Add options to control block creation settings.

This commit adds three new options which are intended to to be used by the
upcoming mining-related block template creation code.

config.go

@@ -38,6 +38,11 @@ const (
 	defaultVerifyEnabled     = false
 	defaultDbType            = "leveldb"
 	defaultFreeTxRelayLimit  = 15.0
+	defaultBlockMinSize      = 0
+	defaultBlockMaxSize      = 750000
+	blockMaxSizeMin          = 1000
+	blockMaxSizeMax          = btcwire.MaxBlockPayload - 1000
+	defaultBlockPrioritySize = 50000
 )
 
 var (
@@ -95,6 +100,9 @@ type config struct {
 	DebugLevel         string        `short:"d" long:"debuglevel" description:"Logging level for all subsystems {trace, debug, info, warn, error, critical} -- You may also specify <subsystem>=<level>,<subsystem2>=<level>,... to set the log level for individual subsystems -- Use show to list available subsystems"`
 	Upnp               bool          `long:"upnp" description:"Use UPnP to map our listening port outside of NAT"`
 	FreeTxRelayLimit   float64       `long:"limitfreerelay" description:"Limit relay of transactions with no transaction fee to the given amount in thousands of bytes per minute"`
+	BlockMinSize       uint32        `long:"blockminsize" description:"Mininum block size in bytes to be used when creating a block"`
+	BlockMaxSize       uint32        `long:"blockmaxsize" description:"Maximum block size in bytes to be used when creating a block"`
+	BlockPrioritySize  uint32        `long:"blockprioritysize" description:"Size in bytes for high-priority/low-fee transactions when creating a block"`
 	onionlookup        func(string) ([]net.IP, error)
 	lookup             func(string) ([]net.IP, error)
 	oniondial          func(string, string) (net.Conn, error)
@@ -296,6 +304,9 @@ func loadConfig() (*config, []string, error) {
 		RPCKey:            defaultRPCKeyFile,
 		RPCCert:           defaultRPCCertFile,
 		FreeTxRelayLimit:  defaultFreeTxRelayLimit,
+		BlockMinSize:      defaultBlockMinSize,
+		BlockMaxSize:      defaultBlockMaxSize,
+		BlockPrioritySize: defaultBlockPrioritySize,
 	}
 
 	// Service options which are only added on Windows.
@@ -493,6 +504,23 @@ func loadConfig() (*config, []string, error) {
 
 	}
 
+	// Limit the max block size to a sane value.
+	if cfg.BlockMaxSize < blockMaxSizeMin || cfg.BlockMaxSize >
+		blockMaxSizeMax {
+
+		str := "%s: The blockmaxsize option must be in between %d " +
+			"and %d -- parsed [%d]"
+		err := fmt.Errorf(str, "loadConfig", blockMaxSizeMin,
+			blockMaxSizeMax, cfg.BlockMaxSize)
+		fmt.Fprintln(os.Stderr, err)
+		parser.WriteHelp(os.Stderr)
+		return nil, nil, err
+	}
+
+	// Limit the block priority and minimum block sizes to max block size.
+	cfg.BlockPrioritySize = minUint32(cfg.BlockPrioritySize, cfg.BlockMaxSize)
+	cfg.BlockMinSize = minUint32(cfg.BlockMinSize, cfg.BlockMaxSize)
+
 	// Add default port to all listener addresses if needed and remove
 	// duplicate addresses.
 	cfg.Listeners = normalizeAddresses(cfg.Listeners,

mempool.go

@@ -71,11 +71,6 @@ const (
 	// base for calculating minimum required fees for larger transactions.
 	// This value is in Satoshi/KB (kilobyte, not kibibyte).
 	minTxRelayFee = 1000
-
-	// blockPrioritySize is the number of bytes reserved in a block for
-	// high-priority transactions.  It is mainly used to help determine the
-	// minimum required fee for a transaction.
-	blockPrioritySize = 50000
 )
 
 // TxDesc is a descriptor containing a transaction in the mempool and the
@@ -378,7 +373,7 @@ func calcMinRelayFee(tx *btcutil.Tx) int64 {
 	// transaction does not exceeed 1000 less than the reserved space for
 	// high-priority transactions, don't require a fee for it.
 	serializedLen := int64(tx.MsgTx().SerializeSize())
-	if serializedLen < (blockPrioritySize - 1000) {
+	if serializedLen < (defaultBlockPrioritySize - 1000) {
 		return 0
 	}