Get the modification time of a config file with a higher precision to fix cases when it's not reloaded after modification/replacement (#8553)

* Get the modification time of a config file with a higher precision to fix cases when it's not reloaded after modification/replacement

The fix is needed to avoid potential problems in Firebird QA.

* Use GetFileAttributesEx to get the config file attributes

* Fix macOS build

* Unify the return type of File::getTime() to make the code cleaner

* Correct the old typo

Author: ilya071294

src/common/config/ConfigCache.cpp

@@ -82,25 +82,38 @@ Firebird::PathName ConfigCache::getFileName()
 	return files->fileName;
 }
 
-time_t ConfigCache::File::getTime()
+ConfigCache::File::PreciseTime ConfigCache::File::getTime()
 {
+#ifdef WIN_NT
+	WIN32_FILE_ATTRIBUTE_DATA fInfo;
+
+	if (!GetFileAttributesEx(fileName.c_str(), GetFileExInfoStandard, &fInfo))
+		return PreciseTime();
+
+	return PreciseTime(fInfo.ftLastWriteTime);
+#else
 	struct STAT st;
 
 	if (os_utils::stat(fileName.c_str(), &st) != 0)
 	{
 		if (errno == ENOENT)
 		{
 			// config file is missing, but this is not our problem
-			return 0;
+			return PreciseTime();
 		}
 		system_call_failed::raise("stat");
 	}
 
-	return st.st_mtime;
+#ifdef DARWIN
+	return PreciseTime(st.st_mtimespec);
+#else
+	return PreciseTime(st.st_mtim);
+#endif
+#endif
 }
 
 ConfigCache::File::File(MemoryPool& p, const PathName& fName)
-	: PermanentStorage(p), fileName(getPool(), fName), fileTime(0), next(NULL)
+	: PermanentStorage(p), fileName(getPool(), fName), next(NULL)
 { }
 
 ConfigCache::File::~File()
@@ -110,7 +123,7 @@ ConfigCache::File::~File()
 
 bool ConfigCache::File::checkLoadConfig(bool set)
 {
-	time_t newTime = getTime();
+	const PreciseTime newTime = getTime();
 	if (fileTime == newTime)
 	{
 		return next ? next->checkLoadConfig(set) : true;

src/common/config/ConfigCache.h

@@ -25,8 +25,8 @@
  *
  */
 
-#ifndef COMMON_CONFIG_CASHE_H
-#define COMMON_CONFIG_CASHE_H
+#ifndef COMMON_CONFIG_CACHE_H
+#define COMMON_CONFIG_CACHE_H
 
 #include "../common/classes/alloc.h"
 #include "../common/classes/fb_string.h"
@@ -48,6 +48,39 @@ class ConfigCache : public Firebird::PermanentStorage
 private:
 	class File : public Firebird::PermanentStorage
 	{
+		class PreciseTime
+		{
+#ifdef WIN_NT
+			using TimeType = FILETIME;
+#else
+			using TimeType = timespec;
+#endif
+
+		public:
+			PreciseTime()
+			{
+			}
+
+			PreciseTime(TimeType time)
+				: m_time(time)
+			{
+			}
+
+			bool operator==(const PreciseTime& other) const
+			{
+#ifdef WIN_NT
+				return m_time.dwLowDateTime == other.m_time.dwLowDateTime &&
+					m_time.dwHighDateTime == other.m_time.dwHighDateTime;
+#else
+				return m_time.tv_sec == other.m_time.tv_sec &&
+					m_time.tv_nsec == other.m_time.tv_nsec;
+#endif
+			}
+
+		private:
+			TimeType m_time = {};
+		};
+
 	public:
 		File(Firebird::MemoryPool& p, const Firebird::PathName& fName);
 		~File();
@@ -60,14 +93,14 @@ class ConfigCache : public Firebird::PermanentStorage
 		Firebird::PathName fileName;
 
 	private:
-		volatile time_t fileTime;
+		PreciseTime fileTime;
 		File* next;
-		time_t getTime();
+		PreciseTime getTime();
 	};
 	File* files;
 
 public:
 	Firebird::RWLock rwLock;
 };
 
-#endif // COMMON_CONFIG_CASHE_H
+#endif // COMMON_CONFIG_CACHE_H