Merge pull request #843 from ethcore/usdgaspricing

USD-based pricing of gas.

Cargo.lock

@@ -14,6 +14,7 @@ dependencies = [
  "ethminer 1.1.0",
  "ethsync 1.1.0",
  "fdlimit 0.1.0",
+ "hyper 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "number_prefix 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",

Cargo.toml

@@ -29,6 +29,10 @@ ethminer = { path = "miner" }
 ethcore-devtools = { path = "devtools" }
 ethcore-rpc = { path = "rpc", optional = true }
 
+[dependencies.hyper]
+version = "0.8"
+default-features = false
+
 [features]
 default = ["rpc"]
 rpc = ["ethcore-rpc"]

parity/main.rs

@@ -36,6 +36,9 @@ extern crate time;
 extern crate number_prefix;
 extern crate rpassword;
 
+// for price_info.rs
+#[macro_use] extern crate hyper;
+
 #[cfg(feature = "rpc")]
 extern crate ethcore_rpc as rpc;
 
@@ -60,6 +63,8 @@ use docopt::Docopt;
 use daemonize::Daemonize;
 use number_prefix::{binary_prefix, Standalone, Prefixed};
 
+mod price_info;
+
 fn die_with_message(msg: &str) -> ! {
 	println!("ERROR: {}", msg);
 	exit(1);
@@ -126,8 +131,11 @@ API and Console Options:
                            [default: web3,eth,net,personal].
 
 Sealing/Mining Options:
-  --gas-price WEI          Minimum amount of Wei to be paid for a transaction
-                           to be accepted for mining [default: 20000000000].
+  --usd-per-tx USD         Amount of USD to be paid for a basic transaction
+                           [default: 0.005]. The minimum gas price is set
+                           accordingly.
+  --usd-per-eth SOURCE     USD value of a single ETH. SOURCE may be either an
+                           amount in USD or a web service [default: etherscan].
   --gas-floor-target GAS   Amount of gas per block to target when sealing a new
                            block [default: 4712388].
   --author ADDRESS         Specify the block author (aka "coinbase") address
@@ -162,7 +170,9 @@ Geth-compatibility Options:
   --rpcport PORT           Equivalent to --jsonrpc-port PORT.
   --rpcapi APIS            Equivalent to --jsonrpc-apis APIS.
   --rpccorsdomain URL      Equivalent to --jsonrpc-cors URL.
-  --gasprice WEI           Equivalent to --gas-price WEI.
+  --gasprice WEI           Minimum amount of Wei per GAS to be paid for a
+                           transaction to be accepted for mining. Overrides
+                           --basic-tx-usd.
   --etherbase ADDRESS      Equivalent to --author ADDRESS.
   --extradata STRING       Equivalent to --extra-data STRING.
 
@@ -204,7 +214,8 @@ struct Args {
 	flag_jsonrpc_cors: String,
 	flag_jsonrpc_apis: String,
 	flag_author: String,
-	flag_gas_price: String,
+	flag_usd_per_tx: String,
+	flag_usd_per_eth: String,
 	flag_gas_floor_target: String,
 	flag_extra_data: Option<String>,
 	flag_logging: Option<String>,
@@ -339,10 +350,29 @@ impl Configuration {
 	}
 
 	fn gas_price(&self) -> U256 {
-		let d = self.args.flag_gasprice.as_ref().unwrap_or(&self.args.flag_gas_price);
-		U256::from_dec_str(d).unwrap_or_else(|_| {
-			die!("{}: Invalid gas price given. Must be a decimal unsigned 256-bit number.", d)
-		})
+		match self.args.flag_gasprice.as_ref() {
+			Some(d) => {
+				U256::from_dec_str(d).unwrap_or_else(|_| {
+					die!("{}: Invalid gas price given. Must be a decimal unsigned 256-bit number.", d)
+				})
+			}
+			_ => {
+				let usd_per_tx: f32 = FromStr::from_str(&self.args.flag_usd_per_tx).unwrap_or_else(|_| {
+					die!("{}: Invalid basic transaction price given in USD. Must be a decimal number.", self.args.flag_usd_per_tx)
+				});
+				let usd_per_eth = match self.args.flag_usd_per_eth.as_str() {
+					"etherscan" => price_info::PriceInfo::get().map(|x| x.ethusd).unwrap_or_else(|| {
+						die!("Unable to retrieve USD value of ETH from etherscan. Rerun with a different value for --usd-per-eth.")
+					}),
+					x => FromStr::from_str(x).unwrap_or_else(|_| die!("{}: Invalid ether price given in USD. Must be a decimal number.", x))
+				};
+				let wei_per_usd: f32 = 1.0e18 / usd_per_eth;
+				let gas_per_tx: f32 = 21000.0;
+				let wei_per_gas: f32 = wei_per_usd * usd_per_tx / gas_per_tx;
+				info!("Using a conversion rate of Ξ1 = US${} ({} wei/gas)", usd_per_eth, wei_per_gas);
+				U256::from_dec_str(&format!("{:.0}", wei_per_gas)).unwrap()
+			}
+		}
 	}
 
 	fn extra_data(&self) -> Bytes {

parity/price_info.rs

@@ -0,0 +1,39 @@
+use rustc_serialize::json::Json;
+use std::io::Read;
+use hyper::Client;
+use hyper::header::Connection;
+use std::str::FromStr;
+
+pub struct PriceInfo {
+	pub ethusd: f32,
+}
+
+impl PriceInfo {
+	pub fn get() -> Option<PriceInfo> {
+		let mut body = String::new();
+		// TODO: actually bother dicking around with the errors and make it proper.
+		match match match Client::new()
+			.get("http://api.etherscan.io/api?module=stats&action=ethprice")
+			.header(Connection::close())
+			.send() {
+			Err(_) => { return None; },
+			Ok(mut s) => s.read_to_string(&mut body),
+		} {
+			Err(_) => { return None; },
+			_ => { Json::from_str(&body) }
+		} {
+			Err(_) => { return None; },
+			Ok(json) => {
+				let ethusd: f32 = if let Some(&Json::String(ref s)) = json.find_path(&["result", "ethusd"]) {
+					FromStr::from_str(&s).unwrap()
+				} else {
+					return None;
+				};
+				Some(PriceInfo {
+					ethusd: ethusd,
+				})
+			}
+		}
+	}
+}
+