feat: add pollTransaction method to SorobanServer to poll transaction status with retry strategy.

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Pending
 
+### Update:
+- feat: add `pollTransaction` method to `SorobanServer` to poll transaction status with retry strategy. ([#696](https://github.com/stellar/java-stellar-sdk/pull/696))
+
 ## 1.5.0
 
 ### Update:

src/main/java/org/stellar/sdk/SorobanServer.java

@@ -14,6 +14,7 @@
 import java.util.Optional;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
+import java.util.function.IntFunction;
 import okhttp3.HttpUrl;
 import okhttp3.MediaType;
 import okhttp3.OkHttpClient;
@@ -298,6 +299,63 @@ public GetTransactionResponse getTransaction(String hash) {
         "getTransaction", params, new TypeToken<SorobanRpcResponse<GetTransactionResponse>>() {});
   }
 
+  /**
+   * An alias for {@link #pollTransaction(String, int, SleepStrategy)} with default parameters,
+   * which {@code maxAttempts} is set to 30, and the sleep strategy is set to a default strategy
+   * that sleeps for 1 second between attempts.
+   *
+   * @param hash The hash of the transaction to poll for.
+   * @return A {@link GetTransactionResponse} object after a "found" response, (which may be success
+   *     or failure) or the last response obtained after polling the maximum number of specified
+   *     attempts.
+   * @throws InterruptedException If the thread is interrupted while sleeping between attempts.
+   */
+  public GetTransactionResponse pollTransaction(String hash) throws InterruptedException {
+    return pollTransaction(
+        hash,
+        30,
+        attempt -> {
+          return 1_000L;
+        });
+  }
+
+  /**
+   * Polls the transaction status until it is completed or the maximum number of attempts is
+   * reached.
+   *
+   * <p>After submitting a transaction, clients can use this to poll for transaction completion and
+   * return a definitive state of success or failure.
+   *
+   * @param hash The hash of the transaction to poll for.
+   * @param maxAttempts The number of attempts to make before returning the last-seen status.
+   * @param sleepStrategy A strategy to determine the sleep duration between attempts. It should
+   *     take the current attempt number and return the sleep duration in milliseconds.
+   * @return A {@link GetTransactionResponse} object after a "found" response, (which may be success
+   *     or failure) or the last response obtained after polling the maximum number of specified
+   *     attempts.
+   * @throws IllegalArgumentException If maxAttempts is less than or equal to 0.
+   * @throws InterruptedException If the thread is interrupted while sleeping between attempts.
+   */
+  public GetTransactionResponse pollTransaction(
+      String hash, int maxAttempts, SleepStrategy sleepStrategy) throws InterruptedException {
+    if (maxAttempts <= 0) {
+      throw new IllegalArgumentException("maxAttempts must be greater than 0");
+    }
+
+    int attempts = 0;
+    GetTransactionResponse getTransactionResponse = null;
+    while (attempts < maxAttempts) {
+      getTransactionResponse = getTransaction(hash);
+      if (!GetTransactionResponse.GetTransactionStatus.NOT_FOUND.equals(
+          getTransactionResponse.getStatus())) {
+        return getTransactionResponse;
+      }
+      attempts++;
+      TimeUnit.MILLISECONDS.sleep(sleepStrategy.apply(attempts));
+    }
+    return getTransactionResponse;
+  }
+
   /**
    * Gets a detailed list of transactions starting from the user specified starting point that you
    * can paginate as long as the pages fall within the history retention of their corresponding RPC
@@ -754,4 +812,11 @@ public enum Durability {
     TEMPORARY,
     PERSISTENT
   }
+
+  /** Strategy for sleeping between retries in a retry loop. */
+  @FunctionalInterface
+  public interface SleepStrategy extends IntFunction<Long> {
+    // apply as in apply(iterationNumber) -> millisecondsToSleep
+    Long apply(int iteration);
+  }
 }

src/test/java/org/stellar/sdk/SorobanServerTest.java

@@ -514,6 +514,54 @@ public MockResponse dispatch(@NotNull RecordedRequest recordedRequest)
     mockWebServer.close();
   }
 
+  @Test
+  public void testPollTransaction() throws IOException, SorobanRpcException, InterruptedException {
+    String txSuccessFilePath = "src/test/resources/soroban_server/get_transaction.json";
+    String txNotFoundFilePath = "src/test/resources/soroban_server/get_transaction_not_found.json";
+    String txSuccessJson = new String(Files.readAllBytes(Paths.get(txSuccessFilePath)));
+    String txNotFoundJson = new String(Files.readAllBytes(Paths.get(txNotFoundFilePath)));
+    String hash = "06dd9ee70bf93bbfe219e2b31363ab5a0361cc6285328592e4d3d1fed4c9025c";
+    MockWebServer mockWebServer = new MockWebServer();
+    Dispatcher dispatcher =
+        new Dispatcher() {
+          private int attempts = 0;
+
+          @NotNull
+          @Override
+          public MockResponse dispatch(@NotNull RecordedRequest recordedRequest)
+              throws InterruptedException {
+            GetTransactionRequest expectedRequest = new GetTransactionRequest(hash);
+            SorobanRpcRequest<GetTransactionRequest> sorobanRpcRequest =
+                gson.fromJson(
+                    recordedRequest.getBody().readUtf8(),
+                    new TypeToken<SorobanRpcRequest<GetTransactionRequest>>() {}.getType());
+            if ("POST".equals(recordedRequest.getMethod())
+                && sorobanRpcRequest.getMethod().equals("getTransaction")
+                && sorobanRpcRequest.getParams().equals(expectedRequest)) {
+              attempts++;
+              if (attempts > 3) {
+                return new MockResponse().setResponseCode(200).setBody(txSuccessJson);
+              } else {
+                return new MockResponse().setResponseCode(200).setBody(txNotFoundJson);
+              }
+            }
+            return new MockResponse().setResponseCode(404);
+          }
+        };
+    mockWebServer.setDispatcher(dispatcher);
+    mockWebServer.start();
+
+    HttpUrl baseUrl = mockWebServer.url("");
+    SorobanServer server = new SorobanServer(baseUrl.toString());
+    GetTransactionResponse tx = server.pollTransaction(hash);
+    assertEquals(tx.getStatus(), GetTransactionResponse.GetTransactionStatus.SUCCESS);
+    assertEquals(
+        tx.getTxHash(), "8faa3e6bb29d9d8469bbcabdbfd800f3be1899f4736a3a2fa83cd58617c072fe");
+
+    server.close();
+    mockWebServer.close();
+  }
+
   @Test
   public void testGetTransactions() throws IOException, SorobanRpcException {
     String filePath = "src/test/resources/soroban_server/get_transactions.json";

src/test/resources/soroban_server/get_transaction_not_found.json

@@ -0,0 +1,16 @@
+{
+  "jsonrpc": "2.0",
+  "id": "198cb1a8-9104-4446-a269-88bf000c2721",
+  "result": {
+    "latestLedger": 57612528,
+    "latestLedgerCloseTime": "1750300167",
+    "oldestLedger": 57491569,
+    "oldestLedgerCloseTime": "1749616481",
+    "status": "NOT_FOUND",
+    "txHash": "8faa3e6bb29d9d8469bbcabdbfd800f3be1899f4736a3a2fa83cd58617c072fe",
+    "applicationOrder": 0,
+    "feeBump": false,
+    "ledger": 0,
+    "createdAt": "0"
+  }
+}