1 /*
   2  * Copyright (c) 2000, 2009, 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
  21  * questions.
  22  *
  23  */
  24 
  25 #include "incls/_precompiled.incl"
  26 #include "incls/_permGen.cpp.incl"
  27 
  28 HeapWord* PermGen::mem_allocate_in_gen(size_t size, Generation* gen) {
  29   GCCause::Cause next_cause = GCCause::_permanent_generation_full;
  30   GCCause::Cause prev_cause = GCCause::_no_gc;
  31   unsigned int gc_count_before, full_gc_count_before;
  32   HeapWord* obj;
  33 
  34   for (;;) {
  35     {
  36       MutexLocker ml(Heap_lock);
  37       if ((obj = gen->allocate(size, false)) != NULL) {
  38         return obj;
  39       }
  40       if (gen->capacity() < _capacity_expansion_limit ||
  41           prev_cause != GCCause::_no_gc) {
  42         obj = gen->expand_and_allocate(size, false);
  43       }
  44       if (obj != NULL || prev_cause == GCCause::_last_ditch_collection) {
  45         return obj;
  46       }
  47       if (GC_locker::is_active_and_needs_gc()) {
  48         // If this thread is not in a jni critical section, we stall
  49         // the requestor until the critical section has cleared and
  50         // GC allowed. When the critical section clears, a GC is
  51         // initiated by the last thread exiting the critical section; so
  52         // we retry the allocation sequence from the beginning of the loop,
  53         // rather than causing more, now probably unnecessary, GC attempts.
  54         JavaThread* jthr = JavaThread::current();
  55         if (!jthr->in_critical()) {
  56           MutexUnlocker mul(Heap_lock);
  57           // Wait for JNI critical section to be exited
  58           GC_locker::stall_until_clear();
  59           continue;
  60         } else {
  61           if (CheckJNICalls) {
  62             fatal("Possible deadlock due to allocating while"
  63                   " in jni critical section");
  64           }
  65           return NULL;
  66         }
  67       }
  68       // Read the GC count while holding the Heap_lock
  69       gc_count_before      = SharedHeap::heap()->total_collections();
  70       full_gc_count_before = SharedHeap::heap()->total_full_collections();
  71     }
  72 
  73     // Give up heap lock above, VMThread::execute below gets it back
  74     VM_GenCollectForPermanentAllocation op(size, gc_count_before, full_gc_count_before,
  75                                            next_cause);
  76     VMThread::execute(&op);
  77     if (!op.prologue_succeeded() || op.gc_locked()) {
  78       assert(op.result() == NULL, "must be NULL if gc_locked() is true");
  79       continue;  // retry and/or stall as necessary
  80     }
  81     obj = op.result();
  82     assert(obj == NULL || SharedHeap::heap()->is_in_reserved(obj),
  83            "result not in heap");
  84     if (obj != NULL) {
  85       return obj;
  86     }
  87     prev_cause = next_cause;
  88     next_cause = GCCause::_last_ditch_collection;
  89   }
  90 }
  91 
  92 CompactingPermGen::CompactingPermGen(ReservedSpace rs,
  93                                      ReservedSpace shared_rs,
  94                                      size_t initial_byte_size,
  95                                      GenRemSet* remset,
  96                                      PermanentGenerationSpec* perm_spec)
  97 {
  98   CompactingPermGenGen* g =
  99     new CompactingPermGenGen(rs, shared_rs, initial_byte_size, -1, remset,
 100                              NULL, perm_spec);
 101   if (g == NULL)
 102     vm_exit_during_initialization("Could not allocate a CompactingPermGen");
 103   _gen = g;
 104 
 105   g->initialize_performance_counters();
 106 
 107   _capacity_expansion_limit = g->capacity() + MaxPermHeapExpansion;
 108 }
 109 
 110 HeapWord* CompactingPermGen::mem_allocate(size_t size) {
 111   return mem_allocate_in_gen(size, _gen);
 112 }
 113 
 114 void CompactingPermGen::compute_new_size() {
 115   size_t desired_capacity = align_size_up(_gen->used(), MinPermHeapExpansion);
 116   if (desired_capacity < PermSize) {
 117     desired_capacity = PermSize;
 118   }
 119   if (_gen->capacity() > desired_capacity) {
 120     _gen->shrink(_gen->capacity() - desired_capacity);
 121   }
 122   _capacity_expansion_limit = _gen->capacity() + MaxPermHeapExpansion;
 123 }