Enable setup output of logs to files at any time. (#1140)

Co-authored-by: Volodymyr Romanishyn <volodymyr.romanishyn@ingenico.com>

lib/inc/drogon/HttpAppFramework.h

@@ -350,6 +350,17 @@ class DROGON_EXPORT HttpAppFramework : public trantor::NonCopyable
         const std::function<void(const HttpRequestPtr &,
                                  const HttpResponsePtr &)> &advice) = 0;
 
+    /// Setup output of logs to files
+    /**
+     * @note
+     * Logs are output to the standard output by default.
+     * Logging is setuped only if output path of logs is defined.
+     * This method is called in run() function, hence use this method only if
+     * you want to setup logging earlier.
+     * @return HttpAppFramework&
+     */
+    virtual HttpAppFramework &setupFileLogger() = 0;
+
     /* End of AOP methods */
 
     /// Load the configuration file with json format.

lib/src/HttpAppFrameworkImpl.cc

@@ -452,7 +452,6 @@ void HttpAppFrameworkImpl::run()
         getLoop()->moveToCurrentThread();
     }
     LOG_TRACE << "Start to run...";
-    trantor::AsyncFileLogger asyncFileLogger;
     // Create dirs for cache files
     for (int i = 0; i < 256; ++i)
     {
@@ -517,33 +516,7 @@ void HttpAppFrameworkImpl::run()
         }
 #endif
     }
-    // set logger
-    if (!logPath_.empty())
-    {
-        // std::filesystem does not provide a method to check access
-        // permissions, so keep existing code
-        if (os_access(utils::toNativePath(logPath_).c_str(), R_OK | W_OK) != 0)
-        {
-            LOG_ERROR << "log file path not exist";
-            abort();
-        }
-        else
-        {
-            std::string baseName = logfileBaseName_;
-            if (baseName.empty())
-            {
-                baseName = "drogon";
-            }
-            asyncFileLogger.setFileName(baseName, ".log", logPath_);
-            asyncFileLogger.startLogging();
-            trantor::Logger::setOutputFunction(
-                [&](const char *msg, const uint64_t len) {
-                    asyncFileLogger.output(msg, len);
-                },
-                [&]() { asyncFileLogger.flush(); });
-            asyncFileLogger.setFileSizeLimit(logfileSize_);
-        }
-    }
+    setupFileLogger();
     if (relaunchOnError_)
     {
         LOG_INFO << "Start child process";
@@ -1120,6 +1093,38 @@ HttpAppFramework &HttpAppFrameworkImpl::setDefaultHandler(
     return *this;
 }
 
+HttpAppFramework &HttpAppFrameworkImpl::setupFileLogger()
+{
+    if (!logPath_.empty() && !asyncFileLoggerPtr_)
+    {
+        // std::filesystem does not provide a method to check access
+        // permissions, so keep existing code
+        if (os_access(utils::toNativePath(logPath_).c_str(), R_OK | W_OK) != 0)
+        {
+            LOG_ERROR << "log file path not exist";
+            abort();
+        }
+        else
+        {
+            std::string baseName = logfileBaseName_;
+            if (baseName.empty())
+            {
+                baseName = "drogon";
+            }
+            asyncFileLoggerPtr_ = std::make_unique<trantor::AsyncFileLogger>();
+            asyncFileLoggerPtr_->setFileName(baseName, ".log", logPath_);
+            asyncFileLoggerPtr_->startLogging();
+            trantor::Logger::setOutputFunction(
+                [this](const char *msg, const uint64_t len) {
+                    asyncFileLoggerPtr_->output(msg, len);
+                },
+                [this]() { asyncFileLoggerPtr_->flush(); });
+            asyncFileLoggerPtr_->setFileSizeLimit(logfileSize_);
+        }
+    }
+    return *this;
+}
+
 HttpAppFramework &HttpAppFrameworkImpl::registerCustomExtensionMime(
     const std::string &ext,
     const std::string &mime)

lib/src/HttpAppFrameworkImpl.h

@@ -205,6 +205,8 @@ class HttpAppFrameworkImpl final : public HttpAppFramework
     }
     HttpAppFramework &setDefaultHandler(DefaultHandler handler) override;
 
+    HttpAppFramework &setupFileLogger() override;
+
     HttpAppFramework &enableSession(const size_t timeout) override
     {
         useSession_ = true;
@@ -634,6 +636,7 @@ class HttpAppFrameworkImpl final : public HttpAppFramework
     std::function<void()> termSignalHandler_{[]() { app().quit(); }};
     std::function<void()> intSignalHandler_{[]() { app().quit(); }};
     std::unique_ptr<SessionManager> sessionManagerPtr_;
+    std::unique_ptr<trantor::AsyncFileLogger> asyncFileLoggerPtr_;
     Json::Value jsonConfig_;
     HttpResponsePtr custom404_;
     std::function<HttpResponsePtr(HttpStatusCode)> customErrorHandler_ =

lib/src/impl_forwards.h

@@ -56,6 +56,7 @@ class EventLoop;
 class TcpConnection;
 using TcpConnectionPtr = std::shared_ptr<TcpConnection>;
 class Resolver;
+class AsyncFileLogger;
 }  // namespace trantor
 
 namespace drogon