add retry on network error

wasm-demo.js

@@ -299,7 +299,7 @@ $('btnEncrypt').onclick = async () => {
     }
 };
 
-async function pollTaskStatus(currentTaskId, currentUid) {
+async function pollTaskStatus(currentTaskId, currentUid, retryCount = 0, maxRetries = 10) {
     try {
         const statusResponse = await fetch(`${SERVER}/get_task_status?task_id=${currentTaskId}&uid=${currentUid}`);
         if (!statusResponse.ok) {
@@ -375,24 +375,64 @@ async function pollTaskStatus(currentTaskId, currentUid) {
             }
             return null;
         } else {
-            setTimeout(() => pollTaskStatus(currentTaskId, currentUid).then(finalStatus => {
+            // Calculate delay with exponential backoff (max 30 seconds)
+            const baseDelay = 5000;
+            const delay = Math.min(baseDelay * Math.pow(1.5, retryCount), 30000);
+            
+            setTimeout(() => pollTaskStatus(currentTaskId, currentUid, retryCount, maxRetries).then(finalStatus => {
                 if (finalStatus && (finalStatus.status === 'success' || finalStatus.status === 'completed')) {
                     getTaskResult(currentTaskId, currentUid, 'synthid');
                 }
-            }), 5000);
+            }), delay);
             return null;
         }
     } catch (e) {
         console.error('[Poll] Polling exception:', e);
-        $('srvStatus').textContent = 'Connection error. Please check your network.';
-        show('spin', false);
-        show('progressContainer', false);
-        window.processingStartTime = null;
-        if (progressTimer) {
-            clearInterval(progressTimer);
-            progressTimer = null;
+        
+        // Check if we've exceeded max retries
+        if (retryCount >= maxRetries) {
+            console.error(`[Poll] Max retries (${maxRetries}) exceeded. Giving up.`);
+            $('srvStatus').textContent = 'Connection failed after multiple attempts. Please try again later.';
+            cleanupPolling();
+            return null;
         }
-        return null;
+        
+        // Distinguish between network errors and other errors
+        const isNetworkError = e.name === 'TypeError' && e.message.includes('fetch');
+        const isDnsError = e.message.includes('ERR_NAME_NOT_RESOLVED');
+        
+        if (isNetworkError || isDnsError) {
+            console.warn(`[Poll] Network error (attempt ${retryCount + 1}/${maxRetries}):`, e.message);
+            $('srvStatus').textContent = `Connection error (attempt ${retryCount + 1}/${maxRetries}). Retrying...`;
+            
+            // Calculate delay with exponential backoff
+            const baseDelay = 5000;
+            const delay = Math.min(baseDelay * Math.pow(1.5, retryCount), 30000);
+            
+            setTimeout(() => pollTaskStatus(currentTaskId, currentUid, retryCount + 1, maxRetries).then(finalStatus => {
+                if (finalStatus && (finalStatus.status === 'success' || finalStatus.status === 'completed')) {
+                    getTaskResult(currentTaskId, currentUid, 'synthid');
+                }
+            }), delay);
+            return null;
+        } else {
+            // Non-network error - don't retry
+            console.error('[Poll] Non-recoverable error:', e);
+            $('srvStatus').textContent = 'An unexpected error occurred. Please try again.';
+            cleanupPolling();
+            return null;
+        }
+    }
+}
+
+function cleanupPolling() {
+    show('spin', false);
+    show('progressContainer', false);
+    $('srvComputing').hidden = true;
+    window.processingStartTime = null;
+    if (progressTimer) {
+        clearInterval(progressTimer);
+        progressTimer = null;
     }
 }
 
@@ -412,7 +452,7 @@ async function getTaskResult(currentTaskId, currentUid, taskName) {
 
         if (!resultResponse.ok) {
             const errorText = await resultResponse.text();
-            throw new Error(`Failed to get results`);
+            throw new Error(`Failed to get results: ${errorText}`);
         }
 
         const resultArrayBuffer = await resultResponse.arrayBuffer();
@@ -482,7 +522,7 @@ $('btnSend').onclick = async () => {
 
         if (!startTaskResponse.ok) {
             const errorText = await startTaskResponse.text();
-            throw new Error(`Server error: ${startTaskResponse.status}`);
+            throw new Error(`Server error: ${startTaskResponse.status} - ${errorText}`);
         }
 
         const { task_id: newTaskId } = await startTaskResponse.json();
@@ -490,7 +530,7 @@ $('btnSend').onclick = async () => {
         console.log('[Main] Task submitted to server. Task ID:', taskId);
         $('srvStatus').textContent = 'Request submitted. Checking status...';
 
-        pollTaskStatus(taskId, sessionUid).then(finalStatus => {
+        pollTaskStatus(taskId, sessionUid, 0, 10).then(finalStatus => {
             if (finalStatus && (finalStatus.status === 'success' || finalStatus.status === 'completed')) {
                 getTaskResult(taskId, sessionUid, 'synthid');
             }
@@ -500,14 +540,7 @@ $('btnSend').onclick = async () => {
         const duration = window.taskStartTime ? ((performance.now() - window.taskStartTime) / 1000).toFixed(2) : 'N/A';
         console.error(`[Main] Task submission failed after ${duration}s:`, e);
         $('srvStatus').textContent = 'Failed to submit request. Please try again.';
-        show('spin', false);
-        show('progressContainer', false);
-        $('srvComputing').hidden = true;
-        window.processingStartTime = null; // Reset processing start time
-        if (progressTimer) {
-            clearInterval(progressTimer);
-            progressTimer = null;
-        }
+        cleanupPolling();
     }
 };