Dev/vasil.pashov/index file refactor (#1472)

Refactor index.hpp

Move the functions in a .cpp file. Add explicit template instantiations
for the CRTP base class in the cpp file.

#### Checklist

<details>
  <summary>
   Checklist for code changes...
  </summary>
 
- [ ] Have you updated the relevant docstrings, documentation and
copyright notice?
- [ ] Is this contribution tested against [all ArcticDB's
features](../docs/mkdocs/docs/technical/contributing.md)?
- [ ] Do all exceptions introduced raise appropriate [error
messages](https://docs.arcticdb.io/error_messages/)?
 - [ ] Are API changes highlighted in the PR description?
- [ ] Is the PR labelled as enhancement or bug so it appears in
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---------

Co-authored-by: Vasil Pashov <[email protected]>

cpp/arcticdb/CMakeLists.txt

@@ -461,6 +461,7 @@ set(arcticdb_srcs
         storage/storage_factory.cpp
         stream/aggregator.cpp
         stream/append_map.cpp
+        stream/index.cpp
         stream/piloted_clock.cpp
         toolbox/library_tool.cpp
         util/allocator.cpp

cpp/arcticdb/stream/index.cpp

@@ -0,0 +1,252 @@
+/* Copyright 2024 Man Group Operations Limited
+ *
+ * Use of this software is governed by the Business Source License 1.1 included in the file licenses/BSL.txt.
+ *
+ * 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 <arcticdb/stream/index.hpp>
+#include <arcticdb/column_store/memory_segment.hpp>
+#include <arcticdb/pipeline/index_fields.hpp>
+#include <arcticdb/entity/type_utils.hpp>
+
+
+namespace arcticdb::stream {
+
+IndexDescriptor::Type get_index_value_type(const AtomKey& key) {
+        return std::holds_alternative<timestamp>(key.start_index()) ? IndexDescriptor::TIMESTAMP
+                                                                    : IndexDescriptor::STRING;
+    }
+
+template <typename Derived>
+    StreamDescriptor BaseIndex<Derived>::create_stream_descriptor(
+    StreamId stream_id,
+    std::initializer_list<FieldRef> fields
+) const {
+    std::vector<FieldRef> fds{fields};
+    return create_stream_descriptor(stream_id, folly::range(fds));
+}
+
+template <typename Derived> const Derived* BaseIndex<Derived>::derived() const {
+    return static_cast<const Derived*>(this);
+}
+
+template <typename Derived> BaseIndex<Derived>::operator IndexDescriptor() const {
+    return {Derived::field_count(), Derived::type()};
+}
+
+template <typename Derived> FieldRef BaseIndex<Derived>::field(size_t) const {
+    return {static_cast<TypeDescriptor>(typename Derived::TypeDescTag{}), std::string_view(derived()->name())};
+}
+
+TimeseriesIndex::TimeseriesIndex(const std::string& name) : name_(name) {}
+
+TimeseriesIndex TimeseriesIndex::default_index() {
+    return TimeseriesIndex(DefaultName);
+}
+
+void TimeseriesIndex::check(const FieldCollection& fields) const {
+    const size_t fields_size = fields.size();
+    constexpr int current_fields_size = int(field_count());
+
+    const TypeDescriptor& first_field_type = fields[0].type();
+    const TypeDescriptor& current_first_field_type = this->field(0).type();
+
+    const bool valid_type_promotion = has_valid_type_promotion(first_field_type, current_first_field_type).has_value();
+    const bool trivial_type_compatibility = trivially_compatible_types(first_field_type, current_first_field_type);
+
+    const bool compatible_types = valid_type_promotion || trivial_type_compatibility;
+
+    util::check_arg(
+        fields_size >= current_fields_size,
+        "expected at least {} fields, actual {}",
+        current_fields_size,
+        fields_size
+    );
+    util::check_arg(compatible_types, "expected field[0]={}, actual {}", this->field(0), fields[0]);
+}
+
+IndexValue TimeseriesIndex::start_value_for_segment(const SegmentInMemory& segment) {
+    if (segment.row_count() == 0)
+        return {NumericIndex{0}};
+    auto first_ts = segment.template scalar_at<timestamp>(0, 0).value();
+    return {first_ts};
+}
+
+IndexValue TimeseriesIndex::end_value_for_segment(const SegmentInMemory& segment) {
+    auto row_count = segment.row_count();
+    if (row_count == 0)
+        return {NumericIndex{0}};
+    auto last_ts = segment.template scalar_at<timestamp>(row_count - 1, 0).value();
+    return {last_ts};
+}
+
+IndexValue TimeseriesIndex::start_value_for_keys_segment(const SegmentInMemory& segment) {
+    if (segment.row_count() == 0)
+        return {NumericIndex{0}};
+    auto start_index_id = int(pipelines::index::Fields::start_index);
+    auto first_ts = segment.template scalar_at<timestamp>(0, start_index_id).value();
+    return {first_ts};
+}
+
+IndexValue TimeseriesIndex::end_value_for_keys_segment(const SegmentInMemory& segment) {
+    auto row_count = segment.row_count();
+    if (row_count == 0)
+        return {NumericIndex{0}};
+    auto end_index_id = int(pipelines::index::Fields::end_index);
+    auto last_ts = segment.template scalar_at<timestamp>(row_count - 1, end_index_id).value();
+    return {last_ts};
+}
+
+const char* TimeseriesIndex::name() const {
+    return name_.c_str();
+}
+
+TimeseriesIndex TimeseriesIndex::make_from_descriptor(const StreamDescriptor& desc) {
+    if (desc.field_count() > 0)
+        return TimeseriesIndex(std::string(desc.fields(0).name()));
+
+    return TimeseriesIndex(DefaultName);
+}
+
+
+TableIndex::TableIndex(const std::string& name) : name_(name) {
+}
+
+TableIndex TableIndex::default_index() {
+    return TableIndex(DefaultName);
+}
+
+void TableIndex::check(const FieldCollection& fields) const {
+    util::check_arg(
+        fields.size() >= int(field_count()),
+        "expected at least {} fields, actual {}",
+        field_count(),
+        fields.size()
+    );
+
+    util::check(fields.ref_at(0) == field(0), "Field descriptor mismatch {} != {}", fields.ref_at(0), field(0));
+}
+
+IndexValue TableIndex::start_value_for_segment(const SegmentInMemory& segment) {
+    auto string_index = segment.string_at(0, 0).value();
+    return {std::string{string_index}};
+}
+
+IndexValue TableIndex::end_value_for_segment(const SegmentInMemory& segment) {
+    auto last_rowid = segment.row_count() - 1;
+    auto string_index = segment.string_at(last_rowid, 0).value();
+    return {std::string{string_index}};
+}
+
+IndexValue TableIndex::start_value_for_keys_segment(const SegmentInMemory& segment) {
+    if (segment.row_count() == 0)
+        return {NumericIndex{0}};
+    auto start_index_id = int(pipelines::index::Fields::start_index);
+    auto string_index = segment.string_at(0, start_index_id).value();
+    return {std::string{string_index}};
+}
+
+IndexValue TableIndex::end_value_for_keys_segment(const SegmentInMemory& segment) {
+    auto row_count = segment.row_count();
+    if (row_count == 0)
+        return {NumericIndex{0}};
+    auto end_index_id = int(pipelines::index::Fields::end_index);
+    auto string_index = segment.string_at(row_count - 1, end_index_id).value();
+    return {std::string{string_index}};
+}
+
+TableIndex TableIndex::make_from_descriptor(const StreamDescriptor& desc) {
+    if (desc.field_count() > 0)
+        return TableIndex(std::string(desc.field(0).name()));
+
+    return TableIndex(DefaultName);
+}
+
+const char* TableIndex::name() const {
+    return name_.c_str();
+}
+
+RowCountIndex RowCountIndex::default_index() {
+    return RowCountIndex{};
+}
+
+
+IndexValue RowCountIndex::start_value_for_segment(const SegmentInMemory& segment) {
+    return static_cast<timestamp>(segment.offset());
+}
+
+IndexValue RowCountIndex::end_value_for_segment(const SegmentInMemory& segment) {
+    return static_cast<timestamp>(segment.offset() + (segment.row_count() - 1));
+}
+
+IndexValue RowCountIndex::start_value_for_keys_segment(const SegmentInMemory& segment) {
+    return static_cast<timestamp>(segment.offset());
+}
+
+IndexValue RowCountIndex::end_value_for_keys_segment(const SegmentInMemory& segment) {
+    return static_cast<timestamp>(segment.offset() + (segment.row_count() - 1));
+}
+
+RowCountIndex RowCountIndex::make_from_descriptor(const StreamDescriptor&) const {
+    return RowCountIndex::default_index();
+}
+
+IndexValue EmptyIndex::start_value_for_segment(const SegmentInMemory& segment) {
+    return static_cast<NumericIndex>(segment.offset());
+}
+
+IndexValue EmptyIndex::end_value_for_segment(const SegmentInMemory& segment) {
+    return static_cast<NumericIndex>(segment.offset());
+}
+
+IndexValue EmptyIndex::start_value_for_keys_segment(const SegmentInMemory& segment) {
+    return static_cast<NumericIndex>(segment.offset());
+}
+
+IndexValue EmptyIndex::end_value_for_keys_segment(const SegmentInMemory& segment) {
+    return static_cast<NumericIndex>(segment.offset());
+}
+
+Index index_type_from_descriptor(const StreamDescriptor& desc) {
+    switch (desc.index().proto().kind()) {
+    case IndexDescriptor::EMPTY: return EmptyIndex{};
+    case IndexDescriptor::TIMESTAMP: return TimeseriesIndex::make_from_descriptor(desc);
+    case IndexDescriptor::STRING: return TableIndex::make_from_descriptor(desc);
+    case IndexDescriptor::ROWCOUNT: return RowCountIndex{};
+    default:
+        util::raise_rte(
+            "Data obtained from storage refers to an index type that this build of ArcticDB doesn't understand ({}).",
+            int(desc.index().proto().kind())
+        );
+    }
+}
+
+Index default_index_type_from_descriptor(const IndexDescriptor::Proto& desc) {
+    switch (desc.kind()) {
+    case IndexDescriptor::EMPTY: return EmptyIndex{};
+    case IndexDescriptor::TIMESTAMP: return TimeseriesIndex::default_index();
+    case IndexDescriptor::STRING: return TableIndex::default_index();
+    case IndexDescriptor::ROWCOUNT: return RowCountIndex::default_index();
+    default: util::raise_rte("Unknown index type {} trying to generate index type", int(desc.kind()));
+    }
+}
+
+Index default_index_type_from_descriptor(const IndexDescriptor& desc) {
+    return default_index_type_from_descriptor(desc.proto());
+}
+
+IndexDescriptor get_descriptor_from_index(const Index& index) {
+    return util::variant_match(index, [](const auto& idx) { return static_cast<IndexDescriptor>(idx); });
+}
+
+Index empty_index() {
+    return RowCountIndex::default_index();
+}
+
+template class BaseIndex<TimeseriesIndex>;
+template class BaseIndex<TableIndex>;
+template class BaseIndex<RowCountIndex>;
+template class BaseIndex<EmptyIndex>;
+}