added a simple message bus

source/core/CMakeLists.txt

@@ -13,8 +13,8 @@ add_library(matador-core STATIC
   ../../include/matador/net/reactor.hpp
   ../../include/matador/net/select_fd_sets.hpp
   ../../include/matador/net/socket_interrupter.hpp
-  ../../include/matador/object/attribute_definition_generator.hpp
   ../../include/matador/object/attribute_definition.hpp
+  ../../include/matador/object/attribute_definition_generator.hpp
   ../../include/matador/object/basic_object_info.hpp
   ../../include/matador/object/error_code.hpp
   ../../include/matador/object/foreign_node_completer.hpp
@@ -30,6 +30,7 @@ add_library(matador-core STATIC
   ../../include/matador/object/schema.hpp
   ../../include/matador/object/schema_node.hpp
   ../../include/matador/object/schema_node_iterator.hpp
+  ../../include/matador/sql/statement_cache.hpp
   ../../include/matador/utils/access.hpp
   ../../include/matador/utils/attribute_reader.hpp
   ../../include/matador/utils/attribute_writer.hpp
@@ -47,13 +48,14 @@ add_library(matador-core STATIC
   ../../include/matador/utils/errors.hpp
   ../../include/matador/utils/export.hpp
   ../../include/matador/utils/fetch_type.hpp
-  ../../include/matador/utils/file.hpp
   ../../include/matador/utils/field_attributes.hpp
+  ../../include/matador/utils/file.hpp
   ../../include/matador/utils/foreign_attributes.hpp
   ../../include/matador/utils/identifier.hpp
   ../../include/matador/utils/leader_follower_thread_pool.hpp
   ../../include/matador/utils/library.hpp
   ../../include/matador/utils/macro_map.hpp
+  ../../include/matador/utils/message_bus.hpp
   ../../include/matador/utils/os.hpp
   ../../include/matador/utils/placeholder.hpp
   ../../include/matador/utils/primary_key_attribute.hpp
@@ -73,8 +75,8 @@ add_library(matador-core STATIC
   logger/log_manager.cpp
   logger/logger.cpp
   logger/rotating_file_sink.cpp
-  object/attribute_definition_generator.cpp
   object/attribute_definition.cpp
+  object/attribute_definition_generator.cpp
   object/basic_object_info.cpp
   object/error_code.cpp
   object/foreign_node_completer.cpp
@@ -93,6 +95,7 @@ add_library(matador-core STATIC
   utils/identifier.cpp
   utils/leader_follower_thread_pool.cpp
   utils/library.cpp
+  utils/message_bus.cpp
   utils/os.cpp
   utils/primary_key_attribute.cpp
   utils/string.cpp
@@ -101,7 +104,6 @@ add_library(matador-core STATIC
   utils/uuid.cpp
   utils/value.cpp
   utils/version.cpp
-        ../../include/matador/sql/statement_cache.hpp
 )
 
 target_link_libraries(matador-core ${CMAKE_DL_LIBS})

source/core/utils/message_bus.cpp

@@ -0,0 +1,97 @@
+#include "matador/utils/message_bus.hpp"
+
+namespace matador::utils {
+message::message()
+: ptr_(nullptr)
+, owner_(nullptr)
+, type_(typeid(void)) {}
+
+bool message::empty() const {
+  return ptr_ == nullptr && !owner_;
+}
+
+std::type_index message::type() const {
+  return type_;
+}
+
+const void * message::msg_ptr() const {
+  return owner_ ? owner_.get() : ptr_;
+}
+
+subscription::subscription(message_bus *bus, const std::type_index type, const uint64_t id)
+: bus_(bus)
+, type_(type)
+, id_(id) {}
+
+subscription::subscription(subscription &&other) noexcept
+: bus_(other.bus_)
+, type_(other.type_)
+, id_(other.id_) {
+  other.bus_ = nullptr;
+}
+
+subscription& subscription::operator=(subscription &&other) noexcept {
+  if (this != &other) {
+    unsubscribe();
+    bus_ = other.bus_;
+    type_ = other.type_;
+    id_ = other.id_;
+    other.bus_ = nullptr;
+  }
+  return *this;
+}
+
+subscription::~subscription() {
+  unsubscribe();
+}
+
+bool subscription::valid() const {
+  return bus_ != nullptr;
+}
+
+void message_bus::unsubscribe(const std::type_index type, HandlerId id) {
+  std::unique_lock writeLock(mutex_);
+  const auto it = handlers_.find(type);
+  if (it == handlers_.end()) {
+    return;
+  }
+  auto &handler_vector = it->second;
+  handler_vector.erase(std::remove_if(handler_vector.begin(), handler_vector.end(),
+                           [id](const Entry &e) { return e.id == id; }),
+            handler_vector.end());
+  if (handler_vector.empty()) {
+    handlers_.erase(it);
+  }
+}
+
+void message_bus::unsubscribe(HandlerId id) {
+  std::unique_lock writeLock(mutex_);
+  for (auto it = handlers_.begin(); it != handlers_.end(); ) {
+    auto &handler_vector = it->second;
+    handler_vector.erase(std::remove_if(handler_vector.begin(), handler_vector.end(),
+                             [id](const Entry &e) { return e.id == id; }),
+              handler_vector.end());
+    if (handler_vector.empty()) it = handlers_.erase(it);
+    else ++it;
+  }
+}
+
+void message_bus::publish(const message &msg) const {
+  if (msg.empty()) {
+    return;
+  }
+  std::vector<Entry> snapshot;
+  {
+    std::shared_lock readLock(mutex_);
+    const auto it = handlers_.find(msg.type());
+    if (it == handlers_.end()) {
+      return;
+    }
+    snapshot = it->second;
+  }
+  const void* p = msg.msg_ptr();
+  for (const auto &e : snapshot) {
+    if (!e.filter || e.filter(p)) e.handler(p);
+  }
+}
+}