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// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package vsync
import "time"
var (
// peerSyncInterval is the duration between two consecutive peer
// contacts. During every peer contact, the initiator obtains any
// pending updates from that peer.
peerSyncInterval = 50 * time.Millisecond
// channelTimeout is the duration at which health checks will be requested on
// connections to peers.
channelTimeout = 2 * time.Second
// NeighborConnectionTimeout is the time duration we wait for a connection to be
// established with a peer discovered from the neighborhood.
// TODO(suharshs): Make the timeouts below more dynamic based on network. (i.e.
// bt vs tcp). Currently bt connection establishment takes ~3 seconds, so
// neighborhood connections get more time than cloud connections.
NeighborConnectionTimeout = 10 * time.Second
// cloudConnectionTimeout is the duration we wait for a connection to be
// established with a cloud peer.
cloudConnectionTimeout = 2 * time.Second
// syncConnectionTimeout is the duration we wait for syncing to begin with a
// peer. A value of 0 means we will only use connections that exist in our
// cache.
// TODO(hpucha): Make sync connection timeout dynamic based on ping latency.
// E.g. perhaps we should use a 2s ping timeout, and use k*pingLatency (for
// some k) as getDeltas timeout
syncConnectionTimeout = 0
// memberViewTTL is the shelf-life of the aggregate view of syncgroup members.
memberViewTTL = 2 * time.Second
// pingFailuresCap is the number of failures to cap off at when
// computing how many peer manager rounds to wait before retrying to
// ping peers via the mount table. This implies that a peer manager will
// backoff a maximum of (2^pingFailuresCap) rounds or
// (2^pingFailuresCap)*peerManagementInterval in terms of duration.
pingFailuresCap uint64 = 6
// pingFanout is the maximum number of peers that can be pinged in
// parallel. TODO(hpucha): support ping fanout of 0.
pingFanout = 10
// peerManagementInterval is the duration between two rounds of peer
// management actions.
peerManagementInterval = peerSyncInterval / 5
// maxLocationsInSignpost is the maximum number of Locations that
// mergeSignposts() will permit in a Signpost. Locations with more
// recent WhenSeen values are kept preferentially. Also, locateBlob
// considers only the first maxLocationsInSignpost entries in a
// Signpost's Locations.
maxLocationsInSignpost = 4
// blobRecencyTimeSlop: Otherwise equivalent devices that last
// synchronized with a server within blobRecencyTimeSlop are considered
// to have equal sync time for the purposes of blob priority.
blobRecencyTimeSlop = 2 * time.Minute
// blobSyncDistanceDecay is used as the decay constant when computing
// the mean sync hops from a server to the device, when computing blob priority.
// Higher values mean more inertia.
blobSyncDistanceDecay = float32(5)
// initialBlobOwnerShares is the initial number of ownership shares that
// a device gives itself when it introduces a BlobRef to a syncgroup.
initialBlobOwnerShares = int32(2)