// -*- C++ -*-
-// Copyright (C) 2007 Free Software Foundation, Inc.
+// Copyright (C) 2007, 2008 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the terms
* Calling them would not make sense in a concurrent setting.
* @param T Contained element type. */
template<typename T>
- class RestrictedBoundedConcurrentQueue
- {
- private:
- /** @brief Array of elements, seen as cyclic buffer. */
- T* base;
-
- /** @brief Maximal number of elements contained at the same time. */
- sequence_index_t max_size;
-
- /** @brief Cyclic begin and end pointers contained in one
- atomically changeable value. */
- _GLIBCXX_VOLATILE lcas_t borders;
-
- public:
- /** @brief Constructor. Not to be called concurrent, of course.
- * @param max_size Maximal number of elements to be contained. */
- RestrictedBoundedConcurrentQueue(sequence_index_t max_size)
+ class RestrictedBoundedConcurrentQueue
{
- this->max_size = max_size;
- base = new T[max_size];
- borders = encode2(0, 0);
+ private:
+ /** @brief Array of elements, seen as cyclic buffer. */
+ T* base;
+
+ /** @brief Maximal number of elements contained at the same time. */
+ sequence_index_t max_size;
+
+ /** @brief Cyclic begin and end pointers contained in one
+ atomically changeable value. */
+ _GLIBCXX_VOLATILE lcas_t borders;
+
+ public:
+ /** @brief Constructor. Not to be called concurrent, of course.
+ * @param max_size Maximal number of elements to be contained. */
+ RestrictedBoundedConcurrentQueue(sequence_index_t max_size)
+ {
+ this->max_size = max_size;
+ base = new T[max_size];
+ borders = encode2(0, 0);
#pragma omp flush
- }
-
- /** @brief Destructor. Not to be called concurrent, of course. */
- ~RestrictedBoundedConcurrentQueue()
- {
- delete[] base;
- }
-
- /** @brief Pushes one element into the queue at the front end.
- * Must not be called concurrently with pop_front(). */
- void push_front(const T& t)
- {
- lcas_t former_borders = borders;
- int former_front, former_back;
- decode2(former_borders, former_front, former_back);
- *(base + former_front % max_size) = t;
+ }
+
+ /** @brief Destructor. Not to be called concurrent, of course. */
+ ~RestrictedBoundedConcurrentQueue()
+ { delete[] base; }
+
+ /** @brief Pushes one element into the queue at the front end.
+ * Must not be called concurrently with pop_front(). */
+ void
+ push_front(const T& t)
+ {
+ lcas_t former_borders = borders;
+ int former_front, former_back;
+ decode2(former_borders, former_front, former_back);
+ *(base + former_front % max_size) = t;
#if _GLIBCXX_ASSERTIONS
- // Otherwise: front - back > max_size eventually.
- _GLIBCXX_PARALLEL_ASSERT(((former_front + 1) - former_back) <= max_size);
+ // Otherwise: front - back > max_size eventually.
+ _GLIBCXX_PARALLEL_ASSERT(((former_front + 1) - former_back)
+ <= max_size);
#endif
- fetch_and_add(&borders, encode2(1, 0));
- }
-
- /** @brief Pops one element from the queue at the front end.
- * Must not be called concurrently with pop_front(). */
- bool pop_front(T& t)
- {
- int former_front, former_back;
+ fetch_and_add(&borders, encode2(1, 0));
+ }
+
+ /** @brief Pops one element from the queue at the front end.
+ * Must not be called concurrently with pop_front(). */
+ bool
+ pop_front(T& t)
+ {
+ int former_front, former_back;
#pragma omp flush
- decode2(borders, former_front, former_back);
- while (former_front > former_back)
- {
- // Chance.
- lcas_t former_borders = encode2(former_front, former_back);
- lcas_t new_borders = encode2(former_front - 1, former_back);
- if (compare_and_swap(&borders, former_borders, new_borders))
- {
- t = *(base + (former_front - 1) % max_size);
- return true;
- }
+ decode2(borders, former_front, former_back);
+ while (former_front > former_back)
+ {
+ // Chance.
+ lcas_t former_borders = encode2(former_front, former_back);
+ lcas_t new_borders = encode2(former_front - 1, former_back);
+ if (compare_and_swap(&borders, former_borders, new_borders))
+ {
+ t = *(base + (former_front - 1) % max_size);
+ return true;
+ }
#pragma omp flush
- decode2(borders, former_front, former_back);
- }
- return false;
- }
-
- /** @brief Pops one element from the queue at the front end.
- * Must not be called concurrently with pop_front(). */
- bool pop_back(T& t) //queue behavior
- {
- int former_front, former_back;
+ decode2(borders, former_front, former_back);
+ }
+ return false;
+ }
+
+ /** @brief Pops one element from the queue at the front end.
+ * Must not be called concurrently with pop_front(). */
+ bool
+ pop_back(T& t) //queue behavior
+ {
+ int former_front, former_back;
#pragma omp flush
- decode2(borders, former_front, former_back);
- while (former_front > former_back)
- {
- // Chance.
- lcas_t former_borders = encode2(former_front, former_back);
- lcas_t new_borders = encode2(former_front, former_back + 1);
- if (compare_and_swap(&borders, former_borders, new_borders))
- {
- t = *(base + former_back % max_size);
- return true;
- }
+ decode2(borders, former_front, former_back);
+ while (former_front > former_back)
+ {
+ // Chance.
+ lcas_t former_borders = encode2(former_front, former_back);
+ lcas_t new_borders = encode2(former_front, former_back + 1);
+ if (compare_and_swap(&borders, former_borders, new_borders))
+ {
+ t = *(base + former_back % max_size);
+ return true;
+ }
#pragma omp flush
- decode2(borders, former_front, former_back);
- }
- return false;
- }
+ decode2(borders, former_front, former_back);
+ }
+ return false;
+ }
};
} //namespace __gnu_parallel
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