mirror of https://github.com/ethereum/go-ethereum
eth/downloader: fix #910, thread safe peers & polishes
Péter Szilágyi
10 years ago
parent
00280e62e3
commit
685862d2ce
@ -1,125 +1,192 @@ |
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// Contains the active peer-set of the downloader, maintaining both failures
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// as well as reputation metrics to prioritize the block retrievals.
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package downloader |
package downloader |
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import ( |
import ( |
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"errors" |
"errors" |
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"sync" |
"sync" |
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"sync/atomic" |
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"github.com/ethereum/go-ethereum/common" |
"github.com/ethereum/go-ethereum/common" |
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"gopkg.in/fatih/set.v0" |
"gopkg.in/fatih/set.v0" |
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) |
) |
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const ( |
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workingState = 2 |
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idleState = 4 |
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) |
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type hashFetcherFn func(common.Hash) error |
type hashFetcherFn func(common.Hash) error |
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type blockFetcherFn func([]common.Hash) error |
type blockFetcherFn func([]common.Hash) error |
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// XXX make threadsafe!!!!
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var ( |
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type peers map[string]*peer |
errAlreadyFetching = errors.New("already fetching blocks from peer") |
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errAlreadyRegistered = errors.New("peer is already registered") |
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errNotRegistered = errors.New("peer is not registered") |
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) |
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func (p peers) reset() { |
// peer represents an active peer from which hashes and blocks are retrieved.
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for _, peer := range p { |
type peer struct { |
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peer.reset() |
id string // Unique identifier of the peer
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} |
head common.Hash // Hash of the peers latest known block
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idle int32 // Current activity state of the peer (idle = 0, active = 1)
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rep int32 // Simple peer reputation (not used currently)
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mu sync.RWMutex |
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ignored *set.Set |
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getHashes hashFetcherFn |
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getBlocks blockFetcherFn |
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} |
} |
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func (p peers) get(state int) []*peer { |
// newPeer create a new downloader peer, with specific hash and block retrieval
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var peers []*peer |
// mechanisms.
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for _, peer := range p { |
func newPeer(id string, head common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) *peer { |
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peer.mu.RLock() |
return &peer{ |
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if peer.state == state { |
id: id, |
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peers = append(peers, peer) |
head: head, |
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} |
getHashes: getHashes, |
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peer.mu.RUnlock() |
getBlocks: getBlocks, |
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ignored: set.New(), |
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} |
} |
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} |
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return peers |
// Reset clears the internal state of a peer entity.
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func (p *peer) Reset() { |
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atomic.StoreInt32(&p.idle, 0) |
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p.ignored.Clear() |
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} |
} |
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func (p peers) setState(id string, state int) { |
// Fetch sends a block retrieval request to the remote peer.
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if peer, exist := p[id]; exist { |
func (p *peer) Fetch(request *fetchRequest) error { |
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peer.mu.Lock() |
// Short circuit if the peer is already fetching
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defer peer.mu.Unlock() |
if !atomic.CompareAndSwapInt32(&p.idle, 0, 1) { |
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peer.state = state |
return errAlreadyFetching |
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} |
} |
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} |
// Convert the hash set to a retrievable slice
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hashes := make([]common.Hash, 0, len(request.Hashes)) |
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for hash, _ := range request.Hashes { |
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hashes = append(hashes, hash) |
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} |
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p.getBlocks(hashes) |
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func (p peers) getPeer(id string) *peer { |
return nil |
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return p[id] |
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} |
} |
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// peer represents an active peer
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// SetIdle sets the peer to idle, allowing it to execute new retrieval requests.
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type peer struct { |
func (p *peer) SetIdle() { |
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state int // Peer state (working, idle)
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atomic.StoreInt32(&p.idle, 0) |
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rep int // TODO peer reputation
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} |
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mu sync.RWMutex |
// Promote increases the peer's reputation.
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id string |
func (p *peer) Promote() { |
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recentHash common.Hash |
atomic.AddInt32(&p.rep, 1) |
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} |
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ignored *set.Set |
// Demote decreases the peer's reputation or leaves it at 0.
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func (p *peer) Demote() { |
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for { |
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// Calculate the new reputation value
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prev := atomic.LoadInt32(&p.rep) |
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next := prev - 2 |
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if next < 0 { |
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next = 0 |
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} |
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// Try to update the old value
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if atomic.CompareAndSwapInt32(&p.rep, prev, next) { |
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return |
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} |
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} |
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} |
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getHashes hashFetcherFn |
// peerSet represents the collection of active peer participating in the block
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getBlocks blockFetcherFn |
// download procedure.
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type peerSet struct { |
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peers map[string]*peer |
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lock sync.RWMutex |
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} |
} |
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// create a new peer
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// newPeerSet creates a new peer set top track the active download sources.
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func newPeer(id string, hash common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) *peer { |
func newPeerSet() *peerSet { |
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return &peer{ |
return &peerSet{ |
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id: id, |
peers: make(map[string]*peer), |
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recentHash: hash, |
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getHashes: getHashes, |
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getBlocks: getBlocks, |
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state: idleState, |
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ignored: set.New(), |
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} |
} |
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} |
} |
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// fetch a chunk using the peer
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// Reset iterates over the current peer set, and resets each of the known peers
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func (p *peer) fetch(request *fetchRequest) error { |
// to prepare for a next batch of block retrieval.
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p.mu.Lock() |
func (ps *peerSet) Reset() { |
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defer p.mu.Unlock() |
ps.lock.RLock() |
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defer ps.lock.RUnlock() |
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if p.state == workingState { |
for _, peer := range ps.peers { |
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return errors.New("peer already fetching chunk") |
peer.Reset() |
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} |
} |
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} |
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// set working state
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// Register injects a new peer into the working set, or returns an error if the
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p.state = workingState |
// peer is already known.
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func (ps *peerSet) Register(p *peer) error { |
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ps.lock.Lock() |
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defer ps.lock.Unlock() |
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// Convert the hash set to a fetchable slice
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if _, ok := ps.peers[p.id]; ok { |
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hashes := make([]common.Hash, 0, len(request.Hashes)) |
return errAlreadyRegistered |
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for hash, _ := range request.Hashes { |
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hashes = append(hashes, hash) |
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} |
} |
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p.getBlocks(hashes) |
ps.peers[p.id] = p |
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return nil |
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} |
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// Unregister removes a remote peer from the active set, disabling any further
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// actions to/from that particular entity.
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func (ps *peerSet) Unregister(id string) error { |
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ps.lock.Lock() |
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defer ps.lock.Unlock() |
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if _, ok := ps.peers[id]; !ok { |
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return errNotRegistered |
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} |
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delete(ps.peers, id) |
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return nil |
return nil |
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} |
} |
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// promote increases the peer's reputation
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// Peer retrieves the registered peer with the given id.
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func (p *peer) promote() { |
func (ps *peerSet) Peer(id string) *peer { |
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p.mu.Lock() |
ps.lock.RLock() |
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defer p.mu.Unlock() |
defer ps.lock.RUnlock() |
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return ps.peers[id] |
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} |
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// Peers returns if the current number of peers in the set.
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func (ps *peerSet) Peers() int { |
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ps.lock.RLock() |
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defer ps.lock.RUnlock() |
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p.rep++ |
return len(ps.peers) |
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} |
} |
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// demote decreases the peer's reputation or leaves it at 0
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// AllPeers retrieves a flat list of all the peers within the set.
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func (p *peer) demote() { |
func (ps *peerSet) AllPeers() []*peer { |
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p.mu.Lock() |
ps.lock.RLock() |
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defer p.mu.Unlock() |
defer ps.lock.RUnlock() |
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if p.rep > 1 { |
list := make([]*peer, 0, len(ps.peers)) |
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p.rep -= 2 |
for _, p := range ps.peers { |
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} else { |
list = append(list, p) |
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p.rep = 0 |
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} |
} |
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return list |
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} |
} |
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func (p *peer) reset() { |
// IdlePeers retrieves a flat list of all the currently idle peers within the
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p.state = idleState |
// active peer set.
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p.ignored.Clear() |
func (ps *peerSet) IdlePeers() []*peer { |
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ps.lock.RLock() |
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defer ps.lock.RUnlock() |
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list := make([]*peer, 0, len(ps.peers)) |
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for _, p := range ps.peers { |
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if atomic.LoadInt32(&p.idle) == 0 { |
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list = append(list, p) |
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} |
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} |
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return list |
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} |
} |
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