8328880: Events::log_exception should limit the size of the logging message

Reviewed-by: shade, kvn

Author: David Holmes

src/hotspot/share/utilities/events.cpp

@@ -151,7 +151,9 @@ void UnloadingEventLog::log(Thread* thread, InstanceKlass* ik) {
   ik->name()->print_value_on(&st);
 }
 
-void ExceptionsEventLog::log(Thread* thread, Handle h_exception, const char* message, const char* file, int line) {
+void ExceptionsEventLog::log(Thread* thread, Handle h_exception,
+                             const char* message, const char* file, int line,
+                             int message_length_limit) {
   if (!should_log()) return;
 
   double timestamp = fetch_timestamp();
@@ -163,8 +165,11 @@ void ExceptionsEventLog::log(Thread* thread, Handle h_exception, const char* mes
                   _records[index].data.size());
   st.print("Exception <");
   h_exception->print_value_on(&st);
-  st.print("%s%s> (" PTR_FORMAT ") \n"
+  if (message != nullptr) {
+    int len = message_length_limit > 0 ? message_length_limit : (int)strlen(message);
+    st.print(": %.*s", len, message);
+  }
+  st.print("> (" PTR_FORMAT ") \n"
            "thrown [%s, line %d]",
-           message ? ": " : "", message ? message : "",
            p2i(h_exception()), file, line);
 }

src/hotspot/share/utilities/events.hpp

@@ -207,7 +207,9 @@ class ExceptionsEventLog : public ExtendedStringEventLog {
   ExceptionsEventLog(const char* name, const char* short_name, int count = LogEventsBufferEntries)
    : ExtendedStringEventLog(name, short_name, count) {}
 
-  void log(Thread* thread, Handle h_exception, const char* message, const char* file, int line);
+  // Message length limit of zero means no limit.
+  void log(Thread* thread, Handle h_exception, const char* message,
+           const char* file, int line, int message_length_limit = 0);
 };
 
 
@@ -275,7 +277,7 @@ class Events : AllStatic {
 
   // Log exception related message
   static void log_exception(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
-  static void log_exception(Thread* thread, Handle h_exception, const char* message, const char* file, int line);
+  static void log_exception(Thread* thread, Handle h_exception, const char* message, const char* file, int line, int message_length_limit = 0);
 
   static void log_redefinition(Thread* thread, const char* format, ...) ATTRIBUTE_PRINTF(2, 3);
 
@@ -345,9 +347,11 @@ inline void Events::log_exception(Thread* thread, const char* format, ...) {
   }
 }
 
-inline void Events::log_exception(Thread* thread, Handle h_exception, const char* message, const char* file, int line) {
+inline void Events::log_exception(Thread* thread, Handle h_exception,
+                                  const char* message, const char* file,
+                                  int line, int message_length_limit) {
   if (LogEvents && _exceptions != nullptr) {
-    _exceptions->log(thread, h_exception, message, file, line);
+    _exceptions->log(thread, h_exception, message, file, line, message_length_limit);
   }
 }
 

src/hotspot/share/utilities/exceptions.cpp

@@ -183,7 +183,7 @@ void Exceptions::_throw(JavaThread* thread, const char* file, int line, Handle h
   thread->set_pending_exception(h_exception(), file, line);
 
   // vm log
-  Events::log_exception(thread, h_exception, message, file, line);
+  Events::log_exception(thread, h_exception, message, file, line, MAX_LEN);
 }