#include "PageCache.h"
PageCache PageCache::_sInst;
Span* PageCache::NewSpan(size_t k)
{
	assert(k > 0);
	if (k > NPAGES - 1)
	{
		Span* kSpan = _spanPool.New();
		void* ptr = SystemAlloc(k);
		kSpan->_pageId = (PAGE_ID)ptr >> PAGE_SHIFT;
		kSpan->_n = k;
		kSpan->_objSize = k * (1 << PAGE_SHIFT);
		//_idSpanMap[kSpan->_pageId] = kSpan;
		_idSpanMap.set(kSpan->_pageId, kSpan);
		return kSpan;
	}
	if (!_spanLists[k].Empty())
	{
		Span* kSpan = _spanLists[k].PopFront();
		for (PAGE_ID i = 0; i < kSpan->_n; i++)
		{
			//_idSpanMap[kSpan->_pageId + i] = kSpan;
			_idSpanMap.set(kSpan->_pageId + i, kSpan);
		}
		kSpan->_isUse = true;
		return kSpan;
	}
	for (size_t i = k + 1; i < NPAGES; i++)
	{
		if (!_spanLists[i].Empty())
		{
			Span* nSpan = _spanLists[i].PopFront();
			Span* kSpan = _spanPool.New();
			kSpan->_pageId = nSpan->_pageId;
			kSpan->_n = k;
			kSpan->_objSize = k * (1 << PAGE_SHIFT);

			nSpan->_pageId += k;
			nSpan->_n -= k;
			_spanLists[nSpan->_n].PushFront(nSpan);
			kSpan->_objSize = k * (1 << PAGE_SHIFT);

			//_idSpanMap[nSpan->_pageId] = nSpan;
			//_idSpanMap[nSpan->_pageId + nSpan->_n - 1] = nSpan;

			_idSpanMap.set(nSpan->_pageId, nSpan);
			_idSpanMap.set(nSpan->_pageId + nSpan->_n - 1, nSpan);
			for (PAGE_ID i = 0; i < kSpan->_n; i++)
			{
				//_idSpanMap[kSpan->_pageId + i] = kSpan;
				_idSpanMap.set(kSpan->_pageId + i, kSpan);
			}
			kSpan->_isUse = true;
			return kSpan;
		}
	}
	//ϵͳڴ
	Span* span = _spanPool.New();
	void* ptr = SystemAlloc(NPAGES - 1);
	span->_pageId = (PAGE_ID)ptr>>PAGE_SHIFT;
	span->_n = NPAGES - 1;
	span->_objSize = span->_n * (1 >> PAGE_SHIFT);
	_spanLists[span->_n].PushFront(span);
	return NewSpan(k);
}


Span* PageCache::MapObjectToSpan(void* obj)
{
	PAGE_ID index = ((PAGE_ID)obj >> PAGE_SHIFT);
	//PageCache::_pageMtx.lock();
	//auto ret = _idSpanMap.find(index);
	Span* ret = (Span*)_idSpanMap.get(index);
	//PageCache::_pageMtx.unlock();
	//if (ret == _idSpanMap.end())
	if (ret == nullptr)
	{	
		assert(false);
		return nullptr;
	}
	else
	{
		//return ret->second;
		return ret;
	}
}
void PageCache::ReleaseSpanToPageCache(Span* span)
{
	if (span->_n > NPAGES - 1)
	{
		void* ptr = (void*)(span->_pageId << PAGE_SHIFT);
		SystemFree(ptr);
		_spanPool.Delete(span);
		return;
	}
	//ǰϲ
	while (true)
	{
		PAGE_ID prev = span->_pageId - 1;
		//auto ret = _idSpanMap.find(prev);
		//if (ret != _idSpanMap.end()&&!ret->second->_isUse)
		//{
		//	if (span->_n + ret->second->_n > NPAGES - 1)
		//		break;
		//	span->_pageId = ret->second->_pageId;
		//	span->_n += ret->second->_n;
		//	_spanLists[ret->second->_n].Erase(ret->second);
		//	_spanPool.Delete(ret->second);
		//}
		Span* ret = (Span*)_idSpanMap.get(prev);
		if (ret != nullptr && !ret->_isUse)
		{
			if (span->_n + ret->_n > NPAGES - 1)
				break;
			span->_pageId = ret->_pageId;
			span->_n += ret->_n;
			_spanLists[ret->_n].Erase(ret);
			_spanPool.Delete(ret);
		}
		else break;
	}
	//ϲ
	while (true)
	{
		PAGE_ID next = span->_pageId + span->_n;
		//auto nextptr = _idSpanMap.find(next);
		//if (nextptr != _idSpanMap.end() && !nextptr->second->_isUse)
		//{
		//	if (span->_n + nextptr->second->_n > NPAGES - 1)
		//		break;
		//	span->_n += nextptr->second->_n;
		//	_spanLists[nextptr->second->_n].Erase(nextptr->second);
		//	_spanPool.Delete(nextptr->second);
		//}
		Span* nextptr = (Span*)_idSpanMap.get(next);
		if (nextptr != nullptr && !nextptr->_isUse)
		{
			if (span->_n + nextptr->_n > NPAGES - 1)
				break;
			span->_n += nextptr->_n;
			_spanLists[nextptr->_n].Erase(nextptr);
			_spanPool.Delete(nextptr);
		}
		else break;
	}
	span->_isUse = false;
	_spanLists[span->_n].PushFront(span);
	//_idSpanMap[span->_pageId] = span;
	//_idSpanMap[span->_pageId + span->_n - 1] = span;
	_idSpanMap.set(span->_pageId, span);
	_idSpanMap.set(span->_pageId + span->_n - 1, span);
}