tag/Tag*: rename several source files

src/tag/Pool.cxx

@@ -0,0 +1,171 @@
+/*
+ * Copyright 2003-2017 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "Pool.hxx"
+#include "Item.hxx"
+#include "util/Cast.hxx"
+#include "util/VarSize.hxx"
+#include "util/StringView.hxx"
+
+#include <limits>
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+
+Mutex tag_pool_lock;
+
+static constexpr size_t NUM_SLOTS = 4093;
+
+struct TagPoolSlot {
+	TagPoolSlot *next;
+	unsigned char ref;
+	TagItem item;
+
+	static constexpr unsigned MAX_REF = std::numeric_limits<decltype(ref)>::max();
+
+	TagPoolSlot(TagPoolSlot *_next, TagType type,
+		    StringView value)
+		:next(_next), ref(1) {
+		item.type = type;
+		memcpy(item.value, value.data, value.size);
+		item.value[value.size] = 0;
+	}
+
+	static TagPoolSlot *Create(TagPoolSlot *_next, TagType type,
+				   StringView value);
+};
+
+TagPoolSlot *
+TagPoolSlot::Create(TagPoolSlot *_next, TagType type,
+		    StringView value)
+{
+	TagPoolSlot *dummy;
+	return NewVarSize<TagPoolSlot>(sizeof(dummy->item.value),
+				       value.size + 1,
+				       _next, type,
+				       value);
+}
+
+static TagPoolSlot *slots[NUM_SLOTS];
+
+static inline unsigned
+calc_hash(TagType type, StringView p)
+{
+	unsigned hash = 5381;
+
+	for (auto ch : p)
+		hash = (hash << 5) + hash + ch;
+
+	return hash ^ type;
+}
+
+static inline unsigned
+calc_hash(TagType type, const char *p)
+{
+	unsigned hash = 5381;
+
+	assert(p != nullptr);
+
+	while (*p != 0)
+		hash = (hash << 5) + hash + *p++;
+
+	return hash ^ type;
+}
+
+#if CLANG_OR_GCC_VERSION(4,7)
+	constexpr
+#endif
+static inline TagPoolSlot *
+tag_item_to_slot(TagItem *item)
+{
+	return &ContainerCast(*item, &TagPoolSlot::item);
+}
+
+static inline TagPoolSlot **
+tag_value_slot_p(TagType type, StringView value)
+{
+	return &slots[calc_hash(type, value) % NUM_SLOTS];
+}
+
+static inline TagPoolSlot **
+tag_value_slot_p(TagType type, const char *value)
+{
+	return &slots[calc_hash(type, value) % NUM_SLOTS];
+}
+
+TagItem *
+tag_pool_get_item(TagType type, StringView value)
+{
+	auto slot_p = tag_value_slot_p(type, value);
+	for (auto slot = *slot_p; slot != nullptr; slot = slot->next) {
+		if (slot->item.type == type &&
+		    value.Equals(slot->item.value) &&
+		    slot->ref < TagPoolSlot::MAX_REF) {
+			assert(slot->ref > 0);
+			++slot->ref;
+			return &slot->item;
+		}
+	}
+
+	auto slot = TagPoolSlot::Create(*slot_p, type, value);
+	*slot_p = slot;
+	return &slot->item;
+}
+
+TagItem *
+tag_pool_dup_item(TagItem *item)
+{
+	TagPoolSlot *slot = tag_item_to_slot(item);
+
+	assert(slot->ref > 0);
+
+	if (slot->ref < TagPoolSlot::MAX_REF) {
+		++slot->ref;
+		return item;
+	} else {
+		/* the reference counter overflows above MAX_REF;
+		   obtain a reference to a different TagPoolSlot which
+		   isn't yet "full" */
+		return tag_pool_get_item(item->type, item->value);
+	}
+}
+
+void
+tag_pool_put_item(TagItem *item)
+{
+	TagPoolSlot **slot_p, *slot;
+
+	slot = tag_item_to_slot(item);
+	assert(slot->ref > 0);
+	--slot->ref;
+
+	if (slot->ref > 0)
+		return;
+
+	for (slot_p = tag_value_slot_p(item->type, item->value);
+	     *slot_p != slot;
+	     slot_p = &(*slot_p)->next) {
+		assert(*slot_p != nullptr);
+	}
+
+	*slot_p = slot->next;
+	DeleteVarSize(slot);
+}