Preparation for V5.

include/boost/regex/v5/mem_block_cache.hpp

@@ -0,0 +1,145 @@
+ /*
+ * Copyright (c) 2002
+ * John Maddock
+ *
+ * Use, modification and distribution are subject to the 
+ * Boost Software License, Version 1.0. (See accompanying file 
+ * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+ *
+ */
+
+ /*
+  *   LOCATION:    see http://www.boost.org for most recent version.
+  *   FILE         mem_block_cache.hpp
+  *   VERSION      see <boost/version.hpp>
+  *   DESCRIPTION: memory block cache used by the non-recursive matcher.
+  */
+
+#ifndef BOOST_REGEX_V4_MEM_BLOCK_CACHE_HPP
+#define BOOST_REGEX_V4_MEM_BLOCK_CACHE_HPP
+
+#include <new>
+#ifdef BOOST_HAS_THREADS
+#include <boost/regex/pending/static_mutex.hpp>
+#endif
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_PREFIX
+#endif
+
+#ifndef BOOST_NO_CXX11_HDR_ATOMIC
+  #include <atomic>
+  #if ATOMIC_POINTER_LOCK_FREE == 2
+    #define BOOST_REGEX_MEM_BLOCK_CACHE_LOCK_FREE
+    #define BOOST_REGEX_ATOMIC_POINTER std::atomic
+  #endif
+#endif
+
+namespace boost{
+namespace BOOST_REGEX_DETAIL_NS{
+
+#ifdef BOOST_REGEX_MEM_BLOCK_CACHE_LOCK_FREE /* lock free implementation */
+struct mem_block_cache
+{
+  std::atomic<void*> cache[BOOST_REGEX_MAX_CACHE_BLOCKS];
+
+   ~mem_block_cache()
+   {
+     for (size_t i = 0;i < BOOST_REGEX_MAX_CACHE_BLOCKS; ++i) {
+       if (cache[i].load()) ::operator delete(cache[i].load());
+     }
+   }
+   void* get()
+   {
+     for (size_t i = 0;i < BOOST_REGEX_MAX_CACHE_BLOCKS; ++i) {
+       void* p = cache[i].load();
+       if (p != NULL) {
+         if (cache[i].compare_exchange_strong(p, NULL)) return p;
+       }
+     }
+     return ::operator new(BOOST_REGEX_BLOCKSIZE);
+   }
+   void put(void* ptr)
+   {
+     for (size_t i = 0;i < BOOST_REGEX_MAX_CACHE_BLOCKS; ++i) {
+       void* p = cache[i].load();
+       if (p == NULL) {
+         if (cache[i].compare_exchange_strong(p, ptr)) return;
+       }
+     }
+     ::operator delete(ptr);
+   }
+};
+
+
+#else /* lock-based implementation */
+
+
+struct mem_block_node
+{
+   mem_block_node* next;
+};
+
+struct mem_block_cache
+{
+   // this member has to be statically initialsed:
+   mem_block_node* next;
+   unsigned cached_blocks;
+#ifdef BOOST_HAS_THREADS
+   boost::static_mutex mut;
+#endif
+
+   ~mem_block_cache()
+   {
+      while(next)
+      {
+         mem_block_node* old = next;
+         next = next->next;
+         ::operator delete(old);
+      }
+   }
+   void* get()
+   {
+#ifdef BOOST_HAS_THREADS
+      boost::static_mutex::scoped_lock g(mut);
+#endif
+     if(next)
+      {
+         mem_block_node* result = next;
+         next = next->next;
+         --cached_blocks;
+         return result;
+      }
+      return ::operator new(BOOST_REGEX_BLOCKSIZE);
+   }
+   void put(void* p)
+   {
+#ifdef BOOST_HAS_THREADS
+      boost::static_mutex::scoped_lock g(mut);
+#endif
+      if(cached_blocks >= BOOST_REGEX_MAX_CACHE_BLOCKS)
+      {
+         ::operator delete(p);
+      }
+      else
+      {
+         mem_block_node* old = static_cast<mem_block_node*>(p);
+         old->next = next;
+         next = old;
+         ++cached_blocks;
+      }
+   }
+};
+#endif
+
+extern mem_block_cache block_cache;
+
+}
+} // namespace boost
+
+#ifdef BOOST_HAS_ABI_HEADERS
+#  include BOOST_ABI_SUFFIX
+#endif
+
+#endif
+