int get(int key) {
auto got = cache_map.find(key);
if (got == cache_map.end())
return -1;
cache_list.splice(cache_list.begin(), cache_list, got->second);
return got->second->second;
}
void set(int key, int value) {
auto got = cache_map.find(key);
if (got != cache_map.end()) {
cache_list.erase(got->second);
cache_map.erase(got);
}
cache_list.push_front(make_pair(key, value));
cache_map.insert(make_pair(key, cache_list.begin()));
clean();
}
void cache_display()
{
HTTP_header* http_hdr;
HTTP_pointer* ptr;
CACHE_LIST::iterator N;//use a standard iterator variable to move through the cache
string LR_key, last;
time_t last_accessed;
cout<<endl;
cout<<"_____________________Files Cache____________________________"<<endl;
N= cache.begin();
while(N != cache.end())
{
LR_key = N->first;//first element in cache
ptr = N->second;//pointer to the next
http_hdr = ptr->getHeader();
last_accessed = http_hdr->get_last_accessed();
last = UTC_convert(last_accessed);
cout<<"page: "<<LR_key<<", was last accessed at: "<<last<<endl;
N++;
}
}
void update_cache(string url, HTTP_pointer* entity,int status)
{
if(status == 0)
{
//first check if cache has empty places
double MTD=INT_MIN;//minimum access time
time_t currentTime = time_current();
if(cache.size() < MAX)
{
//just insert it and return
cout<<"Current size of cache: "<<cache.size()<<endl;
entity = set_Time(entity);
cache.insert(make_pair(url, entity));
return;
}
//now if cache is full, find the entry with the oldest access time
//
int i=0;
CACHE_LIST::iterator Least_recent_key;
CACHE_LIST::iterator N = cache.begin();
time_t last;
for(; N != cache.end(); N++)
{
HTTP_pointer* en = N->second;
last = en->getHeader()->get_last_accessed();
double timediff = difftime(currentTime, last);
if(timediff > MTD)
{
MTD = timediff;//find the minima
Least_recent_key = N;
}
i++;
}
//now we have the least recently used key in index leastRecent
cout<<"The least recently used(LRU) page is "<<Least_recent_key->first<<", hence this entry will be deleted in the cache"<<endl;
cache.erase(Least_recent_key);
cache.insert(make_pair(url, entity));
}
else
{
//method to replace existing entries in cache
string key;
CACHE_LIST::iterator N = cache.begin();
for(; N != cache.end(); N++)
{
key = N->first;
if(key == url)
{
cout<<"Entry found for page "<<key<<", this will be replaced with the new page now"<<endl;
cache.erase(key);
entity = set_Time(entity);
cache.insert(make_pair(url, entity));
break;
}
}
}
}