feat: implement initial MemoryCatalog functionality with namespace and table support

Author: gty404

src/iceberg/CMakeLists.txt

@@ -19,6 +19,7 @@ set(ICEBERG_INCLUDES "$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/src>"
                      "$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/src>")
 set(ICEBERG_SOURCES
     arrow_c_data_internal.cc
+    catalog/memory_catalog.cc
     demo.cc
     json_internal.cc
     schema.cc

src/iceberg/catalog/memory_catalog.cc

@@ -0,0 +1,246 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "iceberg/catalog/memory_catalog.h"
+
+#include "iceberg/exception.h"
+#include "iceberg/table.h"
+
+namespace iceberg {
+
+MemoryCatalog::MemoryCatalog(std::shared_ptr<FileIO> file_io,
+                             std::optional<std::string> warehouse_location)
+    : file_io_(std::move(file_io)),
+      warehouse_location_(std::move(warehouse_location)),
+      root_container_(std::make_unique<NamespaceContainer>()) {}
+
+void MemoryCatalog::Initialize(
+    const std::string& name,
+    const std::unordered_map<std::string, std::string>& properties) {
+  catalog_name_ = name;
+  properties_ = properties;
+}
+
+std::string_view MemoryCatalog::name() const { return catalog_name_; }
+
+Result<std::vector<TableIdentifier>> MemoryCatalog::ListTables(
+    const Namespace& ns) const {
+  std::unique_lock lock(mutex_);
+  const auto& table_names = root_container_->ListTables(ns);
+  std::vector<TableIdentifier> table_idents;
+  table_idents.reserve(table_names.size());
+  std::ranges::transform(
+      table_names, std::back_inserter(table_idents),
+      [&ns](auto const& table_name) { return TableIdentifier(ns, table_name); });
+  return table_idents;
+}
+
+Result<std::unique_ptr<Table>> MemoryCatalog::CreateTable(
+    const TableIdentifier& identifier, const Schema& schema, const PartitionSpec& spec,
+    const std::string& location,
+    const std::unordered_map<std::string, std::string>& properties) {
+  throw IcebergError("not implemented");
+}
+
+Result<std::unique_ptr<Table>> MemoryCatalog::UpdateTable(
+    const TableIdentifier& identifier,
+    const std::vector<std::unique_ptr<UpdateRequirement>>& requirements,
+    const std::vector<std::unique_ptr<MetadataUpdate>>& updates) {
+  throw IcebergError("not implemented");
+}
+
+Result<std::shared_ptr<Transaction>> MemoryCatalog::StageCreateTable(
+    const TableIdentifier& identifier, const Schema& schema, const PartitionSpec& spec,
+    const std::string& location,
+    const std::unordered_map<std::string, std::string>& properties) {
+  throw IcebergError("not implemented");
+}
+
+bool MemoryCatalog::TableExists(const TableIdentifier& identifier) const {
+  std::unique_lock lock(mutex_);
+  return root_container_->TableExists(identifier);
+}
+
+bool MemoryCatalog::DropTable(const TableIdentifier& identifier, bool purge) {
+  std::unique_lock lock(mutex_);
+  // TODO: Delete all metadata files if purge is true.
+  return root_container_->UnregisterTable(identifier);
+}
+
+Result<std::shared_ptr<Table>> MemoryCatalog::LoadTable(
+    const TableIdentifier& identifier) const {
+  throw IcebergError("not implemented");
+}
+
+Result<std::shared_ptr<Table>> MemoryCatalog::RegisterTable(
+    const TableIdentifier& identifier, const std::string& metadata_file_location) {
+  std::unique_lock lock(mutex_);
+  if (!root_container_->NamespaceExists(identifier.ns)) {
+    return unexpected<Error>({.kind = ErrorKind::kNoSuchNamespace,
+                              .message = "table namespace does not exist"});
+  }
+  if (!root_container_->RegisterTable(identifier, metadata_file_location)) {
+    return unexpected<Error>(
+        {.kind = ErrorKind::kUnknownError, .message = "The registry failed."});
+  }
+  return LoadTable(identifier);
+}
+
+std::unique_ptr<TableBuilder> MemoryCatalog::BuildTable(const TableIdentifier& identifier,
+                                                        const Schema& schema) const {
+  throw IcebergError("not implemented");
+}
+
+/// Implementation of NamespaceContainer
+NamespaceContainer* NamespaceContainer::GetNamespaceContainer(
+    NamespaceContainer* root, const Namespace& namespace_ident) {
+  return GetNamespaceContainerImpl(root, namespace_ident);
+}
+
+const NamespaceContainer* NamespaceContainer::GetNamespaceContainer(
+    const NamespaceContainer* root, const Namespace& namespace_ident) {
+  return GetNamespaceContainerImpl(root, namespace_ident);
+}
+
+bool NamespaceContainer::NamespaceExists(const Namespace& namespace_ident) const {
+  return GetNamespaceContainer(this, namespace_ident) != nullptr;
+}
+
+std::vector<std::string> NamespaceContainer::ListChildrenNamespaces(
+    const std::optional<Namespace>& parent_namespace_ident) const {
+  auto container = this;
+  if (parent_namespace_ident.has_value()) {
+    container = GetNamespaceContainer(this, *parent_namespace_ident);
+    if (!container) return {};
+  }
+
+  std::vector<std::string> names;
+  names.reserve(container->children_.size());
+  std::ranges::transform(container->children_, std::back_inserter(names),
+                         [](const auto& pair) { return pair.first; });
+  return names;
+}
+
+bool NamespaceContainer::CreateNamespace(
+    const Namespace& namespace_ident,
+    const std::unordered_map<std::string, std::string>& properties) {
+  auto container = this;
+  bool newly_created = false;
+
+  for (const auto& part_level : namespace_ident.levels) {
+    if (auto it = container->children_.find(part_level);
+        it == container->children_.end()) {
+      container->children_[part_level] = std::make_unique<NamespaceContainer>();
+      container = container->children_[part_level].get();
+      newly_created = true;
+    } else {
+      container = it->second.get();
+    }
+  }
+
+  if (!newly_created) return false;
+
+  container->properties_ = properties;
+  return true;
+}
+
+bool NamespaceContainer::DeleteNamespace(const Namespace& namespace_ident) {
+  if (namespace_ident.levels.empty()) return false;
+
+  auto parent_namespace_ident = namespace_ident;
+  const auto to_delete = parent_namespace_ident.levels.back();
+  parent_namespace_ident.levels.pop_back();
+
+  auto* parent = GetNamespaceContainer(this, parent_namespace_ident);
+  if (!parent) return false;
+
+  auto it = parent->children_.find(to_delete);
+  if (it == parent->children_.end()) return false;
+
+  const auto& target = *it->second;
+  if (!target.children_.empty() || !target.table_metadata_locations_.empty()) {
+    return false;
+  }
+
+  return parent->children_.erase(to_delete) > 0;
+}
+
+std::optional<std::unordered_map<std::string, std::string>>
+NamespaceContainer::GetProperties(const Namespace& namespace_ident) const {
+  const auto container = GetNamespaceContainer(this, namespace_ident);
+  if (!container) return std::nullopt;
+  return container->properties_;
+}
+
+bool NamespaceContainer::ReplaceProperties(
+    const Namespace& namespace_ident,
+    const std::unordered_map<std::string, std::string>& properties) {
+  const auto container = GetNamespaceContainer(this, namespace_ident);
+  if (!container) return false;
+  container->properties_ = properties;
+  return true;
+}
+
+std::vector<std::string> NamespaceContainer::ListTables(
+    const Namespace& namespace_ident) const {
+  const auto container = GetNamespaceContainer(this, namespace_ident);
+  if (!container) return {};
+
+  std::vector<std::string> table_names;
+  table_names.reserve(container->table_metadata_locations_.size());
+
+  std::ranges::transform(container->table_metadata_locations_,
+                         std::back_inserter(table_names),
+                         [](const auto& pair) { return pair.first; });
+
+  std::ranges::sort(table_names);
+
+  return table_names;
+}
+
+bool NamespaceContainer::RegisterTable(TableIdentifier const& table_ident,
+                                       const std::string& metadata_location) {
+  const auto container = GetNamespaceContainer(this, table_ident.ns);
+  if (!container) return false;
+  if (container->table_metadata_locations_.contains(table_ident.name)) return false;
+  container->table_metadata_locations_[table_ident.name] = metadata_location;
+  return true;
+}
+
+bool NamespaceContainer::UnregisterTable(TableIdentifier const& table_ident) {
+  const auto container = GetNamespaceContainer(this, table_ident.ns);
+  if (!container) return false;
+  return container->table_metadata_locations_.erase(table_ident.name) > 0;
+}
+
+bool NamespaceContainer::TableExists(TableIdentifier const& table_ident) const {
+  const auto container = GetNamespaceContainer(this, table_ident.ns);
+  if (!container) return false;
+  return container->table_metadata_locations_.contains(table_ident.name);
+}
+
+std::optional<std::string> NamespaceContainer::GetTableMetadataLocation(
+    TableIdentifier const& table_ident) const {
+  const auto container = GetNamespaceContainer(this, table_ident.ns);
+  if (!container) return std::nullopt;
+  const auto it = container->table_metadata_locations_.find(table_ident.name);
+  if (it == container->table_metadata_locations_.end()) return std::nullopt;
+  return it->second;
+}
+}  // namespace iceberg