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/*
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* Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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// A "CollectedHeap" is an implementation of a java heap for HotSpot. This
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// is an abstract class: there may be many different kinds of heaps. This
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// class defines the functions that a heap must implement, and contains
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// infrastructure common to all heaps.
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class BarrierSet;
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class ThreadClosure;
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class AdaptiveSizePolicy;
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class Thread;
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//
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// CollectedHeap
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// SharedHeap
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// GenCollectedHeap
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// G1CollectedHeap
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// ParallelScavengeHeap
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//
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class CollectedHeap : public CHeapObj {
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friend class VMStructs;
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friend class IsGCActiveMark; // Block structured external access to _is_gc_active
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#ifdef ASSERT
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static int _fire_out_of_memory_count;
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#endif
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protected:
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MemRegion _reserved;
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BarrierSet* _barrier_set;
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bool _is_gc_active;
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unsigned int _total_collections; // ... started
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unsigned int _total_full_collections; // ... started
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size_t _max_heap_capacity;
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NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
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NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
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// Reason for current garbage collection. Should be set to
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// a value reflecting no collection between collections.
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GCCause::Cause _gc_cause;
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GCCause::Cause _gc_lastcause;
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PerfStringVariable* _perf_gc_cause;
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PerfStringVariable* _perf_gc_lastcause;
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// Constructor
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CollectedHeap();
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// Create a new tlab
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virtual HeapWord* allocate_new_tlab(size_t size);
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// Fix up tlabs to make the heap well-formed again,
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// optionally retiring the tlabs.
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virtual void fill_all_tlabs(bool retire);
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// Accumulate statistics on all tlabs.
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virtual void accumulate_statistics_all_tlabs();
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// Reinitialize tlabs before resuming mutators.
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virtual void resize_all_tlabs();
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debug_only(static void check_for_valid_allocation_state();)
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protected:
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// Allocate from the current thread's TLAB, with broken-out slow path.
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inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);
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static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);
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// Allocate an uninitialized block of the given size, or returns NULL if
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// this is impossible.
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inline static HeapWord* common_mem_allocate_noinit(size_t size, bool is_noref, TRAPS);
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// Like allocate_init, but the block returned by a successful allocation
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// is guaranteed initialized to zeros.
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inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS);
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// Same as common_mem version, except memory is allocated in the permanent area
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// If there is no permanent area, revert to common_mem_allocate_noinit
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inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);
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// Same as common_mem version, except memory is allocated in the permanent area
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// If there is no permanent area, revert to common_mem_allocate_init
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inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);
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// Helper functions for (VM) allocation.
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inline static void post_allocation_setup_common(KlassHandle klass,
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HeapWord* obj, size_t size);
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inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
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HeapWord* objPtr,
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size_t size);
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inline static void post_allocation_setup_obj(KlassHandle klass,
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HeapWord* obj, size_t size);
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inline static void post_allocation_setup_array(KlassHandle klass,
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HeapWord* obj, size_t size,
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int length);
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// Clears an allocated object.
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inline static void init_obj(HeapWord* obj, size_t size);
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// Verification functions
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virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
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PRODUCT_RETURN;
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virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
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PRODUCT_RETURN;
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public:
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enum Name {
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Abstract,
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SharedHeap,
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GenCollectedHeap,
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ParallelScavengeHeap,
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G1CollectedHeap
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};
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virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
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/**
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* Returns JNI error code JNI_ENOMEM if memory could not be allocated,
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* and JNI_OK on success.
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*/
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virtual jint initialize() = 0;
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// In many heaps, there will be a need to perform some initialization activities
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// after the Universe is fully formed, but before general heap allocation is allowed.
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// This is the correct place to place such initialization methods.
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virtual void post_initialize() = 0;
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MemRegion reserved_region() const { return _reserved; }
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// Return the number of bytes currently reserved, committed, and used,
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// respectively, for holding objects.
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size_t reserved_obj_bytes() const { return _reserved.byte_size(); }
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// Future cleanup here. The following functions should specify bytes or
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// heapwords as part of their signature.
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virtual size_t capacity() const = 0;
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virtual size_t used() const = 0;
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// Return "true" if the part of the heap that allocates Java
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// objects has reached the maximal committed limit that it can
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// reach, without a garbage collection.
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virtual bool is_maximal_no_gc() const = 0;
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virtual size_t permanent_capacity() const = 0;
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virtual size_t permanent_used() const = 0;
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// Support for java.lang.Runtime.maxMemory(): return the maximum amount of
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// memory that the vm could make available for storing 'normal' java objects.
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// This is based on the reserved address space, but should not include space
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// that the vm uses internally for bookkeeping or temporary storage (e.g.,
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// perm gen space or, in the case of the young gen, one of the survivor
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// spaces).
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virtual size_t max_capacity() const = 0;
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// Returns "TRUE" if "p" points into the reserved area of the heap.
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bool is_in_reserved(const void* p) const {
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return _reserved.contains(p);
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}
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bool is_in_reserved_or_null(const void* p) const {
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return p == NULL || is_in_reserved(p);
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}
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// Returns "TRUE" if "p" points to the head of an allocated object in the
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// heap. Since this method can be expensive in general, we restrict its
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// use to assertion checking only.
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virtual bool is_in(const void* p) const = 0;
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bool is_in_or_null(const void* p) const {
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return p == NULL || is_in(p);
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}
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// Let's define some terms: a "closed" subset of a heap is one that
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//
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// 1) contains all currently-allocated objects, and
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//
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// 2) is closed under reference: no object in the closed subset
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// references one outside the closed subset.
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//
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// Membership in a heap's closed subset is useful for assertions.
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// Clearly, the entire heap is a closed subset, so the default
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// implementation is to use "is_in_reserved". But this may not be too
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// liberal to perform useful checking. Also, the "is_in" predicate
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// defines a closed subset, but may be too expensive, since "is_in"
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// verifies that its argument points to an object head. The
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// "closed_subset" method allows a heap to define an intermediate
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// predicate, allowing more precise checking than "is_in_reserved" at
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// lower cost than "is_in."
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// One important case is a heap composed of disjoint contiguous spaces,
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// such as the Garbage-First collector. Such heaps have a convenient
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// closed subset consisting of the allocated portions of those
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// contiguous spaces.
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// Return "TRUE" iff the given pointer points into the heap's defined
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// closed subset (which defaults to the entire heap).
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virtual bool is_in_closed_subset(const void* p) const {
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return is_in_reserved(p);
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}
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bool is_in_closed_subset_or_null(const void* p) const {
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return p == NULL || is_in_closed_subset(p);
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}
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// Returns "TRUE" if "p" is allocated as "permanent" data.
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// If the heap does not use "permanent" data, returns the same
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// value is_in_reserved() would return.
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// NOTE: this actually returns true if "p" is in reserved space
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// for the space not that it is actually allocated (i.e. in committed
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// space). If you need the more conservative answer use is_permanent().
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virtual bool is_in_permanent(const void *p) const = 0;
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// Returns "TRUE" if "p" is in the committed area of "permanent" data.
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// If the heap does not use "permanent" data, returns the same
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// value is_in() would return.
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virtual bool is_permanent(const void *p) const = 0;
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bool is_in_permanent_or_null(const void *p) const {
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return p == NULL || is_in_permanent(p);
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}
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// Returns "TRUE" if "p" is a method oop in the
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// current heap, with high probability. This predicate
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// is not stable, in general.
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bool is_valid_method(oop p) const;
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void set_gc_cause(GCCause::Cause v) {
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if (UsePerfData) {
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_gc_lastcause = _gc_cause;
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_perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
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_perf_gc_cause->set_value(GCCause::to_string(v));
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}
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_gc_cause = v;
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}
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GCCause::Cause gc_cause() { return _gc_cause; }
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// Preload classes into the shared portion of the heap, and then dump
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// that data to a file so that it can be loaded directly by another
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// VM (then terminate).
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virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }
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// General obj/array allocation facilities.
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inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
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inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
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inline static oop large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS);
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// Special obj/array allocation facilities.
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// Some heaps may want to manage "permanent" data uniquely. These default
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// to the general routines if the heap does not support such handling.
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inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);
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// permanent_obj_allocate_no_klass_install() does not do the installation of
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// the klass pointer in the newly created object (as permanent_obj_allocate()
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// above does). This allows for a delay in the installation of the klass
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// pointer that is needed during the create of klassKlass's. The
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// method post_allocation_install_obj_klass() is used to install the
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// klass pointer.
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inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,
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int size,
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TRAPS);
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inline static void post_allocation_install_obj_klass(KlassHandle klass,
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oop obj,
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int size);
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inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);
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// Raw memory allocation facilities
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// The obj and array allocate methods are covers for these methods.
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// The permanent allocation method should default to mem_allocate if
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// permanent memory isn't supported.
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virtual HeapWord* mem_allocate(size_t size,
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bool is_noref,
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bool is_tlab,
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bool* gc_overhead_limit_was_exceeded) = 0;
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virtual HeapWord* permanent_mem_allocate(size_t size) = 0;
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// The boundary between a "large" and "small" array of primitives, in words.
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virtual size_t large_typearray_limit() = 0;
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// Some heaps may offer a contiguous region for shared non-blocking
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// allocation, via inlined code (by exporting the address of the top and
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// end fields defining the extent of the contiguous allocation region.)
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// This function returns "true" iff the heap supports this kind of
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// allocation. (Default is "no".)
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virtual bool supports_inline_contig_alloc() const {
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return false;
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}
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// These functions return the addresses of the fields that define the
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// boundaries of the contiguous allocation area. (These fields should be
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// physically near to one another.)
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virtual HeapWord** top_addr() const {
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guarantee(false, "inline contiguous allocation not supported");
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return NULL;
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}
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virtual HeapWord** end_addr() const {
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guarantee(false, "inline contiguous allocation not supported");
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return NULL;
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}
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// Some heaps may be in an unparseable state at certain times between
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// collections. This may be necessary for efficient implementation of
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// certain allocation-related activities. Calling this function before
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// attempting to parse a heap ensures that the heap is in a parsable
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// state (provided other concurrent activity does not introduce
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// unparsability). It is normally expected, therefore, that this
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// method is invoked with the world stopped.
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// NOTE: if you override this method, make sure you call
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// super::ensure_parsability so that the non-generational
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// part of the work gets done. See implementation of
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// CollectedHeap::ensure_parsability and, for instance,
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// that of GenCollectedHeap::ensure_parsability().
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// The argument "retire_tlabs" controls whether existing TLABs
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// are merely filled or also retired, thus preventing further
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// allocation from them and necessitating allocation of new TLABs.
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virtual void ensure_parsability(bool retire_tlabs);
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// Return an estimate of the maximum allocation that could be performed
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// without triggering any collection or expansion activity. In a
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// generational collector, for example, this is probably the largest
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// allocation that could be supported (without expansion) in the youngest
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// generation. It is "unsafe" because no locks are taken; the result
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// should be treated as an approximation, not a guarantee, for use in
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// heuristic resizing decisions.
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virtual size_t unsafe_max_alloc() = 0;
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// Section on thread-local allocation buffers (TLABs)
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// If the heap supports thread-local allocation buffers, it should override
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// the following methods:
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// Returns "true" iff the heap supports thread-local allocation buffers.
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// The default is "no".
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virtual bool supports_tlab_allocation() const {
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return false;
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}
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// The amount of space available for thread-local allocation buffers.
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virtual size_t tlab_capacity(Thread *thr) const {
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guarantee(false, "thread-local allocation buffers not supported");
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return 0;
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}
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// An estimate of the maximum allocation that could be performed
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// for thread-local allocation buffers without triggering any
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// collection or expansion activity.
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virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
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guarantee(false, "thread-local allocation buffers not supported");
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return 0;
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}
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// Can a compiler initialize a new object without store barriers?
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// This permission only extends from the creation of a new object
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// via a TLAB up to the first subsequent safepoint.
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virtual bool can_elide_tlab_store_barriers() const {
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guarantee(kind() < CollectedHeap::G1CollectedHeap, "else change or refactor this");
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return true;
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}
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// If a compiler is eliding store barriers for TLAB-allocated objects,
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// there is probably a corresponding slow path which can produce
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// an object allocated anywhere. The compiler's runtime support
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// promises to call this function on such a slow-path-allocated
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379 |
// object before performing initializations that have elided
|
|
380 |
// store barriers. Returns new_obj, or maybe a safer copy thereof.
|
|
381 |
virtual oop new_store_barrier(oop new_obj);
|
|
382 |
|
|
383 |
// Can a compiler elide a store barrier when it writes
|
|
384 |
// a permanent oop into the heap? Applies when the compiler
|
|
385 |
// is storing x to the heap, where x->is_perm() is true.
|
|
386 |
virtual bool can_elide_permanent_oop_store_barriers() const;
|
|
387 |
|
|
388 |
// Does this heap support heap inspection (+PrintClassHistogram?)
|
|
389 |
virtual bool supports_heap_inspection() const {
|
|
390 |
return false; // Until RFE 5023697 is implemented
|
|
391 |
}
|
|
392 |
|
|
393 |
// Perform a collection of the heap; intended for use in implementing
|
|
394 |
// "System.gc". This probably implies as full a collection as the
|
|
395 |
// "CollectedHeap" supports.
|
|
396 |
virtual void collect(GCCause::Cause cause) = 0;
|
|
397 |
|
|
398 |
// This interface assumes that it's being called by the
|
|
399 |
// vm thread. It collects the heap assuming that the
|
|
400 |
// heap lock is already held and that we are executing in
|
|
401 |
// the context of the vm thread.
|
|
402 |
virtual void collect_as_vm_thread(GCCause::Cause cause) = 0;
|
|
403 |
|
|
404 |
// Returns the barrier set for this heap
|
|
405 |
BarrierSet* barrier_set() { return _barrier_set; }
|
|
406 |
|
|
407 |
// Returns "true" iff there is a stop-world GC in progress. (I assume
|
|
408 |
// that it should answer "false" for the concurrent part of a concurrent
|
|
409 |
// collector -- dld).
|
|
410 |
bool is_gc_active() const { return _is_gc_active; }
|
|
411 |
|
|
412 |
// Total number of GC collections (started)
|
|
413 |
unsigned int total_collections() const { return _total_collections; }
|
|
414 |
unsigned int total_full_collections() const { return _total_full_collections;}
|
|
415 |
|
|
416 |
// Increment total number of GC collections (started)
|
|
417 |
// Should be protected but used by PSMarkSweep - cleanup for 1.4.2
|
|
418 |
void increment_total_collections(bool full = false) {
|
|
419 |
_total_collections++;
|
|
420 |
if (full) {
|
|
421 |
increment_total_full_collections();
|
|
422 |
}
|
|
423 |
}
|
|
424 |
|
|
425 |
void increment_total_full_collections() { _total_full_collections++; }
|
|
426 |
|
|
427 |
// Return the AdaptiveSizePolicy for the heap.
|
|
428 |
virtual AdaptiveSizePolicy* size_policy() = 0;
|
|
429 |
|
|
430 |
// Iterate over all the ref-containing fields of all objects, calling
|
|
431 |
// "cl.do_oop" on each. This includes objects in permanent memory.
|
|
432 |
virtual void oop_iterate(OopClosure* cl) = 0;
|
|
433 |
|
|
434 |
// Iterate over all objects, calling "cl.do_object" on each.
|
|
435 |
// This includes objects in permanent memory.
|
|
436 |
virtual void object_iterate(ObjectClosure* cl) = 0;
|
|
437 |
|
|
438 |
// Behaves the same as oop_iterate, except only traverses
|
|
439 |
// interior pointers contained in permanent memory. If there
|
|
440 |
// is no permanent memory, does nothing.
|
|
441 |
virtual void permanent_oop_iterate(OopClosure* cl) = 0;
|
|
442 |
|
|
443 |
// Behaves the same as object_iterate, except only traverses
|
|
444 |
// object contained in permanent memory. If there is no
|
|
445 |
// permanent memory, does nothing.
|
|
446 |
virtual void permanent_object_iterate(ObjectClosure* cl) = 0;
|
|
447 |
|
|
448 |
// NOTE! There is no requirement that a collector implement these
|
|
449 |
// functions.
|
|
450 |
//
|
|
451 |
// A CollectedHeap is divided into a dense sequence of "blocks"; that is,
|
|
452 |
// each address in the (reserved) heap is a member of exactly
|
|
453 |
// one block. The defining characteristic of a block is that it is
|
|
454 |
// possible to find its size, and thus to progress forward to the next
|
|
455 |
// block. (Blocks may be of different sizes.) Thus, blocks may
|
|
456 |
// represent Java objects, or they might be free blocks in a
|
|
457 |
// free-list-based heap (or subheap), as long as the two kinds are
|
|
458 |
// distinguishable and the size of each is determinable.
|
|
459 |
|
|
460 |
// Returns the address of the start of the "block" that contains the
|
|
461 |
// address "addr". We say "blocks" instead of "object" since some heaps
|
|
462 |
// may not pack objects densely; a chunk may either be an object or a
|
|
463 |
// non-object.
|
|
464 |
virtual HeapWord* block_start(const void* addr) const = 0;
|
|
465 |
|
|
466 |
// Requires "addr" to be the start of a chunk, and returns its size.
|
|
467 |
// "addr + size" is required to be the start of a new chunk, or the end
|
|
468 |
// of the active area of the heap.
|
|
469 |
virtual size_t block_size(const HeapWord* addr) const = 0;
|
|
470 |
|
|
471 |
// Requires "addr" to be the start of a block, and returns "TRUE" iff
|
|
472 |
// the block is an object.
|
|
473 |
virtual bool block_is_obj(const HeapWord* addr) const = 0;
|
|
474 |
|
|
475 |
// Returns the longest time (in ms) that has elapsed since the last
|
|
476 |
// time that any part of the heap was examined by a garbage collection.
|
|
477 |
virtual jlong millis_since_last_gc() = 0;
|
|
478 |
|
|
479 |
// Perform any cleanup actions necessary before allowing a verification.
|
|
480 |
virtual void prepare_for_verify() = 0;
|
|
481 |
|
|
482 |
virtual void print() const = 0;
|
|
483 |
virtual void print_on(outputStream* st) const = 0;
|
|
484 |
|
|
485 |
// Print all GC threads (other than the VM thread)
|
|
486 |
// used by this heap.
|
|
487 |
virtual void print_gc_threads_on(outputStream* st) const = 0;
|
|
488 |
void print_gc_threads() { print_gc_threads_on(tty); }
|
|
489 |
// Iterator for all GC threads (other than VM thread)
|
|
490 |
virtual void gc_threads_do(ThreadClosure* tc) const = 0;
|
|
491 |
|
|
492 |
// Print any relevant tracing info that flags imply.
|
|
493 |
// Default implementation does nothing.
|
|
494 |
virtual void print_tracing_info() const = 0;
|
|
495 |
|
|
496 |
// Heap verification
|
|
497 |
virtual void verify(bool allow_dirty, bool silent) = 0;
|
|
498 |
|
|
499 |
// Non product verification and debugging.
|
|
500 |
#ifndef PRODUCT
|
|
501 |
// Support for PromotionFailureALot. Return true if it's time to cause a
|
|
502 |
// promotion failure. The no-argument version uses
|
|
503 |
// this->_promotion_failure_alot_count as the counter.
|
|
504 |
inline bool promotion_should_fail(volatile size_t* count);
|
|
505 |
inline bool promotion_should_fail();
|
|
506 |
|
|
507 |
// Reset the PromotionFailureALot counters. Should be called at the end of a
|
|
508 |
// GC in which promotion failure ocurred.
|
|
509 |
inline void reset_promotion_should_fail(volatile size_t* count);
|
|
510 |
inline void reset_promotion_should_fail();
|
|
511 |
#endif // #ifndef PRODUCT
|
|
512 |
|
|
513 |
#ifdef ASSERT
|
|
514 |
static int fired_fake_oom() {
|
|
515 |
return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
|
|
516 |
}
|
|
517 |
#endif
|
|
518 |
};
|
|
519 |
|
|
520 |
// Class to set and reset the GC cause for a CollectedHeap.
|
|
521 |
|
|
522 |
class GCCauseSetter : StackObj {
|
|
523 |
CollectedHeap* _heap;
|
|
524 |
GCCause::Cause _previous_cause;
|
|
525 |
public:
|
|
526 |
GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
|
|
527 |
assert(SafepointSynchronize::is_at_safepoint(),
|
|
528 |
"This method manipulates heap state without locking");
|
|
529 |
_heap = heap;
|
|
530 |
_previous_cause = _heap->gc_cause();
|
|
531 |
_heap->set_gc_cause(cause);
|
|
532 |
}
|
|
533 |
|
|
534 |
~GCCauseSetter() {
|
|
535 |
assert(SafepointSynchronize::is_at_safepoint(),
|
|
536 |
"This method manipulates heap state without locking");
|
|
537 |
_heap->set_gc_cause(_previous_cause);
|
|
538 |
}
|
|
539 |
};
|