--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/memory/sharedHeap.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,272 @@
+/*
+ * 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);
+};