condition_variable: move exception factory functions out of line

Error path need not be implemented in the header file.
Also mark them noexcept as broken_condition_variable
and condition_variable_timed_out are nothrow default constructible.

Signed-off-by: Benny Halevy <[email protected]>

CMakeLists.txt

@@ -631,6 +631,7 @@ add_library (seastar STATIC
   src/core/vla.hh
   src/core/io_queue.cc
   src/core/semaphore.cc
+  src/core/condition-variable.cc
   src/http/api_docs.cc
   src/http/common.cc
   src/http/file_handler.cc

include/seastar/core/condition-variable.hh

@@ -34,19 +34,15 @@ namespace seastar {
 class broken_condition_variable : public std::exception {
 public:
     /// Reports the exception reason.
-    virtual const char* what() const noexcept {
-        return "Condition variable is broken";
-    }
+    virtual const char* what() const noexcept;
 };
 
 /// Exception thrown when wait() operation times out
 /// \ref condition_variable::wait(time_point timeout).
 class condition_variable_timed_out : public std::exception {
 public:
     /// Reports the exception reason.
-    virtual const char* what() const noexcept {
-        return "Condition variable timed out";
-    }
+    virtual const char* what() const noexcept;
 };
 
 /// \brief Conditional variable.
@@ -67,12 +63,8 @@ class condition_variable {
     using clock = semaphore::clock;
     using time_point = semaphore::time_point;
     struct condition_variable_exception_factory {
-        static condition_variable_timed_out timeout() {
-            return condition_variable_timed_out();
-        }
-        static broken_condition_variable broken() {
-            return broken_condition_variable();
-        }
+        static condition_variable_timed_out timeout() noexcept;
+        static broken_condition_variable broken() noexcept;
     };
     basic_semaphore<condition_variable_exception_factory> _sem;
 public:

src/core/condition-variable.cc

@@ -0,0 +1,44 @@
+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  You may not use this file except in compliance with the License.
+ *
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*
+ * Copyright (C) 2020 ScyllaDB, Ltd.
+ */
+
+#include <seastar/core/condition-variable.hh>
+
+namespace seastar {
+
+const char* broken_condition_variable::what() const noexcept {
+    return "Condition variable is broken";
+}
+
+const char* condition_variable_timed_out::what() const noexcept {
+    return "Condition variable timed out";
+}
+
+condition_variable_timed_out condition_variable::condition_variable_exception_factory::timeout() noexcept {
+    static_assert(std::is_nothrow_default_constructible_v<condition_variable_timed_out>);
+    return condition_variable_timed_out();
+}
+
+broken_condition_variable condition_variable::condition_variable_exception_factory::broken() noexcept {
+    static_assert(std::is_nothrow_default_constructible_v<broken_condition_variable>);
+    return broken_condition_variable();
+}
+
+} // namespace seastar