feat(example): add memory benchmark example

Author: not-matthias

examples/google_benchmark_bazel/memory_bench.hpp

@@ -0,0 +1 @@
+../google_benchmark_cmake/memory_bench.hpp

examples/google_benchmark_cmake/main.cpp

@@ -4,6 +4,7 @@
 
 #include "fibonacci_bench.hpp"
 #include "fixture_bench.hpp"
+#include "memory_bench.hpp"
 #include "multithread_bench.hpp"
 #include "pause_timing_bench.hpp"
 #include "sleep_bench.hpp"

examples/google_benchmark_cmake/memory_bench.hpp

@@ -0,0 +1,197 @@
+#pragma once
+
+#include <benchmark/benchmark.h>
+
+#include <string>
+#include <vector>
+
+// Run-length encoding: compress consecutive repeated characters
+// Example: "aaabbbccc" -> "3a3b3c"
+// NOTE: Intentionally inefficient - no pre-allocation to show multiple
+// allocations
+static std::string rle_encode(const std::string& input) {
+  if (input.empty()) return "";
+
+  std::string result;  // No reserve - will trigger multiple reallocations
+
+  char current = input[0];
+  size_t count = 1;
+
+  for (size_t i = 1; i < input.size(); ++i) {
+    if (input[i] == current) {
+      count++;
+    } else {
+      // Create intermediate strings for each run
+      std::string count_str = std::to_string(count);
+      std::string run_encoded = count_str + current;
+      result += run_encoded;  // Concatenation causes reallocations
+      current = input[i];
+      count = 1;
+    }
+  }
+
+  // Final run
+  std::string count_str = std::to_string(count);
+  std::string final_run = count_str + current;
+  result += final_run;
+
+  return result;
+}
+
+// Run-length decoding: decompress RLE encoded string
+// Example: "3a3b3c" -> "aaabbbccc"
+static std::string rle_decode(const std::string& input) {
+  std::string result;
+  size_t i = 0;
+
+  while (i < input.size()) {
+    // Parse the count
+    size_t count = 0;
+    while (i < input.size() && std::isdigit(input[i])) {
+      count = count * 10 + (input[i] - '0');
+      i++;
+    }
+
+    // Get the character
+    if (i < input.size()) {
+      char ch = input[i];
+      result.append(count, ch);
+      i++;
+    }
+  }
+
+  return result;
+}
+
+// Generate a string with patterns for RLE
+static std::string generate_rle_input(size_t size, size_t run_length) {
+  std::string result;
+  result.reserve(size);
+
+  const std::string chars = "abcdefghijklmnopqrstuvwxyz";
+  size_t char_idx = 0;
+
+  while (result.size() < size) {
+    size_t count = std::min(run_length, size - result.size());
+    result.append(count, chars[char_idx % chars.size()]);
+    char_idx++;
+  }
+
+  return result;
+}
+
+// Benchmark: RLE encoding with small runs (high compression)
+static void BM_RLE_Encode_SmallRuns(benchmark::State& state) {
+  const size_t input_size = state.range(0);
+  std::string input = generate_rle_input(input_size, 3);
+
+  for (auto _ : state) {
+    std::string encoded = rle_encode(input);
+    benchmark::DoNotOptimize(encoded);
+    benchmark::ClobberMemory();
+  }
+
+  state.SetBytesProcessed(state.iterations() * input_size);
+}
+BENCHMARK(BM_RLE_Encode_SmallRuns)
+    ->Arg(100)
+    ->Arg(1000)
+    ->Arg(10000)
+    ->Arg(100000);
+
+// Benchmark: RLE encoding with large runs (low compression)
+static void BM_RLE_Encode_LargeRuns(benchmark::State& state) {
+  const size_t input_size = state.range(0);
+  std::string input = generate_rle_input(input_size, 100);
+
+  for (auto _ : state) {
+    std::string encoded = rle_encode(input);
+    benchmark::DoNotOptimize(encoded);
+    benchmark::ClobberMemory();
+  }
+
+  state.SetBytesProcessed(state.iterations() * input_size);
+}
+BENCHMARK(BM_RLE_Encode_LargeRuns)
+    ->Arg(100)
+    ->Arg(1000)
+    ->Arg(10000)
+    ->Arg(100000);
+
+// Benchmark: RLE decoding
+static void BM_RLE_Decode(benchmark::State& state) {
+  const size_t input_size = state.range(0);
+  std::string input = generate_rle_input(input_size, 10);
+  std::string encoded = rle_encode(input);
+
+  for (auto _ : state) {
+    std::string decoded = rle_decode(encoded);
+    benchmark::DoNotOptimize(decoded);
+    benchmark::ClobberMemory();
+  }
+
+  state.SetBytesProcessed(state.iterations() * encoded.size());
+}
+BENCHMARK(BM_RLE_Decode)->Arg(100)->Arg(1000)->Arg(10000)->Arg(100000);
+
+// Benchmark: Vector allocations (resizing pattern)
+static void BM_Vector_PushBack(benchmark::State& state) {
+  const size_t count = state.range(0);
+
+  for (auto _ : state) {
+    std::vector<int> vec;
+    for (size_t i = 0; i < count; ++i) {
+      vec.push_back(static_cast<int>(i));
+    }
+    benchmark::DoNotOptimize(vec);
+    benchmark::ClobberMemory();
+  }
+}
+BENCHMARK(BM_Vector_PushBack)->Arg(10)->Arg(100)->Arg(1000)->Arg(10000);
+
+// Benchmark: Vector allocations with reserve (optimized)
+static void BM_Vector_Reserve(benchmark::State& state) {
+  const size_t count = state.range(0);
+
+  for (auto _ : state) {
+    std::vector<int> vec;
+    vec.reserve(count);
+    for (size_t i = 0; i < count; ++i) {
+      vec.push_back(static_cast<int>(i));
+    }
+    benchmark::DoNotOptimize(vec);
+    benchmark::ClobberMemory();
+  }
+}
+BENCHMARK(BM_Vector_Reserve)->Arg(10)->Arg(100)->Arg(1000)->Arg(10000);
+
+// Benchmark: String concatenation (many allocations)
+static void BM_String_Concatenation(benchmark::State& state) {
+  const size_t count = state.range(0);
+
+  for (auto _ : state) {
+    std::string result;
+    for (size_t i = 0; i < count; ++i) {
+      result += "x";
+    }
+    benchmark::DoNotOptimize(result);
+    benchmark::ClobberMemory();
+  }
+}
+BENCHMARK(BM_String_Concatenation)->Arg(10)->Arg(100)->Arg(1000)->Arg(10000);
+
+// Benchmark: String concatenation with reserve (optimized)
+static void BM_String_Reserve(benchmark::State& state) {
+  const size_t count = state.range(0);
+
+  for (auto _ : state) {
+    std::string result;
+    result.reserve(count);
+    for (size_t i = 0; i < count; ++i) {
+      result += "x";
+    }
+    benchmark::DoNotOptimize(result);
+    benchmark::ClobberMemory();
+  }
+}
+BENCHMARK(BM_String_Reserve)->Arg(10)->Arg(100)->Arg(1000)->Arg(10000);