package downloader import ( "errors" "math/big" "sync" "github.com/ethereum/go-ethereum/common" ) const ( workingState = 2 idleState = 4 ) type hashFetcherFn func(common.Hash) error type blockFetcherFn func([]common.Hash) error // XXX make threadsafe!!!! type peers map[string]*peer func (p peers) get(state int) []*peer { var peers []*peer for _, peer := range p { peer.mu.RLock() if peer.state == state { peers = append(peers, peer) } peer.mu.RUnlock() } return peers } func (p peers) setState(id string, state int) { if peer, exist := p[id]; exist { peer.mu.Lock() defer peer.mu.Unlock() peer.state = state } } func (p peers) getPeer(id string) *peer { return p[id] } func (p peers) bestPeer() *peer { var peer *peer for _, cp := range p { if peer == nil || cp.td.Cmp(peer.td) > 0 { peer = cp } } return peer } // peer represents an active peer type peer struct { state int // Peer state (working, idle) rep int // TODO peer reputation mu sync.RWMutex id string td *big.Int recentHash common.Hash getHashes hashFetcherFn getBlocks blockFetcherFn } // create a new peer func newPeer(id string, td *big.Int, hash common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) *peer { return &peer{id: id, td: td, recentHash: hash, getHashes: getHashes, getBlocks: getBlocks, state: idleState} } // fetch a chunk using the peer func (p *peer) fetch(chunk *chunk) error { p.mu.Lock() defer p.mu.Unlock() if p.state == workingState { return errors.New("peer already fetching chunk") } // set working state p.state = workingState // convert the set to a fetchable slice hashes, i := make([]common.Hash, chunk.hashes.Size()), 0 chunk.hashes.Each(func(v interface{}) bool { hashes[i] = v.(common.Hash) i++ return true }) p.getBlocks(hashes) return nil } // promote increases the peer's reputation func (p *peer) promote() { p.mu.Lock() defer p.mu.Unlock() p.rep++ } // demote decreases the peer's reputation or leaves it at 0 func (p *peer) demote() { p.mu.Lock() defer p.mu.Unlock() if p.rep > 1 { p.rep -= 2 } else { p.rep = 0 } }