Add SerdNodes for storing a cache of interned nodes

3 files changed, 209 insertions, 1 deletions

diff --git a/src/node.c b/src/node.c
index eafcec38..25c1a9df 100644
--- a/src/node.c
+++ b/src/node.c
@@ -117,7 +117,6 @@ serd_node_check_padding(const SerdNode* node)
 #endif
 }
 
-static SERD_PURE_FUNC
 size_t
 serd_node_total_size(const SerdNode* const node)
 {
diff --git a/src/node.h b/src/node.h
index bb03f949..eed7cb04 100644
--- a/src/node.h
+++ b/src/node.h
@@ -50,6 +50,10 @@ void
 serd_node_set(SerdNode* SERD_NULLABLE* SERD_NONNULL dst,
               const SerdNode* SERD_NULLABLE         src);
 
+SERD_PURE_FUNC
+size_t
+serd_node_total_size(const SerdNode* SERD_NULLABLE node);
+
 void
 serd_node_zero_pad(SerdNode* SERD_NONNULL node);
 
diff --git a/src/nodes.c b/src/nodes.c
new file mode 100644
index 00000000..e6476f81
--- /dev/null
+++ b/src/nodes.c
@@ -0,0 +1,205 @@
+/*
+  Copyright 2011-2020 David Robillard <d@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 "serd/serd.h"
+#include "zix/common.h"
+#include "zix/digest.h"
+#include "zix/hash.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.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;
+
+  return zix_digest_add(zix_digest_start(), node, serd_node_total_size(node));
+}
+
+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)
+{
+  (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)
+{
+  if (nodes) {
+    zix_hash_foreach(nodes->hash, free_entry, nodes);
+    zix_hash_free(nodes->hash);
+    free(nodes);
+  }
+}
+
+size_t
+serd_nodes_size(const SerdNodes* nodes)
+{
+  return zix_hash_size(nodes->hash);
+}
+
+const SerdNode*
+serd_nodes_intern(SerdNodes* nodes, const SerdNode* node)
+{
+  if (!node) {
+    return NULL;
+  }
+
+  NodesSearchKey key      = {1, node};
+  NodesEntry*    inserted = NULL;
+
+  const ZixStatus st = zix_hash_insert(nodes->hash, &key, (void**)&inserted);
+  if (st == ZIX_STATUS_SUCCESS) {
+    inserted->node = serd_node_copy(node);
+  } else if (st == ZIX_STATUS_EXISTS) {
+    assert(serd_node_equals(inserted->node, node));
+    ++inserted->refs;
+  }
+
+  return inserted ? inserted->node : NULL;
+}
+
+const SerdNode*
+serd_nodes_get(const SerdNodes* const nodes, const SerdNode* const node)
+{
+  if (!node) {
+    return NULL;
+  }
+
+  const NodesSearchKey key   = {1, node};
+  NodesEntry* const    entry = (NodesEntry*)zix_hash_find(nodes->hash, &key);
+
+  return entry ? entry->node : NULL;
+}
+
+const SerdNode*
+serd_nodes_manage(SerdNodes* nodes, SerdNode* node)
+{
+  if (!node) {
+    return NULL;
+  }
+
+  NodesSearchKey key      = {1, node};
+  NodesEntry*    inserted = NULL;
+
+  const ZixStatus st = zix_hash_insert(nodes->hash, &key, (void**)&inserted);
+  if (st == ZIX_STATUS_EXISTS) {
+    assert(serd_node_equals(inserted->node, node));
+    serd_node_free(node);
+    ++inserted->refs;
+  }
+
+  return inserted ? inserted->node : NULL;
+}
+
+/* TODO: Make these methods faster by being smarter internally and avoiding
+   unnecessary allocatio in cases where the node is already in the set. */
+
+const SerdNode*
+serd_nodes_string(SerdNodes* const nodes, const SerdStringView string)
+{
+  return serd_nodes_manage(nodes, serd_new_string(string));
+}
+
+const SerdNode*
+serd_nodes_plain_literal(SerdNodes* const     nodes,
+                         const SerdStringView string,
+                         const SerdStringView language)
+{
+  return serd_nodes_manage(nodes, serd_new_plain_literal(string, language));
+}
+
+const SerdNode*
+serd_nodes_typed_literal(SerdNodes* const     nodes,
+                         const SerdStringView string,
+                         const SerdStringView datatype_uri)
+{
+  return serd_nodes_manage(nodes, serd_new_typed_literal(string, datatype_uri));
+}
+
+const SerdNode*
+serd_nodes_uri(SerdNodes* const nodes, const SerdStringView string)
+{
+  return serd_nodes_manage(nodes, serd_new_uri(string));
+}
+
+const SerdNode*
+serd_nodes_curie(SerdNodes* const nodes, const SerdStringView string)
+{
+  return serd_nodes_manage(nodes, serd_new_curie(string));
+}
+
+const SerdNode*
+serd_nodes_blank(SerdNodes* const nodes, const SerdStringView string)
+{
+  return serd_nodes_manage(nodes, serd_new_blank(string));
+}
+
+void
+serd_nodes_deref(SerdNodes* const nodes, const SerdNode* const node)
+{
+  const NodesSearchKey key   = {1, node};
+  NodesEntry* const    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);
+  }
+}