cosmos to swingset message flow.md

• Cosmos-SDK -based application starts from app.go
• app knows about swingset due to inclusion of swingset.NewAppModule at line 201
• cosmos transaction arrives, containing a message for swingset
• block proposer processes txn from mempool, or validator processes txn from proposed block
• swingset message is parsed/routed to swingset handler x/swingset/handler.go: NewHandler
• message goes to handleMsgDeliverInbound()
• message is wrapped in a DELIVER_INBOUND JSON structure, stringified, sent to CallToNode at handler.go#L123
• CallToNode passes to NodeMessageSender, which is registered at startup time (lib/daemon/main.go line 67) to point at sendToNode
• sendToNode (lib/agcosmosdaemon.go line 34) is a Go function that calls a C function toNode, which is passed into RunAG_COSMOS by runAG_COSMOS (lib/agcosmosdaemon-node.cc line 144) where it comes from SendToNode
• SendToNode is defined in agcosmosdaemon-node.cc line 73
• ... additional magic happens ...
• something appears in javascript in toSwingSet (lib/ag-chain-cosmos line 80)
• that calls toSwingSet0 wrapped in some error-reporting then()s
• toSwingSet0 starts swingset, if necessary, then calls deliverInbound()
  • that's for messages in transactions
  • BeginBlock follows a similar pathway and langes on deliverStartBlock()
• deliverInbound() dispatches into lib/launch-chain line 113
• that calls a method on the Mailbox device (md.deliverInbound) which might add a delivery to the kernel run-queue
• if so:
  • it calls turnCrank(), which uses controller.run() to cycle the kernel run-queue to completion
  • then it copies any outgoing messages into mailboxStorage, which routes back into Go
    • that lands in x/swingset/storage.go storageHandler.Receive line 58
    • that goes to the Keeper in x/swingset/internal/keeper.go
    • that adds it to the Cosmos-SDK application state, where it gets hashed into the next block, and can be queried by clients like ag-cosmos-helper