a few small changes to make the dht more efficient

[whyrusleeping]

Was watching biham during a reproviding round. Its eating up some serious CPU time, this should help alleviate a small amount of that.

License: MIT
Signed-off-by: Jeromy why@ipfs.io

[Kubuxu]

LGTM

[whyrusleeping]

should improve #2828

[jbenet]

this no longer protects rt.local, which is fine. BUT it would be nice if the RoutingTable struct was more clear about what the mutex protects.

now

// RoutingTable defines the routing table.
type RoutingTable struct {

    // ID of the local peer
    local ID

    // Blanket lock, refine later for better performance
    tabLock sync.RWMutex

    // latency metrics
    metrics pstore.Metrics

    // Maximum acceptable latency for peers in this cluster
    maxLatency time.Duration

    // kBuckets define all the fingers to other nodes.
    Buckets    []*Bucket
    bucketsize int
}

better

// RoutingTable defines the routing table.
type RoutingTable struct {

    local      ID  // ID of the local peer
    bucketsize int

    // the following fields are all protected by tabLock
    tabLock    sync.RWMutex   // Blanket lock, refine later for better performance
    metrics    pstore.Metrics // latency metrics
    maxLatency time.Duration  // Maximum acceptable latency for peers in this cluster
    Buckets    []*Bucket      // kBuckets define all the fingers to other nodes.
}

[jbenet]

Or at least say:

    // Blanket lock, refine later for better performance
    // protects metrics, maxLatency, and Buckets
    tabLock sync.RWMutex