From b95fa961d4b10e08e0a320ae7215ab52e118aa26 Mon Sep 17 00:00:00 2001
From: Chenhao Ye <ye.chenhao.ych@gmail.com>
Date: Tue, 9 Apr 2024 11:41:42 -0500
Subject: [PATCH] separate cache stat out

---
 include/gcache/ghost_cache.h  | 59 +++--------------------------------
 include/gcache/shared_cache.h |  4 +--
 include/gcache/stat.h         | 55 ++++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 57 deletions(-)
 create mode 100644 include/gcache/stat.h

diff --git a/include/gcache/ghost_cache.h b/include/gcache/ghost_cache.h
index e83ddc4..a4315b5 100644
--- a/include/gcache/ghost_cache.h
+++ b/include/gcache/ghost_cache.h
@@ -1,17 +1,13 @@
 #pragma once
 
-#include <bit>
 #include <cassert>
 #include <cstdint>
-#include <functional>
-#include <iomanip>
-#include <limits>
 #include <vector>
 
-#include "gcache/hash.h"
-#include "gcache/lru_cache.h"
-#include "gcache/node.h"
-#include "gcache/table.h"
+#include "hash.h"
+#include "lru_cache.h"
+#include "node.h"
+#include "stat.h"
 
 namespace gcache {
 
@@ -23,53 +19,6 @@ enum AccessMode : uint8_t {
   NOOP,     // do not update
 };
 
-struct CacheStat {
-  uint64_t hit_cnt;
-  uint64_t miss_cnt;
-
- public:
-  CacheStat() : hit_cnt(0), miss_cnt(0) {}
-  void add_hit() { ++hit_cnt; }
-  void add_miss() { ++miss_cnt; }
-
-  // we may read an inconsistent version if the reader thread is not the writer,
-  // but most inaccuracy is tolerable, unless it produces a unreasonable value,
-  // e.g., hit_rate > 100%.
-  // we don't use atomic here because we find it is too expensive.
-  [[nodiscard]] double get_hit_rate() const {
-    uint64_t acc_cnt = hit_cnt + miss_cnt;
-    if (acc_cnt == 0) return std::numeric_limits<double>::infinity();
-    return double(hit_cnt) / double(acc_cnt);
-  }
-
-  [[nodiscard]] double get_miss_rate() const {
-    uint64_t acc_cnt = hit_cnt + miss_cnt;
-    if (acc_cnt == 0) return std::numeric_limits<double>::infinity();
-    return double(miss_cnt) / double(acc_cnt);
-  }
-
-  void reset() {
-    hit_cnt = 0;
-    miss_cnt = 0;
-  }
-
-  std::ostream& print(std::ostream& os, int width = 0) const {
-    uint64_t acc_cnt = hit_cnt + miss_cnt;
-    if (acc_cnt == 0)
-      return os << "    NAN (" << std::setw(width) << std::fixed << hit_cnt
-                << '/' << std::setw(width) << std::fixed << acc_cnt << ')';
-    return os << std::setw(6) << std::fixed << std::setprecision(2)
-              << get_hit_rate() * 100 << "% (" << std::setw(width) << std::fixed
-              << hit_cnt << '/' << std::setw(width) << std::fixed << acc_cnt
-              << ')';
-  }
-
-  // print for debugging
-  friend std::ostream& operator<<(std::ostream& os, const CacheStat& s) {
-    return s.print(os, 0);
-  }
-};
-
 /**
  * Simulate a set of page cache.
  */
diff --git a/include/gcache/shared_cache.h b/include/gcache/shared_cache.h
index 310337b..3bd36ae 100644
--- a/include/gcache/shared_cache.h
+++ b/include/gcache/shared_cache.h
@@ -3,8 +3,8 @@
 #include <unordered_map>
 #include <vector>
 
-#include "gcache/lru_cache.h"
-#include "gcache/node.h"
+#include "lru_cache.h"
+#include "node.h"
 
 namespace gcache {
 
diff --git a/include/gcache/stat.h b/include/gcache/stat.h
new file mode 100644
index 0000000..a409bf4
--- /dev/null
+++ b/include/gcache/stat.h
@@ -0,0 +1,55 @@
+#pragma once
+
+#include <cstdint>
+#include <iomanip>
+#include <limits>
+
+namespace gcache {
+
+struct CacheStat {
+  uint64_t hit_cnt;
+  uint64_t miss_cnt;
+
+ public:
+  CacheStat() : hit_cnt(0), miss_cnt(0) {}
+  void add_hit() { ++hit_cnt; }
+  void add_miss() { ++miss_cnt; }
+
+  // we may read an inconsistent version if the reader thread is not the writer,
+  // but most inaccuracy is tolerable, unless it produces a unreasonable value,
+  // e.g., hit_rate > 100%.
+  // we don't use atomic here because we find it is too expensive.
+  [[nodiscard]] double get_hit_rate() const {
+    uint64_t acc_cnt = hit_cnt + miss_cnt;
+    if (acc_cnt == 0) return std::numeric_limits<double>::infinity();
+    return double(hit_cnt) / double(acc_cnt);
+  }
+
+  [[nodiscard]] double get_miss_rate() const {
+    uint64_t acc_cnt = hit_cnt + miss_cnt;
+    if (acc_cnt == 0) return std::numeric_limits<double>::infinity();
+    return double(miss_cnt) / double(acc_cnt);
+  }
+
+  void reset() {
+    hit_cnt = 0;
+    miss_cnt = 0;
+  }
+
+  std::ostream& print(std::ostream& os, int width = 0) const {
+    uint64_t acc_cnt = hit_cnt + miss_cnt;
+    if (acc_cnt == 0)
+      return os << "    NAN (" << std::setw(width) << std::fixed << hit_cnt
+                << '/' << std::setw(width) << std::fixed << acc_cnt << ')';
+    return os << std::setw(6) << std::fixed << std::setprecision(2)
+              << get_hit_rate() * 100 << "% (" << std::setw(width) << std::fixed
+              << hit_cnt << '/' << std::setw(width) << std::fixed << acc_cnt
+              << ')';
+  }
+
+  // print for debugging
+  friend std::ostream& operator<<(std::ostream& os, const CacheStat& s) {
+    return s.print(os, 0);
+  }
+};
+}  // namespace gcache
\ No newline at end of file