Implement full canonical Burst in NN util code

Bug: 180492058
Bug: 177267324
Test: mma
Test: presubmit
Change-Id: I5018f6cf2dbaf705f74f4f46318142c64433e19d
Merged-In: I5018f6cf2dbaf705f74f4f46318142c64433e19d
(cherry picked from commit acff4063b63c04cbb28af87eab61e9a1fa70980a)
diff --git a/neuralnetworks/1.2/utils/src/ExecutionBurstUtils.cpp b/neuralnetworks/1.2/utils/src/ExecutionBurstUtils.cpp
index f0275f9..ca3a52c 100644
--- a/neuralnetworks/1.2/utils/src/ExecutionBurstUtils.cpp
+++ b/neuralnetworks/1.2/utils/src/ExecutionBurstUtils.cpp
@@ -19,11 +19,15 @@
 #include "ExecutionBurstUtils.h"
 
 #include <android-base/logging.h>
+#include <android-base/properties.h>
 #include <android/hardware/neuralnetworks/1.0/types.h>
 #include <android/hardware/neuralnetworks/1.1/types.h>
 #include <android/hardware/neuralnetworks/1.2/types.h>
 #include <fmq/MessageQueue.h>
 #include <hidl/MQDescriptor.h>
+#include <nnapi/Result.h>
+#include <nnapi/Types.h>
+#include <nnapi/hal/ProtectCallback.h>
 
 #include <atomic>
 #include <chrono>
@@ -39,84 +43,97 @@
 constexpr V1_2::Timing kNoTiming = {std::numeric_limits<uint64_t>::max(),
                                     std::numeric_limits<uint64_t>::max()};
 
+std::chrono::microseconds getPollingTimeWindow(const std::string& property) {
+    constexpr int32_t kDefaultPollingTimeWindow = 0;
+#ifdef NN_DEBUGGABLE
+    constexpr int32_t kMinPollingTimeWindow = 0;
+    const int32_t selectedPollingTimeWindow =
+            base::GetIntProperty(property, kDefaultPollingTimeWindow, kMinPollingTimeWindow);
+    return std::chrono::microseconds(selectedPollingTimeWindow);
+#else
+    (void)property;
+    return std::chrono::microseconds(kDefaultPollingTimeWindow);
+#endif  // NN_DEBUGGABLE
+}
+
+}  // namespace
+
+std::chrono::microseconds getBurstControllerPollingTimeWindow() {
+    return getPollingTimeWindow("debug.nn.burst-controller-polling-window");
+}
+
+std::chrono::microseconds getBurstServerPollingTimeWindow() {
+    return getPollingTimeWindow("debug.nn.burst-server-polling-window");
 }
 
 // serialize a request into a packet
 std::vector<FmqRequestDatum> serialize(const V1_0::Request& request, V1_2::MeasureTiming measure,
                                        const std::vector<int32_t>& slots) {
     // count how many elements need to be sent for a request
-    size_t count = 2 + request.inputs.size() + request.outputs.size() + request.pools.size();
+    size_t count = 2 + request.inputs.size() + request.outputs.size() + slots.size();
     for (const auto& input : request.inputs) {
         count += input.dimensions.size();
     }
     for (const auto& output : request.outputs) {
         count += output.dimensions.size();
     }
+    CHECK_LE(count, std::numeric_limits<uint32_t>::max());
 
     // create buffer to temporarily store elements
     std::vector<FmqRequestDatum> data;
     data.reserve(count);
 
     // package packetInfo
-    {
-        FmqRequestDatum datum;
-        datum.packetInformation(
-                {/*.packetSize=*/static_cast<uint32_t>(count),
-                 /*.numberOfInputOperands=*/static_cast<uint32_t>(request.inputs.size()),
-                 /*.numberOfOutputOperands=*/static_cast<uint32_t>(request.outputs.size()),
-                 /*.numberOfPools=*/static_cast<uint32_t>(request.pools.size())});
-        data.push_back(datum);
-    }
+    data.emplace_back();
+    data.back().packetInformation(
+            {.packetSize = static_cast<uint32_t>(count),
+             .numberOfInputOperands = static_cast<uint32_t>(request.inputs.size()),
+             .numberOfOutputOperands = static_cast<uint32_t>(request.outputs.size()),
+             .numberOfPools = static_cast<uint32_t>(slots.size())});
 
     // package input data
     for (const auto& input : request.inputs) {
         // package operand information
-        FmqRequestDatum datum;
-        datum.inputOperandInformation(
-                {/*.hasNoValue=*/input.hasNoValue,
-                 /*.location=*/input.location,
-                 /*.numberOfDimensions=*/static_cast<uint32_t>(input.dimensions.size())});
-        data.push_back(datum);
+        data.emplace_back();
+        data.back().inputOperandInformation(
+                {.hasNoValue = input.hasNoValue,
+                 .location = input.location,
+                 .numberOfDimensions = static_cast<uint32_t>(input.dimensions.size())});
 
         // package operand dimensions
         for (uint32_t dimension : input.dimensions) {
-            FmqRequestDatum datum;
-            datum.inputOperandDimensionValue(dimension);
-            data.push_back(datum);
+            data.emplace_back();
+            data.back().inputOperandDimensionValue(dimension);
         }
     }
 
     // package output data
     for (const auto& output : request.outputs) {
         // package operand information
-        FmqRequestDatum datum;
-        datum.outputOperandInformation(
-                {/*.hasNoValue=*/output.hasNoValue,
-                 /*.location=*/output.location,
-                 /*.numberOfDimensions=*/static_cast<uint32_t>(output.dimensions.size())});
-        data.push_back(datum);
+        data.emplace_back();
+        data.back().outputOperandInformation(
+                {.hasNoValue = output.hasNoValue,
+                 .location = output.location,
+                 .numberOfDimensions = static_cast<uint32_t>(output.dimensions.size())});
 
         // package operand dimensions
         for (uint32_t dimension : output.dimensions) {
-            FmqRequestDatum datum;
-            datum.outputOperandDimensionValue(dimension);
-            data.push_back(datum);
+            data.emplace_back();
+            data.back().outputOperandDimensionValue(dimension);
         }
     }
 
     // package pool identifier
     for (int32_t slot : slots) {
-        FmqRequestDatum datum;
-        datum.poolIdentifier(slot);
-        data.push_back(datum);
+        data.emplace_back();
+        data.back().poolIdentifier(slot);
     }
 
     // package measureTiming
-    {
-        FmqRequestDatum datum;
-        datum.measureTiming(measure);
-        data.push_back(datum);
-    }
+    data.emplace_back();
+    data.back().measureTiming(measure);
+
+    CHECK_EQ(data.size(), count);
 
     // return packet
     return data;
@@ -137,46 +154,38 @@
     data.reserve(count);
 
     // package packetInfo
-    {
-        FmqResultDatum datum;
-        datum.packetInformation({/*.packetSize=*/static_cast<uint32_t>(count),
-                                 /*.errorStatus=*/errorStatus,
-                                 /*.numberOfOperands=*/static_cast<uint32_t>(outputShapes.size())});
-        data.push_back(datum);
-    }
+    data.emplace_back();
+    data.back().packetInformation({.packetSize = static_cast<uint32_t>(count),
+                                   .errorStatus = errorStatus,
+                                   .numberOfOperands = static_cast<uint32_t>(outputShapes.size())});
 
     // package output shape data
     for (const auto& operand : outputShapes) {
         // package operand information
-        FmqResultDatum::OperandInformation info{};
-        info.isSufficient = operand.isSufficient;
-        info.numberOfDimensions = static_cast<uint32_t>(operand.dimensions.size());
-
-        FmqResultDatum datum;
-        datum.operandInformation(info);
-        data.push_back(datum);
+        data.emplace_back();
+        data.back().operandInformation(
+                {.isSufficient = operand.isSufficient,
+                 .numberOfDimensions = static_cast<uint32_t>(operand.dimensions.size())});
 
         // package operand dimensions
         for (uint32_t dimension : operand.dimensions) {
-            FmqResultDatum datum;
-            datum.operandDimensionValue(dimension);
-            data.push_back(datum);
+            data.emplace_back();
+            data.back().operandDimensionValue(dimension);
         }
     }
 
     // package executionTiming
-    {
-        FmqResultDatum datum;
-        datum.executionTiming(timing);
-        data.push_back(datum);
-    }
+    data.emplace_back();
+    data.back().executionTiming(timing);
+
+    CHECK_EQ(data.size(), count);
 
     // return result
     return data;
 }
 
 // deserialize request
-std::optional<std::tuple<V1_0::Request, std::vector<int32_t>, V1_2::MeasureTiming>> deserialize(
+nn::Result<std::tuple<V1_0::Request, std::vector<int32_t>, V1_2::MeasureTiming>> deserialize(
         const std::vector<FmqRequestDatum>& data) {
     using discriminator = FmqRequestDatum::hidl_discriminator;
 
@@ -184,8 +193,7 @@
 
     // validate packet information
     if (data.size() == 0 || data[index].getDiscriminator() != discriminator::packetInformation) {
-        LOG(ERROR) << "FMQ Request packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Request packet ill-formed";
     }
 
     // unpackage packet information
@@ -198,8 +206,7 @@
 
     // verify packet size
     if (data.size() != packetSize) {
-        LOG(ERROR) << "FMQ Request packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Request packet ill-formed";
     }
 
     // unpackage input operands
@@ -208,8 +215,7 @@
     for (size_t operand = 0; operand < numberOfInputOperands; ++operand) {
         // validate input operand information
         if (data[index].getDiscriminator() != discriminator::inputOperandInformation) {
-            LOG(ERROR) << "FMQ Request packet ill-formed";
-            return std::nullopt;
+            return NN_ERROR() << "FMQ Request packet ill-formed";
         }
 
         // unpackage operand information
@@ -226,8 +232,7 @@
         for (size_t i = 0; i < numberOfDimensions; ++i) {
             // validate dimension
             if (data[index].getDiscriminator() != discriminator::inputOperandDimensionValue) {
-                LOG(ERROR) << "FMQ Request packet ill-formed";
-                return std::nullopt;
+                return NN_ERROR() << "FMQ Request packet ill-formed";
             }
 
             // unpackage dimension
@@ -240,7 +245,7 @@
 
         // store result
         inputs.push_back(
-                {/*.hasNoValue=*/hasNoValue, /*.location=*/location, /*.dimensions=*/dimensions});
+                {.hasNoValue = hasNoValue, .location = location, .dimensions = dimensions});
     }
 
     // unpackage output operands
@@ -249,8 +254,7 @@
     for (size_t operand = 0; operand < numberOfOutputOperands; ++operand) {
         // validate output operand information
         if (data[index].getDiscriminator() != discriminator::outputOperandInformation) {
-            LOG(ERROR) << "FMQ Request packet ill-formed";
-            return std::nullopt;
+            return NN_ERROR() << "FMQ Request packet ill-formed";
         }
 
         // unpackage operand information
@@ -267,8 +271,7 @@
         for (size_t i = 0; i < numberOfDimensions; ++i) {
             // validate dimension
             if (data[index].getDiscriminator() != discriminator::outputOperandDimensionValue) {
-                LOG(ERROR) << "FMQ Request packet ill-formed";
-                return std::nullopt;
+                return NN_ERROR() << "FMQ Request packet ill-formed";
             }
 
             // unpackage dimension
@@ -281,7 +284,7 @@
 
         // store result
         outputs.push_back(
-                {/*.hasNoValue=*/hasNoValue, /*.location=*/location, /*.dimensions=*/dimensions});
+                {.hasNoValue = hasNoValue, .location = location, .dimensions = dimensions});
     }
 
     // unpackage pools
@@ -290,8 +293,7 @@
     for (size_t pool = 0; pool < numberOfPools; ++pool) {
         // validate input operand information
         if (data[index].getDiscriminator() != discriminator::poolIdentifier) {
-            LOG(ERROR) << "FMQ Request packet ill-formed";
-            return std::nullopt;
+            return NN_ERROR() << "FMQ Request packet ill-formed";
         }
 
         // unpackage operand information
@@ -304,8 +306,7 @@
 
     // validate measureTiming
     if (data[index].getDiscriminator() != discriminator::measureTiming) {
-        LOG(ERROR) << "FMQ Request packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Request packet ill-formed";
     }
 
     // unpackage measureTiming
@@ -314,27 +315,23 @@
 
     // validate packet information
     if (index != packetSize) {
-        LOG(ERROR) << "FMQ Result packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Result packet ill-formed";
     }
 
     // return request
-    V1_0::Request request = {/*.inputs=*/inputs, /*.outputs=*/outputs, /*.pools=*/{}};
+    V1_0::Request request = {.inputs = inputs, .outputs = outputs, .pools = {}};
     return std::make_tuple(std::move(request), std::move(slots), measure);
 }
 
 // deserialize a packet into the result
-std::optional<std::tuple<V1_0::ErrorStatus, std::vector<V1_2::OutputShape>, V1_2::Timing>>
-deserialize(const std::vector<FmqResultDatum>& data) {
+nn::Result<std::tuple<V1_0::ErrorStatus, std::vector<V1_2::OutputShape>, V1_2::Timing>> deserialize(
+        const std::vector<FmqResultDatum>& data) {
     using discriminator = FmqResultDatum::hidl_discriminator;
-
-    std::vector<V1_2::OutputShape> outputShapes;
     size_t index = 0;
 
     // validate packet information
     if (data.size() == 0 || data[index].getDiscriminator() != discriminator::packetInformation) {
-        LOG(ERROR) << "FMQ Result packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Result packet ill-formed";
     }
 
     // unpackage packet information
@@ -346,16 +343,16 @@
 
     // verify packet size
     if (data.size() != packetSize) {
-        LOG(ERROR) << "FMQ Result packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Result packet ill-formed";
     }
 
     // unpackage operands
+    std::vector<V1_2::OutputShape> outputShapes;
+    outputShapes.reserve(numberOfOperands);
     for (size_t operand = 0; operand < numberOfOperands; ++operand) {
         // validate operand information
         if (data[index].getDiscriminator() != discriminator::operandInformation) {
-            LOG(ERROR) << "FMQ Result packet ill-formed";
-            return std::nullopt;
+            return NN_ERROR() << "FMQ Result packet ill-formed";
         }
 
         // unpackage operand information
@@ -370,8 +367,7 @@
         for (size_t i = 0; i < numberOfDimensions; ++i) {
             // validate dimension
             if (data[index].getDiscriminator() != discriminator::operandDimensionValue) {
-                LOG(ERROR) << "FMQ Result packet ill-formed";
-                return std::nullopt;
+                return NN_ERROR() << "FMQ Result packet ill-formed";
             }
 
             // unpackage dimension
@@ -383,13 +379,12 @@
         }
 
         // store result
-        outputShapes.push_back({/*.dimensions=*/dimensions, /*.isSufficient=*/isSufficient});
+        outputShapes.push_back({.dimensions = dimensions, .isSufficient = isSufficient});
     }
 
     // validate execution timing
     if (data[index].getDiscriminator() != discriminator::executionTiming) {
-        LOG(ERROR) << "FMQ Result packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Result packet ill-formed";
     }
 
     // unpackage execution timing
@@ -398,123 +393,113 @@
 
     // validate packet information
     if (index != packetSize) {
-        LOG(ERROR) << "FMQ Result packet ill-formed";
-        return std::nullopt;
+        return NN_ERROR() << "FMQ Result packet ill-formed";
     }
 
     // return result
     return std::make_tuple(errorStatus, std::move(outputShapes), timing);
 }
 
-V1_0::ErrorStatus legacyConvertResultCodeToErrorStatus(int resultCode) {
-    return convertToV1_0(convertResultCodeToErrorStatus(resultCode));
-}
-
 // RequestChannelSender methods
 
-std::pair<std::unique_ptr<RequestChannelSender>, const FmqRequestDescriptor*>
+nn::GeneralResult<
+        std::pair<std::unique_ptr<RequestChannelSender>, const MQDescriptorSync<FmqRequestDatum>*>>
 RequestChannelSender::create(size_t channelLength) {
-    std::unique_ptr<FmqRequestChannel> fmqRequestChannel =
-            std::make_unique<FmqRequestChannel>(channelLength, /*confEventFlag=*/true);
-    if (!fmqRequestChannel->isValid()) {
-        LOG(ERROR) << "Unable to create RequestChannelSender";
-        return {nullptr, nullptr};
+    auto requestChannelSender =
+            std::make_unique<RequestChannelSender>(PrivateConstructorTag{}, channelLength);
+    if (!requestChannelSender->mFmqRequestChannel.isValid()) {
+        return NN_ERROR() << "Unable to create RequestChannelSender";
     }
 
-    const FmqRequestDescriptor* descriptor = fmqRequestChannel->getDesc();
-    return std::make_pair(std::make_unique<RequestChannelSender>(std::move(fmqRequestChannel)),
-                          descriptor);
+    const MQDescriptorSync<FmqRequestDatum>* descriptor =
+            requestChannelSender->mFmqRequestChannel.getDesc();
+    return std::make_pair(std::move(requestChannelSender), descriptor);
 }
 
-RequestChannelSender::RequestChannelSender(std::unique_ptr<FmqRequestChannel> fmqRequestChannel)
-    : mFmqRequestChannel(std::move(fmqRequestChannel)) {}
+RequestChannelSender::RequestChannelSender(PrivateConstructorTag /*tag*/, size_t channelLength)
+    : mFmqRequestChannel(channelLength, /*configureEventFlagWord=*/true) {}
 
-bool RequestChannelSender::send(const V1_0::Request& request, V1_2::MeasureTiming measure,
-                                const std::vector<int32_t>& slots) {
+nn::Result<void> RequestChannelSender::send(const V1_0::Request& request,
+                                            V1_2::MeasureTiming measure,
+                                            const std::vector<int32_t>& slots) {
     const std::vector<FmqRequestDatum> serialized = serialize(request, measure, slots);
     return sendPacket(serialized);
 }
 
-bool RequestChannelSender::sendPacket(const std::vector<FmqRequestDatum>& packet) {
+nn::Result<void> RequestChannelSender::sendPacket(const std::vector<FmqRequestDatum>& packet) {
     if (!mValid) {
-        return false;
+        return NN_ERROR() << "FMQ object is invalid";
     }
 
-    if (packet.size() > mFmqRequestChannel->availableToWrite()) {
-        LOG(ERROR)
-                << "RequestChannelSender::sendPacket -- packet size exceeds size available in FMQ";
-        return false;
+    if (packet.size() > mFmqRequestChannel.availableToWrite()) {
+        return NN_ERROR()
+               << "RequestChannelSender::sendPacket -- packet size exceeds size available in FMQ";
     }
 
-    // Always send the packet with "blocking" because this signals the futex and
-    // unblocks the consumer if it is waiting on the futex.
-    return mFmqRequestChannel->writeBlocking(packet.data(), packet.size());
+    // Always send the packet with "blocking" because this signals the futex and unblocks the
+    // consumer if it is waiting on the futex.
+    const bool success = mFmqRequestChannel.writeBlocking(packet.data(), packet.size());
+    if (!success) {
+        return NN_ERROR()
+               << "RequestChannelSender::sendPacket -- FMQ's writeBlocking returned an error";
+    }
+
+    return {};
 }
 
-void RequestChannelSender::invalidate() {
+void RequestChannelSender::notifyAsDeadObject() {
     mValid = false;
 }
 
 // RequestChannelReceiver methods
 
-std::unique_ptr<RequestChannelReceiver> RequestChannelReceiver::create(
-        const FmqRequestDescriptor& requestChannel, std::chrono::microseconds pollingTimeWindow) {
-    std::unique_ptr<FmqRequestChannel> fmqRequestChannel =
-            std::make_unique<FmqRequestChannel>(requestChannel);
+nn::GeneralResult<std::unique_ptr<RequestChannelReceiver>> RequestChannelReceiver::create(
+        const MQDescriptorSync<FmqRequestDatum>& requestChannel,
+        std::chrono::microseconds pollingTimeWindow) {
+    auto requestChannelReceiver = std::make_unique<RequestChannelReceiver>(
+            PrivateConstructorTag{}, requestChannel, pollingTimeWindow);
 
-    if (!fmqRequestChannel->isValid()) {
-        LOG(ERROR) << "Unable to create RequestChannelReceiver";
-        return nullptr;
+    if (!requestChannelReceiver->mFmqRequestChannel.isValid()) {
+        return NN_ERROR() << "Unable to create RequestChannelReceiver";
     }
-    if (fmqRequestChannel->getEventFlagWord() == nullptr) {
-        LOG(ERROR)
-                << "RequestChannelReceiver::create was passed an MQDescriptor without an EventFlag";
-        return nullptr;
+    if (requestChannelReceiver->mFmqRequestChannel.getEventFlagWord() == nullptr) {
+        return NN_ERROR()
+               << "RequestChannelReceiver::create was passed an MQDescriptor without an EventFlag";
     }
 
-    return std::make_unique<RequestChannelReceiver>(std::move(fmqRequestChannel),
-                                                    pollingTimeWindow);
+    return requestChannelReceiver;
 }
 
-RequestChannelReceiver::RequestChannelReceiver(std::unique_ptr<FmqRequestChannel> fmqRequestChannel,
-                                               std::chrono::microseconds pollingTimeWindow)
-    : mFmqRequestChannel(std::move(fmqRequestChannel)), kPollingTimeWindow(pollingTimeWindow) {}
+RequestChannelReceiver::RequestChannelReceiver(
+        PrivateConstructorTag /*tag*/, const MQDescriptorSync<FmqRequestDatum>& requestChannel,
+        std::chrono::microseconds pollingTimeWindow)
+    : mFmqRequestChannel(requestChannel), kPollingTimeWindow(pollingTimeWindow) {}
 
-std::optional<std::tuple<V1_0::Request, std::vector<int32_t>, V1_2::MeasureTiming>>
+nn::Result<std::tuple<V1_0::Request, std::vector<int32_t>, V1_2::MeasureTiming>>
 RequestChannelReceiver::getBlocking() {
-    const auto packet = getPacketBlocking();
-    if (!packet) {
-        return std::nullopt;
-    }
-
-    return deserialize(*packet);
+    const auto packet = NN_TRY(getPacketBlocking());
+    return deserialize(packet);
 }
 
 void RequestChannelReceiver::invalidate() {
     mTeardown = true;
 
     // force unblock
-    // ExecutionBurstServer is by default waiting on a request packet. If the
-    // client process destroys its burst object, the server may still be waiting
-    // on the futex. This force unblock wakes up any thread waiting on the
-    // futex.
-    // TODO: look for a different/better way to signal/notify the futex to wake
-    // up any thread waiting on it
-    FmqRequestDatum datum;
-    datum.packetInformation({/*.packetSize=*/0, /*.numberOfInputOperands=*/0,
-                             /*.numberOfOutputOperands=*/0, /*.numberOfPools=*/0});
-    mFmqRequestChannel->writeBlocking(&datum, 1);
+    // ExecutionBurstServer is by default waiting on a request packet. If the client process
+    // destroys its burst object, the server may still be waiting on the futex. This force unblock
+    // wakes up any thread waiting on the futex.
+    const auto data = serialize(V1_0::Request{}, V1_2::MeasureTiming::NO, {});
+    mFmqRequestChannel.writeBlocking(data.data(), data.size());
 }
 
-std::optional<std::vector<FmqRequestDatum>> RequestChannelReceiver::getPacketBlocking() {
+nn::Result<std::vector<FmqRequestDatum>> RequestChannelReceiver::getPacketBlocking() {
     if (mTeardown) {
-        return std::nullopt;
+        return NN_ERROR() << "FMQ object is being torn down";
     }
 
-    // First spend time polling if results are available in FMQ instead of
-    // waiting on the futex. Polling is more responsive (yielding lower
-    // latencies), but can take up more power, so only poll for a limited period
-    // of time.
+    // First spend time polling if results are available in FMQ instead of waiting on the futex.
+    // Polling is more responsive (yielding lower latencies), but can take up more power, so only
+    // poll for a limited period of time.
 
     auto& getCurrentTime = std::chrono::high_resolution_clock::now;
     const auto timeToStopPolling = getCurrentTime() + kPollingTimeWindow;
@@ -522,173 +507,144 @@
     while (getCurrentTime() < timeToStopPolling) {
         // if class is being torn down, immediately return
         if (mTeardown.load(std::memory_order_relaxed)) {
-            return std::nullopt;
+            return NN_ERROR() << "FMQ object is being torn down";
         }
 
-        // Check if data is available. If it is, immediately retrieve it and
-        // return.
-        const size_t available = mFmqRequestChannel->availableToRead();
+        // Check if data is available. If it is, immediately retrieve it and return.
+        const size_t available = mFmqRequestChannel.availableToRead();
         if (available > 0) {
-            // This is the first point when we know an execution is occurring,
-            // so begin to collect systraces. Note that a similar systrace does
-            // not exist at the corresponding point in
-            // ResultChannelReceiver::getPacketBlocking because the execution is
-            // already in flight.
-            NNTRACE_FULL(NNTRACE_LAYER_IPC, NNTRACE_PHASE_EXECUTION,
-                         "ExecutionBurstServer getting packet");
             std::vector<FmqRequestDatum> packet(available);
-            const bool success = mFmqRequestChannel->read(packet.data(), available);
+            const bool success = mFmqRequestChannel.readBlocking(packet.data(), available);
             if (!success) {
-                LOG(ERROR) << "Error receiving packet";
-                return std::nullopt;
+                return NN_ERROR() << "Error receiving packet";
             }
-            return std::make_optional(std::move(packet));
+            return packet;
         }
     }
 
-    // If we get to this point, we either stopped polling because it was taking
-    // too long or polling was not allowed. Instead, perform a blocking call
-    // which uses a futex to save power.
+    // If we get to this point, we either stopped polling because it was taking too long or polling
+    // was not allowed. Instead, perform a blocking call which uses a futex to save power.
 
     // wait for request packet and read first element of request packet
     FmqRequestDatum datum;
-    bool success = mFmqRequestChannel->readBlocking(&datum, 1);
-
-    // This is the first point when we know an execution is occurring, so begin
-    // to collect systraces. Note that a similar systrace does not exist at the
-    // corresponding point in ResultChannelReceiver::getPacketBlocking because
-    // the execution is already in flight.
-    NNTRACE_FULL(NNTRACE_LAYER_IPC, NNTRACE_PHASE_EXECUTION, "ExecutionBurstServer getting packet");
+    bool success = mFmqRequestChannel.readBlocking(&datum, 1);
 
     // retrieve remaining elements
-    // NOTE: all of the data is already available at this point, so there's no
-    // need to do a blocking wait to wait for more data. This is known because
-    // in FMQ, all writes are published (made available) atomically. Currently,
-    // the producer always publishes the entire packet in one function call, so
-    // if the first element of the packet is available, the remaining elements
-    // are also available.
-    const size_t count = mFmqRequestChannel->availableToRead();
+    // NOTE: all of the data is already available at this point, so there's no need to do a blocking
+    // wait to wait for more data. This is known because in FMQ, all writes are published (made
+    // available) atomically. Currently, the producer always publishes the entire packet in one
+    // function call, so if the first element of the packet is available, the remaining elements are
+    // also available.
+    const size_t count = mFmqRequestChannel.availableToRead();
     std::vector<FmqRequestDatum> packet(count + 1);
     std::memcpy(&packet.front(), &datum, sizeof(datum));
-    success &= mFmqRequestChannel->read(packet.data() + 1, count);
+    success &= mFmqRequestChannel.read(packet.data() + 1, count);
 
     // terminate loop
     if (mTeardown) {
-        return std::nullopt;
+        return NN_ERROR() << "FMQ object is being torn down";
     }
 
     // ensure packet was successfully received
     if (!success) {
-        LOG(ERROR) << "Error receiving packet";
-        return std::nullopt;
+        return NN_ERROR() << "Error receiving packet";
     }
 
-    return std::make_optional(std::move(packet));
+    return packet;
 }
 
 // ResultChannelSender methods
 
-std::unique_ptr<ResultChannelSender> ResultChannelSender::create(
-        const FmqResultDescriptor& resultChannel) {
-    std::unique_ptr<FmqResultChannel> fmqResultChannel =
-            std::make_unique<FmqResultChannel>(resultChannel);
+nn::GeneralResult<std::unique_ptr<ResultChannelSender>> ResultChannelSender::create(
+        const MQDescriptorSync<FmqResultDatum>& resultChannel) {
+    auto resultChannelSender =
+            std::make_unique<ResultChannelSender>(PrivateConstructorTag{}, resultChannel);
 
-    if (!fmqResultChannel->isValid()) {
-        LOG(ERROR) << "Unable to create RequestChannelSender";
-        return nullptr;
+    if (!resultChannelSender->mFmqResultChannel.isValid()) {
+        return NN_ERROR() << "Unable to create RequestChannelSender";
     }
-    if (fmqResultChannel->getEventFlagWord() == nullptr) {
-        LOG(ERROR) << "ResultChannelSender::create was passed an MQDescriptor without an EventFlag";
-        return nullptr;
+    if (resultChannelSender->mFmqResultChannel.getEventFlagWord() == nullptr) {
+        return NN_ERROR()
+               << "ResultChannelSender::create was passed an MQDescriptor without an EventFlag";
     }
 
-    return std::make_unique<ResultChannelSender>(std::move(fmqResultChannel));
+    return resultChannelSender;
 }
 
-ResultChannelSender::ResultChannelSender(std::unique_ptr<FmqResultChannel> fmqResultChannel)
-    : mFmqResultChannel(std::move(fmqResultChannel)) {}
+ResultChannelSender::ResultChannelSender(PrivateConstructorTag /*tag*/,
+                                         const MQDescriptorSync<FmqResultDatum>& resultChannel)
+    : mFmqResultChannel(resultChannel) {}
 
-bool ResultChannelSender::send(V1_0::ErrorStatus errorStatus,
+void ResultChannelSender::send(V1_0::ErrorStatus errorStatus,
                                const std::vector<V1_2::OutputShape>& outputShapes,
                                V1_2::Timing timing) {
     const std::vector<FmqResultDatum> serialized = serialize(errorStatus, outputShapes, timing);
-    return sendPacket(serialized);
+    sendPacket(serialized);
 }
 
-bool ResultChannelSender::sendPacket(const std::vector<FmqResultDatum>& packet) {
-    if (packet.size() > mFmqResultChannel->availableToWrite()) {
+void ResultChannelSender::sendPacket(const std::vector<FmqResultDatum>& packet) {
+    if (packet.size() > mFmqResultChannel.availableToWrite()) {
         LOG(ERROR)
                 << "ResultChannelSender::sendPacket -- packet size exceeds size available in FMQ";
         const std::vector<FmqResultDatum> errorPacket =
                 serialize(V1_0::ErrorStatus::GENERAL_FAILURE, {}, kNoTiming);
 
-        // Always send the packet with "blocking" because this signals the futex
-        // and unblocks the consumer if it is waiting on the futex.
-        return mFmqResultChannel->writeBlocking(errorPacket.data(), errorPacket.size());
+        // Always send the packet with "blocking" because this signals the futex and unblocks the
+        // consumer if it is waiting on the futex.
+        mFmqResultChannel.writeBlocking(errorPacket.data(), errorPacket.size());
+    } else {
+        // Always send the packet with "blocking" because this signals the futex and unblocks the
+        // consumer if it is waiting on the futex.
+        mFmqResultChannel.writeBlocking(packet.data(), packet.size());
     }
-
-    // Always send the packet with "blocking" because this signals the futex and
-    // unblocks the consumer if it is waiting on the futex.
-    return mFmqResultChannel->writeBlocking(packet.data(), packet.size());
 }
 
 // ResultChannelReceiver methods
 
-std::pair<std::unique_ptr<ResultChannelReceiver>, const FmqResultDescriptor*>
+nn::GeneralResult<
+        std::pair<std::unique_ptr<ResultChannelReceiver>, const MQDescriptorSync<FmqResultDatum>*>>
 ResultChannelReceiver::create(size_t channelLength, std::chrono::microseconds pollingTimeWindow) {
-    std::unique_ptr<FmqResultChannel> fmqResultChannel =
-            std::make_unique<FmqResultChannel>(channelLength, /*confEventFlag=*/true);
-    if (!fmqResultChannel->isValid()) {
-        LOG(ERROR) << "Unable to create ResultChannelReceiver";
-        return {nullptr, nullptr};
+    auto resultChannelReceiver = std::make_unique<ResultChannelReceiver>(
+            PrivateConstructorTag{}, channelLength, pollingTimeWindow);
+    if (!resultChannelReceiver->mFmqResultChannel.isValid()) {
+        return NN_ERROR() << "Unable to create ResultChannelReceiver";
     }
 
-    const FmqResultDescriptor* descriptor = fmqResultChannel->getDesc();
-    return std::make_pair(
-            std::make_unique<ResultChannelReceiver>(std::move(fmqResultChannel), pollingTimeWindow),
-            descriptor);
+    const MQDescriptorSync<FmqResultDatum>* descriptor =
+            resultChannelReceiver->mFmqResultChannel.getDesc();
+    return std::make_pair(std::move(resultChannelReceiver), descriptor);
 }
 
-ResultChannelReceiver::ResultChannelReceiver(std::unique_ptr<FmqResultChannel> fmqResultChannel,
+ResultChannelReceiver::ResultChannelReceiver(PrivateConstructorTag /*tag*/, size_t channelLength,
                                              std::chrono::microseconds pollingTimeWindow)
-    : mFmqResultChannel(std::move(fmqResultChannel)), kPollingTimeWindow(pollingTimeWindow) {}
+    : mFmqResultChannel(channelLength, /*configureEventFlagWord=*/true),
+      kPollingTimeWindow(pollingTimeWindow) {}
 
-std::optional<std::tuple<V1_0::ErrorStatus, std::vector<V1_2::OutputShape>, V1_2::Timing>>
+nn::Result<std::tuple<V1_0::ErrorStatus, std::vector<V1_2::OutputShape>, V1_2::Timing>>
 ResultChannelReceiver::getBlocking() {
-    const auto packet = getPacketBlocking();
-    if (!packet) {
-        return std::nullopt;
-    }
-
-    return deserialize(*packet);
+    const auto packet = NN_TRY(getPacketBlocking());
+    return deserialize(packet);
 }
 
-void ResultChannelReceiver::invalidate() {
+void ResultChannelReceiver::notifyAsDeadObject() {
     mValid = false;
 
     // force unblock
-    // ExecutionBurstController waits on a result packet after sending a
-    // request. If the driver containing ExecutionBurstServer crashes, the
-    // controller may be waiting on the futex. This force unblock wakes up any
-    // thread waiting on the futex.
-    // TODO: look for a different/better way to signal/notify the futex to
-    // wake up any thread waiting on it
-    FmqResultDatum datum;
-    datum.packetInformation({/*.packetSize=*/0,
-                             /*.errorStatus=*/V1_0::ErrorStatus::GENERAL_FAILURE,
-                             /*.numberOfOperands=*/0});
-    mFmqResultChannel->writeBlocking(&datum, 1);
+    // ExecutionBurstController waits on a result packet after sending a request. If the driver
+    // containing ExecutionBurstServer crashes, the controller may be waiting on the futex. This
+    // force unblock wakes up any thread waiting on the futex.
+    const auto data = serialize(V1_0::ErrorStatus::GENERAL_FAILURE, {}, kNoTiming);
+    mFmqResultChannel.writeBlocking(data.data(), data.size());
 }
 
-std::optional<std::vector<FmqResultDatum>> ResultChannelReceiver::getPacketBlocking() {
+nn::Result<std::vector<FmqResultDatum>> ResultChannelReceiver::getPacketBlocking() {
     if (!mValid) {
-        return std::nullopt;
+        return NN_ERROR() << "FMQ object is invalid";
     }
 
-    // First spend time polling if results are available in FMQ instead of
-    // waiting on the futex. Polling is more responsive (yielding lower
-    // latencies), but can take up more power, so only poll for a limited period
-    // of time.
+    // First spend time polling if results are available in FMQ instead of waiting on the futex.
+    // Polling is more responsive (yielding lower latencies), but can take up more power, so only
+    // poll for a limited period of time.
 
     auto& getCurrentTime = std::chrono::high_resolution_clock::now;
     const auto timeToStopPolling = getCurrentTime() + kPollingTimeWindow;
@@ -696,54 +652,49 @@
     while (getCurrentTime() < timeToStopPolling) {
         // if class is being torn down, immediately return
         if (!mValid.load(std::memory_order_relaxed)) {
-            return std::nullopt;
+            return NN_ERROR() << "FMQ object is invalid";
         }
 
-        // Check if data is available. If it is, immediately retrieve it and
-        // return.
-        const size_t available = mFmqResultChannel->availableToRead();
+        // Check if data is available. If it is, immediately retrieve it and return.
+        const size_t available = mFmqResultChannel.availableToRead();
         if (available > 0) {
             std::vector<FmqResultDatum> packet(available);
-            const bool success = mFmqResultChannel->read(packet.data(), available);
+            const bool success = mFmqResultChannel.readBlocking(packet.data(), available);
             if (!success) {
-                LOG(ERROR) << "Error receiving packet";
-                return std::nullopt;
+                return NN_ERROR() << "Error receiving packet";
             }
-            return std::make_optional(std::move(packet));
+            return packet;
         }
     }
 
-    // If we get to this point, we either stopped polling because it was taking
-    // too long or polling was not allowed. Instead, perform a blocking call
-    // which uses a futex to save power.
+    // If we get to this point, we either stopped polling because it was taking too long or polling
+    // was not allowed. Instead, perform a blocking call which uses a futex to save power.
 
     // wait for result packet and read first element of result packet
     FmqResultDatum datum;
-    bool success = mFmqResultChannel->readBlocking(&datum, 1);
+    bool success = mFmqResultChannel.readBlocking(&datum, 1);
 
     // retrieve remaining elements
-    // NOTE: all of the data is already available at this point, so there's no
-    // need to do a blocking wait to wait for more data. This is known because
-    // in FMQ, all writes are published (made available) atomically. Currently,
-    // the producer always publishes the entire packet in one function call, so
-    // if the first element of the packet is available, the remaining elements
-    // are also available.
-    const size_t count = mFmqResultChannel->availableToRead();
+    // NOTE: all of the data is already available at this point, so there's no need to do a blocking
+    // wait to wait for more data. This is known because in FMQ, all writes are published (made
+    // available) atomically. Currently, the producer always publishes the entire packet in one
+    // function call, so if the first element of the packet is available, the remaining elements are
+    // also available.
+    const size_t count = mFmqResultChannel.availableToRead();
     std::vector<FmqResultDatum> packet(count + 1);
     std::memcpy(&packet.front(), &datum, sizeof(datum));
-    success &= mFmqResultChannel->read(packet.data() + 1, count);
+    success &= mFmqResultChannel.read(packet.data() + 1, count);
 
     if (!mValid) {
-        return std::nullopt;
+        return NN_ERROR() << "FMQ object is invalid";
     }
 
     // ensure packet was successfully received
     if (!success) {
-        LOG(ERROR) << "Error receiving packet";
-        return std::nullopt;
+        return NN_ERROR() << "Error receiving packet";
     }
 
-    return std::make_optional(std::move(packet));
+    return packet;
 }
 
 }  // namespace android::hardware::neuralnetworks::V1_2::utils