- lru_demote and lruhash_insert_or_retrieve functions for getdns.

git-svn-id: file:///svn/unbound/trunk@4068 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/Changelog

@@ -2,6 +2,7 @@
 	- #1217. DNSCrypt support, with --enable-dnscrypt, libsodium and then
 	  enabled in the config file from Manu Bretelle.
 	- make depend, autoconf, remove warnings about statement before var.
+	- lru_demote and lruhash_insert_or_retrieve functions for getdns.
 
 17 March 2017: Wouter
 	- Patch for view functionality for local-data-ptr from Björn Ketelaars.

util/storage/lruhash.c

@@ -543,3 +543,89 @@ lruhash_traverse(struct lruhash* h, int wr,
 	}
 	lock_quick_unlock(&h->lock);
 }
+
+/*
+ * Demote: the opposite of touch, move an entry to the bottom
+ * of the LRU pile.
+ */
+
+void
+lru_demote(struct lruhash* table, struct lruhash_entry* entry)
+{
+	log_assert(table && entry);
+	if (entry == table->lru_end)
+		return; /* nothing to do */
+				/* remove from current lru position */
+	lru_remove(table, entry);
+	/* add at end */
+	entry->lru_next = NULL;
+	entry->lru_prev = table->lru_end;
+
+	if (table->lru_end == NULL)
+	{
+		table->lru_start = entry;
+	}
+	else
+	{
+		table->lru_end->lru_next = entry;
+	}
+	table->lru_end = entry;
+}
+
+struct lruhash_entry*
+lruhash_insert_or_retrieve(struct lruhash* table, hashvalue_type hash,
+	struct lruhash_entry* entry, void* data, void* cb_arg)
+{
+	struct lruhash_bin* bin;
+	struct lruhash_entry* found, *reclaimlist = NULL;
+	size_t need_size;
+	fptr_ok(fptr_whitelist_hash_sizefunc(table->sizefunc));
+	fptr_ok(fptr_whitelist_hash_delkeyfunc(table->delkeyfunc));
+	fptr_ok(fptr_whitelist_hash_deldatafunc(table->deldatafunc));
+	fptr_ok(fptr_whitelist_hash_compfunc(table->compfunc));
+	fptr_ok(fptr_whitelist_hash_markdelfunc(table->markdelfunc));
+	need_size = table->sizefunc(entry->key, data);
+	if (cb_arg == NULL) cb_arg = table->cb_arg;
+
+	/* find bin */
+	lock_quick_lock(&table->lock);
+	bin = &table->array[hash & table->size_mask];
+	lock_quick_lock(&bin->lock);
+
+	/* see if entry exists already */
+	if ((found = bin_find_entry(table, bin, hash, entry->key)) != NULL) {
+		/* if so: keep the existing data - acquire a writelock */
+		lock_rw_wrlock(&found->lock);
+	}
+	else
+	{
+		/* if not: add to bin */
+		entry->overflow_next = bin->overflow_list;
+		bin->overflow_list = entry;
+		lru_front(table, entry);
+		table->num++;
+		table->space_used += need_size;
+		/* return the entry that was presented, and lock it */
+		found = entry;
+		lock_rw_wrlock(&found->lock);
+	}
+	lock_quick_unlock(&bin->lock);
+	if (table->space_used > table->space_max)
+		reclaim_space(table, &reclaimlist);
+	if (table->num >= table->size)
+		table_grow(table);
+	lock_quick_unlock(&table->lock);
+
+	/* finish reclaim if any (outside of critical region) */
+	while (reclaimlist) {
+		struct lruhash_entry* n = reclaimlist->overflow_next;
+		void* d = reclaimlist->data;
+		(*table->delkeyfunc)(reclaimlist->key, cb_arg);
+		(*table->deldatafunc)(d, cb_arg);
+		reclaimlist = n;
+	}
+
+	/* return the entry that was selected */
+	return found;
+}
+

util/storage/lruhash.h

@@ -301,6 +301,38 @@ void lru_touch(struct lruhash* table, struct lruhash_entry* entry);
  */
 void lruhash_setmarkdel(struct lruhash* table, lruhash_markdelfunc_type md);
 
+/************************* getdns functions ************************/
+/*** these are used by getdns only and not by unbound. ***/
+
+/**
+ * Demote entry, so it becomes the least recently used in the LRU list.
+ * Caller must hold hash table lock. The entry must be inserted already.
+ * @param table: hash table.
+ * @param entry: entry to make last in LRU.
+ */
+void lru_demote(struct lruhash* table, struct lruhash_entry* entry);
+
+/**
+ * Insert a new element into the hashtable, or retrieve the corresponding
+ * element of it exits.
+ *
+ * If key is already present data pointer in that entry is kept.
+ * If it is not present, a new entry is created. In that case, 
+ * the space calculation function is called with the key, data.
+ * If necessary the least recently used entries are deleted to make space.
+ * If necessary the hash array is grown up.
+ *
+ * @param table: hash table.
+ * @param hash: hash value. User calculates the hash.
+ * @param entry: identifies the entry.
+ * @param data: the data.
+ * @param cb_override: if not null overrides the cb_arg for the deletefunc.
+ * @return: pointer to the existing entry if the key was already present,
+ *     or to the entry argument if it was not.
+ */
+struct lruhash_entry* lruhash_insert_or_retrieve(struct lruhash* table, hashvalue_type hash,
+        struct lruhash_entry* entry, void* data, void* cb_arg);
+
 /************************* Internal functions ************************/
 /*** these are only exposed for unit tests. ***/