DDSketch

.gitignore

@@ -6,6 +6,9 @@
 # Visual Studio Code
 .vscode/
 
+# Intellij
+.idea/
+
 # OSX files
 .DS_Store
 
@@ -43,3 +46,9 @@ _*/
 
 docs
 java
+
+# clang 
+.clangd
+
+# CMakeFiles
+CMakeFiles/

CMakeLists.txt

@@ -120,12 +120,13 @@ add_subdirectory(count)
 add_subdirectory(density)
 add_subdirectory(tdigest)
 add_subdirectory(filters)
+add_subdirectory(ddsketch)
 
 if (WITH_PYTHON)
   add_subdirectory(python)
 endif()
 
-target_link_libraries(datasketches INTERFACE hll cpc kll fi theta sampling req quantiles count)
+target_link_libraries(datasketches INTERFACE hll cpc kll fi theta sampling req quantiles count ddsketch)
 
 if (COVERAGE)
   find_program(LCOV_PATH NAMES "lcov")

Doxyfile

@@ -955,6 +955,7 @@ INPUT                  = common/include \
                          fi/include \
                          count/include \
                          req/include \
+                         ddsketch/include \
                          README.md
 
 # This tag can be used to specify the character encoding of the source files

ddsketch/CMakeLists.txt

@@ -0,0 +1,67 @@
+# 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.
+
+add_library(ddsketch INTERFACE)
+
+add_library(${PROJECT_NAME}::DDSKETCH ALIAS ddsketch)
+
+if (BUILD_TESTS)
+    add_subdirectory(test)
+endif()
+
+target_include_directories(ddsketch
+        INTERFACE
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+        $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include>
+)
+
+target_link_libraries(ddsketch INTERFACE common)
+
+install(TARGETS ddsketch
+        EXPORT ${PROJECT_NAME}
+)
+
+install(FILES
+        include/bin.hpp
+        include/bin_impl.hpp
+        include/collapsing_dense_store.hpp
+        include/collapsing_dense_store_impl.hpp
+        include/collapsing_highest_dense_store.hpp
+        include/collapsing_highest_dense_store_impl.hpp
+        include/collapsing_lowest_dense_store.hpp
+        include/collapsing_lowest_dense_store_impl.hpp
+        include/ddsketch.hpp
+        include/ddsketch_impl.hpp
+        include/dense_store.hpp
+        include/dense_store_impl.hpp
+        include/index_mapping.hpp
+        include/index_mapping_factory.hpp
+        include/index_mapping_impl.hpp
+        include/linearly_interpolated_mapping.hpp
+        include/linearly_interpolated_mapping_impl.hpp
+        include/log_like_index_mapping.hpp
+        include/log_like_index_mapping_impl.hpp
+        include/logarithmic_mapping.hpp
+        include/logarithmic_mapping_impl.hpp
+        include/quadratically_interpolated_mapping.hpp
+        include/quadratically_interpolated_mapping_impl.hpp
+        include/sparse_store.hpp
+        include/sparse_store_impl.hpp
+        include/store_factory.hpp
+        include/unbounded_size_dense_store.hpp
+        include/unbounded_size_dense_store_impl.hpp
+        DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/DataSketches")

ddsketch/include/bin.hpp

@@ -0,0 +1,73 @@
+/*
+ * 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.
+ */
+#ifndef BIN_H
+#define BIN_H
+
+#include <cstdint>
+#include <string>
+
+namespace datasketches {
+
+/**
+ * @class Bin
+ * @brief Represents a bucket of counts in a DDSketch store.
+ *
+ * A Bin corresponds to a mapped value index and its associated count.
+ * It is the fundamental unit used in DenseStore, SparseStore, and their variants.
+ */
+class Bin {
+public:
+  /**
+    * @brief Construct a new Bin.
+    * @param index The index representing the mapped value bucket.
+    * @param count The number of samples in this bin.
+    */
+  Bin(int index, double count);
+
+  ~Bin() = default;
+
+  /**
+   * @brief Equality operator.
+   * @param other The other bin to compare with.
+   * @return True if both bins have the same index and count.
+   */
+  bool operator==(const Bin& other) const;
+  std::string to_string() const;
+
+  /**
+   * @brief Get the count of this bin.
+   * @return The number of samples in the bin.
+   */
+  double get_count() const;
+
+  /**
+   * @brief Get the index of this bin.
+   * @return The integer index.
+   */
+  int get_index() const;
+
+private:
+  int index;
+  double count;
+};
+}
+
+#include "bin_impl.hpp"
+
+#endif //BIN_H

ddsketch/include/bin_impl.hpp

@@ -0,0 +1,48 @@
+/*
+ * 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.
+ */
+
+#ifndef BIN_IMPL_H
+#define BIN_IMPL_H
+
+#include "bin.hpp"
+
+namespace datasketches {
+inline Bin::Bin(int index, double count): index(index), count(count) {};
+
+inline bool Bin::operator==(const Bin& other) const {
+  if (this == &other) {
+    return true;
+  }
+  return index == other.index && count == other.count;
+};
+
+inline double Bin::get_count() const {
+  return count;
+}
+
+inline int Bin::get_index() const {
+  return index;
+}
+
+inline std::string Bin::to_string() const {
+  return "Bin{index= " + std::to_string(index) + ", count= " + std::to_string(count) + "}";
+}
+
+}
+#endif //BIN_IMPL_H

ddsketch/include/collapsing_dense_store.hpp

@@ -0,0 +1,90 @@
+/*
+ * 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.
+ */
+
+#ifndef COLLAPSING_DENSE_STORE_HPP
+#define COLLAPSING_DENSE_STORE_HPP
+
+#include "dense_store.hpp"
+
+namespace datasketches {
+
+/**
+ * @class CollapsingDenseStore
+ * @brief Common logic for capacity-bounded dense stores with tail-collapsing.
+ */
+template<class Derived, int N, typename Allocator>
+class CollapsingDenseStore : public DenseStore<Derived, Allocator> {
+public:
+
+  using size_type = typename DenseStore<Derived, Allocator>::size_type;
+  CollapsingDenseStore();
+
+  /**
+   * Copy assignment
+   * @param other sketch to be copied
+   * @return reference to this sketch
+   */
+  CollapsingDenseStore<Derived, N, Allocator>& operator=(const CollapsingDenseStore<Derived, N, Allocator>& other);
+
+  /**
+   * This method serializes the store into a given stream in a binary form
+   * @param os output stream
+   */
+  void serialize(std::ostream& os) const;
+
+  /**
+   * @brief Deserialize the store from a stream (replacing current contents).
+   * @param is Input stream.
+   */
+  static Derived deserialize(std::istream& is);
+
+  /**
+   * Computes size needed to serialize the current state of the sketch.
+   * @return size in bytes needed to serialize this sketch
+   */
+  int get_serialized_size_bytes() const;
+
+  ~CollapsingDenseStore() = default;
+
+  /**
+   * @brief Clear all contents of the store.
+   *
+   * Removes all bins and resets counts to zero while preserving configuration
+   * (e.g., capacity limits). After this call, @c total_count() is 0 and the
+   * store contains no non-empty bins.
+   */
+  void clear();
+
+protected:
+  bool is_collapsed;
+
+  /**
+   * @brief Compute the resized backing-array length for a target index span.
+   *
+   * @param new_min_index Lowest bin index to be retained (inclusive).
+   * @param new_max_index Highest bin index to be retained (inclusive).
+   * @return size_type New backing-array capacity (in bins).
+   */
+  size_type get_new_length(size_type new_min_index, size_type new_max_index) const;
+};
+}
+
+#include "collapsing_dense_store_impl.hpp"
+
+#endif //COLLAPSING_DENSE_STORE_HPP