Add SerdNodes class for storing a cache of nodes

1 files changed, 137 insertions, 0 deletions

diff --git a/src/nodes.c b/src/nodes.c
new file mode 100644
index 00000000..7a200c9f
--- /dev/null
+++ b/src/nodes.c
@@ -0,0 +1,137 @@
+/*
+  Copyright 2011-2018 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "node.h"
+
+#include "zix/common.h"
+#include "zix/digest.h"
+#include "zix/hash.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct {
+	size_t    refs;
+	SerdNode* node;
+} NodesEntry;
+
+typedef struct {
+	size_t          refs;
+	const SerdNode* node;
+} NodesSearchKey;
+
+struct SerdNodesImpl {
+	ZixHash* hash;
+};
+
+static uint32_t
+nodes_hash(const void* n)
+{
+	const SerdNode* node = ((const NodesEntry*)n)->node;
+	uint32_t        hash = zix_digest_start();
+	hash = zix_digest_add(hash, node, serd_node_total_size(node));
+	return hash;
+}
+
+static bool
+nodes_equal(const void* a, const void* b)
+{
+	const SerdNode* a_node = ((const NodesEntry*)a)->node;
+	const SerdNode* b_node = ((const NodesEntry*)b)->node;
+	const size_t    a_size = serd_node_total_size(a_node);
+	const size_t    b_size = serd_node_total_size(b_node);
+	return ((a_node == b_node) ||
+	        (a_size == b_size && !memcmp(a_node, b_node, a_size)));
+}
+
+static void
+free_entry(void* value, void* user_data)
+{
+	NodesEntry* entry = (NodesEntry*)value;
+	serd_node_free(entry->node);
+}
+
+SerdNodes*
+serd_nodes_new(void)
+{
+	SerdNodes* nodes = (SerdNodes*)calloc(1, sizeof(SerdNodes));
+	nodes->hash = zix_hash_new(nodes_hash, nodes_equal, sizeof(NodesEntry));
+	return nodes;
+}
+
+void
+serd_nodes_free(SerdNodes* nodes)
+{
+	zix_hash_foreach(nodes->hash, free_entry, nodes);
+	zix_hash_free(nodes->hash);
+	free(nodes);
+}
+
+const SerdNode*
+serd_nodes_intern(SerdNodes* nodes, const SerdNode* node)
+{
+	if (!node) {
+		return NULL;
+	}
+
+	NodesSearchKey key      = { 1, node };
+	NodesEntry*    inserted = NULL;
+	switch (zix_hash_insert(nodes->hash, &key, (const void**)&inserted)) {
+	case ZIX_STATUS_EXISTS:
+		assert(serd_node_equals(inserted->node, node));
+		++inserted->refs;
+		break;
+	case ZIX_STATUS_SUCCESS:
+		inserted->node = serd_node_copy(node);
+	default: break;
+	}
+
+	return inserted ? inserted->node : NULL;
+}
+
+const SerdNode*
+serd_nodes_manage(SerdNodes* nodes, SerdNode* node)
+{
+	if (!node) {
+		return NULL;
+	}
+
+	NodesSearchKey key      = { 1, node };
+	NodesEntry*    inserted = NULL;
+	switch (zix_hash_insert(nodes->hash, &key, (const void**)&inserted)) {
+	case ZIX_STATUS_EXISTS:
+		assert(serd_node_equals(inserted->node, node));
+		serd_node_free(node);
+		++inserted->refs;
+		break;
+	default: break;
+	}
+
+	return inserted ? inserted->node : NULL;
+}
+
+void
+serd_nodes_deref(SerdNodes* nodes, const SerdNode* node)
+{
+	NodesSearchKey key   = { 1, node };
+	NodesEntry*    entry = (NodesEntry*)zix_hash_find(nodes->hash, &key);
+	if (entry && --entry->refs == 0) {
+		SerdNode* const intern_node = entry->node;
+		zix_hash_remove(nodes->hash, entry);
+		serd_node_free(intern_node);
+	}
+}