Masternode Sync

Dash Core performs full masternode synchronization as required. There are four conditions that initiate a start/restart the sync process:

• Initial startup of Dash Core
• More than 60 minutes have passed since the last activation
• A failure occurred during the last sync attempt (after a 1 minute cooldown before sync restarts)
• Issuing a mnsync reset RPC command

Initial Masternode Sync

The deterministic masternode lists introduced by DIP3 eliminated several steps of the sync process related to the masternode list and masternode payments. Since that information is now available on-chain, P2P messages related to those steps were deprecated.

This diagram shows the order in which P2P messages are sent to perform masternode synchronization initially after startup.

The following table details the data flow of P2P messages exchanged during initial masternode synchronization after the activation of DIP3 and Spork 15.

Syncing Node Message	Direction	Masternode Response	Description
1. Sporks
getsporks message	→		Syncing node requests sporks
	←	spork message(s)
2. Mempool
mempool message	→		Syncing node requests mempool entries
	←	inv message(s)	inv message(s) containing TXIDs of mempool transactions
3. Governance			See Governance sync

Masternode Sync Status

There are several status values used to track masternode synchronization. They are used in both ssc messages and the mnsync RPC.

Value	Status	Description
-1	MASTERNODE_SYNC_FAILED	Removed in Dash Core 0.16.0 Synchronization failed
0	MASTERNODE_SYNC_INITIAL	Deprecated (merged with MASTERNODE_SYNC_WAITING in Dash Core 0.16.0) Synchronization just started, was reset recently, or is still in IBD
1	MASTERNODE_SYNC_BLOCKCHAIN (previously MASTERNODE_SYNC_WAITING)	Renamed in Dash Core 0.16.0 Synchronization pending - waiting after initial to check for more headers/blocks.
4	MASTERNODE_SYNC_GOVERNANCE	Synchronizing governance objects
999	MASTERNODE_SYNC_FINISHED	Synchronization finished

Ongoing Masternode Sync

Once a masternode completes an initial full sync, continuing synchronization is maintained by the exchange of P2P messages with other nodes. This diagram shows an overview of the messages exchanged to keep governance objects synchronized between masternodes.

Governance

After the initial governance synchronization, governance information is kept current by the govobj messages and govobjvote messages relayed on the network. Unsynchronized peers may send govsync messages to request governance sync.

Masternode Sync Schedule

The following tables detail the timing of various functions used to keep the masternodes in sync with each other. This information is derived from the scheduler section of AppInitMain in src/init.cpp.

Period (seconds)	Action	Description
6	MN Sync	Synchronizes sporks and governance objects (masternode-sync.cpp)

The following actions only run when the masternode sync is past MASTERNODE_SYNC_WAITING status.

Period (seconds)	Action	Description
60	Process MN Connections	Disconnects some masternodes (masternodeman.cpp)
60	InstantSend Check/Remove	Remove expired/orphaned/invalid InstantSend candidates and votes (instantx.cpp)
300	Maintenance	Check/remove/reprocess governance objects (governance.cpp)