예제 #1
0
// reserveHashes reserves a set of hashes for the given peer, skipping previously
// failed ones.
//
// Note, this method expects the queue lock to be already held for writing. The
// reason the lock is not obtained in here is because the parameters already need
// to access the queue, so they already need a lock anyway.
func (q *queue) reserveHashes(p *peer, count int, taskQueue *prque.Prque, taskGen func(int), pendPool map[string]*fetchRequest, maxPending int) *fetchRequest {
	// Short circuit if the peer's already downloading something (sanity check to
	// not corrupt state)
	if _, ok := pendPool[p.id]; ok {
		return nil
	}
	// Calculate an upper limit on the hashes we might fetch (i.e. throttling)
	allowance := maxPending
	if allowance > 0 {
		for _, request := range pendPool {
			allowance -= len(request.Hashes)
		}
	}
	// If there's a task generator, ask it to fill our task queue
	if taskGen != nil && taskQueue.Size() < allowance {
		taskGen(allowance - taskQueue.Size())
	}
	if taskQueue.Empty() {
		return nil
	}
	// Retrieve a batch of hashes, skipping previously failed ones
	send := make(map[common.Hash]int)
	skip := make(map[common.Hash]int)

	for proc := 0; (allowance == 0 || proc < allowance) && len(send) < count && !taskQueue.Empty(); proc++ {
		hash, priority := taskQueue.Pop()
		if p.Lacks(hash.(common.Hash)) {
			skip[hash.(common.Hash)] = int(priority)
		} else {
			send[hash.(common.Hash)] = int(priority)
		}
	}
	// Merge all the skipped hashes back
	for hash, index := range skip {
		taskQueue.Push(hash, float32(index))
	}
	// Assemble and return the block download request
	if len(send) == 0 {
		return nil
	}
	request := &fetchRequest{
		Peer:   p,
		Hashes: send,
		Time:   time.Now(),
	}
	pendPool[p.id] = request

	return request
}
예제 #2
0
// reserveHeaders reserves a set of data download operations for a given peer,
// skipping any previously failed ones. This method is a generic version used
// by the individual special reservation functions.
//
// Note, this method expects the queue lock to be already held for writing. The
// reason the lock is not obtained in here is because the parameters already need
// to access the queue, so they already need a lock anyway.
func (q *queue) reserveHeaders(p *peer, count int, taskPool map[common.Hash]*types.Header, taskQueue *prque.Prque,
	pendPool map[string]*fetchRequest, donePool map[common.Hash]struct{}, isNoop func(*types.Header) bool) (*fetchRequest, bool, error) {
	// Short circuit if the pool has been depleted, or if the peer's already
	// downloading something (sanity check not to corrupt state)
	if taskQueue.Empty() {
		return nil, false, nil
	}
	if _, ok := pendPool[p.id]; ok {
		return nil, false, nil
	}
	// Calculate an upper limit on the items we might fetch (i.e. throttling)
	space := len(q.resultCache) - len(donePool)
	for _, request := range pendPool {
		space -= len(request.Headers)
	}
	// Retrieve a batch of tasks, skipping previously failed ones
	send := make([]*types.Header, 0, count)
	skip := make([]*types.Header, 0)

	progress := false
	for proc := 0; proc < space && len(send) < count && !taskQueue.Empty(); proc++ {
		header := taskQueue.PopItem().(*types.Header)

		// If we're the first to request this task, initialise the result container
		index := int(header.Number.Int64() - int64(q.resultOffset))
		if index >= len(q.resultCache) || index < 0 {
			common.Report("index allocation went beyond available resultCache space")
			return nil, false, errInvalidChain
		}
		if q.resultCache[index] == nil {
			components := 1
			if q.mode == FastSync && header.Number.Uint64() <= q.fastSyncPivot {
				components = 2
			}
			q.resultCache[index] = &fetchResult{
				Pending: components,
				Header:  header,
			}
		}
		// If this fetch task is a noop, skip this fetch operation
		if isNoop(header) {
			donePool[header.Hash()] = struct{}{}
			delete(taskPool, header.Hash())

			space, proc = space-1, proc-1
			q.resultCache[index].Pending--
			progress = true
			continue
		}
		// Otherwise unless the peer is known not to have the data, add to the retrieve list
		if p.Lacks(header.Hash()) {
			skip = append(skip, header)
		} else {
			send = append(send, header)
		}
	}
	// Merge all the skipped headers back
	for _, header := range skip {
		taskQueue.Push(header, -float32(header.Number.Uint64()))
	}
	if progress {
		// Wake WaitResults, resultCache was modified
		q.active.Signal()
	}
	// Assemble and return the block download request
	if len(send) == 0 {
		return nil, progress, nil
	}
	request := &fetchRequest{
		Peer:    p,
		Headers: send,
		Time:    time.Now(),
	}
	pendPool[p.id] = request

	return request, progress, nil
}