1 files changed, 175 insertions, 0 deletions
diff --git a/lib/src/util/pool.c b/lib/src/util/pool.c
new file mode 100644
index 000000000..2c1e90b5e
--- /dev/null
+++ b/lib/src/util/pool.c
@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) 2021 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * \file pool.c
+ * \brief Implementation of fixed-size pool allocator.
+ *
+ * NOTE:
+ *  - Ideally, we should have a single realloc per resize, that would encompass
+ *  both the free indices vector and bitmap, by nesting data structures.
+ * Because of the added complexity, and by lack of evidence of the need for
+ * this, we currently rely on a simpler implementation.
+ */
+
+#include <assert.h>
+#include <stdlib.h> // calloc
+
+#include <hicn/util/pool.h>
+#include <hicn/util/log.h>
+
+#include <stdio.h> // XXX
+
+void
+_pool_init (void **pool_ptr, size_t elt_size, size_t init_size,
+	    size_t max_size)
+{
+  assert (pool_ptr);
+  assert (elt_size);
+
+  init_size = next_pow2 (init_size);
+
+  if (max_size && init_size > max_size)
+    goto ERR_MAX_SIZE;
+
+  /* The initial pool size is rounded to the next power of two */
+  size_t alloc_size = next_pow2 (init_size);
+
+  pool_hdr_t *ph = calloc (POOL_HDRLEN + alloc_size * elt_size, 1);
+  if (!ph)
+    goto ERR_MALLOC;
+
+  ph->elt_size = elt_size;
+  ph->alloc_size = alloc_size;
+  ph->max_size = max_size;
+
+  /* Free indices */
+  off_t *free_indices;
+  vector_init (free_indices, init_size, max_size);
+  for (unsigned i = 0; i < init_size; i++)
+    free_indices[i] = (init_size - 1) - i;
+  vector_len (free_indices) = init_size;
+  ph->free_indices = free_indices;
+
+  /* Free bitmap */
+  bitmap_t *fb = ph->free_bitmap;
+  bitmap_init (fb, init_size, max_size);
+  bitmap_set_to (fb, init_size);
+  ph->free_bitmap = fb;
+
+  *pool_ptr = (uint8_t *) ph + POOL_HDRLEN;
+
+  return;
+
+ERR_MALLOC:
+ERR_MAX_SIZE:
+  *pool_ptr = NULL;
+  return;
+}
+
+void
+_pool_free (void **pool_ptr)
+{
+  pool_hdr_t *ph = pool_hdr (*pool_ptr);
+  vector_free (ph->free_indices);
+  bitmap_free (ph->free_bitmap);
+
+  free (pool_hdr (*pool_ptr));
+  *pool_ptr = NULL;
+}
+
+bool
+_pool_validate_id (void **pool_ptr, off_t id)
+{
+  pool_hdr_t *ph = pool_hdr (*pool_ptr);
+  size_t pool_size = pool_get_alloc_size (*pool_ptr);
+  if (id >= pool_size || !bitmap_is_unset (ph->free_bitmap, id))
+    return false;
+
+  return true;
+}
+
+void
+_pool_resize (void **pool_ptr, size_t elt_size)
+{
+  pool_hdr_t *ph = pool_hdr (*pool_ptr);
+  size_t old_size = ph->alloc_size;
+  size_t new_size = old_size * 2;
+
+  WARN ("pool_resize to %lu", new_size);
+
+  if (ph->max_size && new_size > ph->max_size)
+    goto ERR_MAX_SIZE;
+
+  /* Double pool storage */
+  ph = realloc (ph, POOL_HDRLEN + new_size * elt_size);
+  if (!ph)
+    goto ERR_REALLOC;
+  ph->elt_size = elt_size;
+  ph->alloc_size = new_size;
+
+  /*
+   * After resize, the pool will have new free indices, ranging from
+   * old_size to (new_size - 1)
+   */
+  vector_ensure_pos (ph->free_indices, old_size);
+  for (unsigned i = 0; i < old_size; i++)
+    ph->free_indices[i] = new_size - 1 - i;
+  vector_len (ph->free_indices) = old_size;
+
+  /* We also need to update the bitmap */
+  bitmap_ensure_pos (&(ph->free_bitmap), new_size - 1);
+  bitmap_set_range (ph->free_bitmap, old_size, new_size - 1);
+
+  /* Reassign pool pointer */
+  *pool_ptr = (uint8_t *) ph + POOL_HDRLEN;
+
+  return;
+
+ERR_REALLOC:
+ERR_MAX_SIZE:
+  *pool_ptr = NULL;
+  return;
+}
+
+off_t
+_pool_get (void **pool_ptr, void **elt, size_t elt_size)
+{
+  pool_hdr_t *ph = pool_hdr (*pool_ptr);
+  uint64_t l = vector_len (ph->free_indices);
+  if (l == 0)
+    {
+      _pool_resize (pool_ptr, elt_size);
+      ph = pool_hdr (*pool_ptr);
+      l = vector_len (ph->free_indices);
+    }
+  off_t free_id = ph->free_indices[l - 1];
+  vector_len (ph->free_indices)--;
+  bitmap_unset (ph->free_bitmap, free_id);
+  *elt = *pool_ptr + free_id * elt_size;
+  return free_id;
+}
+
+void
+_pool_put (void **pool_ptr, void **elt, size_t elt_size)
+{
+  pool_hdr_t *ph = pool_hdr (*pool_ptr);
+  uint64_t l = vector_len (ph->free_indices);
+  vector_ensure_pos (ph->free_indices, l);
+  off_t freed_id = (*elt - *pool_ptr) / elt_size;
+  ph->free_indices[l] = freed_id;
+  vector_len (ph->free_indices)++;
+  bitmap_set (ph->free_bitmap, freed_id);
+}