1 files changed, 124 insertions, 0 deletions
diff --git a/src/mgr/TTLCache.h b/src/mgr/TTLCache.h
new file mode 100644
index 000000000..a6d5ddf2e
--- /dev/null
+++ b/src/mgr/TTLCache.h
@@ -0,0 +1,124 @@
+#pragma once
+
+#include <atomic>
+#include <chrono>
+#include <functional>
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "PyUtil.h"
+
+using namespace std;
+
+template <class Key, class Value> class Cache {
+ private:
+  std::atomic<uint64_t> hits, misses;
+
+ protected:
+  unsigned int capacity;
+  Cache(unsigned int size = UINT16_MAX) : hits{0}, misses{0}, capacity{size} {};
+  std::map<Key, Value> content;
+  std::vector<string> allowed_keys = {"osd_map", "pg_dump", "pg_stats"};
+
+  void mark_miss() {
+    misses++;
+  }
+
+  void mark_hit() {
+    hits++;
+  }
+
+  unsigned int get_misses() { return misses; }
+  unsigned int get_hits() { return hits; }
+  void throw_key_not_found(Key key) {
+    std::stringstream ss;
+    ss << "Key " << key << " couldn't be found\n";
+    throw std::out_of_range(ss.str());
+  }
+
+ public:
+  void insert(Key key, Value value) {
+    mark_miss();
+    if (content.size() < capacity) {
+      content.insert({key, value});
+    }
+  }
+  Value get(Key key, bool count_hit = true) {
+    if (count_hit) {
+      mark_hit();
+    }
+    return content[key];
+  }
+  void erase(Key key) { content.erase(content.find(key)); }
+  void clear() { content.clear(); }
+  bool exists(Key key) { return content.find(key) != content.end(); }
+  std::pair<uint64_t, uint64_t> get_hit_miss_ratio() {
+    return std::make_pair(hits.load(), misses.load());
+  }
+  bool is_cacheable(Key key) {
+    for (auto k : allowed_keys) {
+      if (key == k) return true;
+    }
+    return false;
+  }
+  int size() { return content.size(); }
+
+  ~Cache(){};
+};
+
+using ttl_time_point = std::chrono::time_point<std::chrono::steady_clock>;
+template <class Key, class Value>
+class TTLCacheBase : public Cache<Key, std::pair<Value, ttl_time_point>> {
+ private:
+  uint16_t ttl;
+  float ttl_spread_ratio;
+  using value_type = std::pair<Value, ttl_time_point>;
+  using cache = Cache<Key, value_type>;
+
+ protected:
+  Value get_value(Key key, bool count_hit = true);
+  ttl_time_point get_value_time_point(Key key);
+  bool exists(Key key);
+  bool expired(Key key);
+  void finish_get(Key key);
+  void finish_erase(Key key);
+  void throw_key_not_found(Key key);
+
+ public:
+  TTLCacheBase(uint16_t ttl_ = 0, uint16_t size = UINT16_MAX,
+               float spread = 0.25)
+      : Cache<Key, value_type>(size), ttl{ttl_}, ttl_spread_ratio{spread} {}
+  ~TTLCacheBase(){};
+  void insert(Key key, Value value);
+  Value get(Key key);
+  void erase(Key key);
+  void clear();
+  uint16_t get_ttl() { return ttl; };
+  void set_ttl(uint16_t ttl);
+};
+
+template <class Key, class Value>
+class TTLCache : public TTLCacheBase<Key, Value> {
+ public:
+  TTLCache(uint16_t ttl_ = 0, uint16_t size = UINT16_MAX, float spread = 0.25)
+      : TTLCacheBase<Key, Value>(ttl_, size, spread) {}
+  ~TTLCache(){};
+};
+
+template <class Key>
+class TTLCache<Key, PyObject*> : public TTLCacheBase<Key, PyObject*> {
+ public:
+  TTLCache(uint16_t ttl_ = 0, uint16_t size = UINT16_MAX, float spread = 0.25)
+      : TTLCacheBase<Key, PyObject*>(ttl_, size, spread) {}
+  ~TTLCache(){};
+  PyObject* get(Key key);
+  void erase(Key key);
+
+ private:
+  using ttl_base = TTLCacheBase<Key, PyObject*>;
+};
+
+#include "TTLCache.cc"
+