Inspector+LibCore+rpcdump: Rework the RPC stuff to be request/response

RPC clients now send JSON-encoded requests to the RPC server.
The connection also stays alive instead of disconnecting automatically
after the initial CObject graph dump.

JSON payloads are preceded by a single host-order encoded 32-bit int
containing the length of the payload.

So far, we have three RPC commands:

    - Identify
    - GetAllObjects
    - Disconnect

We'll be adding more of these as we go along. :^)

DevTools/Inspector/RemoteProcess.cpp

@@ -11,10 +11,80 @@ RemoteProcess::RemoteProcess(pid_t pid)
 {
 }
 
+void RemoteProcess::handle_identify_response(const JsonObject& response)
+{
+    int pid = response.get("pid").to_int();
+    ASSERT(pid == m_pid);
+
+    m_process_name = response.get("process_name").as_string_or({});
+
+    if (on_update)
+        on_update();
+}
+
+void RemoteProcess::handle_get_all_objects_response(const JsonObject& response)
+{
+    // FIXME: It would be good if we didn't have to make a local copy of the array value here!
+    auto objects = response.get("objects");
+    auto& object_array = objects.as_array();
+
+    NonnullOwnPtrVector<RemoteObject> remote_objects;
+    HashMap<String, RemoteObject*> objects_by_address;
+
+    for (auto& value : object_array.values()) {
+        ASSERT(value.is_object());
+        auto& object = value.as_object();
+        auto remote_object = make<RemoteObject>();
+        remote_object->address = object.get("address").to_string();
+        remote_object->parent_address = object.get("parent").to_string();
+        remote_object->name = object.get("name").to_string();
+        remote_object->class_name = object.get("class_name").to_string();
+        remote_object->json = object;
+        objects_by_address.set(remote_object->address, remote_object);
+        remote_objects.append(move(remote_object));
+    }
+
+    for (int i = 0; i < remote_objects.size(); ++i) {
+        auto& remote_object = remote_objects.ptr_at(i);
+        auto* parent = objects_by_address.get(remote_object->parent_address).value_or(nullptr);
+        if (!parent) {
+            m_roots.append(move(remote_object));
+        } else {
+            remote_object->parent = parent;
+            parent->children.append(move(remote_object));
+        }
+    }
+
+    m_object_graph_model->update();
+
+    if (on_update)
+        on_update();
+}
+
+void RemoteProcess::send_request(const JsonObject& request)
+{
+    auto serialized = request.to_string();
+    i32 length = serialized.length();
+    m_socket.write((const u8*)&length, sizeof(length));
+    m_socket.write(serialized);
+}
+
 void RemoteProcess::update()
 {
     m_socket.on_connected = [this] {
         dbg() << "Connected to PID " << m_pid;
+
+        {
+            JsonObject request;
+            request.set("type", "Identify");
+            send_request(request);
+        }
+
+        {
+            JsonObject request;
+            request.set("type", "GetAllObjects");
+            send_request(request);
+        }
     };
 
     m_socket.on_ready_to_read = [this] {
@@ -24,39 +94,35 @@ void RemoteProcess::update()
             return;
         }
 
-        auto data = m_socket.read_all();
+        i32 length;
+        int nread = m_socket.read((u8*)&length, sizeof(length));
+        ASSERT(nread == sizeof(length));
+
+        auto data = m_socket.read(length);
+        ASSERT(data.size() == length);
+
+        dbg() << "Got packet size " << length << " and read that many bytes";
+
         auto json_value = JsonValue::from_string(data);
-        ASSERT(json_value.is_array());
-        auto& object_array = json_value.as_array();
+        ASSERT(json_value.is_object());
 
-        Vector<NonnullOwnPtr<RemoteObject>> remote_objects;
-        HashMap<String, RemoteObject*> objects_by_address;
+        dbg() << "Got JSON response " << json_value.to_string();
 
-        for (auto& value : object_array.values()) {
-            ASSERT(value.is_object());
-            auto& object = value.as_object();
-            auto remote_object = make<RemoteObject>();
-            remote_object->address = object.get("address").to_string();
-            remote_object->parent_address = object.get("parent").to_string();
-            remote_object->name = object.get("name").to_string();
-            remote_object->class_name = object.get("class_name").to_string();
-            remote_object->json = object;
-            objects_by_address.set(remote_object->address, remote_object);
-            remote_objects.append(move(remote_object));
+        auto& response = json_value.as_object();
+
+        auto response_type = response.get("type").as_string_or({});
+        if (response_type.is_null())
+            return;
+
+        if (response_type == "GetAllObjects") {
+            handle_get_all_objects_response(response);
+            return;
         }
 
-        for (int i = 0; i < remote_objects.size(); ++i) {
-            auto& remote_object = remote_objects[i];
-            auto* parent = objects_by_address.get(remote_object->parent_address).value_or(nullptr);
-            if (!parent) {
-                m_roots.append(move(remote_object));
-            } else {
-                remote_object->parent = parent;
-                parent->children.append(move(remote_object));
-            }
+        if (response_type == "Identify") {
+            handle_identify_response(response);
+            return;
         }
-
-        m_object_graph_model->update();
     };
 
     auto success = m_socket.connect(CSocketAddress::local(String::format("/tmp/rpc.%d", m_pid)));

DevTools/Inspector/RemoteProcess.h

@@ -3,6 +3,10 @@
 #include <AK/NonnullOwnPtrVector.h>
 #include <LibCore/CLocalSocket.h>
 
+namespace AK {
+class JsonObject;
+}
+
 class RemoteObjectGraphModel;
 class RemoteObject;
 
@@ -11,11 +15,22 @@ public:
     explicit RemoteProcess(pid_t);
     void update();
 
+    pid_t pid() const { return m_pid; }
+    const String& process_name() const { return m_process_name; }
+
     RemoteObjectGraphModel& object_graph_model() { return *m_object_graph_model; }
     const NonnullOwnPtrVector<RemoteObject>& roots() const { return m_roots; }
 
+    Function<void()> on_update;
+
 private:
+    void handle_get_all_objects_response(const AK::JsonObject&);
+    void handle_identify_response(const AK::JsonObject&);
+
+    void send_request(const AK::JsonObject&);
+
     pid_t m_pid { -1 };
+    String m_process_name;
     NonnullRefPtr<RemoteObjectGraphModel> m_object_graph_model;
     CLocalSocket m_socket;
     NonnullOwnPtrVector<RemoteObject> m_roots;

DevTools/Inspector/main.cpp

@@ -41,6 +41,11 @@ int main(int argc, char** argv)
 
     RemoteProcess remote_process(pid);
 
+    remote_process.on_update = [&] {
+        if (!remote_process.process_name().is_null())
+            window->set_title(String::format("Inspector: %s (%d)", remote_process.process_name().characters(), remote_process.pid()));
+    };
+
     auto* tree_view = new GTreeView(splitter);
     tree_view->set_model(remote_process.object_graph_model());
     tree_view->set_activates_on_selection(true);

Libraries/LibCore/CEventLoop.cpp

@@ -31,6 +31,96 @@ int CEventLoop::s_next_timer_id = 1;
 int CEventLoop::s_wake_pipe_fds[2];
 CLocalServer CEventLoop::s_rpc_server;
 
+class RPCClient : public CObject {
+    C_OBJECT(RPCClient)
+public:
+    explicit RPCClient(CLocalSocket& socket)
+        : m_socket(socket)
+    {
+        add_child(socket);
+
+        m_socket.on_ready_to_read = [this] {
+            i32 length;
+            int nread = m_socket.read((u8*)&length, sizeof(length));
+            if (nread == 0) {
+                dbg() << "RPC client disconnected";
+                delete_later();
+                return;
+            }
+            ASSERT(nread == sizeof(length));
+            auto request = m_socket.read(length);
+
+            auto request_json = JsonValue::from_string(request);
+            if (!request_json.is_object()) {
+                dbg() << "RPC client sent invalid request";
+                delete_later();
+                return;
+            }
+
+            handle_request(request_json.as_object());
+        };
+    }
+    virtual ~RPCClient() override
+    {
+    }
+
+    void send_response(const JsonObject& response)
+    {
+        auto serialized = response.to_string();
+        i32 length = serialized.length();
+        m_socket.write((const u8*)&length, sizeof(length));
+        m_socket.write(serialized);
+    }
+
+    void handle_request(const JsonObject& request)
+    {
+        auto type = request.get("type").as_string_or({});
+
+        if (type.is_null()) {
+            dbg() << "RPC client sent request without type field";
+            return;
+        }
+
+        if (type == "Identify") {
+            JsonObject response;
+            response.set("type", type);
+            response.set("pid", getpid());
+#ifdef __serenity__
+            char buffer[1024];
+            if (get_process_name(buffer, sizeof(buffer)) >= 0) {
+                response.set("process_name", buffer);
+            } else {
+                response.set("process_name", JsonValue());
+            }
+#endif
+            send_response(response);
+            return;
+        }
+
+        if (type == "GetAllObjects") {
+            JsonObject response;
+            response.set("type", type);
+            JsonArray objects;
+            for (auto& object : CObject::all_objects()) {
+                JsonObject json_object;
+                object.save_to(json_object);
+                objects.append(move(json_object));
+            }
+            response.set("objects", move(objects));
+            send_response(response);
+            return;
+        }
+
+        if (type == "Disconnect") {
+            delete_later();
+            return;
+        }
+    }
+
+private:
+    CLocalSocket& m_socket;
+};
+
 CEventLoop::CEventLoop()
 {
     if (!s_event_loop_stack) {
@@ -45,7 +135,6 @@ CEventLoop::CEventLoop()
         ASSERT(rc == 0);
         s_event_loop_stack->append(this);
 
-
         auto rpc_path = String::format("/tmp/rpc.%d", getpid());
         rc = unlink(rpc_path.characters());
         if (rc < 0 && errno != ENOENT) {
@@ -56,16 +145,9 @@ CEventLoop::CEventLoop()
         ASSERT(listening);
 
         s_rpc_server.on_ready_to_accept = [&] {
-            auto* client = s_rpc_server.accept();
-            ASSERT(client);
-            JsonArray objects;
-            for (auto& object : CObject::all_objects()) {
-                JsonObject json_object;
-                object.save_to(json_object);
-                objects.append(move(json_object));
-            }
-            client->write(objects.to_string());
-            client->delete_later();
+            auto* client_socket = s_rpc_server.accept();
+            ASSERT(client_socket);
+            new RPCClient(*client_socket);
         };
     }
 

Userland/rpcdump.cpp

@@ -1,3 +1,5 @@
+#include <AK/JsonObject.h>
+#include <AK/JsonValue.h>
 #include <LibCore/CEventLoop.h>
 #include <LibCore/CLocalSocket.h>
 #include <stdio.h>
@@ -18,6 +20,13 @@ int main(int argc, char** argv)
 
     socket.on_connected = [&] {
         dbg() << "Connected to PID " << pid;
+
+        JsonObject request;
+        request.set("type", "GetAllObjects");
+        auto serialized = request.to_string();
+        i32 length = serialized.length();
+        socket.write((const u8*)&length, sizeof(length));
+        socket.write(serialized);
     };
 
     socket.on_ready_to_read = [&] {
@@ -32,6 +41,8 @@ int main(int argc, char** argv)
         for (int i = 0; i < data.size(); ++i)
             putchar(data[i]);
         printf("\n");
+
+        loop.quit(0);
     };
 
     auto success = socket.connect(CSocketAddress::local(String::format("/tmp/rpc.%d", pid)));