feat: add support for getSupply RPC method

web3.js/module.d.ts

@@ -173,6 +173,13 @@ declare module '@solana/web3.js' {
     firstNormalSlot: number;
   };
 
+  export type Supply = {
+    total: number;
+    circulating: number;
+    nonCirculating: number;
+    nonCirculatingAccounts: Array<PublicKey>;
+  };
+
   export type VoteAccountStatus = {
     current: Array<VoteAccountInfo>;
     delinquent: Array<VoteAccountInfo>;
@@ -200,6 +207,7 @@ declare module '@solana/web3.js' {
     getBalance(publicKey: PublicKey, commitment?: Commitment): Promise<number>;
     getBlockTime(slot: number): Promise<number | null>;
     getMinimumLedgerSlot(): Promise<number>;
+    getSupply(commitment?: Commitment): Promise<RpcResponseAndContext<Supply>>;
     getClusterNodes(): Promise<Array<ContactInfo>>;
     getConfirmedBlock(slot: number): Promise<ConfirmedBlock>;
     getConfirmedTransaction(

web3.js/module.flow.js

@@ -186,6 +186,13 @@ declare module '@solana/web3.js' {
     absoluteSlot: number,
   };
 
+  declare export type Supply = {
+    total: number,
+    circulating: number,
+    nonCirculating: number,
+    nonCirculatingAccounts: Array<PublicKey>,
+  };
+
   declare export type VoteAccountStatus = {
     current: Array<VoteAccountInfo>,
     delinquent: Array<VoteAccountInfo>,
@@ -213,6 +220,7 @@ declare module '@solana/web3.js' {
     getBalance(publicKey: PublicKey, commitment: ?Commitment): Promise<number>;
     getBlockTime(slot: number): Promise<number | null>;
     getMinimumLedgerSlot(): Promise<number>;
+    getSupply(commitment: ?Commitment): Promise<RpcResponseAndContext<Supply>>;
     getClusterNodes(): Promise<Array<ContactInfo>>;
     getConfirmedBlock(slot: number): Promise<ConfirmedBlock>;
     getConfirmedTransaction(

web3.js/src/connection.js

@@ -403,6 +403,34 @@ const MinimumLedgerSlotRpcResult = struct({
   result: 'number',
 });
 
+/**
+ * Supply
+ *
+ * @typedef {Object} Supply
+ * @property {number} total Total supply in lamports
+ * @property {number} circulating Circulating supply in lamports
+ * @property {number} nonCirculating Non-circulating supply in lamports
+ * @property {Array<PublicKey>} nonCirculatingAccounts List of non-circulating account addresses
+ */
+type Supply = {
+  total: number,
+  circulating: number,
+  nonCirculating: number,
+  nonCirculatingAccounts: Array<PublicKey>,
+};
+
+/**
+ * Expected JSON RPC response for the "getSupply" message
+ */
+const GetSupplyRpcResult = jsonRpcResultAndContext(
+  struct({
+    total: 'number',
+    circulating: 'number',
+    nonCirculating: 'number',
+    nonCirculatingAccounts: struct.array(['string']),
+  }),
+);
+
 /**
  * Expected JSON RPC response for the "getVersion" message
  */
@@ -1016,6 +1044,25 @@ export class Connection {
     return res.result;
   }
 
+  /**
+   * Fetch information about the current supply
+   */
+  async getSupply(
+    commitment: ?Commitment,
+  ): Promise<RpcResponseAndContext<Supply>> {
+    const args = this._argsWithCommitment([], commitment);
+    const unsafeRes = await this._rpcRequest('getSupply', args);
+    const res = GetSupplyRpcResult(unsafeRes);
+    if (res.error) {
+      throw new Error('failed to get supply: ' + res.error.message);
+    }
+    assert(typeof res.result !== 'undefined');
+    res.result.value.nonCirculatingAccounts = res.result.value.nonCirculatingAccounts.map(
+      account => new PublicKey(account),
+    );
+    return res.result;
+  }
+
   /**
    * Fetch all the account info for the specified public key, return with context
    */

web3.js/test/connection.test.js

@@ -1109,6 +1109,38 @@ test('get minimum ledger slot', async () => {
   expect(minimumLedgerSlot).toBeGreaterThanOrEqual(0);
 });
 
+test('get supply', async () => {
+  const connection = new Connection(url);
+
+  mockRpc.push([
+    url,
+    {
+      method: 'getSupply',
+      params: [],
+    },
+    {
+      error: null,
+      result: {
+        context: {
+          slot: 1,
+        },
+        value: {
+          total: 1000,
+          circulating: 100,
+          nonCirculating: 900,
+          nonCirculatingAccounts: [new Account().publicKey.toBase58()],
+        },
+      },
+    },
+  ]);
+
+  const supply = (await connection.getSupply()).value;
+  expect(supply.total).toBeGreaterThan(0);
+  expect(supply.circulating).toBeGreaterThan(0);
+  expect(supply.nonCirculating).toBeGreaterThan(0);
+  expect(supply.nonCirculatingAccounts.length).toBeGreaterThan(0);
+});
+
 test('getVersion', async () => {
   const connection = new Connection(url);