Implement connection recovery procedures in client
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53857bc613
commit
b522ef8a98
@ -1,33 +1,221 @@
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namespace StudySystemClient {
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public class Connection {
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public signal void response_received(uint8[] response);
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public signal void received(uint8[] msg);
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private TlsClientConnection tls_client;
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private SessionManager session_manager;
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private Worker worker;
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public Connection(string cert_dir) throws Error {
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var loopback = new InetAddress.loopback(SocketFamily.IPV6);
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var host = new InetSocketAddress(loopback, 12888);
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var session_factory
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= new SessionFactory(loopback, 12888, cert_dir);
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session_manager = new SessionManager(
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session_factory, (msg) => {
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var msg_copy = new uint8[msg.length];
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Memory.copy(msg_copy, msg, msg.length);
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Idle.add(() => {
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received(msg_copy);
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return false;
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}, GLib.Priority.DEFAULT_IDLE);
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});
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worker = new Worker(session_manager);
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}
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public void send(owned uint8[] msg) {
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session_manager.send(msg);
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}
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}
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private class Worker {
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private uint TASK_PERIOD_MS = 10;
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private SessionManager session_manager;
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private bool exit;
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private Thread<void> thread;
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public Worker(SessionManager session_manager) {
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this.session_manager = session_manager;
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exit = false;
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thread = new Thread<void>("connection_worker", body);
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}
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~Worker() {
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exit = true;
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thread.join();
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}
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private void body() {
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while (!exit) {
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session_manager.task();
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Thread.usleep(1000 * TASK_PERIOD_MS);
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}
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}
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}
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private class SessionManager {
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public delegate void ReceiveCallback(uint8[] msg);
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private const uint INIT_RECONNECT_WAIT_MS = 500;
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private const uint MAX_RECONNECT_WAIT_MS = 60000;
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private const double RECONNECT_BACKOFF = 1.6;
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private SessionFactory session_factory;
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private ReceiveCallback receive_callback;
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private Session? session;
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private AsyncQueue<OutgoingMessage> queue;
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private uint reconnect_wait_ms;
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public SessionManager(SessionFactory session_factory,
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owned ReceiveCallback receive_callback) {
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this.session_factory = session_factory;
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this.receive_callback = (owned) receive_callback;
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this.session = null;
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queue = new AsyncQueue<OutgoingMessage>();
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reconnect_wait_ms = INIT_RECONNECT_WAIT_MS;
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}
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public void send(uint8[] msg) {
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queue.push(new OutgoingMessage(msg));
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}
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public void task() {
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if (session != null) {
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var failed_msg = session.task(queue);
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if (failed_msg != null)
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handle_failed_msg(failed_msg);
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} else {
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try_start_session();
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}
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}
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private void handle_failed_msg(OutgoingMessage msg) {
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msg.has_failed();
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if (msg.should_retry())
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queue.push(msg);
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session = null;
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}
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private void try_start_session() {
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try {
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session = session_factory.start_session();
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session.received.connect(
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(msg) => receive_callback(msg));
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reconnect_wait_ms = INIT_RECONNECT_WAIT_MS;
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} catch (Error _) {
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Thread.usleep(1000 * reconnect_wait_ms);
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update_reconnect_wait();
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}
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}
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private void update_reconnect_wait() {
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var new_wait = RECONNECT_BACKOFF * reconnect_wait_ms;
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if (new_wait < MAX_RECONNECT_WAIT_MS)
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reconnect_wait_ms = (uint)new_wait;
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else
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reconnect_wait_ms = MAX_RECONNECT_WAIT_MS;
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}
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}
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private class SessionFactory {
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private const string CA_FILENAME = "/ca.pem";
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private const string CERT_FILENAME = "/client.pem";
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private const uint TIMEOUT_S = 1;
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private InetSocketAddress host;
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private TlsCertificate cert;
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private TlsDatabase ca_db;
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public SessionFactory(InetAddress host_addr, uint16 host_port,
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string cert_dir) throws Error {
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host = new InetSocketAddress(host_addr, host_port);
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var cert_path = cert_dir + CERT_FILENAME;
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cert = new TlsCertificate.from_file(cert_path);
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var ca_path = cert_dir + CA_FILENAME;
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var db_type = TlsBackend.get_default().get_file_database_type();
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var ca_path = cert_dir + "/ca.pem";
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var db = Object.new(db_type, "anchors", ca_path) as TlsDatabase;
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var cert_path = cert_dir + "/client.pem";
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var cert = new TlsCertificate.from_file(cert_path);
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ca_db = Object.new(db_type, "anchors", ca_path) as TlsDatabase;
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}
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public Session start_session() throws Error {
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var plain_client = new SocketClient();
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plain_client.set_timeout(TIMEOUT_S);
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var plain_connection = plain_client.connect(host);
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tls_client = TlsClientConnection.new(plain_connection, host);
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tls_client.set_database(db);
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tls_client.set_certificate(cert);
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tls_client.handshake();
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var connection = TlsClientConnection.new(plain_connection, host);
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connection.set_database(ca_db);
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connection.set_certificate(cert);
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connection.handshake();
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return new Session(connection);
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}
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}
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public async void send(uint8[] message) throws Error {
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yield tls_client.output_stream.write_async(message);
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var response = new uint8[1024];
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var len = yield tls_client.input_stream.read_async(response);
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response_received(response[0:len]);
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private class Session {
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public signal void received(uint8[] msg);
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private const uint MAX_BATCH_SIZE = 10;
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private const uint MAX_MSG_LEN = 1024;
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private TlsClientConnection connection;
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public Session(TlsClientConnection connection) {
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this.connection = connection;
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}
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public OutgoingMessage? task(AsyncQueue<OutgoingMessage> queue) {
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for (int i = 0; i < MAX_BATCH_SIZE; ++i) {
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if (queue.length() == 0)
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break;
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var msg = queue.pop();
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var success = true;
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success &= send(msg);
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success &= receive();
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if (!success)
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return msg;
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}
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return null;
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}
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private bool send(OutgoingMessage msg) {
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try {
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size_t written;
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connection.output_stream.write_all(msg.content, out written);
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return true;
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} catch (IOError _) {
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return false;
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}
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}
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private bool receive() {
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try {
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var buffer = new uint8[MAX_MSG_LEN];
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var len = connection.input_stream.read(buffer);
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if (len <= 0)
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return false;
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received(buffer[0:len]);
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return true;
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} catch (IOError _) {
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return false;
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}
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}
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}
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private class OutgoingMessage {
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public uint8[] content { get; private set; }
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private const uint MAX_FAIL_COUNT = 10;
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private uint fail_count;
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public OutgoingMessage(owned uint8[] content) {
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this.content = (owned)content;
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fail_count = 0;
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}
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public void has_failed() {
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++fail_count;
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}
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public bool should_retry() {
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return fail_count < MAX_FAIL_COUNT;
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}
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}
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}
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@ -13,8 +13,8 @@ namespace StudySystemClient {
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default_height = 580;
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this.connection = connection;
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connection.response_received.connect((response) => {
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response_label.label = "Response: " + (string)response;
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connection.received.connect((msg) => {
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response_label.label = "Response: " + (string)msg;
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});
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var box = new Gtk.Box(Gtk.Orientation.VERTICAL, 10);
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@ -24,7 +24,7 @@ namespace StudySystemClient {
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box.margin_bottom = 10;
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send_button = new Gtk.Button.with_label("Send");
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send_button.clicked.connect(on_send_clicked);
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send_button.clicked.connect(() => connection.send("Foo".data));
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box.append(send_button);
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response_label = new Gtk.Label("");
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@ -35,13 +35,5 @@ namespace StudySystemClient {
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present();
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}
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private async void on_send_clicked() {
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try {
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yield connection.send("Foo".data);
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} catch (Error e) {
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response_label.label = "Error: " + e.message;
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}
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}
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}
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}
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