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hotspot/src/share/vm/memory/sharedHeap.cpp

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+/*
+ * Copyright 2000-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_sharedHeap.cpp.incl"
+
+SharedHeap* SharedHeap::_sh;
+
+// The set of potentially parallel tasks in strong root scanning.
+enum SH_process_strong_roots_tasks {
+  SH_PS_Universe_oops_do,
+  SH_PS_JNIHandles_oops_do,
+  SH_PS_ObjectSynchronizer_oops_do,
+  SH_PS_FlatProfiler_oops_do,
+  SH_PS_Management_oops_do,
+  SH_PS_SystemDictionary_oops_do,
+  SH_PS_jvmti_oops_do,
+  SH_PS_vmSymbols_oops_do,
+  SH_PS_SymbolTable_oops_do,
+  SH_PS_StringTable_oops_do,
+  SH_PS_CodeCache_oops_do,
+  // Leave this one last.
+  SH_PS_NumElements
+};
+
+SharedHeap::SharedHeap(CollectorPolicy* policy_) :
+  CollectedHeap(),
+  _collector_policy(policy_),
+  _perm_gen(NULL), _rem_set(NULL),
+  _strong_roots_parity(0),
+  _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
+  _workers(NULL), _n_par_threads(0)
+{
+  if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
+    vm_exit_during_initialization("Failed necessary allocation.");
+  }
+  _sh = this;  // ch is static, should be set only once.
+  if ((UseParNewGC ||
+      (UseConcMarkSweepGC && CMSParallelRemarkEnabled)) &&
+      ParallelGCThreads > 0) {
+    _workers = new WorkGang("Parallel GC Threads", ParallelGCThreads, true);
+    if (_workers == NULL) {
+      vm_exit_during_initialization("Failed necessary allocation.");
+    }
+  }
+}
+
+
+void SharedHeap::set_par_threads(int t) {
+  _n_par_threads = t;
+  _process_strong_tasks->set_par_threads(t);
+}
+
+class AssertIsPermClosure: public OopClosure {
+public:
+  void do_oop(oop* p) {
+    assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
+  }
+};
+static AssertIsPermClosure assert_is_perm_closure;
+
+void SharedHeap::change_strong_roots_parity() {
+  // Also set the new collection parity.
+  assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
+         "Not in range.");
+  _strong_roots_parity++;
+  if (_strong_roots_parity == 3) _strong_roots_parity = 1;
+  assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
+         "Not in range.");
+}
+
+void SharedHeap::process_strong_roots(bool collecting_perm_gen,
+                                      ScanningOption so,
+                                      OopClosure* roots,
+                                      OopsInGenClosure* perm_blk) {
+  // General strong roots.
+  if (n_par_threads() == 0) change_strong_roots_parity();
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
+    Universe::oops_do(roots);
+    ReferenceProcessor::oops_do(roots);
+    // Consider perm-gen discovered lists to be strong.
+    perm_gen()->ref_processor()->weak_oops_do(roots);
+  }
+  // Global (strong) JNI handles
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
+    JNIHandles::oops_do(roots);
+  // All threads execute this; the individual threads are task groups.
+  if (ParallelGCThreads > 0) {
+    Threads::possibly_parallel_oops_do(roots);
+  } else {
+    Threads::oops_do(roots);
+  }
+  if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
+    ObjectSynchronizer::oops_do(roots);
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
+    FlatProfiler::oops_do(roots);
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
+    Management::oops_do(roots);
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
+    JvmtiExport::oops_do(roots);
+
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
+    if (so & SO_AllClasses) {
+      SystemDictionary::oops_do(roots);
+    } else
+      if (so & SO_SystemClasses) {
+        SystemDictionary::always_strong_oops_do(roots);
+      }
+  }
+
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_SymbolTable_oops_do)) {
+    if (so & SO_Symbols) {
+      SymbolTable::oops_do(roots);
+    }
+    // Verify if the symbol table contents are in the perm gen
+    NOT_PRODUCT(SymbolTable::oops_do(&assert_is_perm_closure));
+  }
+
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
+     if (so & SO_Strings) {
+       StringTable::oops_do(roots);
+     }
+    // Verify if the string table contents are in the perm gen
+    NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
+  }
+
+  if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
+     if (so & SO_CodeCache) {
+       CodeCache::oops_do(roots);
+     }
+    // Verify if the code cache contents are in the perm gen
+    NOT_PRODUCT(CodeCache::oops_do(&assert_is_perm_closure));
+  }
+
+  // Roots that should point only into permanent generation.
+  {
+    OopClosure* blk = NULL;
+    if (collecting_perm_gen) {
+      blk = roots;
+    } else {
+      debug_only(blk = &assert_is_perm_closure);
+    }
+    if (blk != NULL) {
+      if (!_process_strong_tasks->is_task_claimed(SH_PS_vmSymbols_oops_do))
+        vmSymbols::oops_do(blk);
+    }
+  }
+
+  if (!collecting_perm_gen) {
+    // All threads perform this; coordination is handled internally.
+
+    rem_set()->younger_refs_iterate(perm_gen(), perm_blk);
+  }
+  _process_strong_tasks->all_tasks_completed();
+}
+
+class AlwaysTrueClosure: public BoolObjectClosure {
+public:
+  void do_object(oop p) { ShouldNotReachHere(); }
+  bool do_object_b(oop p) { return true; }
+};
+static AlwaysTrueClosure always_true;
+
+class SkipAdjustingSharedStrings: public OopClosure {
+  OopClosure* _clo;
+public:
+  SkipAdjustingSharedStrings(OopClosure* clo) : _clo(clo) {}
+
+  void do_oop(oop* p) {
+    oop o = (*p);
+    if (!o->is_shared_readwrite()) {
+      _clo->do_oop(p);
+    }
+  }
+};
+
+// Unmarked shared Strings in the StringTable (which got there due to
+// being in the constant pools of as-yet unloaded shared classes) were
+// not marked and therefore did not have their mark words preserved.
+// These entries are also deliberately not purged from the string
+// table during unloading of unmarked strings. If an identity hash
+// code was computed for any of these objects, it will not have been
+// cleared to zero during the forwarding process or by the
+// RecursiveAdjustSharedObjectClosure, and will be confused by the
+// adjusting process as a forwarding pointer. We need to skip
+// forwarding StringTable entries which contain unmarked shared
+// Strings. Actually, since shared strings won't be moving, we can
+// just skip adjusting any shared entries in the string table.
+
+void SharedHeap::process_weak_roots(OopClosure* root_closure,
+                                    OopClosure* non_root_closure) {
+  // Global (weak) JNI handles
+  JNIHandles::weak_oops_do(&always_true, root_closure);
+
+  CodeCache::oops_do(non_root_closure);
+  SymbolTable::oops_do(root_closure);
+  if (UseSharedSpaces && !DumpSharedSpaces) {
+    SkipAdjustingSharedStrings skip_closure(root_closure);
+    StringTable::oops_do(&skip_closure);
+  } else {
+    StringTable::oops_do(root_closure);
+  }
+}
+
+void SharedHeap::set_barrier_set(BarrierSet* bs) {
+  _barrier_set = bs;
+  // Cached barrier set for fast access in oops
+  oopDesc::set_bs(bs);
+}
+
+void SharedHeap::post_initialize() {
+  ref_processing_init();
+}
+
+void SharedHeap::ref_processing_init() {
+  perm_gen()->ref_processor_init();
+}
+
+void SharedHeap::fill_region_with_object(MemRegion mr) {
+  // Disable the posting of JVMTI VMObjectAlloc events as we
+  // don't want the filling of tlabs with filler arrays to be
+  // reported to the profiler.
+  NoJvmtiVMObjectAllocMark njm;
+
+  // Disable low memory detector because there is no real allocation.
+  LowMemoryDetectorDisabler lmd_dis;
+
+  // It turns out that post_allocation_setup_array takes a handle, so the
+  // call below contains an implicit conversion.  Best to free that handle
+  // as soon as possible.
+  HandleMark hm;
+
+  size_t word_size = mr.word_size();
+  size_t aligned_array_header_size =
+    align_object_size(typeArrayOopDesc::header_size(T_INT));
+
+  if (word_size >= aligned_array_header_size) {
+    const size_t array_length =
+      pointer_delta(mr.end(), mr.start()) -
+      typeArrayOopDesc::header_size(T_INT);
+    const size_t array_length_words =
+      array_length * (HeapWordSize/sizeof(jint));
+    post_allocation_setup_array(Universe::intArrayKlassObj(),
+                                mr.start(),
+                                mr.word_size(),
+                                (int)array_length_words);
+#ifdef ASSERT
+    HeapWord* elt_words = (mr.start() + typeArrayOopDesc::header_size(T_INT));
+    Copy::fill_to_words(elt_words, array_length, 0xDEAFBABE);
+#endif
+  } else {
+    assert(word_size == (size_t)oopDesc::header_size(), "Unaligned?");
+    post_allocation_setup_obj(SystemDictionary::object_klass(),
+                              mr.start(),
+                              mr.word_size());
+  }
+}
+
+// Some utilities.
+void SharedHeap::print_size_transition(size_t bytes_before,
+                                       size_t bytes_after,
+                                       size_t capacity) {
+  tty->print(" %d%s->%d%s(%d%s)",
+             byte_size_in_proper_unit(bytes_before),
+             proper_unit_for_byte_size(bytes_before),
+             byte_size_in_proper_unit(bytes_after),
+             proper_unit_for_byte_size(bytes_after),
+             byte_size_in_proper_unit(capacity),
+             proper_unit_for_byte_size(capacity));
+}