to be solved now.`
             );
+        }
+        const sql = 'SELECT blockID, hostname, ip FROM pools WHERE last_checkin > DATE_SUB(NOW(), INTERVAL 30 MINUTE)';
+        global.mysql.query(sql).then(pools => {
+            pools.forEach(({ blockID, hostname, ip }) => {
+                if (blockID < block.height - 3) {
+                    global.support.sendEmail(
+                        global.config.general.adminEmail,
+                        'Pool server is behind in blocks',
+                        `The pool server: ${hostname} with IP: ${ip} is ${(block.height - blockID)} blocks behind.`
+                    );
+                }
+            })
         });
+        
     });
 }