8187443: Forest Consolidation: Move files to unified layout

Reviewed-by: darcy, ihse

src/hotspot/share/gc/shared/taskqueue.hpp

@@ -0,0 +1,563 @@
+/*
+ * Copyright (c) 2001, 2017, 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_SHARED_TASKQUEUE_HPP
+#define SHARE_VM_GC_SHARED_TASKQUEUE_HPP
+
+#include "memory/allocation.hpp"
+#include "utilities/stack.hpp"
+
+// Simple TaskQueue stats that are collected by default in debug builds.
+
+#if !defined(TASKQUEUE_STATS) && defined(ASSERT)
+#define TASKQUEUE_STATS 1
+#elif !defined(TASKQUEUE_STATS)
+#define TASKQUEUE_STATS 0
+#endif
+
+#if TASKQUEUE_STATS
+#define TASKQUEUE_STATS_ONLY(code) code
+#else
+#define TASKQUEUE_STATS_ONLY(code)
+#endif // TASKQUEUE_STATS
+
+#if TASKQUEUE_STATS
+class TaskQueueStats {
+public:
+  enum StatId {
+    push,             // number of taskqueue pushes
+    pop,              // number of taskqueue pops
+    pop_slow,         // subset of taskqueue pops that were done slow-path
+    steal_attempt,    // number of taskqueue steal attempts
+    steal,            // number of taskqueue steals
+    overflow,         // number of overflow pushes
+    overflow_max_len, // max length of overflow stack
+    last_stat_id
+  };
+
+public:
+  inline TaskQueueStats()       { reset(); }
+
+  inline void record_push()     { ++_stats[push]; }
+  inline void record_pop()      { ++_stats[pop]; }
+  inline void record_pop_slow() { record_pop(); ++_stats[pop_slow]; }
+  inline void record_steal(bool success);
+  inline void record_overflow(size_t new_length);
+
+  TaskQueueStats & operator +=(const TaskQueueStats & addend);
+
+  inline size_t get(StatId id) const { return _stats[id]; }
+  inline const size_t* get() const   { return _stats; }
+
+  inline void reset();
+
+  // Print the specified line of the header (does not include a line separator).
+  static void print_header(unsigned int line, outputStream* const stream = tty,
+                           unsigned int width = 10);
+  // Print the statistics (does not include a line separator).
+  void print(outputStream* const stream = tty, unsigned int width = 10) const;
+
+  DEBUG_ONLY(void verify() const;)
+
+private:
+  size_t                    _stats[last_stat_id];
+  static const char * const _names[last_stat_id];
+};
+
+void TaskQueueStats::record_steal(bool success) {
+  ++_stats[steal_attempt];
+  if (success) ++_stats[steal];
+}
+
+void TaskQueueStats::record_overflow(size_t new_len) {
+  ++_stats[overflow];
+  if (new_len > _stats[overflow_max_len]) _stats[overflow_max_len] = new_len;
+}
+
+void TaskQueueStats::reset() {
+  memset(_stats, 0, sizeof(_stats));
+}
+#endif // TASKQUEUE_STATS
+
+// TaskQueueSuper collects functionality common to all GenericTaskQueue instances.
+
+template <unsigned int N, MEMFLAGS F>
+class TaskQueueSuper: public CHeapObj<F> {
+protected:
+  // Internal type for indexing the queue; also used for the tag.
+  typedef NOT_LP64(uint16_t) LP64_ONLY(uint32_t) idx_t;
+
+  // The first free element after the last one pushed (mod N).
+  volatile uint _bottom;
+
+  enum { MOD_N_MASK = N - 1 };
+
+  class Age {
+  public:
+    Age(size_t data = 0)         { _data = data; }
+    Age(const Age& age)          { _data = age._data; }
+    Age(idx_t top, idx_t tag)    { _fields._top = top; _fields._tag = tag; }
+
+    Age   get()        const volatile { return _data; }
+    void  set(Age age) volatile       { _data = age._data; }
+
+    idx_t top()        const volatile { return _fields._top; }
+    idx_t tag()        const volatile { return _fields._tag; }
+
+    // Increment top; if it wraps, increment tag also.
+    void increment() {
+      _fields._top = increment_index(_fields._top);
+      if (_fields._top == 0) ++_fields._tag;
+    }
+
+    Age cmpxchg(const Age new_age, const Age old_age) volatile;
+
+    bool operator ==(const Age& other) const { return _data == other._data; }
+
+  private:
+    struct fields {
+      idx_t _top;
+      idx_t _tag;
+    };
+    union {
+      size_t _data;
+      fields _fields;
+    };
+  };
+
+  volatile Age _age;
+
+  // These both operate mod N.
+  static uint increment_index(uint ind) {
+    return (ind + 1) & MOD_N_MASK;
+  }
+  static uint decrement_index(uint ind) {
+    return (ind - 1) & MOD_N_MASK;
+  }
+
+  // Returns a number in the range [0..N).  If the result is "N-1", it should be
+  // interpreted as 0.
+  uint dirty_size(uint bot, uint top) const {
+    return (bot - top) & MOD_N_MASK;
+  }
+
+  // Returns the size corresponding to the given "bot" and "top".
+  uint size(uint bot, uint top) const {
+    uint sz = dirty_size(bot, top);
+    // Has the queue "wrapped", so that bottom is less than top?  There's a
+    // complicated special case here.  A pair of threads could perform pop_local
+    // and pop_global operations concurrently, starting from a state in which
+    // _bottom == _top+1.  The pop_local could succeed in decrementing _bottom,
+    // and the pop_global in incrementing _top (in which case the pop_global
+    // will be awarded the contested queue element.)  The resulting state must
+    // be interpreted as an empty queue.  (We only need to worry about one such
+    // event: only the queue owner performs pop_local's, and several concurrent
+    // threads attempting to perform the pop_global will all perform the same
+    // CAS, and only one can succeed.)  Any stealing thread that reads after
+    // either the increment or decrement will see an empty queue, and will not
+    // join the competitors.  The "sz == -1 || sz == N-1" state will not be
+    // modified by concurrent queues, so the owner thread can reset the state to
+    // _bottom == top so subsequent pushes will be performed normally.
+    return (sz == N - 1) ? 0 : sz;
+  }
+
+public:
+  TaskQueueSuper() : _bottom(0), _age() {}
+
+  // Return true if the TaskQueue contains/does not contain any tasks.
+  bool peek()     const { return _bottom != _age.top(); }
+  bool is_empty() const { return size() == 0; }
+
+  // Return an estimate of the number of elements in the queue.
+  // The "careful" version admits the possibility of pop_local/pop_global
+  // races.
+  uint size() const {
+    return size(_bottom, _age.top());
+  }
+
+  uint dirty_size() const {
+    return dirty_size(_bottom, _age.top());
+  }
+
+  void set_empty() {
+    _bottom = 0;
+    _age.set(0);
+  }
+
+  // Maximum number of elements allowed in the queue.  This is two less
+  // than the actual queue size, for somewhat complicated reasons.
+  uint max_elems() const { return N - 2; }
+
+  // Total size of queue.
+  static const uint total_size() { return N; }
+
+  TASKQUEUE_STATS_ONLY(TaskQueueStats stats;)
+};
+
+//
+// GenericTaskQueue implements an ABP, Aurora-Blumofe-Plaxton, double-
+// ended-queue (deque), intended for use in work stealing. Queue operations
+// are non-blocking.
+//
+// A queue owner thread performs push() and pop_local() operations on one end
+// of the queue, while other threads may steal work using the pop_global()
+// method.
+//
+// The main difference to the original algorithm is that this
+// implementation allows wrap-around at the end of its allocated
+// storage, which is an array.
+//
+// The original paper is:
+//
+// Arora, N. S., Blumofe, R. D., and Plaxton, C. G.
+// Thread scheduling for multiprogrammed multiprocessors.
+// Theory of Computing Systems 34, 2 (2001), 115-144.
+//
+// The following paper provides an correctness proof and an
+// implementation for weakly ordered memory models including (pseudo-)
+// code containing memory barriers for a Chase-Lev deque. Chase-Lev is
+// similar to ABP, with the main difference that it allows resizing of the
+// underlying storage:
+//
+// Le, N. M., Pop, A., Cohen A., and Nardell, F. Z.
+// Correct and efficient work-stealing for weak memory models
+// Proceedings of the 18th ACM SIGPLAN symposium on Principles and
+// practice of parallel programming (PPoPP 2013), 69-80
+//
+
+template <class E, MEMFLAGS F, unsigned int N = TASKQUEUE_SIZE>
+class GenericTaskQueue: public TaskQueueSuper<N, F> {
+protected:
+  typedef typename TaskQueueSuper<N, F>::Age Age;
+  typedef typename TaskQueueSuper<N, F>::idx_t idx_t;
+
+  using TaskQueueSuper<N, F>::_bottom;
+  using TaskQueueSuper<N, F>::_age;
+  using TaskQueueSuper<N, F>::increment_index;
+  using TaskQueueSuper<N, F>::decrement_index;
+  using TaskQueueSuper<N, F>::dirty_size;
+
+public:
+  using TaskQueueSuper<N, F>::max_elems;
+  using TaskQueueSuper<N, F>::size;
+
+#if  TASKQUEUE_STATS
+  using TaskQueueSuper<N, F>::stats;
+#endif
+
+private:
+  // Slow paths for push, pop_local.  (pop_global has no fast path.)
+  bool push_slow(E t, uint dirty_n_elems);
+  bool pop_local_slow(uint localBot, Age oldAge);
+
+public:
+  typedef E element_type;
+
+  // Initializes the queue to empty.
+  GenericTaskQueue();
+
+  void initialize();
+
+  // Push the task "t" on the queue.  Returns "false" iff the queue is full.
+  inline bool push(E t);
+
+  // Attempts to claim a task from the "local" end of the queue (the most
+  // recently pushed).  If successful, returns true and sets t to the task;
+  // otherwise, returns false (the queue is empty).
+  inline bool pop_local(volatile E& t);
+
+  // Like pop_local(), but uses the "global" end of the queue (the least
+  // recently pushed).
+  bool pop_global(volatile E& t);
+
+  // Delete any resource associated with the queue.
+  ~GenericTaskQueue();
+
+  // Apply fn to each element in the task queue.  The queue must not
+  // be modified while iterating.
+  template<typename Fn> void iterate(Fn fn);
+
+private:
+  // Element array.
+  volatile E* _elems;
+};
+
+template<class E, MEMFLAGS F, unsigned int N>
+GenericTaskQueue<E, F, N>::GenericTaskQueue() {
+  assert(sizeof(Age) == sizeof(size_t), "Depends on this.");
+}
+
+// OverflowTaskQueue is a TaskQueue that also includes an overflow stack for
+// elements that do not fit in the TaskQueue.
+//
+// This class hides two methods from super classes:
+//
+// push() - push onto the task queue or, if that fails, onto the overflow stack
+// is_empty() - return true if both the TaskQueue and overflow stack are empty
+//
+// Note that size() is not hidden--it returns the number of elements in the
+// TaskQueue, and does not include the size of the overflow stack.  This
+// simplifies replacement of GenericTaskQueues with OverflowTaskQueues.
+template<class E, MEMFLAGS F, unsigned int N = TASKQUEUE_SIZE>
+class OverflowTaskQueue: public GenericTaskQueue<E, F, N>
+{
+public:
+  typedef Stack<E, F>               overflow_t;
+  typedef GenericTaskQueue<E, F, N> taskqueue_t;
+
+  TASKQUEUE_STATS_ONLY(using taskqueue_t::stats;)
+
+  // Push task t onto the queue or onto the overflow stack.  Return true.
+  inline bool push(E t);
+  // Try to push task t onto the queue only. Returns true if successful, false otherwise.
+  inline bool try_push_to_taskqueue(E t);
+
+  // Attempt to pop from the overflow stack; return true if anything was popped.
+  inline bool pop_overflow(E& t);
+
+  inline overflow_t* overflow_stack() { return &_overflow_stack; }
+
+  inline bool taskqueue_empty() const { return taskqueue_t::is_empty(); }
+  inline bool overflow_empty()  const { return _overflow_stack.is_empty(); }
+  inline bool is_empty()        const {
+    return taskqueue_empty() && overflow_empty();
+  }
+
+private:
+  overflow_t _overflow_stack;
+};
+
+class TaskQueueSetSuper {
+protected:
+  static int randomParkAndMiller(int* seed0);
+public:
+  // Returns "true" if some TaskQueue in the set contains a task.
+  virtual bool peek() = 0;
+};
+
+template <MEMFLAGS F> class TaskQueueSetSuperImpl: public CHeapObj<F>, public TaskQueueSetSuper {
+};
+
+template<class T, MEMFLAGS F>
+class GenericTaskQueueSet: public TaskQueueSetSuperImpl<F> {
+private:
+  uint _n;
+  T** _queues;
+
+public:
+  typedef typename T::element_type E;
+
+  GenericTaskQueueSet(int n);
+
+  bool steal_best_of_2(uint queue_num, int* seed, E& t);
+
+  void register_queue(uint i, T* q);
+
+  T* queue(uint n);
+
+  // The thread with queue number "queue_num" (and whose random number seed is
+  // at "seed") is trying to steal a task from some other queue.  (It may try
+  // several queues, according to some configuration parameter.)  If some steal
+  // succeeds, returns "true" and sets "t" to the stolen task, otherwise returns
+  // false.
+  bool steal(uint queue_num, int* seed, E& t);
+
+  bool peek();
+
+  uint size() const { return _n; }
+};
+
+template<class T, MEMFLAGS F> void
+GenericTaskQueueSet<T, F>::register_queue(uint i, T* q) {
+  assert(i < _n, "index out of range.");
+  _queues[i] = q;
+}
+
+template<class T, MEMFLAGS F> T*
+GenericTaskQueueSet<T, F>::queue(uint i) {
+  return _queues[i];
+}
+
+template<class T, MEMFLAGS F>
+bool GenericTaskQueueSet<T, F>::peek() {
+  // Try all the queues.
+  for (uint j = 0; j < _n; j++) {
+    if (_queues[j]->peek())
+      return true;
+  }
+  return false;
+}
+
+// When to terminate from the termination protocol.
+class TerminatorTerminator: public CHeapObj<mtInternal> {
+public:
+  virtual bool should_exit_termination() = 0;
+};
+
+// A class to aid in the termination of a set of parallel tasks using
+// TaskQueueSet's for work stealing.
+
+#undef TRACESPINNING
+
+class ParallelTaskTerminator: public StackObj {
+private:
+  uint _n_threads;
+  TaskQueueSetSuper* _queue_set;
+  uint _offered_termination;
+
+#ifdef TRACESPINNING
+  static uint _total_yields;
+  static uint _total_spins;
+  static uint _total_peeks;
+#endif
+
+  bool peek_in_queue_set();
+protected:
+  virtual void yield();
+  void sleep(uint millis);
+
+public:
+
+  // "n_threads" is the number of threads to be terminated.  "queue_set" is a
+  // queue sets of work queues of other threads.
+  ParallelTaskTerminator(uint n_threads, TaskQueueSetSuper* queue_set);
+
+  // The current thread has no work, and is ready to terminate if everyone
+  // else is.  If returns "true", all threads are terminated.  If returns
+  // "false", available work has been observed in one of the task queues,
+  // so the global task is not complete.
+  bool offer_termination() {
+    return offer_termination(NULL);
+  }
+
+  // As above, but it also terminates if the should_exit_termination()
+  // method of the terminator parameter returns true. If terminator is
+  // NULL, then it is ignored.
+  bool offer_termination(TerminatorTerminator* terminator);
+
+  // Reset the terminator, so that it may be reused again.
+  // The caller is responsible for ensuring that this is done
+  // in an MT-safe manner, once the previous round of use of
+  // the terminator is finished.
+  void reset_for_reuse();
+  // Same as above but the number of parallel threads is set to the
+  // given number.
+  void reset_for_reuse(uint n_threads);
+
+#ifdef TRACESPINNING
+  static uint total_yields() { return _total_yields; }
+  static uint total_spins() { return _total_spins; }
+  static uint total_peeks() { return _total_peeks; }
+  static void print_termination_counts();
+#endif
+};
+
+typedef GenericTaskQueue<oop, mtGC>             OopTaskQueue;
+typedef GenericTaskQueueSet<OopTaskQueue, mtGC> OopTaskQueueSet;
+
+#ifdef _MSC_VER
+#pragma warning(push)
+// warning C4522: multiple assignment operators specified
+#pragma warning(disable:4522)
+#endif
+
+// This is a container class for either an oop* or a narrowOop*.
+// Both are pushed onto a task queue and the consumer will test is_narrow()
+// to determine which should be processed.
+class StarTask {
+  void*  _holder;        // either union oop* or narrowOop*
+
+  enum { COMPRESSED_OOP_MASK = 1 };
+
+ public:
+  StarTask(narrowOop* p) {
+    assert(((uintptr_t)p & COMPRESSED_OOP_MASK) == 0, "Information loss!");
+    _holder = (void *)((uintptr_t)p | COMPRESSED_OOP_MASK);
+  }
+  StarTask(oop* p)       {
+    assert(((uintptr_t)p & COMPRESSED_OOP_MASK) == 0, "Information loss!");
+    _holder = (void*)p;
+  }
+  StarTask()             { _holder = NULL; }
+  operator oop*()        { return (oop*)_holder; }
+  operator narrowOop*()  {
+    return (narrowOop*)((uintptr_t)_holder & ~COMPRESSED_OOP_MASK);
+  }
+
+  StarTask& operator=(const StarTask& t) {
+    _holder = t._holder;
+    return *this;
+  }
+  volatile StarTask& operator=(const volatile StarTask& t) volatile {
+    _holder = t._holder;
+    return *this;
+  }
+
+  bool is_narrow() const {
+    return (((uintptr_t)_holder & COMPRESSED_OOP_MASK) != 0);
+  }
+};
+
+class ObjArrayTask
+{
+public:
+  ObjArrayTask(oop o = NULL, int idx = 0): _obj(o), _index(idx) { }
+  ObjArrayTask(oop o, size_t idx): _obj(o), _index(int(idx)) {
+    assert(idx <= size_t(max_jint), "too big");
+  }
+  ObjArrayTask(const ObjArrayTask& t): _obj(t._obj), _index(t._index) { }
+
+  ObjArrayTask& operator =(const ObjArrayTask& t) {
+    _obj = t._obj;
+    _index = t._index;
+    return *this;
+  }
+  volatile ObjArrayTask&
+  operator =(const volatile ObjArrayTask& t) volatile {
+    (void)const_cast<oop&>(_obj = t._obj);
+    _index = t._index;
+    return *this;
+  }
+
+  inline oop obj()   const { return _obj; }
+  inline int index() const { return _index; }
+
+  DEBUG_ONLY(bool is_valid() const); // Tasks to be pushed/popped must be valid.
+
+private:
+  oop _obj;
+  int _index;
+};
+
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
+typedef OverflowTaskQueue<StarTask, mtGC>           OopStarTaskQueue;
+typedef GenericTaskQueueSet<OopStarTaskQueue, mtGC> OopStarTaskQueueSet;
+
+typedef OverflowTaskQueue<size_t, mtGC>             RegionTaskQueue;
+typedef GenericTaskQueueSet<RegionTaskQueue, mtGC>  RegionTaskQueueSet;
+
+#endif // SHARE_VM_GC_SHARED_TASKQUEUE_HPP