diff --git a/nearby/service/java/com/android/server/nearby/common/bluetooth/util/BluetoothOperationExecutor.java b/nearby/service/java/com/android/server/nearby/common/bluetooth/util/BluetoothOperationExecutor.java
new file mode 100644
index 0000000..fecf483
--- /dev/null
+++ b/nearby/service/java/com/android/server/nearby/common/bluetooth/util/BluetoothOperationExecutor.java
@@ -0,0 +1,548 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.nearby.common.bluetooth.util;
+
+import android.bluetooth.BluetoothGatt;
+import android.util.Log;
+
+import com.android.server.nearby.common.bluetooth.BluetoothException;
+import com.android.server.nearby.common.bluetooth.BluetoothGattException;
+import com.android.server.nearby.common.bluetooth.testability.NonnullProvider;
+import com.android.server.nearby.common.bluetooth.testability.TimeProvider;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Joiner;
+import com.google.common.base.Objects;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Queue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.LinkedBlockingDeque;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import javax.annotation.Nullable;
+
+/**
+ * Scheduler to coordinate parallel bluetooth operations.
+ */
+public class BluetoothOperationExecutor {
+
+    private static final String TAG = BluetoothOperationExecutor.class.getSimpleName();
+
+    /**
+     * Special value to indicate that the result is null (since {@link BlockingQueue} doesn't allow
+     * null elements).
+     */
+    private static final Object NULL_RESULT = new Object();
+
+    /**
+     * Special value to indicate that there should be no timeout on the operation.
+     */
+    private static final long NO_TIMEOUT = -1;
+
+    private final NonnullProvider<BlockingQueue<Object>> mBlockingQueueProvider;
+    private final TimeProvider mTimeProvider;
+    @VisibleForTesting
+    final Map<Operation<?>, Queue<Object>> mOperationResultQueues = new HashMap<>();
+    private final Semaphore mOperationSemaphore;
+
+    /**
+     * New instance that limits concurrent operations to maxConcurrentOperations.
+     */
+    public BluetoothOperationExecutor(int maxConcurrentOperations) {
+        this(
+                new Semaphore(maxConcurrentOperations, true),
+                new TimeProvider(),
+                new NonnullProvider<BlockingQueue<Object>>() {
+                    @Override
+                    public BlockingQueue<Object> get() {
+                        return new LinkedBlockingDeque<Object>();
+                    }
+                });
+    }
+
+    /**
+     * Constructor for unit tests.
+     */
+    @VisibleForTesting
+    BluetoothOperationExecutor(Semaphore operationSemaphore,
+            TimeProvider timeProvider,
+            NonnullProvider<BlockingQueue<Object>> blockingQueueProvider) {
+        mOperationSemaphore = operationSemaphore;
+        mTimeProvider = timeProvider;
+        mBlockingQueueProvider = blockingQueueProvider;
+    }
+
+    /**
+     * Executes the operation and waits for its completion.
+     */
+    @Nullable
+    public <T> T execute(Operation<T> operation) throws BluetoothException {
+        return getResult(schedule(operation));
+    }
+
+    /**
+     * Executes the operation and waits for its completion and returns a non-null result.
+     */
+    public <T> T executeNonnull(Operation<T> operation) throws BluetoothException {
+        T result = getResult(schedule(operation));
+        if (result == null) {
+            throw new BluetoothException(
+                    String.format(Locale.US, "Operation %s returned a null result.", operation));
+        }
+        return result;
+    }
+
+    /**
+     * Executes the operation and waits for its completion with a timeout.
+     */
+    @Nullable
+    public <T> T execute(Operation<T> bluetoothOperation, long timeoutMillis)
+            throws BluetoothException, BluetoothOperationTimeoutException {
+        return getResult(schedule(bluetoothOperation), timeoutMillis);
+    }
+
+    /**
+     * Executes the operation and waits for its completion with a timeout and returns a non-null
+     * result.
+     */
+    public <T> T executeNonnull(Operation<T> bluetoothOperation, long timeoutMillis)
+            throws BluetoothException {
+        T result = getResult(schedule(bluetoothOperation), timeoutMillis);
+        if (result == null) {
+            throw new BluetoothException(
+                    String.format(Locale.US, "Operation %s returned a null result.",
+                            bluetoothOperation));
+        }
+        return result;
+    }
+
+    /**
+     * Schedules an operation and returns a {@link Future} that waits on operation completion and
+     * gets its result.
+     */
+    public <T> Future<T> schedule(Operation<T> bluetoothOperation) {
+        BlockingQueue<Object> resultQueue = mBlockingQueueProvider.get();
+        mOperationResultQueues.put(bluetoothOperation, resultQueue);
+
+        boolean semaphoreAcquired = mOperationSemaphore.tryAcquire();
+        Log.d(TAG, String.format(Locale.US,
+                "Scheduling operation %s; %d permits available; Semaphore acquired: %b",
+                bluetoothOperation,
+                mOperationSemaphore.availablePermits(),
+                semaphoreAcquired));
+
+        if (semaphoreAcquired) {
+            bluetoothOperation.execute(this);
+        }
+        return new BluetoothOperationFuture<T>(resultQueue, bluetoothOperation, semaphoreAcquired);
+    }
+
+    /**
+     * Notifies that this operation has completed with success.
+     */
+    public void notifySuccess(Operation<Void> bluetoothOperation) {
+        postResult(bluetoothOperation, null);
+    }
+
+    /**
+     * Notifies that this operation has completed with success and with a result.
+     */
+    public <T> void notifySuccess(Operation<T> bluetoothOperation, T result) {
+        postResult(bluetoothOperation, result);
+    }
+
+    /**
+     * Notifies that this operation has completed with the given BluetoothGatt status code (which
+     * may indicate success or failure).
+     */
+    public void notifyCompletion(Operation<Void> bluetoothOperation, int status) {
+        notifyCompletion(bluetoothOperation, status, null);
+    }
+
+    /**
+     * Notifies that this operation has completed with the given BluetoothGatt status code (which
+     * may indicate success or failure) and with a result.
+     */
+    public <T> void notifyCompletion(Operation<T> bluetoothOperation, int status,
+            @Nullable T result) {
+        if (status != BluetoothGatt.GATT_SUCCESS) {
+            notifyFailure(bluetoothOperation, new BluetoothGattException(
+                    String.format(Locale.US,
+                            "Operation %s failed: %d - %s.", bluetoothOperation, status,
+                            BluetoothGattUtils.getMessageForStatusCode(status)),
+                    status));
+            return;
+        }
+        postResult(bluetoothOperation, result);
+    }
+
+    /**
+     * Notifies that this operation has completed with failure.
+     */
+    public void notifyFailure(Operation<?> bluetoothOperation, BluetoothException exception) {
+        postResult(bluetoothOperation, exception);
+    }
+
+    private void postResult(Operation<?> bluetoothOperation, @Nullable Object result) {
+        Queue<Object> resultQueue = mOperationResultQueues.get(bluetoothOperation);
+        if (resultQueue == null) {
+            Log.e(TAG, String.format(Locale.US,
+                    "Receive completion for unexpected operation: %s.", bluetoothOperation));
+            return;
+        }
+        resultQueue.add(result == null ? NULL_RESULT : result);
+        mOperationResultQueues.remove(bluetoothOperation);
+        mOperationSemaphore.release();
+        Log.d(TAG, String.format(Locale.US,
+                "Released semaphore for operation %s. There are %d permits left",
+                bluetoothOperation, mOperationSemaphore.availablePermits()));
+    }
+
+    /**
+     * Waits for all future on the list to complete, ignoring the results.
+     */
+    public <T> void waitFor(List<Future<T>> futures) throws BluetoothException {
+        for (Future<T> future : futures) {
+            if (future == null) {
+                continue;
+            }
+            getResult(future);
+        }
+    }
+
+    /**
+     * Waits with timeout for all future on the list to complete, ignoring the results.
+     */
+    public <T> void waitFor(List<Future<T>> futures, long timeoutMillis)
+            throws BluetoothException {
+        long startTime = mTimeProvider.getTimeMillis();
+        for (Future<T> future : futures) {
+            if (future == null) {
+                continue;
+            }
+            getResult(future,
+                    timeoutMillis - (mTimeProvider.getTimeMillis() - startTime));
+        }
+    }
+
+    /**
+     * Waits for a future to complete and returns the result.
+     */
+    @Nullable
+    public static <T> T getResult(Future<T> future) throws BluetoothException {
+        return getResultInternal(future, NO_TIMEOUT);
+    }
+
+    /**
+     * Waits for a future to complete and returns the result with timeout.
+     */
+    @Nullable
+    public static <T> T getResult(Future<T> future, long timeoutMillis) throws BluetoothException {
+        return getResultInternal(future, Math.max(0, timeoutMillis));
+    }
+
+    @Nullable
+    private static <T> T getResultInternal(Future<T> future, long timeoutMillis)
+            throws BluetoothException {
+        try {
+            if (timeoutMillis == NO_TIMEOUT) {
+                return future.get();
+            } else {
+                return future.get(timeoutMillis, TimeUnit.MILLISECONDS);
+            }
+        } catch (InterruptedException e) {
+            try {
+                boolean cancelSuccess = future.cancel(true);
+                if (!cancelSuccess && future.isDone()) {
+                    // Operation has succeeded before we send cancel to it.
+                    return getResultInternal(future, NO_TIMEOUT);
+                }
+            } finally {
+                // Re-interrupt the thread last since we're recursively calling getResultInternal.
+                // We know the future is done, so there's no need to be interrupted while we call.
+                Thread.currentThread().interrupt();
+            }
+            throw new BluetoothException("Wait interrupted");
+        } catch (ExecutionException e) {
+            Throwable cause = e.getCause();
+            if (cause instanceof BluetoothException) {
+                throw (BluetoothException) cause;
+            }
+            throw new RuntimeException(e);
+        } catch (TimeoutException e) {
+            boolean cancelSuccess = future.cancel(true);
+            if (!cancelSuccess && future.isDone()) {
+                // Operation has succeeded before we send cancel to it.
+                return getResultInternal(future, NO_TIMEOUT);
+            }
+            throw new BluetoothOperationTimeoutException(
+                    String.format(Locale.US, "Wait timed out after %s ms.", timeoutMillis), e);
+        }
+    }
+
+    /**
+     * Asynchronous bluetooth operation to schedule.
+     *
+     * <p>An instance that doesn't implemented run() can be used to notify operation result.
+     *
+     * @param <T> Type of provided instance.
+     */
+    public static class Operation<T> {
+
+        private Object[] mElements;
+
+        public Operation(Object... elements) {
+            mElements = elements;
+        }
+
+        /**
+         * Executes operation using executor.
+         */
+        public void execute(BluetoothOperationExecutor executor) {
+            try {
+                run();
+            } catch (BluetoothException e) {
+                executor.postResult(this, e);
+            }
+        }
+
+        /**
+         * Run function. Not supported.
+         */
+        @SuppressWarnings("unused")
+        public void run() throws BluetoothException {
+            throw new RuntimeException("Not implemented");
+        }
+
+        /**
+         * Try to cancel operation when a timeout occurs.
+         */
+        public void cancel() {
+        }
+
+        @Override
+        public boolean equals(@Nullable Object o) {
+            if (o == null) {
+                return false;
+            }
+            if (!Operation.class.isInstance(o)) {
+                return false;
+            }
+            Operation<?> other = (Operation<?>) o;
+            return Arrays.equals(mElements, other.mElements);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hashCode(mElements);
+        }
+
+        @Override
+        public String toString() {
+            return Joiner.on('-').join(mElements);
+        }
+    }
+
+    /**
+     * Synchronous bluetooth operation to schedule.
+     *
+     * @param <T> Type of provided instance.
+     */
+    public static class SynchronousOperation<T> extends Operation<T> {
+
+        public SynchronousOperation(Object... elements) {
+            super(elements);
+        }
+
+        @Override
+        public void execute(BluetoothOperationExecutor executor) {
+            try {
+                Object result = call();
+                if (result == null) {
+                    result = NULL_RESULT;
+                }
+                executor.postResult(this, result);
+            } catch (BluetoothException e) {
+                executor.postResult(this, e);
+            }
+        }
+
+        /**
+         * Call function. Not supported.
+         */
+        @SuppressWarnings("unused")
+        @Nullable
+        public T call() throws BluetoothException {
+            throw new RuntimeException("Not implemented");
+        }
+    }
+
+    /**
+     * {@link Future} to wait / get result of an operation.
+     *
+     * <li>Waits for operation to complete
+     * <li>Handles timeouts if needed
+     * <li>Queues identical Bluetooth operations
+     * <li>Unwraps Exceptions and null values
+     */
+    private class BluetoothOperationFuture<T> implements Future<T> {
+
+        private final Object mLock = new Object();
+
+        /**
+         * Queue that will be used to store the result. It should normally contains one element
+         * maximum, but using a queue avoid some race conditions.
+         */
+        private final BlockingQueue<Object> mResultQueue;
+        private final Operation<T> mBluetoothOperation;
+        private final boolean mOperationExecuted;
+        private boolean mIsCancelled = false;
+        private boolean mIsDone = false;
+
+        BluetoothOperationFuture(BlockingQueue<Object> resultQueue,
+                Operation<T> bluetoothOperation, boolean operationExecuted) {
+            mResultQueue = resultQueue;
+            mBluetoothOperation = bluetoothOperation;
+            mOperationExecuted = operationExecuted;
+        }
+
+        @Override
+        public boolean cancel(boolean mayInterruptIfRunning) {
+            synchronized (mLock) {
+                if (mIsDone) {
+                    return false;
+                }
+                if (mIsCancelled) {
+                    return true;
+                }
+                mBluetoothOperation.cancel();
+                mIsCancelled = true;
+                notifyFailure(mBluetoothOperation, new BluetoothException("Operation cancelled."));
+                return true;
+            }
+        }
+
+        @Override
+        public boolean isCancelled() {
+            synchronized (mLock) {
+                return mIsCancelled;
+            }
+        }
+
+        @Override
+        public boolean isDone() {
+            synchronized (mLock) {
+                return mIsDone;
+            }
+        }
+
+        @Override
+        @Nullable
+        public T get() throws InterruptedException, ExecutionException {
+            try {
+                return getInternal(NO_TIMEOUT, TimeUnit.MILLISECONDS);
+            } catch (TimeoutException e) {
+                throw new RuntimeException(e); // This is not supposed to be thrown
+            }
+        }
+
+        @Override
+        @Nullable
+        public T get(long timeoutMillis, TimeUnit unit)
+                throws InterruptedException, ExecutionException, TimeoutException {
+            return getInternal(Math.max(0, timeoutMillis), unit);
+        }
+
+        @SuppressWarnings("unchecked")
+        @Nullable
+        private T getInternal(long timeoutMillis, TimeUnit unit)
+                throws ExecutionException, InterruptedException, TimeoutException {
+            // Prevent parallel executions of this method.
+            long startTime = mTimeProvider.getTimeMillis();
+            synchronized (this) {
+                synchronized (mLock) {
+                    if (mIsDone) {
+                        throw new ExecutionException(
+                                new BluetoothException("get() called twice..."));
+                    }
+                }
+                if (!mOperationExecuted) {
+                    if (timeoutMillis == NO_TIMEOUT) {
+                        mOperationSemaphore.acquire();
+                    } else {
+                        if (!mOperationSemaphore.tryAcquire(timeoutMillis
+                                - (mTimeProvider.getTimeMillis() - startTime), unit)) {
+                            throw new TimeoutException(String.format(Locale.US,
+                                    "A timeout occurred when processing %s after %s %s.",
+                                    mBluetoothOperation, timeoutMillis, unit));
+                        }
+                    }
+                    mBluetoothOperation.execute(BluetoothOperationExecutor.this);
+                }
+                Object result;
+
+                if (timeoutMillis == NO_TIMEOUT) {
+                    result = mResultQueue.take();
+                } else {
+                    result = mResultQueue.poll(
+                            timeoutMillis - (mTimeProvider.getTimeMillis() - startTime), unit);
+                }
+
+                if (result == null) {
+                    throw new TimeoutException(String.format(Locale.US,
+                            "A timeout occurred when processing %s after %s ms.",
+                            mBluetoothOperation, timeoutMillis));
+                }
+                synchronized (mLock) {
+                    mIsDone = true;
+                }
+                if (result instanceof BluetoothException) {
+                    throw new ExecutionException((BluetoothException) result);
+                }
+                if (result == NULL_RESULT) {
+                    result = null;
+                }
+                return (T) result;
+            }
+        }
+    }
+
+    /**
+     * Exception thrown when an operation execution times out. Since state of the system is unknown
+     * afterward (operation may still complete or not), it is recommended to disconnect and
+     * reconnect.
+     */
+    public static class BluetoothOperationTimeoutException extends BluetoothException {
+
+        public BluetoothOperationTimeoutException(String message) {
+            super(message);
+        }
+
+        public BluetoothOperationTimeoutException(String message, Throwable cause) {
+            super(message, cause);
+        }
+    }
+}
diff --git a/nearby/tests/Android.bp b/nearby/tests/Android.bp
index ed20b7e..ec66b32 100644
--- a/nearby/tests/Android.bp
+++ b/nearby/tests/Android.bp
@@ -28,11 +28,13 @@
     libs: [
         "android.test.runner",
         "android.test.base",
+        "android.test.mock",
     ],
     compile_multilib: "both",
 
     static_libs: [
         "androidx.test.rules",
+        "mockito-target",
         "framework-nearby-pre-jarjar",
         "guava",
         "libprotobuf-java-lite",
diff --git a/nearby/tests/src/com/android/server/nearby/common/bluetooth/util/BluetoothGattUtilsTest.java b/nearby/tests/src/com/android/server/nearby/common/bluetooth/util/BluetoothGattUtilsTest.java
index 53aed6e..a6fbe2a 100644
--- a/nearby/tests/src/com/android/server/nearby/common/bluetooth/util/BluetoothGattUtilsTest.java
+++ b/nearby/tests/src/com/android/server/nearby/common/bluetooth/util/BluetoothGattUtilsTest.java
@@ -40,7 +40,7 @@
 import java.lang.reflect.Modifier;
 import java.util.UUID;
 
-/** Unit tests for {@link BluetoothAddress}. */
+/** Unit tests for {@link BluetoothGattUtils}. */
 @Presubmit
 @SmallTest
 @RunWith(AndroidJUnit4.class)
diff --git a/nearby/tests/src/com/android/server/nearby/common/bluetooth/util/BluetoothOperationExecutorTest.java b/nearby/tests/src/com/android/server/nearby/common/bluetooth/util/BluetoothOperationExecutorTest.java
new file mode 100644
index 0000000..6d1450f
--- /dev/null
+++ b/nearby/tests/src/com/android/server/nearby/common/bluetooth/util/BluetoothOperationExecutorTest.java
@@ -0,0 +1,301 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.nearby.common.bluetooth.util;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.mockito.MockitoAnnotations.initMocks;
+
+import android.bluetooth.BluetoothGatt;
+
+import com.android.server.nearby.common.bluetooth.BluetoothException;
+import com.android.server.nearby.common.bluetooth.testability.NonnullProvider;
+import com.android.server.nearby.common.bluetooth.testability.TimeProvider;
+import com.android.server.nearby.common.bluetooth.util.BluetoothOperationExecutor.BluetoothOperationTimeoutException;
+import com.android.server.nearby.common.bluetooth.util.BluetoothOperationExecutor.Operation;
+import com.android.server.nearby.common.bluetooth.util.BluetoothOperationExecutor.SynchronousOperation;
+
+import junit.framework.TestCase;
+
+import org.mockito.Mock;
+
+import java.util.Arrays;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.Future;
+import java.util.concurrent.LinkedBlockingDeque;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+
+/**
+ * Unit tests for {@link BluetoothOperationExecutor}.
+ */
+public class BluetoothOperationExecutorTest extends TestCase {
+
+    private static final String OPERATION_RESULT = "result";
+    private static final String EXCEPTION_REASON = "exception";
+    private static final long TIME = 1234;
+    private static final long TIMEOUT = 121212;
+
+    @Mock
+    private NonnullProvider<BlockingQueue<Object>> mMockBlockingQueueProvider;
+    @Mock
+    private TimeProvider mMockTimeProvider;
+    @Mock
+    private BlockingQueue<Object> mMockBlockingQueue;
+    @Mock
+    private Semaphore mMockSemaphore;
+    @Mock
+    private Operation<String> mMockStringOperation;
+    @Mock
+    private Operation<Void> mMockVoidOperation;
+    @Mock
+    private Future<Object> mMockFuture;
+    @Mock
+    private Future<Object> mMockFuture2;
+
+    private BluetoothOperationExecutor mBluetoothOperationExecutor;
+
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+
+        initMocks(this);
+
+        when(mMockBlockingQueueProvider.get()).thenReturn(mMockBlockingQueue);
+        when(mMockSemaphore.tryAcquire()).thenReturn(true);
+        when(mMockTimeProvider.getTimeMillis()).thenReturn(TIME);
+
+        mBluetoothOperationExecutor =
+                new BluetoothOperationExecutor(mMockSemaphore, mMockTimeProvider,
+                        mMockBlockingQueueProvider);
+    }
+
+    public void testExecute() throws Exception {
+        when(mMockBlockingQueue.take()).thenReturn(OPERATION_RESULT);
+
+        String result = mBluetoothOperationExecutor.execute(mMockStringOperation);
+
+        verify(mMockStringOperation).execute(mBluetoothOperationExecutor);
+        assertThat(result).isEqualTo(OPERATION_RESULT);
+    }
+
+    public void testExecuteWithTimeout() throws Exception {
+        when(mMockBlockingQueue.poll(TIMEOUT, TimeUnit.MILLISECONDS)).thenReturn(OPERATION_RESULT);
+
+        String result = mBluetoothOperationExecutor.execute(mMockStringOperation, TIMEOUT);
+
+        verify(mMockStringOperation).execute(mBluetoothOperationExecutor);
+        assertThat(result).isEqualTo(OPERATION_RESULT);
+    }
+
+    public void testSchedule() throws Exception {
+        when(mMockBlockingQueue.poll(TIMEOUT, TimeUnit.MILLISECONDS)).thenReturn(OPERATION_RESULT);
+
+        Future<String> result = mBluetoothOperationExecutor.schedule(mMockStringOperation);
+
+        verify(mMockStringOperation).execute(mBluetoothOperationExecutor);
+        assertThat(result.get(TIMEOUT, TimeUnit.MILLISECONDS)).isEqualTo(OPERATION_RESULT);
+    }
+
+    public void testScheduleOtherOperationInProgress() throws Exception {
+        when(mMockSemaphore.tryAcquire()).thenReturn(false);
+        when(mMockBlockingQueue.poll(TIMEOUT, TimeUnit.MILLISECONDS)).thenReturn(OPERATION_RESULT);
+
+        Future<String> result = mBluetoothOperationExecutor.schedule(mMockStringOperation);
+
+        verify(mMockStringOperation, never()).run();
+
+        when(mMockSemaphore.tryAcquire(TIMEOUT, TimeUnit.MILLISECONDS)).thenReturn(true);
+
+        assertThat(result.get(TIMEOUT, TimeUnit.MILLISECONDS)).isEqualTo(OPERATION_RESULT);
+        verify(mMockStringOperation).execute(mBluetoothOperationExecutor);
+    }
+
+    public void testNotifySuccessWithResult() throws Exception {
+        when(mMockBlockingQueueProvider.get()).thenReturn(new LinkedBlockingDeque<Object>());
+        Future<String> future = mBluetoothOperationExecutor.schedule(mMockStringOperation);
+
+        mBluetoothOperationExecutor.notifySuccess(mMockStringOperation, OPERATION_RESULT);
+
+        assertThat(future.get(1, TimeUnit.MILLISECONDS)).isEqualTo(OPERATION_RESULT);
+    }
+
+    public void testNotifySuccessTwice() throws Exception {
+        BlockingQueue<Object> resultQueue = new LinkedBlockingDeque<Object>();
+        when(mMockBlockingQueueProvider.get()).thenReturn(resultQueue);
+        Future<String> future = mBluetoothOperationExecutor.schedule(mMockStringOperation);
+
+        mBluetoothOperationExecutor.notifySuccess(mMockStringOperation, OPERATION_RESULT);
+
+        assertThat(future.get(1, TimeUnit.MILLISECONDS)).isEqualTo(OPERATION_RESULT);
+
+        // the second notification should be ignored
+        mBluetoothOperationExecutor.notifySuccess(mMockStringOperation, OPERATION_RESULT);
+        assertThat(resultQueue).isEmpty();
+    }
+
+    public void testNotifySuccessWithNullResult() throws Exception {
+        when(mMockBlockingQueueProvider.get()).thenReturn(new LinkedBlockingDeque<Object>());
+        Future<String> future = mBluetoothOperationExecutor.schedule(mMockStringOperation);
+
+        mBluetoothOperationExecutor.notifySuccess(mMockStringOperation, null);
+
+        assertThat(future.get(1, TimeUnit.MILLISECONDS)).isNull();
+    }
+
+    public void testNotifySuccess() throws Exception {
+        when(mMockBlockingQueueProvider.get()).thenReturn(new LinkedBlockingDeque<Object>());
+        Future<Void> future = mBluetoothOperationExecutor.schedule(mMockVoidOperation);
+
+        mBluetoothOperationExecutor.notifySuccess(mMockVoidOperation);
+
+        future.get(1, TimeUnit.MILLISECONDS);
+    }
+
+    public void testNotifyCompletionSuccess() throws Exception {
+        when(mMockBlockingQueueProvider.get()).thenReturn(new LinkedBlockingDeque<Object>());
+        Future<Void> future = mBluetoothOperationExecutor.schedule(mMockVoidOperation);
+
+        mBluetoothOperationExecutor
+                .notifyCompletion(mMockVoidOperation, BluetoothGatt.GATT_SUCCESS);
+
+        future.get(1, TimeUnit.MILLISECONDS);
+    }
+
+    public void testNotifyCompletionFailure() throws Exception {
+        when(mMockBlockingQueueProvider.get()).thenReturn(new LinkedBlockingDeque<Object>());
+        Future<Void> future = mBluetoothOperationExecutor.schedule(mMockVoidOperation);
+
+        mBluetoothOperationExecutor
+                .notifyCompletion(mMockVoidOperation, BluetoothGatt.GATT_FAILURE);
+
+        try {
+            BluetoothOperationExecutor.getResult(future, 1);
+            fail("Expected BluetoothException");
+        } catch (BluetoothException e) {
+            //expected
+        }
+    }
+
+    public void testNotifyFailure() throws Exception {
+        when(mMockBlockingQueueProvider.get()).thenReturn(new LinkedBlockingDeque<Object>());
+        Future<Void> future = mBluetoothOperationExecutor.schedule(mMockVoidOperation);
+
+        mBluetoothOperationExecutor
+                .notifyFailure(mMockVoidOperation, new BluetoothException("test"));
+
+        try {
+            BluetoothOperationExecutor.getResult(future, 1);
+            fail("Expected BluetoothException");
+        } catch (BluetoothException e) {
+            //expected
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    public void testWaitFor() throws Exception {
+        mBluetoothOperationExecutor.waitFor(Arrays.asList(mMockFuture, mMockFuture2));
+
+        verify(mMockFuture).get();
+        verify(mMockFuture2).get();
+    }
+
+    @SuppressWarnings("unchecked")
+    public void testWaitForWithTimeout() throws Exception {
+        mBluetoothOperationExecutor.waitFor(
+                Arrays.asList(mMockFuture, mMockFuture2),
+                TIMEOUT);
+
+        verify(mMockFuture).get(TIMEOUT, TimeUnit.MILLISECONDS);
+        verify(mMockFuture2).get(TIMEOUT, TimeUnit.MILLISECONDS);
+    }
+
+    public void testGetResult() throws Exception {
+        when(mMockFuture.get()).thenReturn(OPERATION_RESULT);
+
+        Object result = BluetoothOperationExecutor.getResult(mMockFuture);
+
+        assertThat(result).isEqualTo(OPERATION_RESULT);
+    }
+
+    public void testGetResultWithTimeout() throws Exception {
+        when(mMockFuture.get(TIMEOUT, TimeUnit.MILLISECONDS)).thenThrow(new TimeoutException());
+
+        try {
+            BluetoothOperationExecutor.getResult(mMockFuture, TIMEOUT);
+            fail("Expected BluetoothOperationTimeoutException");
+        } catch (BluetoothOperationTimeoutException e) {
+            //expected
+        }
+        verify(mMockFuture).cancel(true);
+    }
+
+    public void test_SynchronousOperation_execute() throws Exception {
+        when(mMockBlockingQueueProvider.get()).thenReturn(mMockBlockingQueue);
+        SynchronousOperation<String> synchronousOperation = new SynchronousOperation<String>() {
+            @Override
+            public String call() throws BluetoothException {
+                return OPERATION_RESULT;
+            }
+        };
+
+        @SuppressWarnings("unused") // future return.
+        Future<?> possiblyIgnoredError = mBluetoothOperationExecutor.schedule(synchronousOperation);
+
+        verify(mMockBlockingQueue).add(OPERATION_RESULT);
+        verify(mMockSemaphore).release();
+    }
+
+    public void test_SynchronousOperation_exception() throws Exception {
+        final BluetoothException exception = new BluetoothException(EXCEPTION_REASON);
+        when(mMockBlockingQueueProvider.get()).thenReturn(mMockBlockingQueue);
+        SynchronousOperation<String> synchronousOperation = new SynchronousOperation<String>() {
+            @Override
+            public String call() throws BluetoothException {
+                throw exception;
+            }
+        };
+
+        @SuppressWarnings("unused") // future return.
+        Future<?> possiblyIgnoredError = mBluetoothOperationExecutor.schedule(synchronousOperation);
+
+        verify(mMockBlockingQueue).add(exception);
+        verify(mMockSemaphore).release();
+    }
+
+    public void test_AsynchronousOperation_exception() throws Exception {
+        final BluetoothException exception = new BluetoothException(EXCEPTION_REASON);
+        when(mMockBlockingQueueProvider.get()).thenReturn(mMockBlockingQueue);
+        Operation<String> operation = new Operation<String>() {
+            @Override
+            public void run() throws BluetoothException {
+                throw exception;
+            }
+        };
+
+        @SuppressWarnings("unused") // future return.
+        Future<?> possiblyIgnoredError = mBluetoothOperationExecutor.schedule(operation);
+
+        verify(mMockBlockingQueue).add(exception);
+        verify(mMockSemaphore).release();
+    }
+}