Use RAII to protect _rotation_semaphore.

Author: Xin Liu

src/hotspot/share/logging/logConfiguration.cpp

@@ -275,15 +275,6 @@ void LogConfiguration::configure_output(size_t idx, const LogSelectionList& sele
   // 2. asynclog buffer may be holding some log messages targeting to the output 'idx'. It has been disabled by new setting,
   // eg. all=off and is about to be purged in delete_output(idx).
   //
-
-#ifdef ASSERT
-  if (!enabled) {
-    for (LogTagSet* ts = LogTagSet::first(); ts != NULL; ts = ts->next()) {
-      assert(!ts->has_output(output), "The node of output should been removed in ts->set_output_level.");
-    }
-  }
-#endif
-
   AsyncLogWriter::flush();
 
   // It is now safe to set the new decorators for the actual output

src/hotspot/share/logging/logFileOutput.cpp

@@ -33,6 +33,19 @@
 #include "utilities/globalDefinitions.hpp"
 #include "utilities/defaultStream.hpp"
 
+class RotationLocker : public StackObj {
+  Semaphore& _sem;
+
+ public:
+  RotationLocker(Semaphore& sem) : _sem(sem) {
+    sem.wait();
+  }
+
+  ~RotationLocker() {
+    _sem.signal();
+  }
+};
+
 const char* const LogFileOutput::Prefix = "file=";
 const char* const LogFileOutput::FileOpenMode = "a";
 const char* const LogFileOutput::PidFilenamePlaceholder = "%p";
@@ -286,7 +299,7 @@ bool LogFileOutput::initialize(const char* options, outputStream* errstream) {
 }
 
 int LogFileOutput::write_blocking(const LogDecorations& decorations, const char* msg) {
-  _rotation_semaphore.wait();
+  RotationLocker lock(_rotation_semaphore);
   if (_stream == NULL) {
     // An error has occurred with this output, avoid writing to it.
     return 0;
@@ -300,7 +313,6 @@ int LogFileOutput::write_blocking(const LogDecorations& decorations, const char*
       rotate();
     }
   }
-  _rotation_semaphore.signal();
 
   return written;
 }
@@ -332,7 +344,7 @@ int LogFileOutput::write(LogMessageBuffer::Iterator msg_iterator) {
     return 0;
   }
 
-  _rotation_semaphore.wait();
+  RotationLocker lock(_rotation_semaphore);
   int written = LogFileStreamOutput::write(msg_iterator);
   if (written > 0) {
     _current_size += written;
@@ -341,7 +353,6 @@ int LogFileOutput::write(LogMessageBuffer::Iterator msg_iterator) {
       rotate();
     }
   }
-  _rotation_semaphore.signal();
 
   return written;
 }
@@ -368,13 +379,11 @@ void LogFileOutput::force_rotate() {
     // Rotation not possible
     return;
   }
-  _rotation_semaphore.wait();
+  RotationLocker lock(_rotation_semaphore);
   rotate();
-  _rotation_semaphore.signal();
 }
 
 void LogFileOutput::rotate() {
-
   if (fclose(_stream)) {
     jio_fprintf(defaultStream::error_stream(), "Error closing file '%s' during log rotation (%s).\n",
                 _file_name, os::strerror(errno));

test/hotspot/gtest/logging/test_logConfiguration.cpp

@@ -302,9 +302,10 @@ TEST_VM_F(LogConfigurationTest, reconfigure_tags_MT) {
       break;
     }
 
-    // Take turn logging with different decorators, either None or All.
+    // turn on/off the tagset 'logging'.
     set_log_config(TestLogFileName, "logging=off");
     set_log_config(TestLogFileName, "logging=debug", "", "filecount=0");
+    // sleep a prime number milliseconds to allow concurrent logsites write logs
     os::naked_short_nanosleep(137);
   }