1 /*

     2  * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

     3  * Copyright (c) 2019, Google and/or its affiliates. All rights reserved.

     4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     5  *

     6  * This code is free software; you can redistribute it and/or modify it

     7  * under the terms of the GNU General Public License version 2 only, as

     8  * published by the Free Software Foundation.

     9  *

    10  * This code is distributed in the hope that it will be useful, but WITHOUT

    11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    13  * version 2 for more details (a copy is included in the LICENSE file that

    14  * accompanied this code).

    15  *

    16  * You should have received a copy of the GNU General Public License version

    17  * 2 along with this work; if not, write to the Free Software Foundation,

    18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    19  *

    20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    21  * or visit www.oracle.com if you need additional information or have any

    22  * questions.

    23  *

    24  */

    25 

    26 #ifndef SHARE_GC_SHARED_GCOVERHEADCHECKER_HPP

    27 #define SHARE_GC_SHARED_GCOVERHEADCHECKER_HPP

    28 

    29 #include "memory/allocation.hpp"

    30 #include "gc/shared/gcCause.hpp"

    31 

    32 class SoftRefPolicy;

    33 

    34 class GCOverheadTester: public StackObj {

    35 public:

    36   virtual bool is_exceeded() = 0;

    37 };

    38 

    39 class GCOverheadChecker: public CHeapObj<mtGC> {

    40   // This is a hint for the heap:  we've detected that GC times

    41   // are taking longer than GCTimeLimit allows.

    42   bool _gc_overhead_limit_exceeded;

    43   // Use for diagnostics only.  If UseGCOverheadLimit is false,

    44   // this variable is still set.

    45   bool _print_gc_overhead_limit_would_be_exceeded;

    46   // Count of consecutive GC that have exceeded the

    47   // GC time limit criterion

    48   uint _gc_overhead_limit_count;

    49   // This flag signals that GCTimeLimit is being exceeded

    50   // but may not have done so for the required number of consecutive

    51   // collections

    52 

    53 public:

    54   GCOverheadChecker();

    55 

    56   // This is a hint for the heap:  we've detected that gc times

    57   // are taking longer than GCTimeLimit allows.

    58   // Most heaps will choose to throw an OutOfMemoryError when

    59   // this occurs but it is up to the heap to request this information

    60   // of the policy

    61   bool gc_overhead_limit_exceeded() {

    62     return _gc_overhead_limit_exceeded;

    63   }

    64   void set_gc_overhead_limit_exceeded(bool v) {

    65     _gc_overhead_limit_exceeded = v;

    66   }

    67 

    68   // Tests conditions indicate the GC overhead limit is being approached.

    69   bool gc_overhead_limit_near() {

    70     return _gc_overhead_limit_count >= (GCOverheadLimitThreshold - 1);

    71   }

    72   void reset_gc_overhead_limit_count() {

    73     _gc_overhead_limit_count = 0;

    74   }

    75 

    76   // Check the conditions for an out-of-memory due to excessive GC time.

    77   // Set _gc_overhead_limit_exceeded if all the conditions have been met.

    78   void check_gc_overhead_limit(GCOverheadTester* time_overhead,

    79                                GCOverheadTester* space_overhead,

    80                                bool is_full_gc,

    81                                GCCause::Cause gc_cause,

    82                                SoftRefPolicy* soft_ref_policy);

    83 };

    84 

    85 #endif // SHARE_GC_SHARED_GCOVERHEADCHECKER_HPP