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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
#include "common/debug.h"
#include "SimplePolicy.h"
#define dout_context g_ceph_context
#define dout_subsys ceph_subsys_immutable_obj_cache
#undef dout_prefix
#define dout_prefix *_dout << "ceph::cache::SimplePolicy: " << this << " " \
<< __func__ << ": "
namespace ceph {
namespace immutable_obj_cache {
SimplePolicy::SimplePolicy(CephContext *cct, uint64_t cache_size,
uint64_t max_inflight, double watermark)
: cct(cct), m_watermark(watermark), m_max_inflight_ops(max_inflight),
m_max_cache_size(cache_size) {
ldout(cct, 20) << "max cache size= " << m_max_cache_size
<< " ,watermark= " << m_watermark
<< " ,max inflight ops= " << m_max_inflight_ops << dendl;
m_cache_size = 0;
}
SimplePolicy::~SimplePolicy() {
ldout(cct, 20) << dendl;
for (auto it : m_cache_map) {
Entry* entry = (it.second);
delete entry;
}
}
cache_status_t SimplePolicy::alloc_entry(std::string file_name) {
ldout(cct, 20) << "alloc entry for: " << file_name << dendl;
std::unique_lock wlocker{m_cache_map_lock};
// cache hit when promoting
if (m_cache_map.find(file_name) != m_cache_map.end()) {
ldout(cct, 20) << "object is under promoting: " << file_name << dendl;
return OBJ_CACHE_SKIP;
}
if ((m_cache_size < m_max_cache_size) &&
(inflight_ops < m_max_inflight_ops)) {
Entry* entry = new Entry();
ceph_assert(entry != nullptr);
m_cache_map[file_name] = entry;
wlocker.unlock();
update_status(file_name, OBJ_CACHE_SKIP);
return OBJ_CACHE_NONE; // start promotion request
}
// if there's no free entry, return skip to read from rados
return OBJ_CACHE_SKIP;
}
cache_status_t SimplePolicy::lookup_object(std::string file_name) {
ldout(cct, 20) << "lookup: " << file_name << dendl;
std::shared_lock rlocker{m_cache_map_lock};
auto entry_it = m_cache_map.find(file_name);
// simply promote on first lookup
if (entry_it == m_cache_map.end()) {
rlocker.unlock();
return alloc_entry(file_name);
}
Entry* entry = entry_it->second;
if (entry->status == OBJ_CACHE_PROMOTED || entry->status == OBJ_CACHE_DNE) {
// bump pos in lru on hit
m_promoted_lru.lru_touch(entry);
}
return entry->status;
}
void SimplePolicy::update_status(std::string file_name,
cache_status_t new_status, uint64_t size) {
ldout(cct, 20) << "update status for: " << file_name
<< " new status = " << new_status << dendl;
std::unique_lock locker{m_cache_map_lock};
auto entry_it = m_cache_map.find(file_name);
if (entry_it == m_cache_map.end()) {
return;
}
ceph_assert(entry_it != m_cache_map.end());
Entry* entry = entry_it->second;
// to promote
if (entry->status == OBJ_CACHE_NONE && new_status== OBJ_CACHE_SKIP) {
entry->status = new_status;
entry->file_name = file_name;
inflight_ops++;
return;
}
// promoting done
if (entry->status == OBJ_CACHE_SKIP && (new_status== OBJ_CACHE_PROMOTED ||
new_status== OBJ_CACHE_DNE)) {
m_promoted_lru.lru_insert_top(entry);
entry->status = new_status;
entry->size = size;
m_cache_size += entry->size;
inflight_ops--;
return;
}
// promoting failed
if (entry->status == OBJ_CACHE_SKIP && new_status== OBJ_CACHE_NONE) {
// mark this entry as free
entry->file_name = "";
entry->status = new_status;
m_cache_map.erase(entry_it);
inflight_ops--;
delete entry;
return;
}
// to evict
if ((entry->status == OBJ_CACHE_PROMOTED || entry->status == OBJ_CACHE_DNE) &&
new_status== OBJ_CACHE_NONE) {
// mark this entry as free
uint64_t size = entry->size;
entry->file_name = "";
entry->size = 0;
entry->status = new_status;
m_promoted_lru.lru_remove(entry);
m_cache_map.erase(entry_it);
m_cache_size -= size;
delete entry;
return;
}
}
int SimplePolicy::evict_entry(std::string file_name) {
ldout(cct, 20) << "to evict: " << file_name << dendl;
update_status(file_name, OBJ_CACHE_NONE);
return 0;
}
cache_status_t SimplePolicy::get_status(std::string file_name) {
ldout(cct, 20) << file_name << dendl;
std::shared_lock locker{m_cache_map_lock};
auto entry_it = m_cache_map.find(file_name);
if (entry_it == m_cache_map.end()) {
return OBJ_CACHE_NONE;
}
return entry_it->second->status;
}
void SimplePolicy::get_evict_list(std::list<std::string>* obj_list) {
ldout(cct, 20) << dendl;
std::unique_lock locker{m_cache_map_lock};
// check free ratio, pop entries from LRU
if ((double)m_cache_size > m_max_cache_size * m_watermark) {
// TODO(dehao): make this configurable
int evict_num = m_cache_map.size() * 0.1;
for (int i = 0; i < evict_num; i++) {
Entry* entry = reinterpret_cast<Entry*>(m_promoted_lru.lru_expire());
if (entry == nullptr) {
continue;
}
std::string file_name = entry->file_name;
obj_list->push_back(file_name);
}
}
}
// for unit test
uint64_t SimplePolicy::get_free_size() {
return m_max_cache_size - m_cache_size;
}
uint64_t SimplePolicy::get_promoting_entry_num() {
uint64_t index = 0;
std::shared_lock rlocker{m_cache_map_lock};
for (auto it : m_cache_map) {
if (it.second->status == OBJ_CACHE_SKIP) {
index++;
}
}
return index;
}
uint64_t SimplePolicy::get_promoted_entry_num() {
return m_promoted_lru.lru_get_size();
}
std::string SimplePolicy::get_evict_entry() {
Entry* entry = reinterpret_cast<Entry*>(m_promoted_lru.lru_get_next_expire());
if (entry == nullptr) {
return "";
}
return entry->file_name;
}
} // namespace immutable_obj_cache
} // namespace ceph
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