refactor: integrate finder-threads as lambdas

lib_vector_search/include/word_list.h

@@ -1,12 +1,9 @@
 #pragma once
 
 #include <filesystem>
-#include <mutex>
 #include <string>
 #include <vector>
 
-class WordRefList;
-
 class WordList : public std::vector<std::string> {
 public:
   WordList &multiply(size_t factor);
@@ -15,22 +12,10 @@ public:
   static WordList oneCap();
   static WordList fourCaps();
   static WordList fromFile(const std::filesystem::path &path);
-
-  static void find_prefix_in_range(const WordList &word_list,
-                                   const std::string_view &search_prefix,
-                                   size_t start_index, size_t end_index,
-                                   WordRefList &result,
-                                   std::mutex &result_mutex);
 };
 
 class WordRefList : public std::vector<const std::string *> {
 public:
   WordRefList() = default;
   WordRefList(const WordList &source);
-
-  static void find_prefix_in_range(const WordRefList &word_list,
-                                   const std::string_view &search_prefix,
-                                   size_t start_index, size_t end_index,
-                                   WordRefList &result,
-                                   std::mutex &result_mutex);
 };

lib_vector_search/src/grouped_finder.cpp

@@ -19,31 +19,43 @@ WordRefList GroupedFinder::find_prefix(string_view search_prefix) const {
   }
 
   const auto word_list = group->second;
-  const auto word_list_size = word_list.size();
+  const size_t word_list_size = word_list.size();
-
+  const size_t thread_count =
-  const auto thread_count =
       std::min<size_t>(std::thread::hardware_concurrency(), word_list_size);
+  const size_t words_per_thread = word_list_size / thread_count;
 
-  WordRefList result;
+  WordRefList search_results;
-  mutex result_mutex;
+  mutex search_results_mutex;
 
   vector<thread> search_threads;
   for (size_t thread_index = 0; thread_index < thread_count; ++thread_index) {
-    const size_t first_index = thread_index * (word_list_size / thread_count);
+    const bool is_last_thread = thread_index == thread_count - 1;
+    const size_t start_index = thread_index * words_per_thread;
+    const size_t end_index =
+        is_last_thread ? word_list_size : start_index + words_per_thread;
 
-    const size_t last_index =
+    search_threads.emplace_back([&, start_index, end_index] {
-        (thread_index == thread_count - 1)
+      WordRefList local_results;
-            ? word_list_size
-            : (thread_index + 1) * (word_list_size / thread_count);
 
-    search_threads.emplace_back(
+      for (size_t word_index = start_index; word_index < end_index;
-        WordRefList::find_prefix_in_range, cref(word_list), cref(search_prefix),
+           ++word_index) {
-        first_index, last_index, ref(result), ref(result_mutex));
+        const auto *current_word = word_list[word_index];
+        if (current_word->starts_with(search_prefix)) {
+          local_results.push_back(current_word);
+        }
+      }
+
+      if (!local_results.empty()) {
+        const std::lock_guard lock(search_results_mutex);
+        std::move(local_results.begin(), local_results.end(),
+                  std::back_inserter(search_results));
+      }
+    });
   }
 
   for (auto &thread : search_threads) {
     thread.join();
   }
 
-  return result;
+  return search_results;
 }

lib_vector_search/src/parallel_finder.cpp

@@ -9,30 +9,43 @@ ParallelFinder::ParallelFinder(const WordList &word_list)
     : word_list_(word_list) {}
 
 WordRefList ParallelFinder::find_prefix(string_view search_prefix) const {
-  WordRefList result;
+  WordRefList search_results;
-  mutex result_mutex;
+  mutex search_results_mutex;
 
   const size_t word_list_size = word_list_.size();
   const size_t thread_count =
       std::min<size_t>(thread::hardware_concurrency(), word_list_size);
+  const size_t words_per_thread = word_list_size / thread_count;
 
   vector<thread> search_threads;
   for (size_t thread_index = 0; thread_index < thread_count; ++thread_index) {
-    const size_t first_index = thread_index * (word_list_size / thread_count);
+    const bool is_last_thread = thread_index == thread_count - 1;
+    const size_t start_index = thread_index * words_per_thread;
+    const size_t end_index =
+        is_last_thread ? word_list_size : start_index + words_per_thread;
 
-    const size_t last_index =
+    search_threads.emplace_back([&, start_index, end_index] {
-        (thread_index == thread_count - 1)
+      WordRefList local_results;
-            ? word_list_size
-            : (thread_index + 1) * (word_list_size / thread_count);
 
-    search_threads.emplace_back(
+      for (size_t word_index = start_index; word_index < end_index;
-        WordList::find_prefix_in_range, cref(word_list_), cref(search_prefix),
+           ++word_index) {
-        first_index, last_index, ref(result), ref(result_mutex));
+        const auto &current_word = word_list_[word_index];
+        if (current_word.starts_with(search_prefix)) {
+          local_results.push_back(&current_word);
+        }
+      }
+
+      if (!local_results.empty()) {
+        const std::lock_guard lock(search_results_mutex);
+        std::move(local_results.begin(), local_results.end(),
+                  std::back_inserter(search_results));
+      }
+    });
   }
 
   for (auto &thread : search_threads) {
     thread.join();
   }
 
-  return result;
+  return search_results;
 }

lib_vector_search/src/word_list.cpp

@@ -71,50 +71,8 @@ WordList WordList::fromFile(const std::filesystem::path &path) {
   return word_list;
 }
 
-void WordList::find_prefix_in_range(const WordList &word_list,
-                                    const std::string_view &search_prefix,
-                                    size_t start_index, size_t end_index,
-                                    WordRefList &result,
-                                    std::mutex &result_mutex) {
-  WordRefList local_results;
-
-  for (size_t index = start_index; index < end_index; ++index) {
-    const auto &current_word = word_list[index];
-    if (current_word.starts_with(search_prefix)) {
-      local_results.push_back(&current_word);
-    }
-  }
-
-  if (!local_results.empty()) {
-    const std::lock_guard<std::mutex> lock(result_mutex);
-    std::move(local_results.begin(), local_results.end(),
-              std::back_inserter(result));
-  }
-};
-
 WordRefList::WordRefList(const WordList &source) {
   for (const auto &word : source) {
     push_back(&word);
   }
 }
-
-void WordRefList::find_prefix_in_range(const WordRefList &word_list,
-                                       const std::string_view &search_prefix,
-                                       size_t start_index, size_t end_index,
-                                       WordRefList &result,
-                                       std::mutex &result_mutex) {
-  WordRefList local_results;
-
-  for (size_t index = start_index; index < end_index; ++index) {
-    const auto *current_word = word_list[index];
-    if (current_word->starts_with(search_prefix)) {
-      local_results.push_back(current_word);
-    }
-  }
-
-  if (!local_results.empty()) {
-    const std::lock_guard<std::mutex> lock(result_mutex);
-    std::move(local_results.begin(), local_results.end(),
-              std::back_inserter(result));
-  }
-};