Fix all the ConditionalProxyMiddleware errors that happened if you ctrl+c on a "dotnet run" (not "dotnet watch run") since beta-000002.

SteveSandersonMS · SteveSandersonMS · commit 1c4682e50d30 · 2016-12-13T11:32:32.000Z
diff --git a/src/Microsoft.AspNetCore.NodeServices/Content/Node/entrypoint-http.js b/src/Microsoft.AspNetCore.NodeServices/Content/Node/entrypoint-http.js
@@ -125,7 +125,7 @@
 	    // Signal to the NodeServices base class that we're ready to accept invocations
 	    console.log('[Microsoft.AspNetCore.NodeServices:Listening]');
 	});
-	ExitWhenParentExits_1.exitWhenParentExits(parseInt(parsedArgs.parentPid));
+	ExitWhenParentExits_1.exitWhenParentExits(parseInt(parsedArgs.parentPid), /* ignoreSigint */ true);
 	function readRequestBodyAsJson(request, callback) {
 	    var requestBodyAsString = '';
 	    request.on('data', function (chunk) { requestBodyAsString += chunk; });
@@ -255,14 +255,32 @@
 	*/
 	"use strict";
 	var pollIntervalMs = 1000;
-	function exitWhenParentExits(parentPid) {
+	function exitWhenParentExits(parentPid, ignoreSigint) {
 	    setInterval(function () {
 	        if (!processExists(parentPid)) {
 	            // Can't log anything at this point, because out stdout was connected to the parent,
 	            // but the parent is gone.
 	            process.exit();
 	        }
 	    }, pollIntervalMs);
+	    if (ignoreSigint) {
+	        // Pressing ctrl+c in the terminal sends a SIGINT to all processes in the foreground process tree.
+	        // By default, the Node process would then exit before the .NET process, because ASP.NET implements
+	        // a delayed shutdown to allow ongoing requests to complete.
+	        //
+	        // This is problematic, because if Node exits first, the CopyToAsync code in ConditionalProxyMiddleware
+	        // will experience a read fault, and logs a huge load of errors. Fortunately, since the Node process is
+	        // already set up to shut itself down if it detects the .NET process is terminated, all we have to do is
+	        // ignore the SIGINT. The Node process will then terminate automatically after the .NET process does.
+	        //
+	        // A better solution would be to have WebpackDevMiddleware listen for SIGINT and gracefully close any
+	        // ongoing EventSource connections before letting the Node process exit, independently of the .NET
+	        // process exiting. However, doing this well in general is very nontrivial (see all the discussion at
+	        // https://github.com/nodejs/node/issues/2642).
+	        process.on('SIGINT', function () {
+	            console.log('Received SIGINT. Waiting for .NET process to exit...');
+	        });
+	    }
 	}
 	exports.exitWhenParentExits = exitWhenParentExits;
 	function processExists(pid) {
diff --git a/src/Microsoft.AspNetCore.NodeServices/TypeScript/HttpNodeInstanceEntryPoint.ts b/src/Microsoft.AspNetCore.NodeServices/TypeScript/HttpNodeInstanceEntryPoint.ts
@@ -76,7 +76,7 @@ server.listen(requestedPortOrZero, 'localhost', function () {
     console.log('[Microsoft.AspNetCore.NodeServices:Listening]');
 });
 
-exitWhenParentExits(parseInt(parsedArgs.parentPid));
+exitWhenParentExits(parseInt(parsedArgs.parentPid), /* ignoreSigint */ true);
 
 function readRequestBodyAsJson(request, callback) {
     let requestBodyAsString = '';
diff --git a/src/Microsoft.AspNetCore.NodeServices/TypeScript/Util/ExitWhenParentExits.ts b/src/Microsoft.AspNetCore.NodeServices/TypeScript/Util/ExitWhenParentExits.ts
@@ -34,14 +34,33 @@ to check whether the parent PID is still running. So that's what we do here.
 
 const pollIntervalMs = 1000;
 
-export function exitWhenParentExits(parentPid: number) {
+export function exitWhenParentExits(parentPid: number, ignoreSigint: boolean) {
     setInterval(() => {
         if (!processExists(parentPid)) {
             // Can't log anything at this point, because out stdout was connected to the parent,
             // but the parent is gone.
             process.exit();
         }
     }, pollIntervalMs);
+
+    if (ignoreSigint) {
+        // Pressing ctrl+c in the terminal sends a SIGINT to all processes in the foreground process tree.
+        // By default, the Node process would then exit before the .NET process, because ASP.NET implements
+        // a delayed shutdown to allow ongoing requests to complete.
+        //
+        // This is problematic, because if Node exits first, the CopyToAsync code in ConditionalProxyMiddleware
+        // will experience a read fault, and logs a huge load of errors. Fortunately, since the Node process is
+        // already set up to shut itself down if it detects the .NET process is terminated, all we have to do is
+        // ignore the SIGINT. The Node process will then terminate automatically after the .NET process does.
+        //
+        // A better solution would be to have WebpackDevMiddleware listen for SIGINT and gracefully close any
+        // ongoing EventSource connections before letting the Node process exit, independently of the .NET
+        // process exiting. However, doing this well in general is very nontrivial (see all the discussion at
+        // https://github.com/nodejs/node/issues/2642).
+        process.on('SIGINT', () => {
+            console.log('Received SIGINT. Waiting for .NET process to exit...');
+        });
+    }
 }
 
 function processExists(pid: number) {
@@ -56,7 +75,7 @@ function processExists(pid: number) {
         if (ex.code === 'EPERM') {
             throw new Error(`Attempted to check whether process ${pid} was running, but got a permissions error.`);
         }
-        
+
         return false;
     }
 }
