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/*
* Copyright (C) 2020 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.
*/
#ifndef ANDROID_FRAMEWORKS_ML_NN_COMMON_NNAPI_IBURST_H
#define ANDROID_FRAMEWORKS_ML_NN_COMMON_NNAPI_IBURST_H
#include <android-base/scopeguard.h>
#include <functional>
#include <memory>
#include <optional>
#include <utility>
#include <vector>
#include "nnapi/Types.h"
namespace android::nn {
/**
* IBurst represents a burst execution object.
*
* Burst executions are a sequence of executions of the same prepared model that occur in rapid
* succession, such as frames of a camera capture or successive audio samples. A burst object is
* used to control a set of burst executions, and to preserve resources between executions, enabling
* executions to have lower overhead. Burst objects enable some optimizations:
* (1) A burst object is created before a sequence of executions, and freed when the sequence has
* ended. Because of this, the lifetime of the burst object hints to a driver how long it should
* remain in a high performance state.
* (2) A burst object can preserve resources between executions. For example, a driver can map a
* memory object on the first execution and cache the mapping in the burst object for reuse in
* subsequent executions. Any cached resource can be released when the burst object is destroyed
* or when the NNAPI runtime notifies the burst object that the resource is no longer required.
* (3) A burst object may be used for at most one execution at a time. This enables any transient
* execution resources such as intermediate tensors to be allocated once when the burst object
* is created and freed when the burst object is destroyed.
*
* This interface is thread-safe, and any class that implements this interface must be thread-safe.
*/
class IBurst {
public:
using OptionalCacheHold = std::shared_ptr<const base::ScopeGuard<std::function<void()>>>;
/**
* Cache a memory object in the burst.
*
* This can enable multiple executions that reuse the same memory to be more efficient.
*
* @param memory The memory object to be cached as long as CacheHandle is held.
* @return An optional cache handle that will release the corresponding cahced object once the
* cache handle is released, or nullptr.
*/
virtual OptionalCacheHold cacheMemory(const SharedMemory& memory) const = 0;
/**
* Performs a synchronous execution on a prepared model.
*
* At most one execution may occur on a burst object at any given time.
*
* The execution is performed synchronously with respect to the caller. IBurst::execute must
* verify the inputs to the function are correct. If there is an error, IBurst::execute must
* immediately return {@link ErrorStatus::INVALID_ARGUMENT} as a ExecutionError. If the inputs
* to the function are valid and there is no error, IBurst::execute must perform the execution,
* and must not return until the execution is complete.
*
* The caller must not change the content of any data object referenced by request (described by
* the {@link DataLocation} of a {@link RequestArgument}) until IBurst::execute returns.
* IBurst::execute must not change the content of any of the data objects corresponding to
* request inputs.
*
* If the prepared model was prepared from a model wherein all tensor operands have fully
* specified dimensions, and the inputs to the function are valid, and at execution time every
* operation's input operands have legal values, then the execution should complete
* successfully. There must be no failure unless the device itself is in a bad state.
*
* @param request The input and output information on which the prepared model is to be
* executed.
* @param measure Specifies whether or not to measure duration of the execution.
* @param deadline Optional time point. If provided, execute is expected to complete by this
* time point. If it is not able to be completed by the deadline, the execution may be
* aborted.
* @param loopTimeoutDuration The maximum amount of time that should be spent executing a {@link
* OperationType::WHILE} operation. If a loop condition model does not output `false` within
* this duration, the execution must be aborted. If no loop timeout duration is provided,
* the maximum amount of time is {@link kControlFlowTimeoutDefault}. When provided, the
* duration must not exceed {@link kControlFlowTimeoutMaximum}.
* @return A pair consisting of:
* - A list of shape information of model output operands. The index into "outputShapes"
* corresponds to the index of the output operand in the Request outputs vector.
* outputShapes must be empty unless the execution is successful or the ExecutionResult is
* {@link ErrorStatus::OUTPUT_INSUFFICIENT_SIZE}. outputShapes may be empty if the
* execution is successful and all model output operands are fully-specified at execution
* time. outputShapes must have the same number of elements as the number of model output
* operands if the ExecutionResult is {@link ErrorStatus::OUTPUT_INSUFFICIENT_SIZE}, or if
* the execution is successful and the model has at least one output operand that is not
* fully-specified.
* - Duration of execution. Unless measure is YES and the execution is successful, all times
* must be reported as std::nullopt. A driver may choose to report any time as
* std::nullopt, indicating that measurement is not available.
*/
virtual ExecutionResult<std::pair<std::vector<OutputShape>, Timing>> execute(
const Request& request, MeasureTiming measure, const nn::OptionalTimePoint& deadline,
const nn::OptionalDuration& loopTimeoutDuration) const = 0;
/**
* Create a reusable burst execution object.
*
* IBurst::createReusableExecution must verify the inputs to the function are correct. If there
* is an error, IBurst::createReusableExecution must immediately return {@link
* ErrorStatus::INVALID_ARGUMENT} as a GeneralError. If the inputs to the function are valid and
* there is no error, IBurst::createReusableExecution must construct a reusable execution.
*
* @param request The input and output information on which the prepared model is to be
* executed.
* @param measure Specifies whether or not to measure duration of the computation.
* @param loopTimeoutDuration The maximum amount of time that should be spent executing a {@link
* OperationType::WHILE} operation. If a loop condition model does not output `false` within
* this duration, the execution must be aborted. If no loop timeout duration is provided,
* the maximum amount of time is {@link kControlFlowTimeoutDefault}. When provided, the
* duration must not exceed {@link kControlFlowTimeoutMaximum}.
* @return execution An IExecution object representing a reusable burst execution that has been
* specialized for a fixed request, otherwise GeneralError.
*/
virtual GeneralResult<SharedExecution> createReusableExecution(
const Request& request, MeasureTiming measure,
const nn::OptionalDuration& loopTimeoutDuration) const = 0;
// Public virtual destructor to allow objects to be stored (and destroyed) as smart pointers.
// E.g., std::unique_ptr<IBurst>.
virtual ~IBurst() = default;
protected:
// Protect the non-destructor special member functions to prevent object slicing.
IBurst() = default;
IBurst(const IBurst&) = default;
IBurst(IBurst&&) noexcept = default;
IBurst& operator=(const IBurst&) = default;
IBurst& operator=(IBurst&&) noexcept = default;
};
} // namespace android::nn
#endif // ANDROID_FRAMEWORKS_ML_NN_COMMON_NNAPI_IBURST_H