iceberg: initial data structures for logical data types

src/v/iceberg/CMakeLists.txt

@@ -26,7 +26,15 @@ endforeach()
 
 v_cc_library(
   NAME iceberg
-  SRCS ${avro_hdrs}
+  SRCS
+    ${avro_hdrs}
+    datatypes.cc
+    datatypes_json.cc
+    json_utils.cc
+  DEPS
+    v::container
+    v::json
+    v::strings
 )
 
 add_subdirectory(tests)

src/v/iceberg/datatypes.cc

@@ -0,0 +1,263 @@
+// Copyright 2024 Redpanda Data, Inc.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.md
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0
+
+#include "iceberg/datatypes.h"
+
+#include <variant>
+
+namespace iceberg {
+
+struct primitive_type_comparison_visitor {
+    template<typename T, typename U>
+    bool operator()(const T&, const U&) const {
+        return false;
+    }
+    bool operator()(const decimal_type& lhs, const decimal_type& rhs) const {
+        return lhs.precision == rhs.precision && lhs.scale == rhs.scale;
+    }
+    bool operator()(const fixed_type& lhs, const fixed_type& rhs) const {
+        return lhs.length == rhs.length;
+    }
+    template<typename T>
+    bool operator()(const T&, const T&) const {
+        return true;
+    }
+};
+
+bool operator==(const primitive_type& lhs, const primitive_type& rhs) {
+    return std::visit(primitive_type_comparison_visitor{}, lhs, rhs);
+}
+
+struct field_type_comparison_visitor {
+    template<typename T, typename U>
+    bool operator()(const T&, const U&) const {
+        return false;
+    }
+    bool
+    operator()(const primitive_type& lhs, const primitive_type& rhs) const {
+        return lhs == rhs;
+    }
+    bool operator()(const struct_type& lhs, const struct_type& rhs) const {
+        return lhs == rhs;
+    }
+    bool operator()(const list_type& lhs, const list_type& rhs) const {
+        return lhs == rhs;
+    }
+    bool operator()(const map_type& lhs, const map_type& rhs) const {
+        return lhs == rhs;
+    }
+};
+
+bool operator==(const field_type& lhs, const field_type& rhs) {
+    return std::visit(field_type_comparison_visitor{}, lhs, rhs);
+}
+bool operator==(const nested_field& lhs, const nested_field& rhs) {
+    return lhs.id == rhs.id && lhs.required == rhs.required
+           && lhs.name == rhs.name && lhs.type == rhs.type;
+}
+
+std::ostream& operator<<(std::ostream& o, const boolean_type&) {
+    o << "boolean";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const int_type&) {
+    o << "int";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const long_type&) {
+    o << "long";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const float_type&) {
+    o << "float";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const double_type&) {
+    o << "double";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const decimal_type& t) {
+    o << fmt::format("decimal({}, {})", t.precision, t.scale);
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const date_type&) {
+    o << "date";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const time_type&) {
+    o << "time";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const timestamp_type&) {
+    o << "timestamp";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const timestamptz_type&) {
+    o << "timestamptz";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const string_type&) {
+    o << "string";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const uuid_type&) {
+    o << "uuid";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const fixed_type& t) {
+    // NOTE: square brackets to match how fixed type is serialized as JSON,
+    // though this matching isn't necessarily important for operator<<.
+    o << fmt::format("fixed[{}]", t.length);
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const binary_type&) {
+    o << "binary";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const struct_type&) {
+    o << "struct";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const list_type&) {
+    o << "list";
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const map_type&) {
+    o << "map";
+    return o;
+}
+
+bool operator==(const struct_type& lhs, const struct_type& rhs) {
+    if (lhs.fields.size() != rhs.fields.size()) {
+        return false;
+    }
+    for (size_t i = 0; i < lhs.fields.size(); i++) {
+        bool has_lhs = lhs.fields[i] != nullptr;
+        bool has_rhs = rhs.fields[i] != nullptr;
+        if (has_lhs != has_rhs) {
+            return false;
+        }
+        if (has_lhs == false) {
+            continue;
+        }
+        if (*lhs.fields[i] != *rhs.fields[i]) {
+            return false;
+        }
+    }
+    return true;
+}
+bool operator==(const list_type& lhs, const list_type& rhs) {
+    bool has_lhs = lhs.element_field != nullptr;
+    bool has_rhs = rhs.element_field != nullptr;
+    if (has_lhs != has_rhs) {
+        return false;
+    }
+    if (!has_lhs) {
+        // Both nullptr.
+        return true;
+    }
+    return *lhs.element_field == *rhs.element_field;
+}
+bool operator==(const map_type& lhs, const map_type& rhs) {
+    bool has_key_lhs = lhs.key_field != nullptr;
+    bool has_key_rhs = rhs.key_field != nullptr;
+    if (has_key_lhs != has_key_rhs) {
+        return false;
+    }
+    bool has_val_lhs = lhs.value_field != nullptr;
+    bool has_val_rhs = rhs.value_field != nullptr;
+    if (has_val_lhs != has_val_rhs) {
+        return false;
+    }
+    if (has_key_lhs && *lhs.key_field != *rhs.key_field) {
+        return false;
+    }
+    if (has_val_lhs && *lhs.value_field != *rhs.value_field) {
+        return false;
+    }
+    return true;
+}
+
+namespace {
+struct ostream_visitor {
+    explicit ostream_visitor(std::ostream& o)
+      : os(o) {}
+    std::ostream& os;
+
+    template<typename T>
+    void operator()(const T& v) const {
+        os << v;
+    }
+};
+} // namespace
+
+std::ostream& operator<<(std::ostream& o, const primitive_type& t) {
+    std::visit(ostream_visitor{o}, t);
+    return o;
+}
+
+std::ostream& operator<<(std::ostream& o, const field_type& t) {
+    std::visit(ostream_visitor{o}, t);
+    return o;
+}
+
+list_type list_type::create(
+  int32_t element_id, field_required element_required, field_type element) {
+    // NOTE: the element field doesn't have a name. Functionally, the list type
+    // is represented as:
+    // - element-id
+    // - element-type
+    // - element-required
+    // Despite the missing name though, many Iceberg implementations represent
+    // the list with a nested_field.
+    return list_type{
+      .element_field = nested_field::create(
+        element_id, "element", element_required, std::move(element))};
+}
+
+map_type map_type::create(
+  int32_t key_id,
+  field_type key_type,
+  int32_t val_id,
+  field_required val_req,
+  field_type val_type) {
+    // NOTE: the keys and values don't have names, and the key is always
+    // required. Functionally, a map type is represented as:
+    // - key-id
+    // - key-type
+    // - value-id
+    // - value-required
+    // - value-type
+    // Despite the missing names though, many Iceberg implementations represent
+    // the map with two nested_fields.
+    return map_type{
+      .key_field = nested_field::create(
+        key_id, "key", field_required::yes, std::move(key_type)),
+      .value_field = nested_field::create(
+        val_id, "value", val_req, std::move(val_type)),
+    };
+}
+
+} // namespace iceberg