Add a verbose callback with access to solana account data (#38)

* Add verbose callbacks

* update example

* updates

* remove unused imports

* bump version

Co-authored-by: Jayant Krishnamurthy <[email protected]>
Co-authored-by: Daniel Chew <[email protected]>

Author: 3 people

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## 2.8.0
+- Added `onPriceChangeVerbose` callback to `PythConnection` to support getting account keys and slots on each price update.
+
 ## 2.7.2
 ### Changed
 - Added pythtest program key and cluster url

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@pythnetwork/client",
-  "version": "2.7.3",
+  "version": "2.8.0",
   "description": "Client for consuming Pyth price data",
   "homepage": "https://pyth.network",
   "main": "lib/index.js",

src/PythConnection.ts

@@ -1,29 +1,35 @@
-import { Connection, PublicKey, clusterApiUrl, Cluster, Commitment, AccountInfo, Account } from '@solana/web3.js'
+import { Connection, PublicKey, Commitment, AccountInfo } from '@solana/web3.js'
 import {
-  Base,
-  Magic,
-  parseMappingData,
   parseBaseData,
   parsePriceData,
   parseProductData,
-  Price,
   PriceData,
   Product,
   ProductData,
-  Version,
   AccountType,
-  MAX_SLOT_DIFFERENCE,
-  PriceStatus,
 } from './index'
 
 const ONES = '11111111111111111111111111111111'
 
+/** An update to the content of the solana account at `key` that occurred at `slot`. */
+export type AccountUpdate<T> = {
+  key: PublicKey
+  accountInfo: AccountInfo<T>
+  slot: number
+}
+
 /**
  * Type of callback invoked whenever a pyth price account changes. The callback additionally
- * gets access product, which contains the metadata for this price account (e.g., that the symbol is "BTC/USD")
+ * gets `product`, which contains the metadata for this price account (e.g., that the symbol is "BTC/USD")
  */
 export type PythPriceCallback = (product: Product, price: PriceData) => void
 
+/**
+ * A price callback that additionally includes the raw solana account information. Use this if you need
+ * access to account keys and such.
+ */
+export type PythVerbosePriceCallback = (product: AccountUpdate<ProductData>, price: AccountUpdate<PriceData>) => void
+
 /**
  * Reads Pyth price data from a solana web3 connection. This class uses a callback-driven model,
  * similar to the solana web3 methods for tracking updates to accounts.
@@ -33,22 +39,29 @@ export class PythConnection {
   pythProgramKey: PublicKey
   commitment: Commitment
 
-  productAccountKeyToProduct: Record<string, Product> = {}
+  productAccountKeyToProduct: Record<string, AccountUpdate<ProductData>> = {}
   priceAccountKeyToProductAccountKey: Record<string, string> = {}
 
-  callbacks: PythPriceCallback[] = []
+  callbacks: PythVerbosePriceCallback[] = []
 
-  private handleProductAccount(key: PublicKey, account: AccountInfo<Buffer>) {
-    const { priceAccountKey, type, product } = parseProductData(account.data)
-    this.productAccountKeyToProduct[key.toString()] = product
-    if (priceAccountKey.toString() !== ONES) {
-      this.priceAccountKeyToProductAccountKey[priceAccountKey.toString()] = key.toString()
+  private handleProductAccount(key: PublicKey, account: AccountInfo<Buffer>, slot: number) {
+    const productData = parseProductData(account.data)
+    this.productAccountKeyToProduct[key.toString()] = {
+      key,
+      slot,
+      accountInfo: {
+        ...account,
+        data: productData,
+      },
+    }
+    if (productData.priceAccountKey.toString() !== ONES) {
+      this.priceAccountKeyToProductAccountKey[productData.priceAccountKey.toString()] = key.toString()
     }
   }
 
   private handlePriceAccount(key: PublicKey, account: AccountInfo<Buffer>, slot: number) {
-    const product = this.productAccountKeyToProduct[this.priceAccountKeyToProductAccountKey[key.toString()]]
-    if (product === undefined) {
+    const productUpdate = this.productAccountKeyToProduct[this.priceAccountKeyToProductAccountKey[key.toString()]]
+    if (productUpdate === undefined) {
       // This shouldn't happen since we're subscribed to all of the program's accounts,
       // but let's be good defensive programmers.
       throw new Error(
@@ -57,9 +70,17 @@ export class PythConnection {
     }
 
     const priceData = parsePriceData(account.data, slot)
+    const priceUpdate = {
+      key,
+      slot,
+      accountInfo: {
+        ...account,
+        data: priceData,
+      },
+    }
 
     for (const callback of this.callbacks) {
-      callback(product, priceData)
+      callback(productUpdate, priceUpdate)
     }
   }
 
@@ -72,7 +93,7 @@ export class PythConnection {
           // We can skip these because we're going to get every account owned by this program anyway.
           break
         case AccountType.Product:
-          this.handleProductAccount(key, account)
+          this.handleProductAccount(key, account, slot)
           break
         case AccountType.Price:
           if (!productOnly) {
@@ -117,6 +138,11 @@ export class PythConnection {
 
   /** Register callback to receive price updates. */
   public onPriceChange(callback: PythPriceCallback) {
+    this.callbacks.push((product, price) => callback(product.accountInfo.data.product, price.accountInfo.data))
+  }
+
+  /** Register a verbose callback to receive price updates. */
+  public onPriceChangeVerbose(callback: PythVerbosePriceCallback) {
     this.callbacks.push(callback)
   }
 

src/example_ws_usage.ts

@@ -3,12 +3,15 @@ import { PythConnection } from './PythConnection'
 import { getPythClusterApiUrl, getPythProgramKeyForCluster, PythCluster } from './cluster'
 import { PriceStatus } from '.'
 
-const SOLANA_CLUSTER_NAME: PythCluster = 'mainnet-beta'
+const SOLANA_CLUSTER_NAME: PythCluster = 'devnet'
 const connection = new Connection(getPythClusterApiUrl(SOLANA_CLUSTER_NAME))
 const pythPublicKey = getPythProgramKeyForCluster(SOLANA_CLUSTER_NAME)
 
 const pythConnection = new PythConnection(connection, pythPublicKey)
-pythConnection.onPriceChange((product, price) => {
+pythConnection.onPriceChangeVerbose((productAccount, priceAccount) => {
+  // The arguments to the callback include solana account information / the update slot if you need it.
+  const product = productAccount.accountInfo.data.product;
+  const price = priceAccount.accountInfo.data;
   // sample output:
   // SRM/USD: $8.68725 ±$0.0131
   if (price.price && price.confidence) {