feat(DocumentUploadQueue): add configurable batch size infrastructure

src/main/java/com/coveo/pushapiclient/DocumentUploadQueue.java

@@ -8,21 +8,118 @@
 /** Represents a queue for uploading documents using a specified upload strategy */
 class DocumentUploadQueue {
   private static final Logger logger = LogManager.getLogger(DocumentUploadQueue.class);
-  protected final UploadStrategy uploader;
-  protected final int maxQueueSize = 5 * 1024 * 1024;
+
+  /** Maximum allowed queue size based on Stream API limit (256 MB) */
+  protected static final int MAX_ALLOWED_QUEUE_SIZE = 256 * 1024 * 1024;
+
+  /** Default queue size (5 MB) */
+  protected static final int DEFAULT_QUEUE_SIZE = 5 * 1024 * 1024;
+
+  /** System property name for configuring the default batch size */
+  public static final String BATCH_SIZE_PROPERTY = "coveo.push.batchSize";
+
+  protected UploadStrategy uploader;
+  protected final int maxQueueSize;
   protected ArrayList<DocumentBuilder> documentToAddList;
   protected ArrayList<DeleteDocument> documentToDeleteList;
   protected int size;
 
   /**
-   * Constructs a new DocumentUploadQueue object with a default maximum queue size limit of 5MB.
+   * Validates batch size against constraints (> 0 and <= 256MB). Used by getConfiguredBatchSize and
+   * constructors to ensure consistent validation logic.
+   *
+   * @param sizeBytes The batch size in bytes to validate
+   * @throws IllegalArgumentException if size exceeds MAX_ALLOWED_QUEUE_SIZE or is <= 0
+   */
+  protected static void validateBatchSize(int sizeBytes) {
+    if (sizeBytes > MAX_ALLOWED_QUEUE_SIZE) {
+      throw new IllegalArgumentException(
+          String.format(
+              "Batch size (%d bytes) exceeds the Stream API limit of %d bytes (%d MB)",
+              sizeBytes, MAX_ALLOWED_QUEUE_SIZE, MAX_ALLOWED_QUEUE_SIZE / (1024 * 1024)));
+    }
+    if (sizeBytes <= 0) {
+      throw new IllegalArgumentException("Batch size must be greater than 0");
+    }
+  }
+
+  /**
+   * Gets the configured batch size from system properties, or returns the default if not set.
+   *
+   * <p>The system property is read as bytes. When not set, returns DEFAULT_QUEUE_SIZE (5 MB).
+   *
+   * <p>Example: Set a 50 MB batch size via system property:
+   *
+   * <pre>
+   *   java -Dcoveo.push.batchSize=52428800 -jar app.jar  // 50 * 1024 * 1024 bytes
+   * </pre>
+   *
+   * @return The configured batch size in bytes (e.g., 52428800 for 50 MB)
+   * @throws IllegalArgumentException if the configured value exceeds 256MB or is invalid
+   */
+  public static int getConfiguredBatchSize() {
+    String propertyValue = System.getProperty(BATCH_SIZE_PROPERTY);
+    if (propertyValue == null || propertyValue.trim().isEmpty()) {
+      return DEFAULT_QUEUE_SIZE;
+    }
+
+    int configuredSize;
+    try {
+      configuredSize = Integer.parseInt(propertyValue.trim());
+    } catch (NumberFormatException e) {
+      throw new IllegalArgumentException(
+          String.format(
+              "Invalid value for system property %s: '%s'. Must be a valid integer.",
+              BATCH_SIZE_PROPERTY, propertyValue),
+          e);
+    }
+
+    validateBatchSize(configuredSize);
+
+    logger.info(
+        String.format(
+            "Using configured batch size from system property %s: %d bytes (%.2f MB)",
+            BATCH_SIZE_PROPERTY, configuredSize, configuredSize / (1024.0 * 1024.0)));
+    return configuredSize;
+  }
+
+  /**
+   * Constructs a new DocumentUploadQueue with the default batch size.
+   *
+   * <p>Uses the configured batch size from system property "coveo.push.batchSize" if set, otherwise
+   * defaults to DEFAULT_QUEUE_SIZE (5 MB = 5242880 bytes).
    *
    * @param uploader The upload strategy to be used for document uploads.
+   * @throws IllegalArgumentException if the system property value exceeds 256MB or is invalid.
    */
   public DocumentUploadQueue(UploadStrategy uploader) {
+    this(uploader, getConfiguredBatchSize());
+  }
+
+  /**
+   * Constructs a new DocumentUploadQueue object with a configurable maximum queue size limit.
+   *
+   * @param uploader The upload strategy to be used for document uploads.
+   * @param maxQueueSize The maximum queue size in bytes (e.g., 52428800 for 50 MB). Must not exceed
+   *     256MB (Stream API limit).
+   * @throws IllegalArgumentException if maxQueueSize exceeds the API limit of 256MB.
+   */
+  public DocumentUploadQueue(UploadStrategy uploader, int maxQueueSize) {
+    validateBatchSize(maxQueueSize);
     this.documentToAddList = new ArrayList<>();
     this.documentToDeleteList = new ArrayList<>();
     this.uploader = uploader;
+    this.maxQueueSize = maxQueueSize;
+  }
+
+  /**
+   * Default constructor for testing purposes (used by Mockito @InjectMocks). Initializes with
+   * default batch size; uploader is injected by Mockito.
+   */
+  public DocumentUploadQueue() {
+    this.documentToAddList = new ArrayList<>();
+    this.documentToDeleteList = new ArrayList<>();
+    this.maxQueueSize = DEFAULT_QUEUE_SIZE;
   }
 
   /**

src/test/java/com/coveo/pushapiclient/DocumentUploadQueueTest.java

@@ -12,37 +12,31 @@
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
-import org.mockito.InjectMocks;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
 public class DocumentUploadQueueTest {
 
-  @Mock private UploadStrategy uploadStrategy;
+  private static final int TEST_BATCH_SIZE = 5 * 1024 * 1024;
 
-  @InjectMocks private DocumentUploadQueue queue;
+  @Mock private UploadStrategy uploadStrategy;
 
+  private DocumentUploadQueue queue;
   private AutoCloseable closeable;
   private DocumentBuilder documentToAdd;
   private DeleteDocument documentToDelete;
 
   private int oneMegaByte = 1 * 1024 * 1024;
 
   private String generateStringFromBytes(int numBytes) {
-    // Check if the number of bytes is valid
     if (numBytes <= 0) {
       return "";
     }
-
-    // Create a byte array with the specified length
     byte[] bytes = new byte[numBytes];
-
-    // Fill the byte array with a pattern of ASCII characters
-    byte pattern = 65; // ASCII value for 'A'
+    byte pattern = 65;
     for (int i = 0; i < numBytes; i++) {
       bytes[i] = pattern;
     }
-
     return new String(bytes);
   }
 
@@ -53,15 +47,17 @@ private DocumentBuilder generateDocumentFromSize(int numBytes) {
 
   @Before
   public void setup() {
+    closeable = MockitoAnnotations.openMocks(this);
+
+    queue = new DocumentUploadQueue(uploadStrategy, TEST_BATCH_SIZE);
+
     String twoMegaByteData = generateStringFromBytes(2 * oneMegaByte);
 
     documentToAdd =
         new DocumentBuilder("https://my.document.uri?ref=1", "My new document")
             .withData(twoMegaByteData);
 
     documentToDelete = new DeleteDocument("https://my.document.uri?ref=3");
-
-    closeable = MockitoAnnotations.openMocks(this);
   }
 
   @After