Prepare bolts to be safe to use it from Kotlin

Summary:
In this diff I analyzed bolts library to ensure it's ready to be used from kotlin.
I won't convert bolts to kotlin, but this is necessary to be able to convert its callsites (ReactHost) to kotlin

bypass-github-export-checks

changelog: [internal] internal

Reviewed By: fkgozali

Differential Revision: D46194127

fbshipit-source-id: 609e356230b1c87fe26571b811d23430d0168276

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/AggregateException.java

@@ -7,6 +7,8 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import java.io.PrintStream;
 import java.io.PrintWriter;
 import java.util.ArrayList;
@@ -24,7 +26,7 @@ public class AggregateException extends Exception {
 
   private static final String DEFAULT_MESSAGE = "There were multiple errors.";
 
-  private List<Throwable> innerThrowables;
+  @NonNull private final List<Throwable> innerThrowables;
 
   /**
    * Constructs a new {@code AggregateException} with the current stack trace, the specified detail
@@ -33,7 +35,7 @@ public class AggregateException extends Exception {
    * @param detailMessage The detail message for this exception.
    * @param innerThrowables The exceptions that are the cause of the current exception.
    */
-  public AggregateException(String detailMessage, Throwable[] innerThrowables) {
+  public AggregateException(@NonNull String detailMessage, @NonNull Throwable[] innerThrowables) {
     this(detailMessage, Arrays.asList(innerThrowables));
   }
 
@@ -44,11 +46,13 @@ public class AggregateException extends Exception {
    * @param detailMessage The detail message for this exception.
    * @param innerThrowables The exceptions that are the cause of the current exception.
    */
-  public AggregateException(String detailMessage, List<? extends Throwable> innerThrowables) {
+  public AggregateException(
+      @NonNull String detailMessage, @Nullable List<? extends Throwable> innerThrowables) {
     super(
         detailMessage,
         innerThrowables != null && innerThrowables.size() > 0 ? innerThrowables.get(0) : null);
-    this.innerThrowables = Collections.unmodifiableList(innerThrowables);
+    this.innerThrowables =
+        Collections.unmodifiableList(innerThrowables != null ? innerThrowables : new ArrayList<>());
   }
 
   /**
@@ -57,7 +61,7 @@ public class AggregateException extends Exception {
    *
    * @param innerThrowables The exceptions that are the cause of the current exception.
    */
-  public AggregateException(List<? extends Throwable> innerThrowables) {
+  public AggregateException(@Nullable List<? extends Throwable> innerThrowables) {
     this(DEFAULT_MESSAGE, innerThrowables);
   }
 
@@ -65,12 +69,12 @@ public class AggregateException extends Exception {
    * Returns a read-only {@link List} of the {@link Throwable} instances that caused the current
    * exception.
    */
-  public List<Throwable> getInnerThrowables() {
+  public @NonNull List<Throwable> getInnerThrowables() {
     return innerThrowables;
   }
 
   @Override
-  public void printStackTrace(PrintStream err) {
+  public void printStackTrace(@NonNull PrintStream err) {
     super.printStackTrace(err);
 
     int currentIndex = -1;
@@ -85,7 +89,7 @@ public class AggregateException extends Exception {
   }
 
   @Override
-  public void printStackTrace(PrintWriter err) {
+  public void printStackTrace(@NonNull PrintWriter err) {
     super.printStackTrace(err);
 
     int currentIndex = -1;
@@ -101,7 +105,7 @@ public class AggregateException extends Exception {
 
   /** @deprecated Please use {@link #getInnerThrowables()} instead. */
   @Deprecated
-  public List<Exception> getErrors() {
+  public @NonNull List<Exception> getErrors() {
     List<Exception> errors = new ArrayList<Exception>();
     if (innerThrowables == null) {
       return errors;
@@ -119,7 +123,7 @@ public class AggregateException extends Exception {
 
   /** @deprecated Please use {@link #getInnerThrowables()} instead. */
   @Deprecated
-  public Throwable[] getCauses() {
+  public @NonNull Throwable[] getCauses() {
     return innerThrowables.toArray(new Throwable[innerThrowables.size()]);
   }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/AndroidExecutors.java

@@ -11,6 +11,7 @@ import android.annotation.SuppressLint;
 import android.os.Build;
 import android.os.Handler;
 import android.os.Looper;
+import androidx.annotation.NonNull;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.LinkedBlockingQueue;
@@ -32,11 +33,12 @@ import java.util.concurrent.TimeUnit;
  * 0 and maxPoolSize is Integer.MAX_VALUE. This is dangerous because it can create an unchecked
  * amount of threads.
  */
-/* package */ final class AndroidExecutors {
+/* package */
+final class AndroidExecutors {
 
   private static final AndroidExecutors INSTANCE = new AndroidExecutors();
 
-  private final Executor uiThread;
+  @NonNull private final Executor uiThread;
 
   private AndroidExecutors() {
     uiThread = new UIThreadExecutor();
@@ -64,7 +66,7 @@ import java.util.concurrent.TimeUnit;
    *
    * @return the newly created thread pool
    */
-  public static ExecutorService newCachedThreadPool() {
+  public static @NonNull ExecutorService newCachedThreadPool() {
     ThreadPoolExecutor executor =
         new ThreadPoolExecutor(
             CORE_POOL_SIZE,
@@ -89,7 +91,7 @@ import java.util.concurrent.TimeUnit;
    * @param threadFactory the factory to use when creating new threads
    * @return the newly created thread pool
    */
-  public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
+  public static @NonNull ExecutorService newCachedThreadPool(@NonNull ThreadFactory threadFactory) {
     ThreadPoolExecutor executor =
         new ThreadPoolExecutor(
             CORE_POOL_SIZE,
@@ -114,21 +116,21 @@ import java.util.concurrent.TimeUnit;
    * @param value true if should time out, else false
    */
   @SuppressLint("NewApi")
-  public static void allowCoreThreadTimeout(ThreadPoolExecutor executor, boolean value) {
+  public static void allowCoreThreadTimeout(@NonNull ThreadPoolExecutor executor, boolean value) {
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
       executor.allowCoreThreadTimeOut(value);
     }
   }
 
   /** An {@link java.util.concurrent.Executor} that executes tasks on the UI thread. */
-  public static Executor uiThread() {
+  public static @NonNull Executor uiThread() {
     return INSTANCE.uiThread;
   }
 
   /** An {@link java.util.concurrent.Executor} that runs tasks on the UI thread. */
   private static class UIThreadExecutor implements Executor {
     @Override
-    public void execute(Runnable command) {
+    public void execute(@NonNull Runnable command) {
       new Handler(Looper.getMainLooper()).post(command);
     }
   }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/BoltsExecutors.java

@@ -7,6 +7,7 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.NonNull;
 import java.util.Locale;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
@@ -14,7 +15,8 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 
 /** Collection of {@link Executor}s to use in conjunction with {@link Task}. */
-/* package */ final class BoltsExecutors {
+/* package */
+final class BoltsExecutors {
 
   private static final BoltsExecutors INSTANCE = new BoltsExecutors();
 
@@ -26,9 +28,9 @@ import java.util.concurrent.ScheduledExecutorService;
     return javaRuntimeName.toLowerCase(Locale.US).contains("android");
   }
 
-  private final ExecutorService background;
-  private final ScheduledExecutorService scheduled;
-  private final Executor immediate;
+  private final @NonNull ExecutorService background;
+  private final @NonNull ScheduledExecutorService scheduled;
+  private final @NonNull Executor immediate;
 
   private BoltsExecutors() {
     background =
@@ -40,11 +42,11 @@ import java.util.concurrent.ScheduledExecutorService;
   }
 
   /** An {@link java.util.concurrent.Executor} that executes tasks in parallel. */
-  public static ExecutorService background() {
+  public static @NonNull ExecutorService background() {
     return INSTANCE.background;
   }
 
-  /* package */ static ScheduledExecutorService scheduled() {
+  /* package */ static @NonNull ScheduledExecutorService scheduled() {
     return INSTANCE.scheduled;
   }
 
@@ -53,7 +55,7 @@ import java.util.concurrent.ScheduledExecutorService;
    * stack runs too deep, at which point it will delegate to {@link BoltsExecutors#background} in
    * order to trim the stack.
    */
-  /* package */ static Executor immediate() {
+  /* package */ static @NonNull Executor immediate() {
     return INSTANCE.immediate;
   }
 
@@ -102,7 +104,7 @@ import java.util.concurrent.ScheduledExecutorService;
     }
 
     @Override
-    public void execute(Runnable command) {
+    public void execute(@NonNull Runnable command) {
       int depth = incrementDepth();
       try {
         if (depth <= MAX_DEPTH) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/CancellationToken.java

@@ -7,6 +7,7 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.NonNull;
 import java.util.Locale;
 import java.util.concurrent.CancellationException;
 
@@ -29,7 +30,7 @@ public class CancellationToken {
 
   private final CancellationTokenSource tokenSource;
 
-  /* package */ CancellationToken(CancellationTokenSource tokenSource) {
+  /* package */ CancellationToken(@NonNull CancellationTokenSource tokenSource) {
     this.tokenSource = tokenSource;
   }
 
@@ -49,7 +50,7 @@ public class CancellationToken {
    * @return a {@link CancellationTokenRegistration} instance that can be used to unregister the
    *     action.
    */
-  public CancellationTokenRegistration register(Runnable action) {
+  public @NonNull CancellationTokenRegistration register(@NonNull Runnable action) {
     return tokenSource.register(action);
   }
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/CancellationTokenRegistration.java

@@ -7,6 +7,8 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import java.io.Closeable;
 
 /**
@@ -17,12 +19,12 @@ import java.io.Closeable;
 public class CancellationTokenRegistration implements Closeable {
 
   private final Object lock = new Object();
-  private CancellationTokenSource tokenSource;
-  private Runnable action;
+  private @Nullable CancellationTokenSource tokenSource;
+  private @Nullable Runnable action;
   private boolean closed;
 
   /* package */ CancellationTokenRegistration(
-      CancellationTokenSource tokenSource, Runnable action) {
+      @NonNull CancellationTokenSource tokenSource, @NonNull Runnable action) {
     this.tokenSource = tokenSource;
     this.action = action;
   }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/CancellationTokenSource.java

@@ -7,6 +7,8 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import java.io.Closeable;
 import java.util.ArrayList;
 import java.util.List;
@@ -27,9 +29,9 @@ import java.util.concurrent.TimeUnit;
 public class CancellationTokenSource implements Closeable {
 
   private final Object lock = new Object();
-  private final List<CancellationTokenRegistration> registrations = new ArrayList<>();
-  private final ScheduledExecutorService executor = BoltsExecutors.scheduled();
-  private ScheduledFuture<?> scheduledCancellation;
+  private final @NonNull List<CancellationTokenRegistration> registrations = new ArrayList<>();
+  private final @NonNull ScheduledExecutorService executor = BoltsExecutors.scheduled();
+  @Nullable private ScheduledFuture<?> scheduledCancellation;
   private boolean cancellationRequested;
   private boolean closed;
 
@@ -48,7 +50,7 @@ public class CancellationTokenSource implements Closeable {
   }
 
   /** @return the token that can be passed to asynchronous method to control cancellation. */
-  public CancellationToken getToken() {
+  public @NonNull CancellationToken getToken() {
     synchronized (lock) {
       throwIfClosed();
       return new CancellationToken(this);
@@ -84,7 +86,7 @@ public class CancellationTokenSource implements Closeable {
     cancelAfter(delay, TimeUnit.MILLISECONDS);
   }
 
-  private void cancelAfter(long delay, TimeUnit timeUnit) {
+  private void cancelAfter(long delay, @NonNull TimeUnit timeUnit) {
     if (delay < -1) {
       throw new IllegalArgumentException("Delay must be >= -1");
     }
@@ -137,7 +139,8 @@ public class CancellationTokenSource implements Closeable {
     }
   }
 
-  /* package */ CancellationTokenRegistration register(Runnable action) {
+  /* package */ @NonNull
+  CancellationTokenRegistration register(@NonNull Runnable action) {
     CancellationTokenRegistration ctr;
     synchronized (lock) {
       throwIfClosed();
@@ -165,7 +168,7 @@ public class CancellationTokenSource implements Closeable {
     }
   }
 
-  /* package */ void unregister(CancellationTokenRegistration registration) {
+  /* package */ void unregister(@NonNull CancellationTokenRegistration registration) {
     synchronized (lock) {
       throwIfClosed();
       registrations.remove(registration);
@@ -178,7 +181,7 @@ public class CancellationTokenSource implements Closeable {
   // to be synchronized with state changes you should provide external synchronization.
   // If this is invoked without external synchronization there is a probability the token becomes
   // cancelled concurrently.
-  private void notifyListeners(List<CancellationTokenRegistration> registrations) {
+  private void notifyListeners(@NonNull List<CancellationTokenRegistration> registrations) {
     for (CancellationTokenRegistration registration : registrations) {
       registration.runAction();
     }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/Capture.java

@@ -7,25 +7,27 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.Nullable;
+
 /**
  * Provides a class that can be used for capturing variables in an anonymous class implementation.
  *
  * @param <T>
  */
 public class Capture<T> {
-  private T value;
+  private @Nullable T value;
 
   public Capture() {}
 
-  public Capture(T value) {
+  public Capture(@Nullable T value) {
     this.value = value;
   }
 
-  public T get() {
+  public @Nullable T get() {
     return value;
   }
 
-  public void set(T value) {
+  public void set(@Nullable T value) {
     this.value = value;
   }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/Continuation.java

@@ -7,6 +7,9 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 /**
  * A function to be called after a task completes.
  *
@@ -16,5 +19,6 @@ package com.facebook.react.bridgeless.internal.bolts;
  * @see Task
  */
 public interface Continuation<TTaskResult, TContinuationResult> {
-  TContinuationResult then(Task<TTaskResult> task) throws Exception;
+  @Nullable
+  TContinuationResult then(@NonNull Task<TTaskResult> task) throws Exception;
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/ExecutorException.java

@@ -7,13 +7,15 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.Nullable;
+
 /**
  * This is a wrapper class for emphasizing that task failed due to bad {@code Executor}, rather than
  * the continuation block it self.
  */
 public class ExecutorException extends RuntimeException {
 
-  public ExecutorException(Exception e) {
+  public ExecutorException(@Nullable Exception e) {
     super("An exception was thrown by an Executor", e);
   }
 }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/TaskCompletionSource.java

@@ -7,6 +7,9 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 /**
  * Allows safe orchestration of a task's completion, preventing the consumer from prematurely
  * completing the task. Essentially, it represents the producer side of a Task<TResult>, providing
@@ -15,7 +18,7 @@ package com.facebook.react.bridgeless.internal.bolts;
  */
 public class TaskCompletionSource<TResult> {
 
-  private final Task<TResult> task;
+  @NonNull private final Task<TResult> task;
 
   /**
    * Creates a TaskCompletionSource that orchestrates a Task. This allows the creator of a task to
@@ -26,7 +29,7 @@ public class TaskCompletionSource<TResult> {
   }
 
   /** @return the Task associated with this TaskCompletionSource. */
-  public Task<TResult> getTask() {
+  public @NonNull Task<TResult> getTask() {
     return task;
   }
 
@@ -36,12 +39,12 @@ public class TaskCompletionSource<TResult> {
   }
 
   /** Sets the result on the Task if the Task hasn't already been completed. */
-  public boolean trySetResult(TResult result) {
+  public boolean trySetResult(@Nullable TResult result) {
     return task.trySetResult(result);
   }
 
   /** Sets the error on the Task if the Task hasn't already been completed. */
-  public boolean trySetError(Exception error) {
+  public boolean trySetError(@Nullable Exception error) {
     return task.trySetError(error);
   }
 
@@ -53,14 +56,14 @@ public class TaskCompletionSource<TResult> {
   }
 
   /** Sets the result of the Task, throwing if the Task has already been completed. */
-  public void setResult(TResult result) {
+  public void setResult(@Nullable TResult result) {
     if (!trySetResult(result)) {
       throw new IllegalStateException("Cannot set the result of a completed task.");
     }
   }
 
   /** Sets the error of the Task, throwing if the Task has already been completed. */
-  public void setError(Exception error) {
+  public void setError(@Nullable Exception error) {
     if (!trySetError(error)) {
       throw new IllegalStateException("Cannot set the error on a completed task.");
     }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/UnobservedErrorNotifier.java

@@ -7,15 +7,17 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.Nullable;
+
 /**
  * This class is used to retain a faulted task until either its error is observed or it is
  * finalized. If it is finalized with a task, then the uncaught exception handler is exected with an
  * UnobservedTaskException.
  */
 class UnobservedErrorNotifier {
-  private Task<?> task;
+  @Nullable private Task<?> task;
 
-  public UnobservedErrorNotifier(Task<?> task) {
+  public UnobservedErrorNotifier(@Nullable Task<?> task) {
     this.task = task;
   }
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/internal/bolts/UnobservedTaskException.java

@@ -7,9 +7,11 @@
 
 package com.facebook.react.bridgeless.internal.bolts;
 
+import androidx.annotation.Nullable;
+
 /** Used to signify that a Task's error went unobserved. */
 public class UnobservedTaskException extends RuntimeException {
-  public UnobservedTaskException(Throwable cause) {
+  public UnobservedTaskException(@Nullable Throwable cause) {
     super(cause);
   }
 }