Shrink VM Log on startup

src/init.cpp

@@ -1346,6 +1346,7 @@ bool AppInitMain(NodeContext& node)
  // 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
  LogInstance().ShrinkDebugFile();
+ LogInstance().ShrinkVMLogFile();
  }
  }
  if (!LogInstance().StartLogging()) {

src/logging.cpp

@@ -134,6 +134,11 @@ bool BCLog::Logger::WillLogCategory(BCLog::LogFlags category) const
  return (m_categories.load(std::memory_order_relaxed) & category) != 0;
 }
 
+bool BCLog::Logger::DefaultShrinkVMLogFile() const
+{
+ return m_categories == BCLog::NONE;
+}
+
 bool BCLog::Logger::DefaultShrinkDebugFile() const
 {
  return m_categories == BCLog::NONE;
@@ -323,6 +328,47 @@ void BCLog::Logger::LogPrintStr(const std::string& str, bool useVMLog)
  }
 }
 
+void BCLog::Logger::ShrinkVMLogFile()
+{
+ // Amount of vm.log to save at end when shrinking (must fit in memory)
+ constexpr size_t RECENT_DEBUG_HISTORY_SIZE = 10 * 1000000;
+
+ assert(!m_file_pathVM.empty());
+
+ // Scroll vm.log if it's getting too big
+ FILE* file = fsbridge::fopen(m_file_pathVM, "r");
+
+ // Special files (e.g. device nodes) may not have a size.
+ size_t log_size = 0;
+ try {
+ log_size = fs::file_size(m_file_pathVM);
+ } catch (const fs::filesystem_error&) {}
+
+ // If vm.log file is more than 10% bigger the RECENT_DEBUG_HISTORY_SIZE
+ // trim it down by saving only the last RECENT_DEBUG_HISTORY_SIZE bytes
+ if (file && log_size > 11 * (RECENT_DEBUG_HISTORY_SIZE / 10))
+ {
+ // Restart the file with some of the end
+ std::vector<char> vch(RECENT_DEBUG_HISTORY_SIZE, 0);
+ if (fseek(file, -((long)vch.size()), SEEK_END)) {
+ LogPrintf("Failed to shrink VM log file: fseek(...) failed\n");
+ fclose(file);
+ return;
+ }
+ int nBytes = fread(vch.data(), 1, vch.size(), file);
+ fclose(file);
+
+ file = fsbridge::fopen(m_file_pathVM, "w");
+ if (file)
+ {
+ fwrite(vch.data(), 1, nBytes, file);
+ fclose(file);
+ }
+ }
+ else if (file != nullptr)
+ fclose(file);
+}
+
 void BCLog::Logger::ShrinkDebugFile()
 {
  // Amount of debug.log to save at end when shrinking (must fit in memory)

src/logging.h

@@ -123,6 +123,7 @@ namespace BCLog {
  void DisconnectTestLogger();
 
  void ShrinkDebugFile();
+ void ShrinkVMLogFile();
 
  uint32_t GetCategoryMask() const { return m_categories.load(); }
 
@@ -134,6 +135,7 @@ namespace BCLog {
  bool WillLogCategory(LogFlags category) const;
 
  bool DefaultShrinkDebugFile() const;
+ bool DefaultShrinkVMLogFile() const;
  };
 
 } // namespace BCLog