| /* |
| * Copyright 2000-2006 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. |
| * |
| */ |
| |
| // A "SharedHeap" is an implementation of a java heap for HotSpot. This |
| // is an abstract class: there may be many different kinds of heaps. This |
| // class defines the functions that a heap must implement, and contains |
| // infrastructure common to all heaps. |
| |
| class PermGen; |
| class Generation; |
| class BarrierSet; |
| class GenRemSet; |
| class Space; |
| class SpaceClosure; |
| class OopClosure; |
| class OopsInGenClosure; |
| class ObjectClosure; |
| class SubTasksDone; |
| class WorkGang; |
| class CollectorPolicy; |
| class KlassHandle; |
| |
| class SharedHeap : public CollectedHeap { |
| friend class VMStructs; |
| |
| private: |
| // For claiming strong_roots tasks. |
| SubTasksDone* _process_strong_tasks; |
| |
| protected: |
| // There should be only a single instance of "SharedHeap" in a program. |
| // This is enforced with the protected constructor below, which will also |
| // set the static pointer "_sh" to that instance. |
| static SharedHeap* _sh; |
| |
| // All heaps contain a "permanent generation." This is some ways |
| // similar to a generation in a generational system, in other ways not. |
| // See the "PermGen" class. |
| PermGen* _perm_gen; |
| |
| // and the Gen Remembered Set, at least one good enough to scan the perm |
| // gen. |
| GenRemSet* _rem_set; |
| |
| // A gc policy, controls global gc resource issues |
| CollectorPolicy *_collector_policy; |
| |
| // See the discussion below, in the specification of the reader function |
| // for this variable. |
| int _strong_roots_parity; |
| |
| // If we're doing parallel GC, use this gang of threads. |
| WorkGang* _workers; |
| |
| // Number of parallel threads currently working on GC tasks. |
| // O indicates use sequential code; 1 means use parallel code even with |
| // only one thread, for performance testing purposes. |
| int _n_par_threads; |
| |
| // Full initialization is done in a concrete subtype's "initialize" |
| // function. |
| SharedHeap(CollectorPolicy* policy_); |
| |
| public: |
| static SharedHeap* heap() { return _sh; } |
| |
| CollectorPolicy *collector_policy() const { return _collector_policy; } |
| |
| void set_barrier_set(BarrierSet* bs); |
| |
| // Does operations required after initialization has been done. |
| virtual void post_initialize(); |
| |
| // Initialization of ("weak") reference processing support |
| virtual void ref_processing_init(); |
| |
| void set_perm(PermGen* perm_gen) { _perm_gen = perm_gen; } |
| |
| // A helper function that fills an allocated-but-not-yet-initialized |
| // region with a garbage object. |
| static void fill_region_with_object(MemRegion mr); |
| |
| // Minimum garbage fill object size |
| static size_t min_fill_size() { return (size_t)align_object_size(oopDesc::header_size()); } |
| static size_t min_fill_size_in_bytes() { return min_fill_size() * HeapWordSize; } |
| |
| // This function returns the "GenRemSet" object that allows us to scan |
| // generations; at least the perm gen, possibly more in a fully |
| // generational heap. |
| GenRemSet* rem_set() { return _rem_set; } |
| |
| // These function return the "permanent" generation, in which |
| // reflective objects are allocated and stored. Two versions, the second |
| // of which returns the view of the perm gen as a generation. |
| PermGen* perm() const { return _perm_gen; } |
| Generation* perm_gen() const { return _perm_gen->as_gen(); } |
| |
| // Iteration functions. |
| void oop_iterate(OopClosure* cl) = 0; |
| |
| // Same as above, restricted to a memory region. |
| virtual void oop_iterate(MemRegion mr, OopClosure* cl) = 0; |
| |
| // Iterate over all objects allocated since the last collection, calling |
| // "cl->do_object" on each. The heap must have been initialized properly |
| // to support this function, or else this call will fail. |
| virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0; |
| |
| // Iterate over all spaces in use in the heap, in an undefined order. |
| virtual void space_iterate(SpaceClosure* cl) = 0; |
| |
| // A SharedHeap will contain some number of spaces. This finds the |
| // space whose reserved area contains the given address, or else returns |
| // NULL. |
| virtual Space* space_containing(const void* addr) const = 0; |
| |
| bool no_gc_in_progress() { return !is_gc_active(); } |
| |
| // Some collectors will perform "process_strong_roots" in parallel. |
| // Such a call will involve claiming some fine-grained tasks, such as |
| // scanning of threads. To make this process simpler, we provide the |
| // "strong_roots_parity()" method. Collectors that start parallel tasks |
| // whose threads invoke "process_strong_roots" must |
| // call "change_strong_roots_parity" in sequential code starting such a |
| // task. (This also means that a parallel thread may only call |
| // process_strong_roots once.) |
| // |
| // For calls to process_strong_roots by sequential code, the parity is |
| // updated automatically. |
| // |
| // The idea is that objects representing fine-grained tasks, such as |
| // threads, will contain a "parity" field. A task will is claimed in the |
| // current "process_strong_roots" call only if its parity field is the |
| // same as the "strong_roots_parity"; task claiming is accomplished by |
| // updating the parity field to the strong_roots_parity with a CAS. |
| // |
| // If the client meats this spec, then strong_roots_parity() will have |
| // the following properties: |
| // a) to return a different value than was returned before the last |
| // call to change_strong_roots_parity, and |
| // c) to never return a distinguished value (zero) with which such |
| // task-claiming variables may be initialized, to indicate "never |
| // claimed". |
| void change_strong_roots_parity(); |
| int strong_roots_parity() { return _strong_roots_parity; } |
| |
| enum ScanningOption { |
| SO_None = 0x0, |
| SO_AllClasses = 0x1, |
| SO_SystemClasses = 0x2, |
| SO_Symbols = 0x4, |
| SO_Strings = 0x8, |
| SO_CodeCache = 0x10 |
| }; |
| |
| WorkGang* workers() const { return _workers; } |
| |
| // Sets the number of parallel threads that will be doing tasks |
| // (such as process strong roots) subsequently. |
| virtual void set_par_threads(int t); |
| |
| // Number of threads currently working on GC tasks. |
| int n_par_threads() { return _n_par_threads; } |
| |
| // Invoke the "do_oop" method the closure "roots" on all root locations. |
| // If "collecting_perm_gen" is false, then roots that may only contain |
| // references to permGen objects are not scanned. If true, the |
| // "perm_gen" closure is applied to all older-to-younger refs in the |
| // permanent generation. The "so" argument determines which of roots |
| // the closure is applied to: |
| // "SO_None" does none; |
| // "SO_AllClasses" applies the closure to all entries in the SystemDictionary; |
| // "SO_SystemClasses" to all the "system" classes and loaders; |
| // "SO_Symbols" applies the closure to all entries in SymbolsTable; |
| // "SO_Strings" applies the closure to all entries in StringTable; |
| // "SO_CodeCache" applies the closure to all elements of the CodeCache. |
| void process_strong_roots(bool collecting_perm_gen, |
| ScanningOption so, |
| OopClosure* roots, |
| OopsInGenClosure* perm_blk); |
| |
| // Apply "blk" to all the weak roots of the system. These include |
| // JNI weak roots, the code cache, system dictionary, symbol table, |
| // string table. |
| void process_weak_roots(OopClosure* root_closure, |
| OopClosure* non_root_closure); |
| |
| |
| // Like CollectedHeap::collect, but assume that the caller holds the Heap_lock. |
| virtual void collect_locked(GCCause::Cause cause) = 0; |
| |
| // The functions below are helper functions that a subclass of |
| // "SharedHeap" can use in the implementation of its virtual |
| // functions. |
| |
| protected: |
| |
| // Do anything common to GC's. |
| virtual void gc_prologue(bool full) = 0; |
| virtual void gc_epilogue(bool full) = 0; |
| |
| public: |
| // |
| // New methods from CollectedHeap |
| // |
| |
| size_t permanent_capacity() const { |
| assert(perm_gen(), "NULL perm gen"); |
| return perm_gen()->capacity(); |
| } |
| |
| size_t permanent_used() const { |
| assert(perm_gen(), "NULL perm gen"); |
| return perm_gen()->used(); |
| } |
| |
| bool is_in_permanent(const void *p) const { |
| assert(perm_gen(), "NULL perm gen"); |
| return perm_gen()->is_in_reserved(p); |
| } |
| |
| // Different from is_in_permanent in that is_in_permanent |
| // only checks if p is in the reserved area of the heap |
| // and this checks to see if it in the commited area. |
| // This is typically used by things like the forte stackwalker |
| // during verification of suspicious frame values. |
| bool is_permanent(const void *p) const { |
| assert(perm_gen(), "NULL perm gen"); |
| return perm_gen()->is_in(p); |
| } |
| |
| HeapWord* permanent_mem_allocate(size_t size) { |
| assert(perm_gen(), "NULL perm gen"); |
| return _perm_gen->mem_allocate(size); |
| } |
| |
| void permanent_oop_iterate(OopClosure* cl) { |
| assert(perm_gen(), "NULL perm gen"); |
| _perm_gen->oop_iterate(cl); |
| } |
| |
| void permanent_object_iterate(ObjectClosure* cl) { |
| assert(perm_gen(), "NULL perm gen"); |
| _perm_gen->object_iterate(cl); |
| } |
| |
| // Some utilities. |
| void print_size_transition(size_t bytes_before, |
| size_t bytes_after, |
| size_t capacity); |
| }; |