From e4aebe8608c558524db9742801598333476f410e Mon Sep 17 00:00:00 2001
From: Kefu Chai <kchai@redhat.com>
Date: Sun, 3 Feb 2019 13:24:10 +0800
Subject: [PATCH] common/random_cache: remove unused RandomCache

the only consumer of it was KeyValueStore, which was removed in
19c39faead87655d174965d054de8bbbe4d79067 .

Signed-off-by: Kefu Chai <kchai@redhat.com>
---
 src/common/random_cache.hpp | 110 ------------------------------------
 1 file changed, 110 deletions(-)
 delete mode 100644 src/common/random_cache.hpp

diff --git a/src/common/random_cache.hpp b/src/common/random_cache.hpp
deleted file mode 100644
index ad4a5d06a92b..000000000000
--- a/src/common/random_cache.hpp
+++ /dev/null
@@ -1,110 +0,0 @@
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-// vim: ts=8 sw=2 smarttab
-/*
- * Ceph - scalable distributed file system
- *
- * Copyright (C) 2014 UnitedStack <haomai@unitedstack.com>
- *
- * Author: Haomai Wang <haomaiwang@gmail.com>
- *
- * This is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License version 2.1, as published by the Free Software
- * Foundation.  See file COPYING.
- *
- */
-
-#ifndef CEPH_RANDOMCACHE_H
-#define CEPH_RANDOMCACHE_H
-
-#include "common/ceph_mutex.h"
-#include "include/compat.h"
-#include "include/unordered_map.h"
-
-
-// Although This is a ramdom cache implementation, here still consider to make
-// the trim progress more reasonable. Each item owns its lookup frequency,
-// when the cache is full it will randomly pick up several items and compare the
-// frequency associated with. The least frequency of items will be evicted.
-template <class K, class V>
-class RandomCache {
-  // The first element of pair is the frequency of item, it's used to evict item
-  ceph::unordered_map<K, pair<uint64_t, V> > contents;
-  ceph::mutex lock = ceph::make_mutex("RandomCache::lock");
-  uint64_t max_size;
-  K last_trim_key;
-
-  // When cache reach full, consider to evict a certain number of items
-  static const uint64_t EVICT_COUNT = 5;
-  // Avoid too much overhead on comparing items's frequency, the number of
-  // compare items is expected to small.
-  static const uint64_t COMPARE_COUNT = 3;
-
-  // In order to make evict cache progress more lightweight and effective,
-  // several items are expected to evicted in one call
-  void trim_cache(uint64_t evict_count) {
-    typename ceph::unordered_map<K, pair<uint64_t, V> >::iterator it = contents.find(last_trim_key);
-    uint64_t total_compare = evict_count * COMPARE_COUNT;
-    map<uint64_t, K> candidates;
-
-    while (total_compare--) {
-      if (it == contents.end()) {
-        it = contents.begin();
-      }
-
-      candidates[it->second.first] = it->first;
-      it++;
-    }
-    if (it != contents.end())
-      last_trim_key = it->first;
-    else
-      last_trim_key = contents.begin()->first;
-
-    for (typename map<uint64_t, K>::iterator j = candidates.begin(); j != candidates.end(); j++) {
-      contents.erase(j->second);
-      evict_count--;
-      if (!evict_count)
-        break;
-    }
-  }
-
- public:
-  RandomCache(size_t max_size=20) : max_size(max_size) {}
-  ~RandomCache() {
-    contents.clear();
-  }
-
-  void clear(K key) {
-    std::lock_guard l(lock);
-    contents.erase(key);
-  }
-
-  void set_size(size_t new_size) {
-    std::lock_guard l(lock);
-    max_size = new_size;
-    if (max_size <= contents.size()) {
-      trim_cache(contents.size() - max_size);
-    }
-  }
-
-  bool lookup(K key, V *out) {
-    std::lock_guard l(lock);
-    typename ceph::unordered_map<K, pair<uint64_t, V> >::iterator it = contents.find(key);
-    if (it != contents.end()) {
-      it->second.first++;
-      *out = it->second.second;
-      return true;
-    }
-    return false;
-  }
-
-  void add(K key, V value) {
-    std::lock_guard l(lock);
-    if (max_size <= contents.size()) {
-      trim_cache(EVICT_COUNT);
-    }
-    contents[key] = make_pair(1, value);
-  }
-};
-
-#endif
-- 
2.47.3