3 files changed, 81 insertions, 2 deletions

diff --git a/src/vppinfra/bihash_template.c b/src/vppinfra/bihash_template.c
index 41d7c7ce1d6..18d74d9ea2f 100644
--- a/src/vppinfra/bihash_template.c
+++ b/src/vppinfra/bihash_template.c
@@ -269,8 +269,9 @@ BV (split_and_rehash_linear)
   return new_values;
 }
 
-int BV (clib_bihash_add_del)
-  (BVT (clib_bihash) * h, BVT (clib_bihash_kv) * add_v, int is_add)
+static inline int BV (clib_bihash_add_del_inline)
+  (BVT (clib_bihash) * h, BVT (clib_bihash_kv) * add_v, int is_add,
+   int (*is_stale_cb) (BVT (clib_bihash_kv) *, void *), void *arg)
 {
   u32 bucket_index;
   BVT (clib_bihash_bucket) * b, tmp_b;
@@ -366,6 +367,20 @@ int BV (clib_bihash_add_del)
 	      return (0);
 	    }
 	}
+      /* look for stale data to overwrite */
+      if (is_stale_cb)
+	{
+	  for (i = 0; i < limit; i++)
+	    {
+	      if (is_stale_cb (&(v->kvp[i]), arg))
+		{
+		  CLIB_MEMORY_BARRIER ();
+		  clib_memcpy (&(v->kvp[i]), add_v, sizeof (*add_v));
+		  BV (clib_bihash_unlock_bucket) (b);
+		  return (0);
+		}
+	    }
+	}
       /* Out of space in this bucket, split the bucket... */
     }
   else				/* delete case */
@@ -484,6 +499,19 @@ expand_ok:
   return (0);
 }
 
+int BV (clib_bihash_add_del)
+  (BVT (clib_bihash) * h, BVT (clib_bihash_kv) * add_v, int is_add)
+{
+  return BV (clib_bihash_add_del_inline) (h, add_v, is_add, 0, 0);
+}
+
+int BV (clib_bihash_add_or_overwrite_stale)
+  (BVT (clib_bihash) * h, BVT (clib_bihash_kv) * add_v,
+   int (*stale_callback) (BVT (clib_bihash_kv) *, void *), void *arg)
+{
+  return BV (clib_bihash_add_del_inline) (h, add_v, 1, stale_callback, arg);
+}
+
 int BV (clib_bihash_search)
   (BVT (clib_bihash) * h,
    BVT (clib_bihash_kv) * search_key, BVT (clib_bihash_kv) * valuep)
diff --git a/src/vppinfra/bihash_template.h b/src/vppinfra/bihash_template.h
index 9bf4737cd84..cfb8ceac69e 100644
--- a/src/vppinfra/bihash_template.h
+++ b/src/vppinfra/bihash_template.h
@@ -176,6 +176,12 @@ void BV (clib_bihash_free) (BVT (clib_bihash) * h);
 
 int BV (clib_bihash_add_del) (BVT (clib_bihash) * h,
 			      BVT (clib_bihash_kv) * add_v, int is_add);
+int BV (clib_bihash_add_or_overwrite_stale) (BVT (clib_bihash) * h,
+					     BVT (clib_bihash_kv) * add_v,
+					     int (*is_stale_cb) (BVT
+								 (clib_bihash_kv)
+								 *, void *),
+					     void *arg);
 int BV (clib_bihash_search) (BVT (clib_bihash) * h,
 			     BVT (clib_bihash_kv) * search_v,
 			     BVT (clib_bihash_kv) * return_v);
diff --git a/src/vppinfra/test_bihash_template.c b/src/vppinfra/test_bihash_template.c
index 80e11511f62..e52f2740b3b 100644
--- a/src/vppinfra/test_bihash_template.c
+++ b/src/vppinfra/test_bihash_template.c
@@ -35,6 +35,7 @@ typedef struct
   u32 ncycles;
   u32 report_every_n;
   u32 search_iter;
+  u32 noverwritten;
   int careful_delete_tests;
   int verbose;
   int non_random_keys;
@@ -95,6 +96,44 @@ test_bihash_vec64 (test_main_t * tm)
   return 0;
 }
 
+static int
+stale_cb (BVT (clib_bihash_kv) * kv, void *ctx)
+{
+  test_main_t *tm = ctx;
+
+  tm->noverwritten++;
+
+  return 1;
+}
+
+static clib_error_t *
+test_bihash_stale_overwrite (test_main_t * tm)
+{
+  BVT (clib_bihash) * h;
+  BVT (clib_bihash_kv) kv;
+  int i;
+  tm->noverwritten = 0;
+
+  h = &tm->hash;
+
+  BV (clib_bihash_init) (h, "test", tm->nbuckets, tm->hash_memory_size);
+
+  fformat (stdout, "Add %d items to %d buckets\n", tm->nitems, tm->nbuckets);
+
+  for (i = 0; i < tm->nitems; i++)
+    {
+      kv.key = i;
+      kv.value = 1;
+
+      BV (clib_bihash_add_or_overwrite_stale) (h, &kv, stale_cb, tm);
+    }
+
+  fformat (stdout, "%d items overwritten\n", tm->noverwritten);
+  fformat (stdout, "%U", BV (format_bihash), h, 0);
+
+  return 0;
+}
+
 void *
 test_bihash_thread_fn (void *arg)
 {
@@ -424,6 +463,8 @@ test_bihash_main (test_main_t * tm)
 	which = 2;
       else if (unformat (i, "verbose"))
 	tm->verbose = 1;
+      else if (unformat (i, "stale-overwrite"))
+	which = 3;
       else
 	return clib_error_return (0, "unknown input '%U'",
 				  format_unformat_error, i);
@@ -449,6 +490,10 @@ test_bihash_main (test_main_t * tm)
       error = test_bihash_threads (tm);
       break;
 
+    case 3:
+      error = test_bihash_stale_overwrite (tm);
+      break;
+
     default:
       return clib_error_return (0, "no such test?");
     }