Change metadata fee config to only account for contract events. (#127)

Also renamed a couple tx-size related fields for clarity.

Stellar-contract-config-setting.x

@@ -67,24 +67,26 @@ struct ConfigSettingContractHistoricalDataV0
 };
 
 // Meta data (pushed to downstream systems) settings for contracts.
-struct ConfigSettingContractMetaDataV0
+struct ConfigSettingContractEventsV0
 {
-    // Maximum size of extended meta data produced by a transaction
-    uint32 txMaxExtendedMetaDataSizeBytes;
-    // Fee for generating 1KB of extended meta data
-    int64 feeExtendedMetaData1KB;
+    // Maximum size of events that a contract call can emit.
+    uint32 txMaxContractEventsSizeBytes;
+    // Fee for generating 1KB of contract events.
+    int64 feeContractEvents1KB;
 };
 
-// Bandwidth related data settings for contracts
+// Bandwidth related data settings for contracts.
+// We consider bandwidth to only be consumed by the transaction envelopes, hence
+// this concerns only transaction sizes.
 struct ConfigSettingContractBandwidthV0
 {
-    // Maximum size in bytes to propagate per ledger
-    uint32 ledgerMaxPropagateSizeBytes;
+    // Maximum sum of all transaction sizes in the ledger in bytes
+    uint32 ledgerMaxTxsSizeBytes;
     // Maximum size in bytes for a transaction
     uint32 txMaxSizeBytes;
 
-    // Fee for propagating 1KB of data
-    int64 feePropagateData1KB;
+    // Fee for 1 KB of transaction size
+    int64 feeTxSize1KB;
 };
 
 enum ContractCostType {
@@ -217,7 +219,7 @@ case CONFIG_SETTING_CONTRACT_LEDGER_COST_V0:
 case CONFIG_SETTING_CONTRACT_HISTORICAL_DATA_V0:
     ConfigSettingContractHistoricalDataV0 contractHistoricalData;
 case CONFIG_SETTING_CONTRACT_META_DATA_V0:
-    ConfigSettingContractMetaDataV0 contractMetaData;
+    ConfigSettingContractEventsV0 contractEvents;
 case CONFIG_SETTING_CONTRACT_BANDWIDTH_V0:
     ConfigSettingContractBandwidthV0 contractBandwidth;
 case CONFIG_SETTING_CONTRACT_COST_PARAMS_CPU_INSTRUCTIONS: