time-bound memory-pool

O(1) realloc() for use with Lua.
A standard malloc/free/realloc API is exposed for testing and other
potential use-cases.

The current configuration it's performs well for lua-metatables
(regular calls to realloc() with varying tiny chunks ~1-50 bytes)
For the use-case at hand it outperforms TLSF.

1 files changed, 115 insertions, 0 deletions

diff --git a/libs/pbd/pbd/reallocpool.h b/libs/pbd/pbd/reallocpool.h
new file mode 100644
index 0000000000..e79cf9df9e
--- /dev/null
+++ b/libs/pbd/pbd/reallocpool.h
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2016 Robin Gareus <robin@gareus.org>
+ *
+ * This program 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.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ */
+#ifndef _reallocpool_h_
+#define _reallocpool_h_
+
+
+#define RAP_WITH_CALL_STATS // collect statistics on calls counts (light)
+//#define RAP_WITH_HISTOGRAM 513 // collect statistic about allocation size (not bad)
+//#define RAP_WITH_SEGMENT_STATS // collect statistics (expensive)
+
+#ifndef RAP_BLOCKSIZE
+#define RAP_BLOCKSIZE 7 // [bytes] power-of-two minus one (optional)
+#endif
+
+#ifdef RAP_WITH_SEGMENT_STATS
+#define RAP_WITH_CALL_STATS
+#endif
+
+#include <string>
+
+#ifndef LIBPBD_API
+#include "pbd/libpbd_visibility.h"
+#endif
+
+namespace PBD {
+
+class LIBPBD_API ReallocPool
+{
+public:
+	ReallocPool (std::string name, size_t bytes);
+	~ReallocPool ();
+
+	void set_name (const std::string& n) { _name = n; }
+
+	static void * lalloc (void* pool, void *ptr, size_t oldsize, size_t newsize) {
+		return static_cast<ReallocPool*>(pool)->_realloc (ptr, oldsize, newsize);
+	}
+
+	void * malloc (size_t size) {
+		return _realloc (NULL, 0, size);
+	}
+
+	void free (void *ptr) {
+		if (ptr) _realloc (ptr, 0, 0);
+	}
+
+	void * realloc (void *ptr, size_t newsize) {
+		return _realloc (ptr, _asize(ptr), newsize);
+	}
+
+	void printstats ();
+	void dumpsegments ();
+
+private:
+	std::string _name;
+	size_t _poolsize;
+	char *_pool;
+	char *_mru;
+
+#ifdef RAP_WITH_SEGMENT_STATS
+	size_t _cur_avail;
+	size_t _cur_allocated;
+	size_t _max_allocated;
+	size_t _seg_cur_count;
+	size_t _seg_max_count;
+	size_t _seg_max_used;
+	size_t _seg_max_avail;
+	void collect_segment_stats ();
+#endif
+#ifdef RAP_WITH_CALL_STATS
+	size_t _n_alloc;
+	size_t _n_grow;
+	size_t _n_shrink;
+	size_t _n_free;
+	size_t _n_noop;
+	size_t _n_oom;
+	size_t _cur_used; // cheaper _cur_allocated
+	size_t _max_used; // cheaper _max_allocated
+#endif
+#ifdef RAP_WITH_HISTOGRAM
+	size_t _hist_alloc [RAP_WITH_HISTOGRAM];
+	size_t _hist_free [RAP_WITH_HISTOGRAM];
+	size_t _hist_grow [RAP_WITH_HISTOGRAM];
+	size_t _hist_shrink [RAP_WITH_HISTOGRAM];
+
+	unsigned int hist_bin (size_t s) const;
+	void print_histogram (size_t const * const histogram) const;
+#endif
+
+	void *_realloc (void *ptr, size_t oldsize, size_t newsize);
+	void *_malloc (size_t);
+	void _free (void *ptr);
+	void _shrink (void *, size_t);
+	size_t _asize (void *);
+	void consolidate_ptr (char *);
+};
+
+} /* namespace */
+#endif // _reallocpool_h_