[hurd] 10/75: libihash: prefer performance degradation over failure

[Samuel Thibault]

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sthibault pushed a commit to branch dde
in repository hurd.

commit 226a9d9c34a2d187f978a25874488e5b07986d7c
Author: Justus Winter <address@hidden>
Date:   Sun Jun 7 00:58:36 2015 +0200

    libihash: prefer performance degradation over failure
    
    * libihash/ihash.c (hurd_ihash_add): Add the item even though we are
    above the load factor if resizing failed.
---
 libihash/ihash.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/libihash/ihash.c b/libihash/ihash.c
index a97de3e..87d7abf 100644
--- a/libihash/ihash.c
+++ b/libihash/ihash.c
@@ -301,12 +301,14 @@ hurd_ihash_add (hurd_ihash_t ht, hurd_ihash_key_t key, 
hurd_ihash_value_t item)
 {
   struct hurd_ihash old_ht = *ht;
   int was_added;
+  int fatal = 0;       /* bail out on allocation errors */
   unsigned int i;
 
   if (ht->size)
     {
       /* Only fill the hash table up to its maximum load factor.  */
       if (hurd_ihash_get_load (ht) <= ht->max_load)
+      add_one:
        if (add_one (ht, key, item))
          return 0;
     }
@@ -324,7 +326,15 @@ hurd_ihash_add (hurd_ihash_t ht, hurd_ihash_key_t key, 
hurd_ihash_value_t item)
   if (ht->items == NULL)
     {
       *ht = old_ht;
-      return ENOMEM;
+      if (fatal || ht->size == 0)
+        return ENOMEM;
+
+      /* We prefer performance degradation over failure.  Therefore,
+        we add the item even though we are above the load factor.  If
+        the table is full, this will fail.  We set the fatal flag to
+        avoid looping.  */
+      fatal = 1;
+      goto add_one;
     }
 
   /* We have to rehash the old entries.  */

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