Add eth price example (#9)

* Add eth price example

Author: ali-behjati

pyth-sdk-solana/README.md

@@ -43,7 +43,7 @@ The pyth.network website also lists the public keys of the accounts (e.g., [Cryp
 This crate provides utilities for interpreting and manipulating the content of these accounts.
 Applications can obtain the content of these accounts in two different ways:
 * On-chain programs should pass these accounts to the instructions that require price feeds.
-* Off-chain programs can access these accounts using the Solana RPC client (as in the [example program](examples/get_accounts.rs)).
+* Off-chain programs can access these accounts using the Solana RPC client (as in the [eth price example program](examples/eth_price.rs)).
 
 In both cases, the content of the account will be provided to the application as a binary blob (`Vec<u8>`).
 The examples below assume that the user has already obtained this account data.
@@ -139,6 +139,23 @@ Run the following commands to try this example program:
 
 ```
 cargo build --examples
+cargo run --example eth_price
+```
+
+The output of this command is price of ETH/USD over time, such as:
+
+```
+.....ETH/USD.....
+status .......... Trading
+num_publishers .. 19
+price ........... 291958500000 x 10^-8
+conf ............ 163920000 x 10^-8
+twap ............ 291343470000 x 10^-8
+twac ............ 98874533 x 10^-8
+```
+
+For an example of using Solana Account structure please run:
+```
 cargo run --example get_accounts
 ```
 

pyth-sdk-solana/examples/eth_price.rs

@@ -0,0 +1,58 @@
+// example usage of reading pyth price from solana price account
+
+use pyth_sdk_solana::load_price;
+use solana_client::rpc_client::RpcClient;
+use solana_program::pubkey::Pubkey;
+use std::str::FromStr;
+use std::{
+    thread,
+    time,
+};
+
+
+fn main() {
+    let url = "http://api.mainnet-beta.solana.com";
+    // Pyth eth/usd price account on mainnet. can be found from https://pyth.network
+    let key = "JBu1AL4obBcCMqKBBxhpWCNUt136ijcuMZLFvTP7iWdB";
+    let clnt = RpcClient::new(url.to_string());
+    let eth_price_key = Pubkey::from_str(key).unwrap();
+
+    loop {
+        // get price data from key
+        let eth_price_data = clnt.get_account_data(&eth_price_key).unwrap();
+        let eth_price = load_price(&eth_price_data).unwrap();
+
+        println!(".....ETH/USD.....");
+        println!("status .......... {:?}", eth_price.status);
+        println!("num_publishers .. {}", eth_price.num_publishers);
+
+        let maybe_price = eth_price.get_current_price();
+        match maybe_price {
+            Some(p) => {
+                println!("price ........... {} x 10^{}", p.price, p.expo);
+                println!("conf ............ {} x 10^{}", p.conf, p.expo);
+            }
+            None => {
+                println!("price ........... unavailable");
+                println!("conf ............ unavailable");
+            }
+        }
+
+
+        let maybe_twap = eth_price.get_twap();
+        match maybe_twap {
+            Some(twap) => {
+                println!("twap ............ {} x 10^{}", twap.price, twap.expo);
+                println!("twac ............ {} x 10^{}", twap.conf, twap.expo);
+            }
+            None => {
+                println!("twap ............ unavailable");
+                println!("twac ............ unavailable");
+            }
+        }
+
+        println!("");
+
+        thread::sleep(time::Duration::from_secs(1));
+    }
+}