1.1 --- a/src/share/vm/gc_implementation/g1/sparsePRT.hpp Fri Jan 21 11:30:22 2011 -0500
1.2 +++ b/src/share/vm/gc_implementation/g1/sparsePRT.hpp Tue Jan 25 17:58:19 2011 -0500
1.3 @@ -1,5 +1,5 @@
1.4 /*
1.5 - * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
1.6 + * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
1.7 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.8 *
1.9 * This code is free software; you can redistribute it and/or modify it
1.10 @@ -212,8 +212,11 @@
1.11 // mutex.
1.12
1.13 class SparsePRTIter;
1.14 +class SparsePRTCleanupTask;
1.15
1.16 class SparsePRT VALUE_OBJ_CLASS_SPEC {
1.17 + friend class SparsePRTCleanupTask;
1.18 +
1.19 // Iterations are done on the _cur hash table, since they only need to
1.20 // see entries visible at the start of a collection pause.
1.21 // All other operations are done using the _next hash table.
1.22 @@ -238,6 +241,8 @@
1.23 SparsePRT* next_expanded() { return _next_expanded; }
1.24 void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
1.25
1.26 + bool should_be_on_expanded_list();
1.27 +
1.28 static SparsePRT* _head_expanded_list;
1.29
1.30 public:
1.31 @@ -284,12 +289,36 @@
1.32 static void add_to_expanded_list(SparsePRT* sprt);
1.33 static SparsePRT* get_from_expanded_list();
1.34
1.35 + // The purpose of these three methods is to help the GC workers
1.36 + // during the cleanup pause to recreate the expanded list, purging
1.37 + // any tables from it that belong to regions that are freed during
1.38 + // cleanup (if we don't purge those tables, there is a race that
1.39 + // causes various crashes; see CR 7014261).
1.40 + //
1.41 + // We chose to recreate the expanded list, instead of purging
1.42 + // entries from it by iterating over it, to avoid this serial phase
1.43 + // at the end of the cleanup pause.
1.44 + //
1.45 + // The three methods below work as follows:
1.46 + // * reset_for_cleanup_tasks() : Nulls the expanded list head at the
1.47 + // start of the cleanup pause.
1.48 + // * do_cleanup_work() : Called by the cleanup workers for every
1.49 + // region that is not free / is being freed by the cleanup
1.50 + // pause. It creates a list of expanded tables whose head / tail
1.51 + // are on the thread-local SparsePRTCleanupTask object.
1.52 + // * finish_cleanup_task() : Called by the cleanup workers after
1.53 + // they complete their cleanup task. It adds the local list into
1.54 + // the global expanded list. It assumes that the
1.55 + // ParGCRareEvent_lock is being held to ensure MT-safety.
1.56 + static void reset_for_cleanup_tasks();
1.57 + void do_cleanup_work(SparsePRTCleanupTask* sprt_cleanup_task);
1.58 + static void finish_cleanup_task(SparsePRTCleanupTask* sprt_cleanup_task);
1.59 +
1.60 bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const {
1.61 return _next->contains_card(region_id, card_index);
1.62 }
1.63 };
1.64
1.65 -
1.66 class SparsePRTIter: public RSHashTableIter {
1.67 public:
1.68 void init(const SparsePRT* sprt) {
1.69 @@ -300,4 +329,22 @@
1.70 }
1.71 };
1.72
1.73 +// This allows each worker during a cleanup pause to create a
1.74 +// thread-local list of sparse tables that have been expanded and need
1.75 +// to be processed at the beginning of the next GC pause. This lists
1.76 +// are concatenated into the single expanded list at the end of the
1.77 +// cleanup pause.
1.78 +class SparsePRTCleanupTask VALUE_OBJ_CLASS_SPEC {
1.79 +private:
1.80 + SparsePRT* _head;
1.81 + SparsePRT* _tail;
1.82 +
1.83 +public:
1.84 + SparsePRTCleanupTask() : _head(NULL), _tail(NULL) { }
1.85 +
1.86 + void add(SparsePRT* sprt);
1.87 + SparsePRT* head() { return _head; }
1.88 + SparsePRT* tail() { return _tail; }
1.89 +};
1.90 +
1.91 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP
