mm: Handle market params update

This diff updates the market maker to listen for updates to the server
config. If the lot size of a market that a bot is currently trading on
is updated, the number of placements that the bot makes is updated so
that the bot places as many lots as possible without exceeding the amount
that was placed before the lot size update.

client/core/core.go

@@ -8315,6 +8315,7 @@ func (c *Core) handleReconnect(host string) {
 		c.log.Errorf("handleReconnect: Unable to apply new configuration for DEX at %s: %v", host, err)
 		return
 	}
+	c.notify(newServerConfigUpdateNote(host))
 
 	type market struct { // for book re-subscribe
 		name  string

client/core/notification.go

@@ -686,6 +686,21 @@ func newUpgradeNote(topic Topic, subject, details string, severity db.Severity)
 	}
 }
 
+// ServerConfigUpdateNote is sent when a server's configuration is updated.
+type ServerConfigUpdateNote struct {
+	db.Notification
+	Host string `json:"host"`
+}
+
+const TopicServerConfigUpdate Topic = "ServerConfigUpdate"
+
+func newServerConfigUpdateNote(host string) *ServerConfigUpdateNote {
+	return &ServerConfigUpdateNote{
+		Notification: db.NewNotification(NoteTypeServerNotify, TopicServerConfigUpdate, "", "", db.Data),
+		Host:         host,
+	}
+}
+
 // WalletCreationNote is a notification regarding asynchronous wallet creation.
 type WalletCreationNote struct {
 	db.Notification

client/mm/config.go

@@ -3,6 +3,8 @@ package mm
 import (
 	"encoding/json"
 	"fmt"
+
+	"decred.org/dcrdex/dex/utils"
 )
 
 // MarketMakingConfig is the overall configuration of the market maker.
@@ -49,19 +51,40 @@ type AutoRebalanceConfig struct {
 	MinQuoteTransfer uint64 `json:"minQuoteTransfer"`
 }
 
+func (a *AutoRebalanceConfig) copy() *AutoRebalanceConfig {
+	return &AutoRebalanceConfig{
+		MinBaseTransfer:  a.MinBaseTransfer,
+		MinQuoteTransfer: a.MinQuoteTransfer,
+	}
+}
+
 // BotBalanceAllocation is the initial allocation of funds for a bot.
 type BotBalanceAllocation struct {
 	DEX map[uint32]uint64 `json:"dex"`
 	CEX map[uint32]uint64 `json:"cex"`
 }
 
+func (b *BotBalanceAllocation) copy() *BotBalanceAllocation {
+	return &BotBalanceAllocation{
+		DEX: utils.CopyMap(b.DEX),
+		CEX: utils.CopyMap(b.CEX),
+	}
+}
+
 // BotInventoryDiffs is the amount of funds to add or remove from a bot's
 // allocation.
 type BotInventoryDiffs struct {
 	DEX map[uint32]int64 `json:"dex"`
 	CEX map[uint32]int64 `json:"cex"`
 }
 
+func (d *BotInventoryDiffs) copy() *BotInventoryDiffs {
+	return &BotInventoryDiffs{
+		DEX: utils.CopyMap(d.DEX),
+		CEX: utils.CopyMap(d.CEX),
+	}
+}
+
 // balanceDiffsToAllocations converts a BotInventoryDiffs to a
 // BotBalanceAllocation by removing all negative diffs.
 func balanceDiffsToAllocation(diffs *BotInventoryDiffs) *BotBalanceAllocation {
@@ -89,6 +112,18 @@ func balanceDiffsToAllocation(diffs *BotInventoryDiffs) *BotBalanceAllocation {
 // should be created and the event log db should be updated to support both
 // versions.
 
+type rpcConfig struct {
+	Alloc         *BotBalanceAllocation `json:"alloc"`
+	AutoRebalance *AutoRebalanceConfig  `json:"autoRebalance"`
+}
+
+func (r *rpcConfig) copy() *rpcConfig {
+	return &rpcConfig{
+		Alloc:         r.Alloc.copy(),
+		AutoRebalance: r.AutoRebalance.copy(),
+	}
+}
+
 // BotConfig is the configuration for a market making bot.
 // The balance fields are the initial amounts that will be reserved to use for
 // this bot. As the bot trades, the amounts reserved for it will be updated.
@@ -108,17 +143,79 @@ type BotConfig struct {
 
 	// RPCConfig can be used for file-based initial allocations and
 	// auto-rebalance settings.
-	RPCConfig *struct {
-		Alloc         *BotBalanceAllocation `json:"alloc"`
-		AutoRebalance *AutoRebalanceConfig  `json:"autoRebalance"`
-	} `json:"rpcConfig"`
+	RPCConfig *rpcConfig `json:"rpcConfig"`
+
+	// LotSize is the lot size of the market at the time this configuration
+	// was created. It is used to notify the user if the lot size changes
+	// when they are starting the bot.
+	LotSize uint64 `json:"lotSize"`
 
 	// Only one of the following configs should be set
 	BasicMMConfig        *BasicMarketMakingConfig `json:"basicMarketMakingConfig,omitempty"`
 	SimpleArbConfig      *SimpleArbConfig         `json:"simpleArbConfig,omitempty"`
 	ArbMarketMakerConfig *ArbMarketMakerConfig    `json:"arbMarketMakingConfig,omitempty"`
 }
 
+func (c *BotConfig) copy() *BotConfig {
+	b := *c
+
+	b.BaseWalletOptions = utils.CopyMap(c.BaseWalletOptions)
+	b.QuoteWalletOptions = utils.CopyMap(c.QuoteWalletOptions)
+
+	if c.UIConfig != nil {
+		b.UIConfig = make(json.RawMessage, len(c.UIConfig))
+		copy(b.UIConfig, c.UIConfig)
+	}
+	if c.RPCConfig != nil {
+		b.RPCConfig = c.RPCConfig.copy()
+	}
+	if c.BasicMMConfig != nil {
+		b.BasicMMConfig = c.BasicMMConfig.copy()
+	}
+	if c.SimpleArbConfig != nil {
+		b.SimpleArbConfig = c.SimpleArbConfig.copy()
+	}
+	if c.ArbMarketMakerConfig != nil {
+		b.ArbMarketMakerConfig = c.ArbMarketMakerConfig.copy()
+	}
+
+	return &b
+}
+
+// updateLotSize modifies the bot's configuration based on an update to the
+// market's lot size.
+func (c *BotConfig) updateLotSize(oldLotSize, newLotSize uint64) {
+	if c.BasicMMConfig != nil {
+		c.BasicMMConfig.updateLotSize(oldLotSize, newLotSize)
+	} else if c.ArbMarketMakerConfig != nil {
+		c.ArbMarketMakerConfig.updateLotSize(oldLotSize, newLotSize)
+	}
+}
+
+func (c *BotConfig) validate() error {
+	if c.BasicMMConfig != nil {
+		return c.BasicMMConfig.Validate()
+	} else if c.SimpleArbConfig != nil {
+		return c.SimpleArbConfig.Validate()
+	} else if c.ArbMarketMakerConfig != nil {
+		// TODO:
+		// c.ArbMarketMakerConfig.Validate()
+		return nil
+	}
+
+	return fmt.Errorf("no bot config set")
+}
+
+func validateConfigUpdate(old, new *BotConfig) error {
+	if (old.BasicMMConfig == nil) != (new.BasicMMConfig == nil) ||
+		(old.SimpleArbConfig == nil) != (new.SimpleArbConfig == nil) ||
+		(old.ArbMarketMakerConfig == nil) != (new.ArbMarketMakerConfig == nil) {
+		return fmt.Errorf("cannot change bot type")
+	}
+
+	return new.validate()
+}
+
 func (c *BotConfig) requiresPriceOracle() bool {
 	return c.BasicMMConfig != nil
 }