[Improvement] (MG_Util/Misc): Replace byte array with 64-bit bitmap in IndexGenerator.

MobileGL/Includes.h

@@ -89,7 +89,7 @@
 
 typedef int android_LogPriority;
 
-inline int __android_log_print(int prio, const char* tag, const char* fmt, ...) { }
+inline int __android_log_print(int prio, const char* tag, const char* fmt, ...) { return 0; }
 #endif
 
 #include "MG_Util/GLExtensions.h"

MobileGL/MG_Util/Miscellany/IndexGenerator.h

@@ -1,7 +1,4 @@
 #pragma once
-#include <vector>
-#include <algorithm>
-#include <cstdint>
 
 namespace MobileGL {
     template <typename IndexType>
@@ -10,49 +7,79 @@ namespace MobileGL {
         explicit IndexGenerator(size_t initial_capacity = 1024, IndexType first_index = 0)
             : next_index_(first_index)
         {
-            is_valid_.reserve(initial_capacity);
+            const size_t words_needed = (initial_capacity + 63) / 64;
+            is_valid_.resize(words_needed, ~0ull);
+            freed_indices_.reserve(initial_capacity);
         }
 
         void Generate(size_t n, IndexType* indices) {
             if (n == 0) return;
 
             size_t from_freed = std::min(n, freed_indices_.size());
-            for (size_t i = 0; i < from_freed; ++i) {
-                indices[i] = freed_indices_.back();
-                freed_indices_.pop_back();
-                is_valid_[indices[i]] = 1;
+            if (from_freed > 0) {
+                std::copy_n(freed_indices_.end() - from_freed, from_freed, indices);
+                freed_indices_.resize(freed_indices_.size() - from_freed);
+
+                for (size_t i = 0; i < from_freed; ++i) {
+                    SetValid(indices[i], true);
+                }
             }
 
             size_t need_new = n - from_freed;
             if (need_new > 0) {
-                size_t required = next_index_ + need_new;
-                if (required > is_valid_.size()) {
-                    size_t new_cap = std::max(required, is_valid_.size() * 2);
-                    is_valid_.resize(new_cap, 0);
+                size_t required_index = next_index_ + need_new;
+                size_t required_words = (required_index + 63) / 64;
+                if (required_words > is_valid_.size()) {
+                    is_valid_.resize(required_words, ~0ull);
                 }
+
                 for (size_t i = 0; i < need_new; ++i) {
-                    indices[from_freed + i] = next_index_;
-                    is_valid_[next_index_] = 1;
-                    ++next_index_;
+                    indices[from_freed + i] = next_index_++;
                 }
             }
         }
 
         void Delete(IndexType index) {
-            if (index < is_valid_.size() && is_valid_[index]) {
-                is_valid_[index] = 0;
-                freed_indices_.push_back(index);
+            SetValid(index, false);
+            freed_indices_.push_back(index);
+            if (freed_indices_.size() > 1024 && freed_indices_.size() > next_index_ / 2) {
+                CompactFreeList();
             }
         }
 
         bool IsValid(IndexType index) const {
-            return index < is_valid_.size() && is_valid_[index];
+            size_t word = index >> 6;
+            size_t bit = index & 0x3F;
+            return word < is_valid_.size() && (is_valid_[word] & (1ull << bit));
+        }
+
+        size_t FreeListSize() const { return freed_indices_.size(); }
+        size_t ActiveCount() const { return next_index_ - freed_indices_.size(); }
+
+    private:
+        inline void SetValid(IndexType index, bool valid) {
+            size_t word = index >> 6;
+            uint64_t mask = 1ull << (index & 0x3F);
+
+            if (word >= is_valid_.size()) return;
+
+            if (valid) {
+                is_valid_[word] |= mask;
+            }
+            else {
+                is_valid_[word] &= ~mask;
+            }
+        }
+
+        void CompactFreeList() {
+            std::sort(freed_indices_.begin(), freed_indices_.end());
+            auto last = std::unique(freed_indices_.begin(), freed_indices_.end());
+            freed_indices_.erase(last, freed_indices_.end());
         }
 
     private:
         IndexType next_index_ = 0;
-        std::vector<IndexType>  freed_indices_;
-        std::vector<Uint8> is_valid_;
+        std::vector<IndexType> freed_indices_;
+        std::vector<Uint64> is_valid_;
     };
-
-}
+}