refactor: extract WordRefList and thread finder

lib_vector_search/include/grouped_finder.h

@@ -4,15 +4,14 @@
 #include "word_list.h"
 
 #include <map>
-#include <vector>
 
 class GroupedFinder : public Finder {
 private:
-  std::map<char, std::vector<const std::string *>> groups_;
+  std::map<char, WordRefList> groups_;
 
 public:
   GroupedFinder(const WordList &word_list);
 
   virtual std::forward_list<const std::string *>
-  find_prefix(std::string_view search_term) const override;
+  find_prefix(std::string_view search_prefix) const override;
 };

lib_vector_search/include/parallel_finder.h

@@ -11,5 +11,5 @@ public:
   ParallelFinder(const WordList &word_list);
 
   std::forward_list<const std::string *>
-  find_prefix(std::string_view search_term) const override;
+  find_prefix(std::string_view search_prefix) const override;
 };

lib_vector_search/include/sorted_linear_finder.h

@@ -3,11 +3,9 @@
 #include "finder.h"
 #include "word_list.h"
 
-#include <vector>
-
 class SortedLinearFinder : public Finder {
 private:
-  std::vector<const std::string *> word_list_;
+  WordRefList word_list_;
 
 public:
   SortedLinearFinder(const WordList &word_list);

lib_vector_search/include/word_list.h

@@ -1,6 +1,8 @@
 #pragma once
 
 #include <filesystem>
+#include <forward_list>
+#include <mutex>
 #include <string>
 #include <vector>
 
@@ -11,4 +13,17 @@ public:
 
   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,
+      std::forward_list<const std::string *> &result, std::mutex &result_mutex);
+};
+
+class WordRefList : public std::vector<const std::string *> {
+public:
+  static void find_prefix_in_range(
+      const WordRefList &word_list, const std::string_view &search_prefix,
+      size_t start_index, size_t end_index,
+      std::forward_list<const std::string *> &result, std::mutex &result_mutex);
 };

lib_vector_search/src/grouped_finder.cpp

@@ -5,8 +5,8 @@
 #include <thread>
 #include <vector>
 
-using std::mutex, std::vector, std::thread, std::lock_guard, std::string,
-    std::forward_list, std::string_view;
+using std::mutex, std::vector, std::thread, std::string, std::forward_list,
+    std::string_view;
 
 GroupedFinder::GroupedFinder(const WordList &word_list) {
   for (const auto &word : word_list) {
@@ -15,8 +15,8 @@ GroupedFinder::GroupedFinder(const WordList &word_list) {
 }
 
 std::forward_list<const std::string *>
-GroupedFinder::find_prefix(std::string_view search_term) const {
-  const auto group = groups_.find(search_term.front());
+GroupedFinder::find_prefix(std::string_view search_prefix) const {
+  const auto group = groups_.find(search_prefix.front());
   if (group == groups_.cend()) {
     return {};
   }
@@ -27,41 +27,26 @@ GroupedFinder::find_prefix(std::string_view search_term) const {
   const auto thread_count =
       std::min<size_t>(std::thread::hardware_concurrency(), word_list_size);
 
-  forward_list<const string *> matching_words;
-  mutex matching_words_mutex;
+  forward_list<const string *> result;
+  mutex result_mutex;
 
   vector<thread> search_threads;
   for (size_t thread_index = 0; thread_index < thread_count; ++thread_index) {
-    const size_t first_word_index =
-        thread_index * (word_list_size / thread_count);
-    const size_t last_word_index =
+    const size_t first_index = thread_index * (word_list_size / thread_count);
+
+    const size_t last_index =
         (thread_index == thread_count - 1)
             ? word_list_size
             : (thread_index + 1) * (word_list_size / thread_count);
 
     search_threads.emplace_back(
-        [](const vector<const string *> &word_list,
-           const string_view &search_term, forward_list<const string *> &result,
-           size_t start_index, size_t end_index, mutex &result_mutex) {
-          forward_list<const string *> thread_results;
-          for (size_t index = start_index; index < end_index; ++index) {
-            const auto &current_word = word_list[index];
-            if (current_word->starts_with(search_term)) {
-              thread_results.push_front(current_word);
-            }
-          }
-          if (!thread_results.empty()) {
-            const lock_guard<mutex> lock(result_mutex);
-            result.merge(thread_results);
-          }
-        },
-        cref(word_list), cref(search_term), ref(matching_words),
-        first_word_index, last_word_index, ref(matching_words_mutex));
+        WordRefList::find_prefix_in_range, cref(word_list), cref(search_prefix),
+        first_index, last_index, ref(result), ref(result_mutex));
   }
 
   for (auto &thread : search_threads) {
     thread.join();
   }
 
-  return matching_words;
+  return result;
 }

lib_vector_search/src/parallel_finder.cpp

@@ -3,51 +3,36 @@
 #include <mutex>
 #include <thread>
 
-using std::mutex, std::thread, std::lock_guard, std::vector, std::forward_list,
-    std::string, std::string_view;
+using std::mutex, std::thread, std::vector, std::forward_list, std::string,
+    std::string_view;
 
 ParallelFinder::ParallelFinder(const WordList &word_list)
     : word_list_(word_list) {}
 
 forward_list<const string *>
-ParallelFinder::find_prefix(string_view search_term) const {
+ParallelFinder::find_prefix(string_view search_prefix) const {
   forward_list<const string *> result;
   mutex result_mutex;
 
-  const auto word_list_size = word_list_.size();
+  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 thread_count = thread::hardware_concurrency();
-
-  vector<thread> threads;
+  vector<thread> search_threads;
   for (size_t thread_index = 0; thread_index < thread_count; ++thread_index) {
-    const size_t first_word_index =
-        thread_index * (word_list_size / thread_count);
-    const size_t last_word_index =
+    const size_t first_index = thread_index * (word_list_size / thread_count);
+
+    const size_t last_index =
         (thread_index == thread_count - 1)
             ? word_list_size
             : (thread_index + 1) * (word_list_size / thread_count);
 
-    threads.emplace_back(
-        [](const WordList &word_list, const string_view &search_term,
-           forward_list<const string *> &result, size_t start_index,
-           size_t end_index, mutex &result_mutex) {
-          forward_list<const string *> thread_results;
-          for (size_t index = start_index; index < end_index; ++index) {
-            const auto &current_word = word_list[index];
-            if (current_word.starts_with(search_term)) {
-              thread_results.push_front(&current_word);
-            }
-          }
-          if (!thread_results.empty()) {
-            const lock_guard<mutex> lock(result_mutex);
-            result.merge(thread_results);
-          }
-        },
-        cref(word_list_), cref(search_term), ref(result), first_word_index,
-        last_word_index, ref(result_mutex));
+    search_threads.emplace_back(
+        WordList::find_prefix_in_range, cref(word_list_), cref(search_prefix),
+        first_index, last_index, ref(result), ref(result_mutex));
   }
 
-  for (auto &thread : threads) {
+  for (auto &thread : search_threads) {
     thread.join();
   }
 

lib_vector_search/src/sorted_linear_finder.cpp

@@ -14,6 +14,7 @@ SortedLinearFinder::SortedLinearFinder(const WordList &word_list) {
       word_list_.begin(), word_list_.end(),
       [](const string *left, const string *right) { return *left < *right; });
 }
+
 forward_list<const string *>
 SortedLinearFinder::find_prefix(string_view search_term) const {
   forward_list<const string *> matching_words;

lib_vector_search/src/word_list.cpp

@@ -57,3 +57,41 @@ 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,
+    std::forward_list<const std::string *> &result, std::mutex &result_mutex) {
+  std::forward_list<const std::string *> 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_front(&current_word);
+    }
+  }
+
+  if (!local_results.empty()) {
+    const std::lock_guard<std::mutex> lock(result_mutex);
+    result.merge(local_results);
+  }
+};
+
+void WordRefList::find_prefix_in_range(
+    const WordRefList &word_list, const std::string_view &search_prefix,
+    size_t start_index, size_t end_index,
+    std::forward_list<const std::string *> &result, std::mutex &result_mutex) {
+  std::forward_list<const std::string *> 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_front(current_word);
+    }
+  }
+
+  if (!local_results.empty()) {
+    const std::lock_guard<std::mutex> lock(result_mutex);
+    result.merge(local_results);
+  }
+};