Moving NSCP Directory Server from DirectoryBranch to TRUNK, initial drop. (foxworth)ldapserver7x

1 files changed, 65 insertions, 0 deletions

diff --git a/lib/libaccess/access_plhash.cpp b/lib/libaccess/access_plhash.cpp
new file mode 100644
index 00000000..7666e95e
--- /dev/null
+++ b/lib/libaccess/access_plhash.cpp
@@ -0,0 +1,65 @@
+/** BEGIN COPYRIGHT BLOCK
+ * Copyright 2001 Sun Microsystems, Inc.
+ * Portions copyright 1999, 2001-2003 Netscape Communications Corporation.
+ * All rights reserved.
+ * END COPYRIGHT BLOCK **/
+
+/*
+  This file contains a function which augments the standard nspr PL_HashTable
+  api.  The problem is that the hash table lookup function in the standard NSPR
+  actually modifies the hash table being searched, which means that it cannot be
+  used with read locks in a multi threaded environment.  This function is a
+  lookup function which is guaranteed not to modify the hash table passed in,
+  so that it can be used with read locks.
+*/
+
+#include "plhash.h"
+
+/* prototypes */
+NSPR_BEGIN_EXTERN_C
+PR_IMPLEMENT(void *)
+ACL_HashTableLookup_const(PLHashTable *ht, const void *key);
+NSPR_END_EXTERN_C
+
+/*
+** Multiplicative hash, from Knuth 6.4.
+*/
+#define GOLDEN_RATIO    0x9E3779B9U
+
+PR_IMPLEMENT(PLHashEntry **)
+ACL_HashTableRawLookup_const(PLHashTable *ht, PLHashNumber keyHash, const void *key)
+{
+    PLHashEntry *he, **hep;
+    PLHashNumber h;
+
+#ifdef HASHMETER
+    ht->nlookups++;
+#endif
+    h = keyHash * GOLDEN_RATIO;
+    h >>= ht->shift;
+    hep = &ht->buckets[h];
+    while ((he = *hep) != 0) {
+        if (he->keyHash == keyHash && (*ht->keyCompare)(key, he->key)) {
+            return hep;
+        }
+        hep = &he->next;
+#ifdef HASHMETER
+        ht->nsteps++;
+#endif
+    }
+    return hep;
+}
+
+PR_IMPLEMENT(void *)
+ACL_HashTableLookup_const(PLHashTable *ht, const void *key)
+{
+    PLHashNumber keyHash;
+    PLHashEntry *he, **hep;
+
+    keyHash = (*ht->keyHash)(key);
+    hep = ACL_HashTableRawLookup_const(ht, keyHash, key);
+    if ((he = *hep) != 0) {
+        return he->value;
+    }
+    return 0;
+}