Add reading of decimals from Token Mint account data, and implement i…

…t in MarketBuilder

src/main/java/org/p2p/solanaj/serum/Market.java

@@ -34,6 +34,26 @@ public class Market {
     private OrderBook bidOrderBook;
     private OrderBook askOrderBook;
 
+    // Data from token mints
+    private byte baseDecimals;
+    private byte quoteDecimals;
+
+    public byte getBaseDecimals() {
+        return baseDecimals;
+    }
+
+    public void setBaseDecimals(byte baseDecimals) {
+        this.baseDecimals = baseDecimals;
+    }
+
+    public byte getQuoteDecimals() {
+        return quoteDecimals;
+    }
+
+    public void setQuoteDecimals(byte quoteDecimals) {
+        this.quoteDecimals = quoteDecimals;
+    }
+
     public OrderBook getBidOrderBook() {
         return bidOrderBook;
     }
@@ -299,6 +319,10 @@ public String toString() {
                 ", quoteLotSize=" + quoteLotSize +
                 ", feeRateBps=" + feeRateBps +
                 ", referrerRebatesAccrued=" + referrerRebatesAccrued +
+                ", bidOrderBook=" + bidOrderBook +
+                ", askOrderBook=" + askOrderBook +
+                ", baseDecimals=" + baseDecimals +
+                ", quoteDecimals=" + quoteDecimals +
                 '}';
     }
 }

src/main/java/org/p2p/solanaj/serum/MarketBuilder.java

@@ -8,6 +8,7 @@
 
 import java.util.Base64;
 import java.util.List;
+import java.util.logging.Logger;
 
 /**
  * Builds a {@link Market} object, which can have polled data including bid/ask {@link OrderBook}s
@@ -17,6 +18,10 @@ public class MarketBuilder {
     private final RpcClient client = new RpcClient(Cluster.MAINNET);
     private PublicKey publicKey;
     private boolean retrieveOrderbooks = false;
+    private static final Logger LOGGER = Logger.getLogger(MarketBuilder.class.getName());
+
+    // TODO move all publickey consts to it's own static class
+    private static final PublicKey WRAPPED_SOL_MINT = new PublicKey("So11111111111111111111111111111111111111112");
 
     public MarketBuilder setRetrieveOrderBooks(boolean retrieveOrderbooks) {
         this.retrieveOrderbooks = retrieveOrderbooks;
@@ -31,7 +36,7 @@ public Market build() {
         Market market = new Market();
 
         // Get account Info
-        byte[] base64AccountInfo = getAccountData();
+        byte[] base64AccountInfo = retrieveAccountData();
 
         // Read market
         if (base64AccountInfo == null) {
@@ -42,33 +47,56 @@ public Market build() {
 
         // Get Order books
         if (retrieveOrderbooks) {
-            byte[] base64BidOrderbook = getOrderbookData(market.getBids());
-            byte[] base64AskOrderbook = getOrderbookData(market.getAsks());
+            // TODO - multi-thread these
+            // Data from the order books
+            byte[] base64BidOrderbook = retrieveAccountData(market.getBids());
+            byte[] base64AskOrderbook = retrieveAccountData(market.getAsks());
 
             OrderBook bidOrderBook = OrderBook.readOrderBook(base64BidOrderbook);
             OrderBook askOrderBook = OrderBook.readOrderBook(base64AskOrderbook);
 
             market.setBidOrderBook(bidOrderBook);
             market.setAskOrderBook(askOrderBook);
+
+            // Data from the token mints
+            // TODO - multi-thread these
+            byte baseDecimals = getMintDecimals(market.getBaseMint());
+            byte quoteDecimals = getMintDecimals(market.getQuoteMint());
+
+            LOGGER.info(String.format("Base decimals = %d", baseDecimals));
+            LOGGER.info(String.format("Quote decimals = %d", quoteDecimals));
+
+            market.setBaseDecimals(baseDecimals);
+            market.setQuoteDecimals(quoteDecimals);
         }
 
         return market;
     }
 
-    private byte[] getAccountData() {
-        AccountInfo accountInfo = null;
-        try {
-            accountInfo = client.getApi().getAccountInfo(publicKey);
-        } catch (RpcException e) {
-            e.printStackTrace();
+    /**
+     * Retrieves decimals for a given Token Mint's {@link PublicKey} from Solana account data.
+     * @param tokenMint
+     * @return
+     */
+    private byte getMintDecimals(PublicKey tokenMint) {
+        if (tokenMint.equals(WRAPPED_SOL_MINT)) {
+            return 9;
         }
 
-        final List<String> accountData = accountInfo.getValue().getData();
+        // RPC call to get mint's account data into decoded bytes (already base64 decoded)
+        byte[] accountData = retrieveAccountData(tokenMint);
 
-        return Base64.getDecoder().decode(accountData.get(0));
+        // Deserialize accountData into the MINT_LAYOUT enum
+        byte decimals = SerumUtils.readDecimalsFromTokenMintData(accountData);
+
+        return decimals;
+    }
+
+    private byte[] retrieveAccountData() {
+        return retrieveAccountData(publicKey);
     }
 
-    private byte[] getOrderbookData(PublicKey publicKey) {
+    private byte[] retrieveAccountData(PublicKey publicKey) {
         AccountInfo orderBook = null;
 
         try {

src/main/java/org/p2p/solanaj/serum/SerumUtils.java

@@ -4,6 +4,7 @@
 import org.p2p.solanaj.core.PublicKey;
 
 import java.nio.ByteBuffer;
+import java.util.logging.Logger;
 
 /**
  * version 2 market offsets.
@@ -41,6 +42,9 @@
  */
 public class SerumUtils {
 
+    private static final Logger LOGGER = Logger.getLogger(SerumUtils.class.getName());
+
+    // Market
     public static final int OWN_ADDRESS_OFFSET = 13;
     private static final int VAULT_SIGNER_NONCE_OFFSET = 28;
     private static final int BASE_MINT_OFFSET = 53;
@@ -61,8 +65,8 @@ public class SerumUtils {
     private static final int FEE_RATE_BPS_OFFSET = 365;
     private static final int REFERRER_REBATES_ACCRUED_OFFSET = 373;
 
-
-
+    // Token mint
+    private static final int TOKEN_MINT_DECIMALS_OFFSET = 44;
 
     public static PublicKey readOwnAddressPubkey(byte[] bytes) {
         return PublicKey.readPubkey(bytes, OWN_ADDRESS_OFFSET);
@@ -183,4 +187,24 @@ public static void writeClientId(ByteBuffer result, long clientId) {
     public static void writeLimit(ByteBuffer result) {
         result.putShort(49, (short) 65535);
     }
+
+    /**
+     * Reads the decimals value from decoded account data of a given token mint
+     *
+     * Note: MINT_LAYOUT = struct([blob(44), u8('decimals'), blob(37)]);
+     *
+     * 0-43 = other data
+     * index 44 = the single byte of decimals we want
+     * 45-... = other data
+     *
+     * @param accountData decoded account data from the token mint
+     * @return int containing the number of decimals in the token mint
+     */
+    public static byte readDecimalsFromTokenMintData(byte[] accountData) {
+        // Read a SINGLE byte at offset 44
+        byte result = accountData[TOKEN_MINT_DECIMALS_OFFSET];
+        LOGGER.info(String.format("Market decimals byte = %d", result));
+
+        return result;
+    }
 }

src/test/java/org/p2p/solanaj/core/MainnetTest.java

@@ -160,7 +160,7 @@ public void testPriceDeserialization() {
      */
     @Test
     public void marketBuilderSolUsdcTest() {
-        final PublicKey solUsdcPublicKey = new PublicKey("7xMDbYTCqQEcK2aM9LbetGtNFJpzKdfXzLL5juaLh4GJ");;
+        final PublicKey solUsdcPublicKey = new PublicKey("9wFFyRfZBsuAha4YcuxcXLKwMxJR43S7fPfQLusDBzvT");;
 
         final Market solUsdcMarket = new MarketBuilder()
                 .setPublicKey(solUsdcPublicKey)