1 files changed, 702 insertions, 0 deletions
diff --git a/neuralnetworks/1.2/utils/src/BurstUtils.cpp b/neuralnetworks/1.2/utils/src/BurstUtils.cpp
new file mode 100644
index 0000000000..b589c468ce
--- /dev/null
+++ b/neuralnetworks/1.2/utils/src/BurstUtils.cpp
@@ -0,0 +1,702 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#include "BurstUtils.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/1.0/ProtectCallback.h>
+
+#include <atomic>
+#include <chrono>
+#include <memory>
+#include <thread>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+namespace android::hardware::neuralnetworks::V1_2::utils {
+namespace {
+
+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() + 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
+    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
+        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) {
+            data.emplace_back();
+            data.back().inputOperandDimensionValue(dimension);
+        }
+    }
+
+    // package output data
+    for (const auto& output : request.outputs) {
+        // package operand information
+        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) {
+            data.emplace_back();
+            data.back().outputOperandDimensionValue(dimension);
+        }
+    }
+
+    // package pool identifier
+    for (int32_t slot : slots) {
+        data.emplace_back();
+        data.back().poolIdentifier(slot);
+    }
+
+    // package measureTiming
+    data.emplace_back();
+    data.back().measureTiming(measure);
+
+    CHECK_EQ(data.size(), count);
+
+    // return packet
+    return data;
+}
+
+// serialize result
+std::vector<FmqResultDatum> serialize(V1_0::ErrorStatus errorStatus,
+                                      const std::vector<V1_2::OutputShape>& outputShapes,
+                                      V1_2::Timing timing) {
+    // count how many elements need to be sent for a request
+    size_t count = 2 + outputShapes.size();
+    for (const auto& outputShape : outputShapes) {
+        count += outputShape.dimensions.size();
+    }
+
+    // create buffer to temporarily store elements
+    std::vector<FmqResultDatum> data;
+    data.reserve(count);
+
+    // package packetInfo
+    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
+        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) {
+            data.emplace_back();
+            data.back().operandDimensionValue(dimension);
+        }
+    }
+
+    // package executionTiming
+    data.emplace_back();
+    data.back().executionTiming(timing);
+
+    CHECK_EQ(data.size(), count);
+
+    // return result
+    return data;
+}
+
+// deserialize request
+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;
+
+    size_t index = 0;
+
+    // validate packet information
+    if (data.size() == 0 || data[index].getDiscriminator() != discriminator::packetInformation) {
+        return NN_ERROR() << "FMQ Request packet ill-formed";
+    }
+
+    // unpackage packet information
+    const FmqRequestDatum::PacketInformation& packetInfo = data[index].packetInformation();
+    index++;
+    const uint32_t packetSize = packetInfo.packetSize;
+    const uint32_t numberOfInputOperands = packetInfo.numberOfInputOperands;
+    const uint32_t numberOfOutputOperands = packetInfo.numberOfOutputOperands;
+    const uint32_t numberOfPools = packetInfo.numberOfPools;
+
+    // verify packet size
+    if (data.size() != packetSize) {
+        return NN_ERROR() << "FMQ Request packet ill-formed";
+    }
+
+    // unpackage input operands
+    std::vector<V1_0::RequestArgument> inputs;
+    inputs.reserve(numberOfInputOperands);
+    for (size_t operand = 0; operand < numberOfInputOperands; ++operand) {
+        // validate input operand information
+        if (data[index].getDiscriminator() != discriminator::inputOperandInformation) {
+            return NN_ERROR() << "FMQ Request packet ill-formed";
+        }
+
+        // unpackage operand information
+        const FmqRequestDatum::OperandInformation& operandInfo =
+                data[index].inputOperandInformation();
+        index++;
+        const bool hasNoValue = operandInfo.hasNoValue;
+        const V1_0::DataLocation location = operandInfo.location;
+        const uint32_t numberOfDimensions = operandInfo.numberOfDimensions;
+
+        // unpackage operand dimensions
+        std::vector<uint32_t> dimensions;
+        dimensions.reserve(numberOfDimensions);
+        for (size_t i = 0; i < numberOfDimensions; ++i) {
+            // validate dimension
+            if (data[index].getDiscriminator() != discriminator::inputOperandDimensionValue) {
+                return NN_ERROR() << "FMQ Request packet ill-formed";
+            }
+
+            // unpackage dimension
+            const uint32_t dimension = data[index].inputOperandDimensionValue();
+            index++;
+
+            // store result
+            dimensions.push_back(dimension);
+        }
+
+        // store result
+        inputs.push_back(
+                {.hasNoValue = hasNoValue, .location = location, .dimensions = dimensions});
+    }
+
+    // unpackage output operands
+    std::vector<V1_0::RequestArgument> outputs;
+    outputs.reserve(numberOfOutputOperands);
+    for (size_t operand = 0; operand < numberOfOutputOperands; ++operand) {
+        // validate output operand information
+        if (data[index].getDiscriminator() != discriminator::outputOperandInformation) {
+            return NN_ERROR() << "FMQ Request packet ill-formed";
+        }
+
+        // unpackage operand information
+        const FmqRequestDatum::OperandInformation& operandInfo =
+                data[index].outputOperandInformation();
+        index++;
+        const bool hasNoValue = operandInfo.hasNoValue;
+        const V1_0::DataLocation location = operandInfo.location;
+        const uint32_t numberOfDimensions = operandInfo.numberOfDimensions;
+
+        // unpackage operand dimensions
+        std::vector<uint32_t> dimensions;
+        dimensions.reserve(numberOfDimensions);
+        for (size_t i = 0; i < numberOfDimensions; ++i) {
+            // validate dimension
+            if (data[index].getDiscriminator() != discriminator::outputOperandDimensionValue) {
+                return NN_ERROR() << "FMQ Request packet ill-formed";
+            }
+
+            // unpackage dimension
+            const uint32_t dimension = data[index].outputOperandDimensionValue();
+            index++;
+
+            // store result
+            dimensions.push_back(dimension);
+        }
+
+        // store result
+        outputs.push_back(
+                {.hasNoValue = hasNoValue, .location = location, .dimensions = dimensions});
+    }
+
+    // unpackage pools
+    std::vector<int32_t> slots;
+    slots.reserve(numberOfPools);
+    for (size_t pool = 0; pool < numberOfPools; ++pool) {
+        // validate input operand information
+        if (data[index].getDiscriminator() != discriminator::poolIdentifier) {
+            return NN_ERROR() << "FMQ Request packet ill-formed";
+        }
+
+        // unpackage operand information
+        const int32_t poolId = data[index].poolIdentifier();
+        index++;
+
+        // store result
+        slots.push_back(poolId);
+    }
+
+    // validate measureTiming
+    if (data[index].getDiscriminator() != discriminator::measureTiming) {
+        return NN_ERROR() << "FMQ Request packet ill-formed";
+    }
+
+    // unpackage measureTiming
+    const V1_2::MeasureTiming measure = data[index].measureTiming();
+    index++;
+
+    // validate packet information
+    if (index != packetSize) {
+        return NN_ERROR() << "FMQ Result packet ill-formed";
+    }
+
+    // return request
+    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
+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;
+    size_t index = 0;
+
+    // validate packet information
+    if (data.size() == 0 || data[index].getDiscriminator() != discriminator::packetInformation) {
+        return NN_ERROR() << "FMQ Result packet ill-formed";
+    }
+
+    // unpackage packet information
+    const FmqResultDatum::PacketInformation& packetInfo = data[index].packetInformation();
+    index++;
+    const uint32_t packetSize = packetInfo.packetSize;
+    const V1_0::ErrorStatus errorStatus = packetInfo.errorStatus;
+    const uint32_t numberOfOperands = packetInfo.numberOfOperands;
+
+    // verify packet size
+    if (data.size() != packetSize) {
+        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) {
+            return NN_ERROR() << "FMQ Result packet ill-formed";
+        }
+
+        // unpackage operand information
+        const FmqResultDatum::OperandInformation& operandInfo = data[index].operandInformation();
+        index++;
+        const bool isSufficient = operandInfo.isSufficient;
+        const uint32_t numberOfDimensions = operandInfo.numberOfDimensions;
+
+        // unpackage operand dimensions
+        std::vector<uint32_t> dimensions;
+        dimensions.reserve(numberOfDimensions);
+        for (size_t i = 0; i < numberOfDimensions; ++i) {
+            // validate dimension
+            if (data[index].getDiscriminator() != discriminator::operandDimensionValue) {
+                return NN_ERROR() << "FMQ Result packet ill-formed";
+            }
+
+            // unpackage dimension
+            const uint32_t dimension = data[index].operandDimensionValue();
+            index++;
+
+            // store result
+            dimensions.push_back(dimension);
+        }
+
+        // store result
+        outputShapes.push_back({.dimensions = dimensions, .isSufficient = isSufficient});
+    }
+
+    // validate execution timing
+    if (data[index].getDiscriminator() != discriminator::executionTiming) {
+        return NN_ERROR() << "FMQ Result packet ill-formed";
+    }
+
+    // unpackage execution timing
+    const V1_2::Timing timing = data[index].executionTiming();
+    index++;
+
+    // validate packet information
+    if (index != packetSize) {
+        return NN_ERROR() << "FMQ Result packet ill-formed";
+    }
+
+    // return result
+    return std::make_tuple(errorStatus, std::move(outputShapes), timing);
+}
+
+// RequestChannelSender methods
+
+nn::GeneralResult<
+        std::pair<std::unique_ptr<RequestChannelSender>, const MQDescriptorSync<FmqRequestDatum>*>>
+RequestChannelSender::create(size_t channelLength) {
+    auto requestChannelSender =
+            std::make_unique<RequestChannelSender>(PrivateConstructorTag{}, channelLength);
+    if (!requestChannelSender->mFmqRequestChannel.isValid()) {
+        return NN_ERROR() << "Unable to create RequestChannelSender";
+    }
+
+    const MQDescriptorSync<FmqRequestDatum>* descriptor =
+            requestChannelSender->mFmqRequestChannel.getDesc();
+    return std::make_pair(std::move(requestChannelSender), descriptor);
+}
+
+RequestChannelSender::RequestChannelSender(PrivateConstructorTag /*tag*/, size_t channelLength)
+    : mFmqRequestChannel(channelLength, /*configureEventFlagWord=*/true) {}
+
+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);
+}
+
+nn::Result<void> RequestChannelSender::sendPacket(const std::vector<FmqRequestDatum>& packet) {
+    if (!mValid) {
+        return NN_ERROR() << "FMQ object is invalid";
+    }
+
+    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.
+    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::notifyAsDeadObject() {
+    mValid = false;
+}
+
+// RequestChannelReceiver methods
+
+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 (!requestChannelReceiver->mFmqRequestChannel.isValid()) {
+        return NN_ERROR() << "Unable to create RequestChannelReceiver";
+    }
+    if (requestChannelReceiver->mFmqRequestChannel.getEventFlagWord() == nullptr) {
+        return NN_ERROR()
+               << "RequestChannelReceiver::create was passed an MQDescriptor without an EventFlag";
+    }
+
+    return requestChannelReceiver;
+}
+
+RequestChannelReceiver::RequestChannelReceiver(
+        PrivateConstructorTag /*tag*/, const MQDescriptorSync<FmqRequestDatum>& requestChannel,
+        std::chrono::microseconds pollingTimeWindow)
+    : mFmqRequestChannel(requestChannel), kPollingTimeWindow(pollingTimeWindow) {}
+
+nn::Result<std::tuple<V1_0::Request, std::vector<int32_t>, V1_2::MeasureTiming>>
+RequestChannelReceiver::getBlocking() {
+    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.
+    const auto data = serialize(V1_0::Request{}, V1_2::MeasureTiming::NO, {});
+    mFmqRequestChannel.writeBlocking(data.data(), data.size());
+}
+
+nn::Result<std::vector<FmqRequestDatum>> RequestChannelReceiver::getPacketBlocking() {
+    if (mTeardown) {
+        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.
+
+    auto& getCurrentTime = std::chrono::high_resolution_clock::now;
+    const auto timeToStopPolling = getCurrentTime() + kPollingTimeWindow;
+
+    while (getCurrentTime() < timeToStopPolling) {
+        // if class is being torn down, immediately return
+        if (mTeardown.load(std::memory_order_relaxed)) {
+            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();
+        if (available > 0) {
+            std::vector<FmqRequestDatum> packet(available);
+            const bool success = mFmqRequestChannel.readBlocking(packet.data(), available);
+            if (!success) {
+                return NN_ERROR() << "Error receiving packet";
+            }
+            return packet;
+        }
+
+        std::this_thread::yield();
+    }
+
+    // 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);
+
+    // 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();
+    std::vector<FmqRequestDatum> packet(count + 1);
+    std::memcpy(&packet.front(), &datum, sizeof(datum));
+    success &= mFmqRequestChannel.read(packet.data() + 1, count);
+
+    // terminate loop
+    if (mTeardown) {
+        return NN_ERROR() << "FMQ object is being torn down";
+    }
+
+    // ensure packet was successfully received
+    if (!success) {
+        return NN_ERROR() << "Error receiving packet";
+    }
+
+    return packet;
+}
+
+// ResultChannelSender methods
+
+nn::GeneralResult<std::unique_ptr<ResultChannelSender>> ResultChannelSender::create(
+        const MQDescriptorSync<FmqResultDatum>& resultChannel) {
+    auto resultChannelSender =
+            std::make_unique<ResultChannelSender>(PrivateConstructorTag{}, resultChannel);
+
+    if (!resultChannelSender->mFmqResultChannel.isValid()) {
+        return NN_ERROR() << "Unable to create RequestChannelSender";
+    }
+    if (resultChannelSender->mFmqResultChannel.getEventFlagWord() == nullptr) {
+        return NN_ERROR()
+               << "ResultChannelSender::create was passed an MQDescriptor without an EventFlag";
+    }
+
+    return resultChannelSender;
+}
+
+ResultChannelSender::ResultChannelSender(PrivateConstructorTag /*tag*/,
+                                         const MQDescriptorSync<FmqResultDatum>& resultChannel)
+    : mFmqResultChannel(resultChannel) {}
+
+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);
+    sendPacket(serialized);
+}
+
+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.
+        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());
+    }
+}
+
+// ResultChannelReceiver methods
+
+nn::GeneralResult<
+        std::pair<std::unique_ptr<ResultChannelReceiver>, const MQDescriptorSync<FmqResultDatum>*>>
+ResultChannelReceiver::create(size_t channelLength, std::chrono::microseconds pollingTimeWindow) {
+    auto resultChannelReceiver = std::make_unique<ResultChannelReceiver>(
+            PrivateConstructorTag{}, channelLength, pollingTimeWindow);
+    if (!resultChannelReceiver->mFmqResultChannel.isValid()) {
+        return NN_ERROR() << "Unable to create ResultChannelReceiver";
+    }
+
+    const MQDescriptorSync<FmqResultDatum>* descriptor =
+            resultChannelReceiver->mFmqResultChannel.getDesc();
+    return std::make_pair(std::move(resultChannelReceiver), descriptor);
+}
+
+ResultChannelReceiver::ResultChannelReceiver(PrivateConstructorTag /*tag*/, size_t channelLength,
+                                             std::chrono::microseconds pollingTimeWindow)
+    : mFmqResultChannel(channelLength, /*configureEventFlagWord=*/true),
+      kPollingTimeWindow(pollingTimeWindow) {}
+
+nn::Result<std::tuple<V1_0::ErrorStatus, std::vector<V1_2::OutputShape>, V1_2::Timing>>
+ResultChannelReceiver::getBlocking() {
+    const auto packet = NN_TRY(getPacketBlocking());
+    return deserialize(packet);
+}
+
+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.
+    const auto data = serialize(V1_0::ErrorStatus::GENERAL_FAILURE, {}, kNoTiming);
+    mFmqResultChannel.writeBlocking(data.data(), data.size());
+}
+
+nn::Result<std::vector<FmqResultDatum>> ResultChannelReceiver::getPacketBlocking() {
+    if (!mValid) {
+        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.
+
+    auto& getCurrentTime = std::chrono::high_resolution_clock::now;
+    const auto timeToStopPolling = getCurrentTime() + kPollingTimeWindow;
+
+    while (getCurrentTime() < timeToStopPolling) {
+        // if class is being torn down, immediately return
+        if (!mValid.load(std::memory_order_relaxed)) {
+            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();
+        if (available > 0) {
+            std::vector<FmqResultDatum> packet(available);
+            const bool success = mFmqResultChannel.readBlocking(packet.data(), available);
+            if (!success) {
+                return NN_ERROR() << "Error receiving packet";
+            }
+            return packet;
+        }
+
+        std::this_thread::yield();
+    }
+
+    // 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);
+
+    // 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();
+    std::vector<FmqResultDatum> packet(count + 1);
+    std::memcpy(&packet.front(), &datum, sizeof(datum));
+    success &= mFmqResultChannel.read(packet.data() + 1, count);
+
+    if (!mValid) {
+        return NN_ERROR() << "FMQ object is invalid";
+    }
+
+    // ensure packet was successfully received
+    if (!success) {
+        return NN_ERROR() << "Error receiving packet";
+    }
+
+    return packet;
+}
+
+}  // namespace android::hardware::neuralnetworks::V1_2::utils