--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/g1AllocRegion.hpp Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,236 @@
+/*
+ * Copyright (c) 2011, 2015, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_G1ALLOCREGION_HPP
+#define SHARE_VM_GC_G1_G1ALLOCREGION_HPP
+
+#include "gc/g1/heapRegion.hpp"
+
+class G1CollectedHeap;
+
+// 0 -> no tracing, 1 -> basic tracing, 2 -> basic + allocation tracing
+#define G1_ALLOC_REGION_TRACING 0
+
+class ar_ext_msg;
+
+// A class that holds a region that is active in satisfying allocation
+// requests, potentially issued in parallel. When the active region is
+// full it will be retired and replaced with a new one. The
+// implementation assumes that fast-path allocations will be lock-free
+// and a lock will need to be taken when the active region needs to be
+// replaced.
+
+class G1AllocRegion VALUE_OBJ_CLASS_SPEC {
+ friend class ar_ext_msg;
+
+private:
+ // The active allocating region we are currently allocating out
+ // of. The invariant is that if this object is initialized (i.e.,
+ // init() has been called and release() has not) then _alloc_region
+ // is either an active allocating region or the dummy region (i.e.,
+ // it can never be NULL) and this object can be used to satisfy
+ // allocation requests. If this object is not initialized
+ // (i.e. init() has not been called or release() has been called)
+ // then _alloc_region is NULL and this object should not be used to
+ // satisfy allocation requests (it was done this way to force the
+ // correct use of init() and release()).
+ HeapRegion* volatile _alloc_region;
+
+ // Allocation context associated with this alloc region.
+ AllocationContext_t _allocation_context;
+
+ // It keeps track of the distinct number of regions that are used
+ // for allocation in the active interval of this object, i.e.,
+ // between a call to init() and a call to release(). The count
+ // mostly includes regions that are freshly allocated, as well as
+ // the region that is re-used using the set() method. This count can
+ // be used in any heuristics that might want to bound how many
+ // distinct regions this object can used during an active interval.
+ uint _count;
+
+ // When we set up a new active region we save its used bytes in this
+ // field so that, when we retire it, we can calculate how much space
+ // we allocated in it.
+ size_t _used_bytes_before;
+
+ // When true, indicates that allocate calls should do BOT updates.
+ const bool _bot_updates;
+
+ // Useful for debugging and tracing.
+ const char* _name;
+
+ // A dummy region (i.e., it's been allocated specially for this
+ // purpose and it is not part of the heap) that is full (i.e., top()
+ // == end()). When we don't have a valid active region we make
+ // _alloc_region point to this. This allows us to skip checking
+ // whether the _alloc_region is NULL or not.
+ static HeapRegion* _dummy_region;
+
+ // Some of the methods below take a bot_updates parameter. Its value
+ // should be the same as the _bot_updates field. The idea is that
+ // the parameter will be a constant for a particular alloc region
+ // and, given that these methods will be hopefully inlined, the
+ // compiler should compile out the test.
+
+ // Perform a non-MT-safe allocation out of the given region.
+ static inline HeapWord* allocate(HeapRegion* alloc_region,
+ size_t word_size,
+ bool bot_updates);
+
+ // Perform a MT-safe allocation out of the given region.
+ static inline HeapWord* par_allocate(HeapRegion* alloc_region,
+ size_t word_size,
+ bool bot_updates);
+
+ // Ensure that the region passed as a parameter has been filled up
+ // so that noone else can allocate out of it any more.
+ static void fill_up_remaining_space(HeapRegion* alloc_region,
+ bool bot_updates);
+
+ // Retire the active allocating region. If fill_up is true then make
+ // sure that the region is full before we retire it so that noone
+ // else can allocate out of it.
+ void retire(bool fill_up);
+
+ // After a region is allocated by alloc_new_region, this
+ // method is used to set it as the active alloc_region
+ void update_alloc_region(HeapRegion* alloc_region);
+
+ // Allocate a new active region and use it to perform a word_size
+ // allocation. The force parameter will be passed on to
+ // G1CollectedHeap::allocate_new_alloc_region() and tells it to try
+ // to allocate a new region even if the max has been reached.
+ HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);
+
+ void fill_in_ext_msg(ar_ext_msg* msg, const char* message);
+
+protected:
+ // For convenience as subclasses use it.
+ static G1CollectedHeap* _g1h;
+
+ virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
+ virtual void retire_region(HeapRegion* alloc_region,
+ size_t allocated_bytes) = 0;
+
+ G1AllocRegion(const char* name, bool bot_updates);
+
+public:
+ static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);
+
+ HeapRegion* get() const {
+ HeapRegion * hr = _alloc_region;
+ // Make sure that the dummy region does not escape this class.
+ return (hr == _dummy_region) ? NULL : hr;
+ }
+
+ void set_allocation_context(AllocationContext_t context) { _allocation_context = context; }
+ AllocationContext_t allocation_context() { return _allocation_context; }
+
+ uint count() { return _count; }
+
+ // The following two are the building blocks for the allocation method.
+
+ // First-level allocation: Should be called without holding a
+ // lock. It will try to allocate lock-free out of the active region,
+ // or return NULL if it was unable to.
+ inline HeapWord* attempt_allocation(size_t word_size, bool bot_updates);
+
+ // Second-level allocation: Should be called while holding a
+ // lock. It will try to first allocate lock-free out of the active
+ // region or, if it's unable to, it will try to replace the active
+ // alloc region with a new one. We require that the caller takes the
+ // appropriate lock before calling this so that it is easier to make
+ // it conform to its locking protocol.
+ inline HeapWord* attempt_allocation_locked(size_t word_size,
+ bool bot_updates);
+
+ // Should be called to allocate a new region even if the max of this
+ // type of regions has been reached. Should only be called if other
+ // allocation attempts have failed and we are not holding a valid
+ // active region.
+ inline HeapWord* attempt_allocation_force(size_t word_size,
+ bool bot_updates);
+
+ // Should be called before we start using this object.
+ void init();
+
+ // This can be used to set the active region to a specific
+ // region. (Use Example: we try to retain the last old GC alloc
+ // region that we've used during a GC and we can use set() to
+ // re-instate it at the beginning of the next GC.)
+ void set(HeapRegion* alloc_region);
+
+ // Should be called when we want to release the active region which
+ // is returned after it's been retired.
+ virtual HeapRegion* release();
+
+#if G1_ALLOC_REGION_TRACING
+ void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL);
+#else // G1_ALLOC_REGION_TRACING
+ void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL) { }
+#endif // G1_ALLOC_REGION_TRACING
+};
+
+class MutatorAllocRegion : public G1AllocRegion {
+protected:
+ virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
+ virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
+public:
+ MutatorAllocRegion()
+ : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { }
+};
+
+class SurvivorGCAllocRegion : public G1AllocRegion {
+protected:
+ virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
+ virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
+public:
+ SurvivorGCAllocRegion()
+ : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { }
+};
+
+class OldGCAllocRegion : public G1AllocRegion {
+protected:
+ virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
+ virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
+public:
+ OldGCAllocRegion()
+ : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
+
+ // This specialization of release() makes sure that the last card that has
+ // been allocated into has been completely filled by a dummy object. This
+ // avoids races when remembered set scanning wants to update the BOT of the
+ // last card in the retained old gc alloc region, and allocation threads
+ // allocating into that card at the same time.
+ virtual HeapRegion* release();
+};
+
+class ar_ext_msg : public err_msg {
+public:
+ ar_ext_msg(G1AllocRegion* alloc_region, const char *message) : err_msg("%s", "") {
+ alloc_region->fill_in_ext_msg(this, message);
+ }
+};
+
+#endif // SHARE_VM_GC_G1_G1ALLOCREGION_HPP