Add a multiple-size memory pool implementation.

* src/misc/mspool.hh: New file.
* src/misc/Makefile.am: Add it.

ChangeLog

+2011-04-09  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Add a multiple-size memory pool implementation.
+
+	* src/misc/mspool.hh: New file.
+	* src/misc/Makefile.am: Add it.
+
 2011-04-08  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	* src/misc/fixpool.hh: Typo in comment.

src/misc/Makefile.am

@@ -42,6 +42,7 @@ misc_HEADERS = \
   minato.hh \
   memusage.hh \
   modgray.hh \
+  mspool.hh \
   optionmap.hh \
   random.hh \
   timer.hh \

src/misc/mspool.hh

+// Copyright (C) 2011 Laboratoire de Recherche et Developpement de
+// l'Epita (LRDE)
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// Spot 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 for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Spot; see the file COPYING.  If not, write to the Free
+// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+
+#ifndef SPOT_MISC_MSPOOL_HH
+#  define SPOT_MISC_MSPOOL_HH
+
+#include <new>
+#include <cstddef>
+#include <cstdlib>
+#include <cassert>
+#include "misc/hash.hh"
+
+namespace spot
+{
+
+  /// A multiple-size memory pool implementation.
+  class multiple_size_pool
+  {
+    static const size_t alignment_ = 2 * sizeof(size_t) - 1;
+  public:
+    /// Create a pool.
+    multiple_size_pool()
+      : free_start_(0), free_end_(0), chunklist_(0)
+    {
+    }
+
+    /// Free any memory allocated by this pool.
+    ~multiple_size_pool()
+    {
+      while (chunklist_)
+	{
+	  chunk_* prev = chunklist_->prev;
+	  free(chunklist_);
+	  chunklist_ = prev;
+	}
+    }
+
+    size_t fixsize(size_t size) const
+    {
+      if (size < sizeof(block_))
+	size = sizeof(block_);
+
+      return (size + alignment_ - 1) & ~(alignment_ - 1);
+    }
+
+    /// Allocate \a size bytes of memory.
+    void*
+    allocate(size_t size)
+    {
+      size = fixsize(size);
+
+      block_*& f = freelist_[size];
+      // If we have free blocks available, return the first one.
+      if (f)
+	{
+	  block_* first = f;
+	  f = f->next;
+	  return first;
+	}
+
+      // Else, create a block out of the last chunk of allocated
+      // memory.
+
+      // If all the last chunk has been used, allocate one more.
+      if (free_start_ + size > free_end_)
+	{
+	  const size_t requested = (size > 128 ? size : 128) * 8192 - 64;
+	  chunk_* c = reinterpret_cast<chunk_*>(malloc(requested));
+	  if (!c)
+	    throw std::bad_alloc();
+	  c->prev = chunklist_;
+	  chunklist_ = c;
+
+	  free_start_ = c->data_ + size;
+	  free_end_ = c->data_ + requested;
+	}
+
+      void* res = free_start_;
+      free_start_ += size;
+      return res;
+    }
+
+    /// \brief Recycle \a size bytes of memory.
+    ///
+    /// Despite the name, the memory is not really deallocated in the
+    /// "delete" sense: it is still owned by the pool and will be
+    /// reused by allocate as soon as possible.  The memory is only
+    /// freed when the pool is destroyed.
+    ///
+    /// The size argument should be the same as the one passed to
+    /// allocate().
+    void
+    deallocate (const void* ptr, size_t size)
+    {
+      assert(ptr);
+      size = fixsize(size);
+      block_* b = reinterpret_cast<block_*>(const_cast<void*>(ptr));
+      block_*& f = freelist_[size];
+      b->next = f;
+      f = b;
+    }
+
+  private:
+    struct block_ { block_* next; };
+    Sgi::hash_map<size_t, block_*> freelist_;
+    char* free_start_;
+    char* free_end_;
+    // chunk = several agglomerated blocks
+    union chunk_ { chunk_* prev; char data_[1]; }* chunklist_;
+  };
+
+}
+
+#endif // SPOT_MISC_INTVPOOL_HH