Added a simple allocator for fixed-size objects.

diff --git a/lib/Makefile b/lib/Makefile
index fe3d0ff02062d2521119b96b01c4214a073ec2c8..c204d6e664ea8cdcd22b7e4d15395b4ecf5da507 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -10,7 +10,7 @@ endif
 
 LIBUCW_MODS= \
        threads \
-       alloc alloc_str realloc bigalloc mempool mempool-str mempool-fmt \
+       alloc alloc_str realloc bigalloc mempool mempool-str mempool-fmt eltpool \
        mmap pagecache partmap hashfunc \
        lists slists simple-lists sorter bitsig \
        log log-file proctitle \
@@ -101,7 +101,7 @@ $(o)/lib/kmp-test: $(o)/lib/kmp-test.o $(LIBUCW) $(LIBCHARSET)
 $(o)/lib/ipaccess-test: $(o)/lib/ipaccess-test.o $(LIBUCW)
 
 TESTS+=$(addprefix $(o)/lib/,regex.test unicode-utf8.test hash-test.test mempool.test stkstring.test \
-    slists.test kmp-test.test bbuf.test getopt.test fastbuf.test)
+    slists.test kmp-test.test bbuf.test getopt.test fastbuf.test eltpool.test)
 
 $(o)/lib/regex.test: $(o)/lib/regex-t
 $(o)/lib/unicode-utf8.test: $(o)/lib/unicode-utf8-t
@@ -114,6 +114,7 @@ $(o)/lib/kmp-test.test: $(o)/lib/kmp-test
 $(o)/lib/bbuf.test: $(o)/lib/bbuf-t
 $(o)/lib/getopt.test: $(o)/lib/getopt-t
 $(o)/lib/fastbuf.test: $(o)/lib/fb-file-t $(o)/lib/fb-grow-t $(o)/lib/fb-pool-t
+$(o)/lib/eltpool.test: $(o)/lib/eltpool-t
 
 ifdef CONFIG_UCW_THREADS
 TESTS+=$(addprefix $(o)/lib/,asio.test)

diff --git a/lib/eltpool.c b/lib/eltpool.c
new file mode 100644 (file)
index 0000000..f82de84
--- /dev/null
+++ b/lib/eltpool.c
@@ -0,0 +1,100 @@
+/*
+ *     UCW Library -- Fast Allocator for Fixed-Size Elements
+ *
+ *     (c) 2007 Martin Mares <mj@ucw.cz>
+ *
+ *     This software may be freely distributed and used according to the terms
+ *     of the GNU Lesser General Public License.
+ */
+
+/*
+ *  This allocator is optimized for intensive allocation and freeing of small
+ *  blocks of identical sizes. System memory is allocated by multiples of the
+ *  page size and it is returned back only when the whole eltpool is deleted.
+ *
+ *  In the future, we can add returning of memory to the system and also cache
+ *  coloring like in the SLAB allocator used in the Linux kernel.
+ */
+
+#undef LOCAL_DEBUG
+
+#include "lib/lib.h"
+#include "lib/eltpool.h"
+
+struct eltpool *
+ep_new(uns elt_size, uns elts_per_chunk)
+{
+  struct eltpool *pool = xmalloc_zero(sizeof(*pool));
+  pool->elt_size = ALIGN_TO(MAX(elt_size, sizeof(struct eltpool_free)), CPU_STRUCT_ALIGN);
+  pool->chunk_size = CPU_PAGE_SIZE;
+  while (pool->elt_size * elts_per_chunk + sizeof(struct eltpool_chunk) > pool->chunk_size)
+    pool->chunk_size *= 2;
+  pool->elts_per_chunk = (pool->chunk_size - sizeof(struct eltpool_chunk)) / pool->elt_size;
+  DBG("ep_new(): got elt_size=%d, epc=%d; used chunk_size=%d, epc=%d", elt_size, elts_per_chunk, pool->chunk_size, pool->elts_per_chunk);
+  return pool;
+}
+
+void
+ep_delete(struct eltpool *pool)
+{
+  struct eltpool_chunk *ch;
+  while (ch = pool->first_chunk)
+    {
+      pool->first_chunk = ch->next;
+      page_free(ch, pool->chunk_size);
+    }
+  xfree(pool);
+}
+
+void *
+ep_alloc_slow(struct eltpool *pool)
+{
+  struct eltpool_chunk *ch = page_alloc(pool->chunk_size);
+  void *p = (void *)(ch+1);
+  for (uns i=1; i<pool->elts_per_chunk; i++)
+    {
+      struct eltpool_free *f = p;
+      f->next = pool->first_free;
+      pool->first_free = f;
+      p += pool->elt_size;
+    }
+  ch->next = pool->first_chunk;
+  pool->first_chunk = ch;
+  return p;
+}
+
+#ifdef TEST
+
+#include <stdio.h>
+#include "lib/clists.h"
+
+struct argh {
+  cnode n;
+  byte x[1];
+} PACKED;
+
+int main(void)
+{
+  struct eltpool *ep = ep_new(sizeof(struct argh), 64);
+  clist l;
+  clist_init(&l);
+  for (uns i=0; i<65536; i++)
+    {
+      struct argh *a = ep_alloc(ep);
+      if (i % 3)
+       clist_add_tail(&l, &a->n);
+      else
+       clist_add_head(&l, &a->n);
+      if (!(i % 5))
+       {
+         a = clist_head(&l);
+         clist_remove(&a->n);
+         ep_free(ep, a);
+       }
+    }
+  ep_delete(ep);
+  puts("OK");
+  return 0;
+}
+
+#endif

diff --git a/lib/eltpool.h b/lib/eltpool.h
new file mode 100644 (file)
index 0000000..a682405
--- /dev/null
+++ b/lib/eltpool.h
@@ -0,0 +1,62 @@
+/*
+ *     UCW Library -- Fast Allocator for Fixed-Size Elements
+ *
+ *     (c) 2007 Martin Mares <mj@ucw.cz>
+ *
+ *     This software may be freely distributed and used according to the terms
+ *     of the GNU Lesser General Public License.
+ */
+
+#ifndef _UCW_ELTPOOL_H
+#define _UCW_ELTPOOL_H
+
+struct eltpool {
+  struct eltpool_chunk *first_chunk;
+  struct eltpool_free *first_free;
+  uns elt_size;
+  uns chunk_size;
+  uns elts_per_chunk;
+};
+
+struct eltpool_chunk {
+  struct eltpool_chunk *next;
+  /* Chunk data continue here */
+};
+
+struct eltpool_free {
+  struct eltpool_free *next;
+};
+
+struct eltpool *ep_new(uns elt_size, uns elts_per_chunk);
+void ep_delete(struct eltpool *pool);
+void *ep_alloc_slow(struct eltpool *pool);
+
+static inline void *
+ep_alloc(struct eltpool *pool)
+{
+#ifdef CONFIG_FAKE_ELTPOOL
+  return xmalloc(pool->elt_size);
+#else
+  struct eltpool_free *elt;
+  if (elt = pool->first_free)
+    pool->first_free = elt->next;
+  else
+    elt = ep_alloc_slow(pool);
+  return elt;
+#endif
+}
+
+static inline void
+ep_free(struct eltpool *pool, void *p)
+{
+#ifdef CONFIG_FAKE_ELTPOOL
+  (void) pool;
+  xfree(p);
+#else
+  struct eltpool_free *elt = p;
+  elt->next = pool->first_free;
+  pool->first_free = elt;
+#endif
+}
+
+#endif

diff --git a/lib/eltpool.test b/lib/eltpool.test
new file mode 100644 (file)
index 0000000..85bed69
--- /dev/null
+++ b/lib/eltpool.test
@@ -0,0 +1,4 @@
+# Tests for eltpools
+
+Run:   ../obj/lib/eltpool-t
+Out:   OK