mirror of
https://github.com/ceph/ceph
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15350de7ae
OMap is used by PG to store PGLog, so it's called by each write operations. Because leveldb don't play well in random read and "header_lock" limit the concurrence. Add a LRU cache to avoid too much overload on seeking header. Signed-off-by: Haomai Wang <haomaiwang@gmail.com>
104 lines
2.3 KiB
C++
104 lines
2.3 KiB
C++
// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
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// vim: ts=8 sw=2 smarttab
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/*
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* Ceph - scalable distributed file system
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*
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* Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
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*
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* This is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License version 2.1, as published by the Free Software
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* Foundation. See file COPYING.
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*
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*/
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#ifndef CEPH_SIMPLECACHE_H
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#define CEPH_SIMPLECACHE_H
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#include <map>
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#include <list>
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#include <memory>
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#include "common/Mutex.h"
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#include "common/Cond.h"
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template <class K, class V>
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class SimpleLRU {
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Mutex lock;
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size_t max_size;
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map<K, typename list<pair<K, V> >::iterator> contents;
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list<pair<K, V> > lru;
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map<K, V> pinned;
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void trim_cache() {
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while (lru.size() > max_size) {
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contents.erase(lru.back().first);
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lru.pop_back();
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}
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}
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void _add(K key, V value) {
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lru.push_front(make_pair(key, value));
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contents[key] = lru.begin();
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trim_cache();
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}
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public:
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SimpleLRU(size_t max_size) : lock("SimpleLRU::lock"), max_size(max_size) {}
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void pin(K key, V val) {
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Mutex::Locker l(lock);
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pinned.insert(make_pair(key, val));
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}
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void clear_pinned(K e) {
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Mutex::Locker l(lock);
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for (typename map<K, V>::iterator i = pinned.begin();
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i != pinned.end() && i->first <= e;
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pinned.erase(i++)) {
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if (!contents.count(i->first))
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_add(i->first, i->second);
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else
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lru.splice(lru.begin(), lru, contents[i->first]);
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}
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}
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void clear(K key) {
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Mutex::Locker l(lock);
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typename map<K, typename list<pair<K, V> >::iterator>::iterator i =
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contents.find(key);
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if (i == contents.end())
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return;
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lru.erase(i->second);
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contents.erase(i);
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}
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void set_size(size_t new_size) {
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Mutex::Locker l(lock);
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max_size = new_size;
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trim_cache();
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}
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bool lookup(K key, V *out) {
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Mutex::Locker l(lock);
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typename list<pair<K, V> >::iterator loc = contents.count(key) ?
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contents[key] : lru.end();
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if (loc != lru.end()) {
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*out = loc->second;
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lru.splice(lru.begin(), lru, loc);
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return true;
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}
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if (pinned.count(key)) {
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*out = pinned[key];
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return true;
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}
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return false;
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}
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void add(K key, V value) {
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Mutex::Locker l(lock);
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_add(key, value);
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}
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};
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#endif
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