Merge #15266: memory: Construct globals on first use

77777c5624 log: Construct global logger on first use (MarcoFalke)

Pull request description:

  The (de)initialization order is not well defined in C++, so generally it is not safe to use globals as the (de/con)structor of one global could use the (de/con)structor of another global before/after it has been (con/de)structed.

  Specifically this fixes:
  * `g_logger` might not be initialized on the first use, so do that. (Fixes #15111)

Tree-SHA512: eb9c22f4baf31ebc5b0b9ee6a51d1354bae1f0df186cc0ce818b4483c7b5a7f90268d2b549ee96b4c57f8ef36ab239dc6497f74f3e2ef166038f7437c368297d

6 files changed, 34 insertions, 28 deletions

diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index ca60ea43a7..b9ca037c9d 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -364,8 +364,8 @@ bool InitHTTPServer()
     // Update libevent's log handling. Returns false if our version of
     // libevent doesn't support debug logging, in which case we should
     // clear the BCLog::LIBEVENT flag.
-    if (!UpdateHTTPServerLogging(g_logger->WillLogCategory(BCLog::LIBEVENT))) {
-        g_logger->DisableCategory(BCLog::LIBEVENT);
+    if (!UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT))) {
+        LogInstance().DisableCategory(BCLog::LIBEVENT);
     }
 
 #ifdef WIN32
diff --git a/src/init.cpp b/src/init.cpp
index 019b2e469e..b3c99c4382 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -289,7 +289,7 @@ static void HandleSIGTERM(int)
 
 static void HandleSIGHUP(int)
 {
-    g_logger->m_reopen_file = true;
+    LogInstance().m_reopen_file = true;
 }
 #else
 static BOOL WINAPI consoleCtrlHandler(DWORD dwCtrlType)
@@ -833,17 +833,17 @@ static std::string ResolveErrMsg(const char * const optname, const std::string&
  */
 void InitLogging()
 {
-    g_logger->m_print_to_file = !gArgs.IsArgNegated("-debuglogfile");
-    g_logger->m_file_path = AbsPathForConfigVal(gArgs.GetArg("-debuglogfile", DEFAULT_DEBUGLOGFILE));
+    LogInstance().m_print_to_file = !gArgs.IsArgNegated("-debuglogfile");
+    LogInstance().m_file_path = AbsPathForConfigVal(gArgs.GetArg("-debuglogfile", DEFAULT_DEBUGLOGFILE));
 
     // Add newlines to the logfile to distinguish this execution from the last
     // one; called before console logging is set up, so this is only sent to
     // debug.log.
     LogPrintf("\n\n\n\n\n");
 
-    g_logger->m_print_to_console = gArgs.GetBoolArg("-printtoconsole", !gArgs.GetBoolArg("-daemon", false));
-    g_logger->m_log_timestamps = gArgs.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
-    g_logger->m_log_time_micros = gArgs.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
+    LogInstance().m_print_to_console = gArgs.GetBoolArg("-printtoconsole", !gArgs.GetBoolArg("-daemon", false));
+    LogInstance().m_log_timestamps = gArgs.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
+    LogInstance().m_log_time_micros = gArgs.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
 
     fLogIPs = gArgs.GetBoolArg("-logips", DEFAULT_LOGIPS);
 
@@ -981,7 +981,7 @@ bool AppInitParameterInteraction()
         if (std::none_of(categories.begin(), categories.end(),
             [](std::string cat){return cat == "0" || cat == "none";})) {
             for (const auto& cat : categories) {
-                if (!g_logger->EnableCategory(cat)) {
+                if (!LogInstance().EnableCategory(cat)) {
                     InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debug", cat));
                 }
             }
@@ -990,7 +990,7 @@ bool AppInitParameterInteraction()
 
     // Now remove the logging categories which were explicitly excluded
     for (const std::string& cat : gArgs.GetArgs("-debugexclude")) {
-        if (!g_logger->DisableCategory(cat)) {
+        if (!LogInstance().DisableCategory(cat)) {
             InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debugexclude", cat));
         }
     }
@@ -1197,19 +1197,19 @@ bool AppInitMain(InitInterfaces& interfaces)
 #ifndef WIN32
     CreatePidFile(GetPidFile(), getpid());
 #endif
-    if (g_logger->m_print_to_file) {
-        if (gArgs.GetBoolArg("-shrinkdebugfile", g_logger->DefaultShrinkDebugFile())) {
+    if (LogInstance().m_print_to_file) {
+        if (gArgs.GetBoolArg("-shrinkdebugfile", LogInstance().DefaultShrinkDebugFile())) {
             // Do this first since it both loads a bunch of debug.log into memory,
             // and because this needs to happen before any other debug.log printing
-            g_logger->ShrinkDebugFile();
+            LogInstance().ShrinkDebugFile();
         }
-        if (!g_logger->OpenDebugLog()) {
+        if (!LogInstance().OpenDebugLog()) {
             return InitError(strprintf("Could not open debug log file %s",
-                                       g_logger->m_file_path.string()));
+                LogInstance().m_file_path.string()));
         }
     }
 
-    if (!g_logger->m_log_timestamps)
+    if (!LogInstance().m_log_timestamps)
         LogPrintf("Startup time: %s\n", FormatISO8601DateTime(GetTime()));
     LogPrintf("Default data directory %s\n", GetDefaultDataDir().string());
     LogPrintf("Using data directory %s\n", GetDataDir().string());
diff --git a/src/interfaces/node.cpp b/src/interfaces/node.cpp
index c574f960e6..a2b89c3f90 100644
--- a/src/interfaces/node.cpp
+++ b/src/interfaces/node.cpp
@@ -67,7 +67,7 @@ public:
     void initLogging() override { InitLogging(); }
     void initParameterInteraction() override { InitParameterInteraction(); }
     std::string getWarnings(const std::string& type) override { return GetWarnings(type); }
-    uint32_t getLogCategories() override { return g_logger->GetCategoryMask(); }
+    uint32_t getLogCategories() override { return LogInstance().GetCategoryMask(); }
     bool baseInitialize() override
     {
         return AppInitBasicSetup() && AppInitParameterInteraction() && AppInitSanityChecks() &&
diff --git a/src/logging.cpp b/src/logging.cpp
index 77dc2d0939..36cad6573a 100644
--- a/src/logging.cpp
+++ b/src/logging.cpp
@@ -8,6 +8,8 @@
 
 const char * const DEFAULT_DEBUGLOGFILE = "debug.log";
 
+BCLog::Logger& LogInstance()
+{
 /**
  * NOTE: the logger instances is leaked on exit. This is ugly, but will be
  * cleaned up by the OS/libc. Defining a logger as a global object doesn't work
@@ -17,11 +19,15 @@ const char * const DEFAULT_DEBUGLOGFILE = "debug.log";
  * access the logger. When the shutdown sequence is fully audited and tested,
  * explicit destruction of these objects can be implemented by changing this
  * from a raw pointer to a std::unique_ptr.
+ * Since the destructor is never called, the logger and all its members must
+ * have a trivial destructor.
  *
  * This method of initialization was originally introduced in
  * ee3374234c60aba2cc4c5cd5cac1c0aefc2d817c.
  */
-BCLog::Logger* const g_logger = new BCLog::Logger();
+    static BCLog::Logger* g_logger{new BCLog::Logger()};
+    return *g_logger;
+}
 
 bool fLogIPs = DEFAULT_LOGIPS;
 
diff --git a/src/logging.h b/src/logging.h
index 0c8e7f5291..ac9d0dc0c7 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -108,12 +108,12 @@ namespace BCLog {
 
 } // namespace BCLog
 
-extern BCLog::Logger* const g_logger;
+BCLog::Logger& LogInstance();
 
 /** Return true if log accepts specified category */
 static inline bool LogAcceptCategory(BCLog::LogFlags category)
 {
-    return g_logger->WillLogCategory(category);
+    return LogInstance().WillLogCategory(category);
 }
 
 /** Returns a string with the log categories. */
@@ -132,7 +132,7 @@ bool GetLogCategory(BCLog::LogFlags& flag, const std::string& str);
 template <typename... Args>
 static inline void LogPrintf(const char* fmt, const Args&... args)
 {
-    if (g_logger->Enabled()) {
+    if (LogInstance().Enabled()) {
         std::string log_msg;
         try {
             log_msg = tfm::format(fmt, args...);
@@ -140,7 +140,7 @@ static inline void LogPrintf(const char* fmt, const Args&... args)
             /* Original format string will have newline so don't add one here */
             log_msg = "Error \"" + std::string(fmterr.what()) + "\" while formatting log message: " + fmt;
         }
-        g_logger->LogPrintStr(log_msg);
+        LogInstance().LogPrintStr(log_msg);
     }
 }
 
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 9d17a2fc4e..8850cf066b 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -366,9 +366,9 @@ static void EnableOrDisableLogCategories(UniValue cats, bool enable) {
 
         bool success;
         if (enable) {
-            success = g_logger->EnableCategory(cat);
+            success = LogInstance().EnableCategory(cat);
         } else {
-            success = g_logger->DisableCategory(cat);
+            success = LogInstance().DisableCategory(cat);
         }
 
         if (!success) {
@@ -415,14 +415,14 @@ UniValue logging(const JSONRPCRequest& request)
             }.ToString());
     }
 
-    uint32_t original_log_categories = g_logger->GetCategoryMask();
+    uint32_t original_log_categories = LogInstance().GetCategoryMask();
     if (request.params[0].isArray()) {
         EnableOrDisableLogCategories(request.params[0], true);
     }
     if (request.params[1].isArray()) {
         EnableOrDisableLogCategories(request.params[1], false);
     }
-    uint32_t updated_log_categories = g_logger->GetCategoryMask();
+    uint32_t updated_log_categories = LogInstance().GetCategoryMask();
     uint32_t changed_log_categories = original_log_categories ^ updated_log_categories;
 
     // Update libevent logging if BCLog::LIBEVENT has changed.
@@ -431,8 +431,8 @@ UniValue logging(const JSONRPCRequest& request)
     // Throw an error if the user has explicitly asked to change only the libevent
     // flag and it failed.
     if (changed_log_categories & BCLog::LIBEVENT) {
-        if (!UpdateHTTPServerLogging(g_logger->WillLogCategory(BCLog::LIBEVENT))) {
-            g_logger->DisableCategory(BCLog::LIBEVENT);
+        if (!UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT))) {
+            LogInstance().DisableCategory(BCLog::LIBEVENT);
             if (changed_log_categories == BCLog::LIBEVENT) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "libevent logging cannot be updated when using libevent before v2.1.1.");
             }