duke@435: /* jmasa@2188: * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. duke@435: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@435: * duke@435: * This code is free software; you can redistribute it and/or modify it duke@435: * under the terms of the GNU General Public License version 2 only, as duke@435: * published by the Free Software Foundation. duke@435: * duke@435: * This code is distributed in the hope that it will be useful, but WITHOUT duke@435: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@435: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@435: * version 2 for more details (a copy is included in the LICENSE file that duke@435: * accompanied this code). duke@435: * duke@435: * You should have received a copy of the GNU General Public License version duke@435: * 2 along with this work; if not, write to the Free Software Foundation, duke@435: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@435: * trims@1907: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA trims@1907: * or visit www.oracle.com if you need additional information or have any trims@1907: * questions. duke@435: * duke@435: */ duke@435: duke@435: // A "SharedHeap" is an implementation of a java heap for HotSpot. This duke@435: // is an abstract class: there may be many different kinds of heaps. This duke@435: // class defines the functions that a heap must implement, and contains duke@435: // infrastructure common to all heaps. duke@435: duke@435: class PermGen; duke@435: class Generation; duke@435: class BarrierSet; duke@435: class GenRemSet; duke@435: class Space; duke@435: class SpaceClosure; duke@435: class OopClosure; duke@435: class OopsInGenClosure; duke@435: class ObjectClosure; duke@435: class SubTasksDone; duke@435: class WorkGang; jmasa@2188: class FlexibleWorkGang; duke@435: class CollectorPolicy; duke@435: class KlassHandle; duke@435: duke@435: class SharedHeap : public CollectedHeap { duke@435: friend class VMStructs; duke@435: ysr@777: friend class VM_GC_Operation; ysr@777: friend class VM_CGC_Operation; ysr@777: duke@435: private: duke@435: // For claiming strong_roots tasks. duke@435: SubTasksDone* _process_strong_tasks; duke@435: duke@435: protected: duke@435: // There should be only a single instance of "SharedHeap" in a program. duke@435: // This is enforced with the protected constructor below, which will also duke@435: // set the static pointer "_sh" to that instance. duke@435: static SharedHeap* _sh; duke@435: duke@435: // All heaps contain a "permanent generation." This is some ways duke@435: // similar to a generation in a generational system, in other ways not. duke@435: // See the "PermGen" class. duke@435: PermGen* _perm_gen; duke@435: duke@435: // and the Gen Remembered Set, at least one good enough to scan the perm duke@435: // gen. duke@435: GenRemSet* _rem_set; duke@435: duke@435: // A gc policy, controls global gc resource issues duke@435: CollectorPolicy *_collector_policy; duke@435: duke@435: // See the discussion below, in the specification of the reader function duke@435: // for this variable. duke@435: int _strong_roots_parity; duke@435: duke@435: // If we're doing parallel GC, use this gang of threads. jmasa@2188: FlexibleWorkGang* _workers; duke@435: duke@435: // Number of parallel threads currently working on GC tasks. duke@435: // O indicates use sequential code; 1 means use parallel code even with duke@435: // only one thread, for performance testing purposes. duke@435: int _n_par_threads; duke@435: duke@435: // Full initialization is done in a concrete subtype's "initialize" duke@435: // function. duke@435: SharedHeap(CollectorPolicy* policy_); duke@435: ysr@777: // Returns true if the calling thread holds the heap lock, ysr@777: // or the calling thread is a par gc thread and the heap_lock is held ysr@777: // by the vm thread doing a gc operation. ysr@777: bool heap_lock_held_for_gc(); ysr@777: // True if the heap_lock is held by the a non-gc thread invoking a gc ysr@777: // operation. ysr@777: bool _thread_holds_heap_lock_for_gc; ysr@777: duke@435: public: duke@435: static SharedHeap* heap() { return _sh; } duke@435: duke@435: CollectorPolicy *collector_policy() const { return _collector_policy; } duke@435: duke@435: void set_barrier_set(BarrierSet* bs); duke@435: duke@435: // Does operations required after initialization has been done. duke@435: virtual void post_initialize(); duke@435: duke@435: // Initialization of ("weak") reference processing support duke@435: virtual void ref_processing_init(); duke@435: duke@435: void set_perm(PermGen* perm_gen) { _perm_gen = perm_gen; } duke@435: duke@435: // This function returns the "GenRemSet" object that allows us to scan duke@435: // generations; at least the perm gen, possibly more in a fully duke@435: // generational heap. duke@435: GenRemSet* rem_set() { return _rem_set; } duke@435: duke@435: // These function return the "permanent" generation, in which duke@435: // reflective objects are allocated and stored. Two versions, the second duke@435: // of which returns the view of the perm gen as a generation. duke@435: PermGen* perm() const { return _perm_gen; } duke@435: Generation* perm_gen() const { return _perm_gen->as_gen(); } duke@435: duke@435: // Iteration functions. duke@435: void oop_iterate(OopClosure* cl) = 0; duke@435: duke@435: // Same as above, restricted to a memory region. duke@435: virtual void oop_iterate(MemRegion mr, OopClosure* cl) = 0; duke@435: duke@435: // Iterate over all objects allocated since the last collection, calling duke@435: // "cl->do_object" on each. The heap must have been initialized properly duke@435: // to support this function, or else this call will fail. duke@435: virtual void object_iterate_since_last_GC(ObjectClosure* cl) = 0; duke@435: duke@435: // Iterate over all spaces in use in the heap, in an undefined order. duke@435: virtual void space_iterate(SpaceClosure* cl) = 0; duke@435: duke@435: // A SharedHeap will contain some number of spaces. This finds the duke@435: // space whose reserved area contains the given address, or else returns duke@435: // NULL. duke@435: virtual Space* space_containing(const void* addr) const = 0; duke@435: duke@435: bool no_gc_in_progress() { return !is_gc_active(); } duke@435: duke@435: // Some collectors will perform "process_strong_roots" in parallel. duke@435: // Such a call will involve claiming some fine-grained tasks, such as duke@435: // scanning of threads. To make this process simpler, we provide the duke@435: // "strong_roots_parity()" method. Collectors that start parallel tasks duke@435: // whose threads invoke "process_strong_roots" must duke@435: // call "change_strong_roots_parity" in sequential code starting such a duke@435: // task. (This also means that a parallel thread may only call duke@435: // process_strong_roots once.) duke@435: // duke@435: // For calls to process_strong_roots by sequential code, the parity is duke@435: // updated automatically. duke@435: // duke@435: // The idea is that objects representing fine-grained tasks, such as duke@435: // threads, will contain a "parity" field. A task will is claimed in the duke@435: // current "process_strong_roots" call only if its parity field is the duke@435: // same as the "strong_roots_parity"; task claiming is accomplished by duke@435: // updating the parity field to the strong_roots_parity with a CAS. duke@435: // duke@435: // If the client meats this spec, then strong_roots_parity() will have duke@435: // the following properties: duke@435: // a) to return a different value than was returned before the last duke@435: // call to change_strong_roots_parity, and duke@435: // c) to never return a distinguished value (zero) with which such duke@435: // task-claiming variables may be initialized, to indicate "never duke@435: // claimed". jrose@1424: private: duke@435: void change_strong_roots_parity(); jrose@1424: public: duke@435: int strong_roots_parity() { return _strong_roots_parity; } duke@435: jrose@1424: // Call these in sequential code around process_strong_roots. jrose@1424: // strong_roots_prologue calls change_strong_roots_parity, if jrose@1424: // parallel tasks are enabled. jrose@1424: class StrongRootsScope : public MarkingCodeBlobClosure::MarkScope { jrose@1424: public: jrose@1424: StrongRootsScope(SharedHeap* outer, bool activate = true); jrose@1424: ~StrongRootsScope(); jrose@1424: }; jrose@1424: friend class StrongRootsScope; jrose@1424: duke@435: enum ScanningOption { duke@435: SO_None = 0x0, duke@435: SO_AllClasses = 0x1, duke@435: SO_SystemClasses = 0x2, duke@435: SO_Symbols = 0x4, duke@435: SO_Strings = 0x8, duke@435: SO_CodeCache = 0x10 duke@435: }; duke@435: jmasa@2188: FlexibleWorkGang* workers() const { return _workers; } duke@435: duke@435: // Sets the number of parallel threads that will be doing tasks duke@435: // (such as process strong roots) subsequently. duke@435: virtual void set_par_threads(int t); duke@435: duke@435: // Number of threads currently working on GC tasks. duke@435: int n_par_threads() { return _n_par_threads; } duke@435: duke@435: // Invoke the "do_oop" method the closure "roots" on all root locations. duke@435: // If "collecting_perm_gen" is false, then roots that may only contain duke@435: // references to permGen objects are not scanned. If true, the duke@435: // "perm_gen" closure is applied to all older-to-younger refs in the duke@435: // permanent generation. The "so" argument determines which of roots duke@435: // the closure is applied to: duke@435: // "SO_None" does none; duke@435: // "SO_AllClasses" applies the closure to all entries in the SystemDictionary; duke@435: // "SO_SystemClasses" to all the "system" classes and loaders; duke@435: // "SO_Symbols" applies the closure to all entries in SymbolsTable; duke@435: // "SO_Strings" applies the closure to all entries in StringTable; duke@435: // "SO_CodeCache" applies the closure to all elements of the CodeCache. jrose@1424: void process_strong_roots(bool activate_scope, jrose@1424: bool collecting_perm_gen, duke@435: ScanningOption so, duke@435: OopClosure* roots, jrose@1424: CodeBlobClosure* code_roots, duke@435: OopsInGenClosure* perm_blk); duke@435: duke@435: // Apply "blk" to all the weak roots of the system. These include duke@435: // JNI weak roots, the code cache, system dictionary, symbol table, duke@435: // string table. duke@435: void process_weak_roots(OopClosure* root_closure, jrose@1424: CodeBlobClosure* code_roots, duke@435: OopClosure* non_root_closure); duke@435: duke@435: // The functions below are helper functions that a subclass of duke@435: // "SharedHeap" can use in the implementation of its virtual duke@435: // functions. duke@435: ysr@777: public: duke@435: duke@435: // Do anything common to GC's. duke@435: virtual void gc_prologue(bool full) = 0; duke@435: virtual void gc_epilogue(bool full) = 0; duke@435: duke@435: // duke@435: // New methods from CollectedHeap duke@435: // duke@435: duke@435: size_t permanent_capacity() const { duke@435: assert(perm_gen(), "NULL perm gen"); duke@435: return perm_gen()->capacity(); duke@435: } duke@435: duke@435: size_t permanent_used() const { duke@435: assert(perm_gen(), "NULL perm gen"); duke@435: return perm_gen()->used(); duke@435: } duke@435: duke@435: bool is_in_permanent(const void *p) const { duke@435: assert(perm_gen(), "NULL perm gen"); duke@435: return perm_gen()->is_in_reserved(p); duke@435: } duke@435: duke@435: // Different from is_in_permanent in that is_in_permanent duke@435: // only checks if p is in the reserved area of the heap duke@435: // and this checks to see if it in the commited area. duke@435: // This is typically used by things like the forte stackwalker duke@435: // during verification of suspicious frame values. duke@435: bool is_permanent(const void *p) const { duke@435: assert(perm_gen(), "NULL perm gen"); duke@435: return perm_gen()->is_in(p); duke@435: } duke@435: duke@435: HeapWord* permanent_mem_allocate(size_t size) { duke@435: assert(perm_gen(), "NULL perm gen"); duke@435: return _perm_gen->mem_allocate(size); duke@435: } duke@435: duke@435: void permanent_oop_iterate(OopClosure* cl) { duke@435: assert(perm_gen(), "NULL perm gen"); duke@435: _perm_gen->oop_iterate(cl); duke@435: } duke@435: duke@435: void permanent_object_iterate(ObjectClosure* cl) { duke@435: assert(perm_gen(), "NULL perm gen"); duke@435: _perm_gen->object_iterate(cl); duke@435: } duke@435: duke@435: // Some utilities. ysr@777: void print_size_transition(outputStream* out, ysr@777: size_t bytes_before, duke@435: size_t bytes_after, duke@435: size_t capacity); duke@435: };