dnfdaemon: Base.reset() API

This call will re-create libdnf5::Base instance stored in the session.
As a result, the goal and transaction are reset as well.

dnf5daemon-server/dbus/interfaces/org.rpm.dnf.v0.Base.xml

@@ -50,6 +50,18 @@ along with libdnf.  If not, see <https://www.gnu.org/licenses/>.
         <arg name="error_msg" type="s" direction="out"/>
     </method>
 
+    <!--
+        reset:
+        @success: `true` if the session was successfully resetted, `false` otherwise.
+        @error_msg: string, contains errors encountered while resetting the session
+
+        Completely reset the session.
+    -->
+    <method name="reset">
+        <arg name="success" type="b" direction="out"/>
+        <arg name="error_msg" type="s" direction="out"/>
+    </method>
+
     <!--
         download_add_new:
         @session_object_path: object path of the dnf5daemon session

dnf5daemon-server/services/base/base.cpp

@@ -30,6 +30,7 @@ along with libdnf.  If not, see <https://www.gnu.org/licenses/>.
 #include <unistd.h>
 
 #include <iostream>
+#include <mutex>
 #include <string>
 #include <thread>
 #include <unordered_set>
@@ -58,6 +59,16 @@ void Base::dbus_register() {
         [this](sdbus::MethodCall call) -> void {
             session.get_threads_manager().handle_method(*this, &Base::clean, call, session.session_locale);
         });
+    dbus_object->registerMethod(
+        dnfdaemon::INTERFACE_BASE,
+        "reset",
+        "",
+        {},
+        "bs",
+        {"success", "error_msg"},
+        [this](sdbus::MethodCall call) -> void {
+            session.get_threads_manager().handle_method(*this, &Base::reset, call, session.session_locale);
+        });
 
     dbus_object->registerSignal(
         dnfdaemon::INTERFACE_BASE,
@@ -147,3 +158,21 @@ sdbus::MethodReply Base::clean(sdbus::MethodCall & call) {
     reply << error_msg;
     return reply;
 }
+
+sdbus::MethodReply Base::reset(sdbus::MethodCall & call) {
+    bool success{true};
+    std::string error_msg{};
+
+    auto & transaction_mutex = session.get_transaction_mutex();
+    if (!transaction_mutex.try_lock()) {
+        success = false;
+        error_msg = "Cannot reset, an rpm transaction is running.";
+    } else {
+        std::lock_guard<std::mutex> transaction_lock(transaction_mutex, std::adopt_lock);
+        session.reset_base();
+    }
+    auto reply = call.createReply();
+    reply << success;
+    reply << error_msg;
+    return reply;
+}

dnf5daemon-server/services/base/base.hpp

@@ -36,6 +36,7 @@ class Base : public IDbusSessionService {
 
 private:
     sdbus::MethodReply clean(sdbus::MethodCall & call);
+    sdbus::MethodReply reset(sdbus::MethodCall & call);
     sdbus::MethodReply read_all_repos(sdbus::MethodCall & call);
 };
 

dnf5daemon-server/session.cpp

@@ -394,3 +394,7 @@ void Session::reset_goal() {
     transaction.reset(nullptr);
     goal->reset();
 }
+
+void Session::reset_base() {
+    setup_base();
+}

dnf5daemon-server/session.hpp

@@ -101,6 +101,7 @@ class Session {
     std::mutex & get_transaction_mutex() { return transaction_mutex; }
 
     void reset_goal();
+    void reset_base();
 
 private:
     void setup_base();