1 /*
   2  * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 #ifndef SHARE_LOGGING_ASYNC_FLUSHER_HPP
  25 #define SHARE_LOGGING_ASYNC_FLUSHER_HPP
  26 
  27 #include "memory/resourceArea.hpp"
  28 #include "runtime/mutexLocker.hpp"
  29 #include "runtime/task.hpp"
  30 #include "utilities/linkedlist.hpp"
  31 #include "utilities/pair.hpp"
  32 
  33 template <typename E>
  34 class LinkedListFIFO : private LinkedListImpl<E, ResourceObj::C_HEAP, mtLogging> {
  35  private:
  36   LinkedListNode<E>* _tail;
  37 
  38   // this is not a generic FIFO, template parameter is only for testing.
  39  public:
  40   LinkedListFIFO() : _tail(NULL) {}
  41   void push(const E& e) {
  42     if (!_tail)
  43       _tail = this->add(e);
  44     else
  45       _tail = this->insert_after(e, _tail);
  46   }
  47 
  48   void pop_all(LinkedList<E>* logs) {
  49     logs->move(static_cast<LinkedList<E>* >(this));
  50     _tail = NULL;
  51   }
  52 };
  53 
  54 class LogMessageBuffer;
  55 class LogTagSet;
  56 class AsyncLogMessage : private Pair<LogTagSet*, LogMessageBuffer*> {
  57   AsyncLogMessage(LogTagSet* t, LogMessageBuffer* b)
  58                 : Pair<LogTagSet*, LogMessageBuffer*>(t, b) {}
  59 
  60 public:
  61   static AsyncLogMessage create(LogTagSet* t,  LogMessageBuffer* b) {
  62     return AsyncLogMessage(t, b);
  63   }
  64 
  65   bool equals(const AsyncLogMessage& o) const {
  66     return first == o.first && second == o.second;
  67   }
  68 
  69   LogTagSet* tagset() { return first; }
  70   LogMessageBuffer* buffer() { return second; }
  71 };
  72 
  73 typedef LinkedListFIFO<AsyncLogMessage> AsyncLogFIFO;
  74 
  75 class LogAsyncFlusher : public PeriodicTask {
  76   friend class AsyncLogTest_flusher_test_vm_Test;
  77  private:
  78   static LogAsyncFlusher* _instance;
  79   Mutex _lock;
  80   AsyncLogFIFO _fifo;
  81 
  82   LogAsyncFlusher(size_t interval/*ms*/) : PeriodicTask(interval),
  83                   _lock(Mutex::tty, "logAsyncFlusher",
  84                   Mutex::_allow_vm_block_flag, Mutex::_safepoint_check_never) {
  85     this->enroll();
  86   }
  87 
  88   ~LogAsyncFlusher();
  89 
  90  public:
  91   void enqueue(LogTagSet* tagset, LogMessageBuffer* buf);
  92 
  93   virtual void task();
  94   void flush() { task(); }
  95 
  96   // none of following functions are thread-safe.
  97   // Meyer's singleton is not thread-safe until C++11.
  98   static void initialize();
  99   static void cleanup();
 100   static LogAsyncFlusher* instance();
 101 };
 102 
 103 #endif // SHARE_LOGGING_ASYNC_FLUSHER_HPP