C++ EntryList::pop_back方法代码示例

	/**
	 * Stats the given file. If <tt>throttleRate</tt> seconds have passed since
	 * the last time stat() was called on this file, then the file will be
	 * re-stat()ted, otherwise the cached stat information will be returned.
	 *
	 * @param filename The file to stat.
	 * @param stat A pointer to a stat struct; the retrieved stat information
	 *             will be stored here.
	 * @param throttleRate Tells this CachedFileStat that the file may only
	 *        be statted at most every <tt>throttleRate</tt> seconds.
	 * @return 0 if the stat() call succeeded or if the cached stat information was used;
	 *         -1 if something went wrong while statting the file. In the latter
	 *         case, <tt>errno</tt> will be populated with an appropriate error code.
	 * @throws SystemException Something went wrong while retrieving the
	 *         system time. stat() errors will <em>not</em> result in
	 *         SystemException being thrown.
	 * @throws boost::thread_interrupted
	 */
	int stat(const string &filename, struct stat *buf, unsigned int throttleRate = 0) {
		boost::unique_lock<boost::mutex> l(lock);
		EntryMap::iterator it(cache.find(filename));
		EntryPtr entry;
		int ret;
		
		if (it == cache.end()) {
			// Filename not in cache.
			// If cache is full, remove the least recently used
			// cache entry.
			if (maxSize != 0 && cache.size() == maxSize) {
				EntryList::iterator listEnd(entries.end());
				listEnd--;
				string filename((*listEnd)->filename);
				entries.pop_back();
				cache.erase(filename);
			}
			
			// Add to cache as most recently used.
			entry = EntryPtr(new Entry(filename));
			entries.push_front(entry);
			cache[filename] = entries.begin();
		} else {
			// Cache hit.
			entry = *it->second;
			
			// Mark this cache item as most recently used.
			entries.erase(it->second);
			entries.push_front(entry);
			cache[filename] = entries.begin();
		}
		ret = entry->refresh(throttleRate);
		*buf = entry->info;
		return ret;
	}

	/**
	 * Change the maximum size of the cache. If the new size is larger
	 * than the old size, then the oldest entries in the cache are
	 * removed.
	 *
	 * A size of 0 means unlimited.
	 */
	void setMaxSize(unsigned int maxSize) {
		boost::unique_lock<boost::mutex> l(lock);
		if (maxSize != 0) {
			int toRemove = cache.size() - maxSize;
			for (int i = 0; i < toRemove; i++) {
				string filename(entries.back()->filename);
				entries.pop_back();
				cache.erase(filename);
			}
		}
		this->maxSize = maxSize;
	}