graal-jvmci-8: src/share/vm/memory/referenceProcessor.hpp comparison

comparison src/share/vm/memory/referenceProcessor.hpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	ba764ed4b6f2

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+:a61af66fc99e
+/*
+* Copyright 2001-2007 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.
+*
+*/
+// ReferenceProcessor class encapsulates the per-"collector" processing
+// of "weak" references for GC. The interface is useful for supporting
+// a generational abstraction, in particular when there are multiple
+// generations that are being independently collected -- possibly
+// concurrently and/or incrementally.  Note, however, that the
+// ReferenceProcessor class abstracts away from a generational setting
+// by using only a heap interval (called "span" below), thus allowing
+// its use in a straightforward manner in a general, non-generational
+// setting.
+//
+// The basic idea is that each ReferenceProcessor object concerns
+// itself with ("weak") reference processing in a specific "span"
+// of the heap of interest to a specific collector. Currently,
+// the span is a convex interval of the heap, but, efficiency
+// apart, there seems to be no reason it couldn't be extended
+// (with appropriate modifications) to any "non-convex interval".
+// forward references
+class ReferencePolicy;
+class AbstractRefProcTaskExecutor;
+class DiscoveredList;
+class ReferenceProcessor : public CHeapObj {
+friend class DiscoveredList;
+friend class DiscoveredListIterator;
+protected:
+// End of list marker
+static oop  _sentinelRef;
+MemRegion   _span; // (right-open) interval of heap
+// subject to wkref discovery
+bool        _discovering_refs;      // true when discovery enabled
+bool        _discovery_is_atomic;   // if discovery is atomic wrt
+// other collectors in configuration
+bool        _discovery_is_mt;       // true if reference discovery is MT.
+bool        _enqueuing_is_done;     // true if all weak references enqueued
+bool        _processing_is_mt;      // true during phases when
+// reference processing is MT.
+int         _next_id;               // round-robin counter in
+// support of work distribution
+// For collectors that do not keep GC marking information
+// in the object header, this field holds a closure that
+// helps the reference processor determine the reachability
+// of an oop (the field is currently initialized to NULL for
+// all collectors but the CMS collector).
+BoolObjectClosure* _is_alive_non_header;
+// The discovered ref lists themselves
+int             _num_q;       // the MT'ness degree of the queues below
+DiscoveredList* _discoveredSoftRefs; // pointer to array of oops
+DiscoveredList* _discoveredWeakRefs;
+DiscoveredList* _discoveredFinalRefs;
+DiscoveredList* _discoveredPhantomRefs;
+public:
+int  num_q()                           { return _num_q; }
+DiscoveredList* discovered_soft_refs() { return _discoveredSoftRefs; }
+static oop* sentinel_ref()             { return &_sentinelRef; }
+public:
+// Process references with a certain reachability level.
+void process_discovered_reflist(DiscoveredList               refs_lists[],
+ReferencePolicy*             policy,
+bool                         clear_referent,
+BoolObjectClosure*           is_alive,
+OopClosure*                  keep_alive,
+VoidClosure*                 complete_gc,
+AbstractRefProcTaskExecutor* task_executor);
+void process_phaseJNI(BoolObjectClosure* is_alive,
+OopClosure*        keep_alive,
+VoidClosure*       complete_gc);
+// Work methods used by the method process_discovered_reflist
+// Phase1: keep alive all those referents that are otherwise
+// dead but which must be kept alive by policy (and their closure).
+void process_phase1(DiscoveredList&     refs_list_addr,
+ReferencePolicy*    policy,
+BoolObjectClosure*  is_alive,
+OopClosure*         keep_alive,
+VoidClosure*        complete_gc);
+// Phase2: remove all those references whose referents are
+// reachable.
+inline void process_phase2(DiscoveredList&    refs_list_addr,
+BoolObjectClosure* is_alive,
+OopClosure*        keep_alive,
+VoidClosure*       complete_gc) {
+if (discovery_is_atomic()) {
+// complete_gc is ignored in this case for this phase
+pp2_work(refs_list_addr, is_alive, keep_alive);
+} else {
+assert(complete_gc != NULL, "Error");
+pp2_work_concurrent_discovery(refs_list_addr, is_alive,
+keep_alive, complete_gc);
+}
+}
+// Work methods in support of process_phase2
+void pp2_work(DiscoveredList&    refs_list_addr,
+BoolObjectClosure* is_alive,
+OopClosure*        keep_alive);
+void pp2_work_concurrent_discovery(
+DiscoveredList&    refs_list_addr,
+BoolObjectClosure* is_alive,
+OopClosure*        keep_alive,
+VoidClosure*       complete_gc);
+// Phase3: process the referents by either clearing them
+// or keeping them alive (and their closure)
+void process_phase3(DiscoveredList&    refs_list_addr,
+bool               clear_referent,
+BoolObjectClosure* is_alive,
+OopClosure*        keep_alive,
+VoidClosure*       complete_gc);
+// Enqueue references with a certain reachability level
+void enqueue_discovered_reflist(DiscoveredList& refs_list, oop* pending_list_addr);
+// "Preclean" all the discovered reference lists
+// by removing references with strongly reachable referents.
+// The first argument is a predicate on an oop that indicates
+// its (strong) reachability and the second is a closure that
+// may be used to incrementalize or abort the precleaning process.
+// The caller is responsible for taking care of potential
+// interference with concurrent operations on these lists
+// (or predicates involved) by other threads. Currently
+// only used by the CMS collector.
+void preclean_discovered_references(BoolObjectClosure* is_alive,
+OopClosure*        keep_alive,
+VoidClosure*       complete_gc,
+YieldClosure*      yield);
+// Delete entries in the discovered lists that have
+// either a null referent or are not active. Such
+// Reference objects can result from the clearing
+// or enqueueing of Reference objects concurrent
+// with their discovery by a (concurrent) collector.
+// For a definition of "active" see java.lang.ref.Reference;
+// Refs are born active, become inactive when enqueued,
+// and never become active again. The state of being
+// active is encoded as follows: A Ref is active
+// if and only if its "next" field is NULL.
+void clean_up_discovered_references();
+void clean_up_discovered_reflist(DiscoveredList& refs_list);
+// Returns the name of the discovered reference list
+// occupying the i / _num_q slot.
+const char* list_name(int i);
+protected:
+// "Preclean" the given discovered reference list
+// by removing references with strongly reachable referents.
+// Currently used in support of CMS only.
+void preclean_discovered_reflist(DiscoveredList&    refs_list,
+BoolObjectClosure* is_alive,
+OopClosure*        keep_alive,
+VoidClosure*       complete_gc,
+YieldClosure*      yield);
+void enqueue_discovered_reflists(oop* pending_list_addr, AbstractRefProcTaskExecutor* task_executor);
+int next_id() {
+int id = _next_id;
+if (++_next_id == _num_q) {
+_next_id = 0;
+}
+return id;
+}
+DiscoveredList* get_discovered_list(ReferenceType rt);
+inline void add_to_discovered_list_mt(DiscoveredList& refs_list, oop obj,
+oop* discovered_addr);
+void verify_ok_to_handle_reflists() PRODUCT_RETURN;
+void abandon_partial_discovered_list(DiscoveredList& refs_list);
+void abandon_partial_discovered_list_arr(DiscoveredList refs_lists[]);
+// Calculate the number of jni handles.
+unsigned int count_jni_refs();
+// Balances reference queues.
+void balance_queues(DiscoveredList ref_lists[]);
+// Update (advance) the soft ref master clock field.
+void update_soft_ref_master_clock();
+public:
+// constructor
+ReferenceProcessor():
+_span((HeapWord*)NULL, (HeapWord*)NULL),
+_discoveredSoftRefs(NULL),  _discoveredWeakRefs(NULL),
+_discoveredFinalRefs(NULL), _discoveredPhantomRefs(NULL),
+_discovering_refs(false),
+_discovery_is_atomic(true),
+_enqueuing_is_done(false),
+_discovery_is_mt(false),
+_is_alive_non_header(NULL),
+_num_q(0),
+_processing_is_mt(false),
+_next_id(0)
+{}
+ReferenceProcessor(MemRegion span, bool atomic_discovery,
+bool mt_discovery, int mt_degree = 1,
+bool mt_processing = false);
+// Allocates and initializes a reference processor.
+static ReferenceProcessor* create_ref_processor(
+MemRegion          span,
+bool               atomic_discovery,
+bool               mt_discovery,
+BoolObjectClosure* is_alive_non_header = NULL,
+int                parallel_gc_threads = 1,
+bool               mt_processing = false);
+// RefDiscoveryPolicy values
+enum {
+ReferenceBasedDiscovery = 0,
+ReferentBasedDiscovery  = 1
+};
+static void init_statics();
+public:
+// get and set "is_alive_non_header" field
+BoolObjectClosure* is_alive_non_header() {
+return _is_alive_non_header;
+}
+void set_is_alive_non_header(BoolObjectClosure* is_alive_non_header) {
+_is_alive_non_header = is_alive_non_header;
+}
+// get and set span
+MemRegion span()                   { return _span; }
+void      set_span(MemRegion span) { _span = span; }
+// start and stop weak ref discovery
+void enable_discovery()   { _discovering_refs = true;  }
+void disable_discovery()  { _discovering_refs = false; }
+bool discovery_enabled()  { return _discovering_refs;  }
+// whether discovery is atomic wrt other collectors
+bool discovery_is_atomic() const { return _discovery_is_atomic; }
+void set_atomic_discovery(bool atomic) { _discovery_is_atomic = atomic; }
+// whether discovery is done by multiple threads same-old-timeously
+bool discovery_is_mt() const { return _discovery_is_mt; }
+void set_mt_discovery(bool mt) { _discovery_is_mt = mt; }
+// Whether we are in a phase when _processing_ is MT.
+bool processing_is_mt() const { return _processing_is_mt; }
+void set_mt_processing(bool mt) { _processing_is_mt = mt; }
+// whether all enqueuing of weak references is complete
+bool enqueuing_is_done()  { return _enqueuing_is_done; }
+void set_enqueuing_is_done(bool v) { _enqueuing_is_done = v; }
+// iterate over oops
+void weak_oops_do(OopClosure* f);       // weak roots
+static void oops_do(OopClosure* f);     // strong root(s)
+// Discover a Reference object, using appropriate discovery criteria
+bool discover_reference(oop obj, ReferenceType rt);
+// Process references found during GC (called by the garbage collector)
+void process_discovered_references(ReferencePolicy*             policy,
+BoolObjectClosure*           is_alive,
+OopClosure*                  keep_alive,
+VoidClosure*                 complete_gc,
+AbstractRefProcTaskExecutor* task_executor);
+public:
+// Enqueue references at end of GC (called by the garbage collector)
+bool enqueue_discovered_references(AbstractRefProcTaskExecutor* task_executor = NULL);
+// debugging
+void verify_no_references_recorded() PRODUCT_RETURN;
+static void verify();
+// clear the discovered lists (unlinking each entry).
+void clear_discovered_references() PRODUCT_RETURN;
+};
+// A utility class to disable reference discovery in
+// the scope which contains it, for given ReferenceProcessor.
+class NoRefDiscovery: StackObj {
+private:
+ReferenceProcessor* _rp;
+bool _was_discovering_refs;
+public:
+NoRefDiscovery(ReferenceProcessor* rp) : _rp(rp) {
+if (_was_discovering_refs = _rp->discovery_enabled()) {
+_rp->disable_discovery();
+}
+}
+~NoRefDiscovery() {
+if (_was_discovering_refs) {
+_rp->enable_discovery();
+}
+}
+};
+// A utility class to temporarily mutate the span of the
+// given ReferenceProcessor in the scope that contains it.
+class ReferenceProcessorSpanMutator: StackObj {
+private:
+ReferenceProcessor* _rp;
+MemRegion           _saved_span;
+public:
+ReferenceProcessorSpanMutator(ReferenceProcessor* rp,
+MemRegion span):
+_rp(rp) {
+_saved_span = _rp->span();
+_rp->set_span(span);
+}
+~ReferenceProcessorSpanMutator() {
+_rp->set_span(_saved_span);
+}
+};
+// A utility class to temporarily change the MT'ness of
+// reference discovery for the given ReferenceProcessor
+// in the scope that contains it.
+class ReferenceProcessorMTMutator: StackObj {
+private:
+ReferenceProcessor* _rp;
+bool                _saved_mt;
+public:
+ReferenceProcessorMTMutator(ReferenceProcessor* rp,
+bool mt):
+_rp(rp) {
+_saved_mt = _rp->discovery_is_mt();
+_rp->set_mt_discovery(mt);
+}
+~ReferenceProcessorMTMutator() {
+_rp->set_mt_discovery(_saved_mt);
+}
+};
+// A utility class to temporarily change the disposition
+// of the "is_alive_non_header" closure field of the
+// given ReferenceProcessor in the scope that contains it.
+class ReferenceProcessorIsAliveMutator: StackObj {
+private:
+ReferenceProcessor* _rp;
+BoolObjectClosure*  _saved_cl;
+public:
+ReferenceProcessorIsAliveMutator(ReferenceProcessor* rp,
+BoolObjectClosure*  cl):
+_rp(rp) {
+_saved_cl = _rp->is_alive_non_header();
+_rp->set_is_alive_non_header(cl);
+}
+~ReferenceProcessorIsAliveMutator() {
+_rp->set_is_alive_non_header(_saved_cl);
+}
+};
+// A utility class to temporarily change the disposition
+// of the "discovery_is_atomic" field of the
+// given ReferenceProcessor in the scope that contains it.
+class ReferenceProcessorAtomicMutator: StackObj {
+private:
+ReferenceProcessor* _rp;
+bool                _saved_atomic_discovery;
+public:
+ReferenceProcessorAtomicMutator(ReferenceProcessor* rp,
+bool atomic):
+_rp(rp) {
+_saved_atomic_discovery = _rp->discovery_is_atomic();
+_rp->set_atomic_discovery(atomic);
+}
+~ReferenceProcessorAtomicMutator() {
+_rp->set_atomic_discovery(_saved_atomic_discovery);
+}
+};
+// A utility class to temporarily change the MT processing
+// disposition of the given ReferenceProcessor instance
+// in the scope that contains it.
+class ReferenceProcessorMTProcMutator: StackObj {
+private:
+ReferenceProcessor* _rp;
+bool  _saved_mt;
+public:
+ReferenceProcessorMTProcMutator(ReferenceProcessor* rp,
+bool mt):
+_rp(rp) {
+_saved_mt = _rp->processing_is_mt();
+_rp->set_mt_processing(mt);
+}
+~ReferenceProcessorMTProcMutator() {
+_rp->set_mt_processing(_saved_mt);
+}
+};
+// This class is an interface used to implement task execution for the
+// reference processing.
+class AbstractRefProcTaskExecutor {
+public:
+// Abstract tasks to execute.
+class ProcessTask;
+class EnqueueTask;
+// Executes a task using worker threads.
+virtual void execute(ProcessTask& task) = 0;
+virtual void execute(EnqueueTask& task) = 0;
+// Switch to single threaded mode.
+virtual void set_single_threaded_mode() { };
+};
+// Abstract reference processing task to execute.
+class AbstractRefProcTaskExecutor::ProcessTask {
+protected:
+ProcessTask(ReferenceProcessor& ref_processor,
+DiscoveredList      refs_lists[],
+bool                marks_oops_alive)
+: _ref_processor(ref_processor),
+_refs_lists(refs_lists),
+_marks_oops_alive(marks_oops_alive)
+{ }
+public:
+virtual void work(unsigned int work_id, BoolObjectClosure& is_alive,
+OopClosure& keep_alive,
+VoidClosure& complete_gc) = 0;
+// Returns true if a task marks some oops as alive.
+bool marks_oops_alive() const
+{ return _marks_oops_alive; }
+protected:
+ReferenceProcessor& _ref_processor;
+DiscoveredList*     _refs_lists;
+const bool          _marks_oops_alive;
+};
+// Abstract reference processing task to execute.
+class AbstractRefProcTaskExecutor::EnqueueTask {
+protected:
+EnqueueTask(ReferenceProcessor& ref_processor,
+DiscoveredList      refs_lists[],
+oop*                pending_list_addr,
+oop                 sentinel_ref,
+int                 n_queues)
+: _ref_processor(ref_processor),
+_refs_lists(refs_lists),
+_pending_list_addr(pending_list_addr),
+_sentinel_ref(sentinel_ref),
+_n_queues(n_queues)
+{ }
+public:
+virtual void work(unsigned int work_id) = 0;
+protected:
+ReferenceProcessor& _ref_processor;
+DiscoveredList*     _refs_lists;
+oop*                _pending_list_addr;
+oop                 _sentinel_ref;
+int                 _n_queues;
+};

Mercurial > hg > graal-jvmci-8

comparison src/share/vm/memory/referenceProcessor.hpp @ 0:a61af66fc99e jdk7-b24