sample_web_server: fix CTRL-C and high cpu usage issue

fix #4

src/sample_web_server.zig

@@ -76,7 +76,7 @@ pub fn main() !void {
         io.accept(*Acceptor, &acceptor, acceptCallback, &acceptor_completion, listener);
 
         // Wait while accepting.
-        while (acceptor.accepting) try io.tick();
+        while (acceptor.accepting and running.load(.monotonic)) try io.run_for_ns(1 * std.time.ns_per_ms);
 
         // Reset accepting flag.
         acceptor.accepting = true;
@@ -111,7 +111,8 @@ fn logError(queue_mutex: *Thread.Mutex, queue: *Queue) void {
 
 const Client = struct {
     allocator: mem.Allocator,
-    completion: IO.Completion,
+    send_completion: IO.Completion,
+    recv_completion: IO.Completion,
     io: *IO,
     recv_buf: [Config.recv_buf_len]u8,
     socket: posix.socket_t,
@@ -143,7 +144,8 @@ fn handleClient(queue_mutex: *Thread.Mutex, queue: *Queue) !void {
             var client_ptr = try allocator.create(Client);
             client_ptr.allocator = allocator;
             client_ptr.io = &io;
-            client_ptr.completion = undefined;
+            client_ptr.send_completion = undefined;
+            client_ptr.recv_completion = undefined;
             client_ptr.recv_buf = undefined;
             client_ptr.socket = socket;
             client_ptr.thread_id = thread_id;
@@ -153,13 +155,13 @@ fn handleClient(queue_mutex: *Thread.Mutex, queue: *Queue) !void {
                 *Client,
                 client_ptr,
                 recvCallback,
-                &client_ptr.completion,
+                &client_ptr.recv_completion,
                 socket,
                 &client_ptr.recv_buf,
             );
         }
 
-        try io.tick();
+        try io.run_for_ns(1 * std.time.ns_per_ms);
     }
 }
 
@@ -187,6 +189,16 @@ fn recvCallback(
         return;
     }
 
+    // Try to receive from client again (keep-alive).
+    client_ptr.io.recv(
+        *Client,
+        client_ptr,
+        recvCallback,
+        completion,
+        client_ptr.socket,
+        &client_ptr.recv_buf,
+    );
+
     const response =
         \\HTTP/1.1 200 OK
         \\Connection: Keep-Alive
@@ -203,7 +215,7 @@ fn recvCallback(
         *Client,
         client_ptr,
         sendCallback,
-        completion,
+        &client_ptr.send_completion,
         client_ptr.socket,
         response,
     );
@@ -214,18 +226,9 @@ fn sendCallback(
     completion: *IO.Completion,
     result: IO.SendError!usize,
 ) void {
+    _ = completion; // autofix
     const sent = result catch @panic("sendCallback");
     log.debug("{}: Sent {} to {}", .{ client_ptr.thread_id, sent, client_ptr.socket });
-
-    // Try to receive from client again (keep-alive).
-    client_ptr.io.recv(
-        *Client,
-        client_ptr,
-        recvCallback,
-        completion,
-        client_ptr.socket,
-        &client_ptr.recv_buf,
-    );
 }
 
 fn closeCallback(