logging: Add member for arbitrary print callbacks

2 files changed, 26 insertions, 1 deletions

diff --git a/src/logging.cpp b/src/logging.cpp
index 60ab486198..b01177f23f 100644
--- a/src/logging.cpp
+++ b/src/logging.cpp
@@ -67,6 +67,9 @@ bool BCLog::Logger::StartLogging()
 
         if (m_print_to_file) FileWriteStr(s, m_fileout);
         if (m_print_to_console) fwrite(s.data(), 1, s.size(), stdout);
+        for (const auto& cb : m_print_callbacks) {
+            cb(s);
+        }
 
         m_msgs_before_open.pop_front();
     }
@@ -81,6 +84,7 @@ void BCLog::Logger::DisconnectTestLogger()
     m_buffering = true;
     if (m_fileout != nullptr) fclose(m_fileout);
     m_fileout = nullptr;
+    m_print_callbacks.clear();
 }
 
 void BCLog::Logger::EnableCategory(BCLog::LogFlags flag)
@@ -270,6 +274,9 @@ void BCLog::Logger::LogPrintStr(const std::string& str)
         fwrite(str_prefixed.data(), 1, str_prefixed.size(), stdout);
         fflush(stdout);
     }
+    for (const auto& cb : m_print_callbacks) {
+        cb(str_prefixed);
+    }
     if (m_print_to_file) {
         assert(m_fileout != nullptr);
 
diff --git a/src/logging.h b/src/logging.h
index e37c0c823b..9ed41c2b98 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -77,6 +77,9 @@ namespace BCLog {
 
         std::string LogTimestampStr(const std::string& str);
 
+        /** Slots that connect to the print signal */
+        std::list<std::function<void(const std::string&)>> m_print_callbacks /* GUARDED_BY(m_cs) */ {};
+
     public:
         bool m_print_to_console = false;
         bool m_print_to_file = false;
@@ -95,7 +98,22 @@ namespace BCLog {
         bool Enabled() const
         {
             std::lock_guard<std::mutex> scoped_lock(m_cs);
-            return m_buffering || m_print_to_console || m_print_to_file;
+            return m_buffering || m_print_to_console || m_print_to_file || !m_print_callbacks.empty();
+        }
+
+        /** Connect a slot to the print signal and return the connection */
+        std::list<std::function<void(const std::string&)>>::iterator PushBackCallback(std::function<void(const std::string&)> fun)
+        {
+            std::lock_guard<std::mutex> scoped_lock(m_cs);
+            m_print_callbacks.push_back(std::move(fun));
+            return --m_print_callbacks.end();
+        }
+
+        /** Delete a connection */
+        void DeleteCallback(std::list<std::function<void(const std::string&)>>::iterator it)
+        {
+            std::lock_guard<std::mutex> scoped_lock(m_cs);
+            m_print_callbacks.erase(it);
         }
 
         /** Start logging (and flush all buffered messages) */