/*
 * 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 android.os;

import android.annotation.FlaggedApi;
import android.annotation.IntDef;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.SystemService;
import android.annotation.TestApi;
import android.content.Context;

import com.android.internal.util.Preconditions;

import java.io.Closeable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.ref.Reference;
import java.util.Objects;


/** The PerformanceHintManager allows apps to send performance hint to system. */
@SystemService(Context.PERFORMANCE_HINT_SERVICE)
public final class PerformanceHintManager {
    private final long mNativeManagerPtr;

    /** @hide */
    public static PerformanceHintManager create() throws ServiceManager.ServiceNotFoundException {
        long nativeManagerPtr = nativeAcquireManager();
        if (nativeManagerPtr == 0) {
            throw new ServiceManager.ServiceNotFoundException(Context.PERFORMANCE_HINT_SERVICE);
        }
        return new PerformanceHintManager(nativeManagerPtr);
    }

    private PerformanceHintManager(long nativeManagerPtr) {
        mNativeManagerPtr = nativeManagerPtr;
    }

    /**
     * Get preferred update rate information for this device.
     *
     * @return the preferred update rate supported by device software
     */
    public long getPreferredUpdateRateNanos() {
        return nativeGetPreferredUpdateRateNanos(mNativeManagerPtr);
    }

    /**
     * Creates a {@link Session} for the given set of threads and sets their initial target work
     * duration.
     *
     * @param tids The list of threads to be associated with this session. They must be part of
     *     this process' thread group
     * @param initialTargetWorkDurationNanos The desired duration in nanoseconds for the new
     *     session
     * @return the new session if it is supported on this device, null if hint session is not
     *     supported on this device or the tid doesn't belong to the application
     * @throws IllegalArgumentException if the thread id list is empty, or
     *                                  initialTargetWorkDurationNanos is non-positive
     */
    @Nullable
    public Session createHintSession(@NonNull int[] tids, long initialTargetWorkDurationNanos) {
        Objects.requireNonNull(tids, "tids cannot be null");
        if (tids.length == 0) {
            throw new IllegalArgumentException("thread id list can't be empty.");
        }
        Preconditions.checkArgumentPositive(initialTargetWorkDurationNanos,
                "the hint target duration should be positive.");
        long nativeSessionPtr = nativeCreateSession(mNativeManagerPtr, tids,
                initialTargetWorkDurationNanos);
        if (nativeSessionPtr == 0) return null;
        return new Session(nativeSessionPtr);
    }

    /**
     * A Session represents a group of threads with an inter-related workload such that hints for
     * their performance should be considered as a unit. The threads in a given session should be
     * long-lived and not created or destroyed dynamically.
     *
     * The work duration API can be used with periodic workloads to dynamically adjust thread
     * performance and keep the work on schedule while optimizing the available power budget.
     * When using the work duration API, the starting target duration should be specified
     * while creating the session, but can later be adjusted with
     * {@link #updateTargetWorkDuration(long)}. While using the work duration API, the client is be
     * expected to call {@link #reportActualWorkDuration(long)} each cycle to report the actual
     * time taken to complete to the system.
     *
     * Any call in this class will change its internal data, so you must do your own thread
     * safety to protect from racing.
     *
     * All timings should be in {@link SystemClock#uptimeNanos()}.
     */
    public static class Session implements Closeable {
        private long mNativeSessionPtr;

        /** @hide */
        public Session(long nativeSessionPtr) {
            mNativeSessionPtr = nativeSessionPtr;
        }

        /**
        * This hint indicates a sudden increase in CPU workload intensity. It means
        * that this hint session needs extra CPU resources immediately to meet the
        * target duration for the current work cycle.
        *
        * @hide
        */
        @TestApi
        public static final int CPU_LOAD_UP = 0;
        /**
        * This hint indicates a decrease in CPU workload intensity. It means that
        * this hint session can reduce CPU resources and still meet the target duration.
        *
        * @hide
        */
        @TestApi
        public static final int CPU_LOAD_DOWN = 1;
        /**
        * This hint indicates an upcoming CPU workload that is completely changed and
        * unknown. It means that the hint session should reset CPU resources to a known
        * baseline to prepare for an arbitrary load, and must wake up if inactive.
        *
        * @hide
        */
        @TestApi
        public static final int CPU_LOAD_RESET = 2;
        /**
        * This hint indicates that the most recent CPU workload is resuming after a
        * period of inactivity. It means that the hint session should allocate similar
        * CPU resources to what was used previously, and must wake up if inactive.
        *
        * @hide
        */
        @TestApi
        public static final int CPU_LOAD_RESUME = 3;

        /**
         * This hint indicates an increase in GPU workload intensity. It means that
         * this hint session needs extra GPU resources to meet the target duration.
         * This hint must be sent before reporting the actual duration to the session.
         *
         * @hide
         */
        @TestApi
        @FlaggedApi(Flags.FLAG_ADPF_GPU_REPORT_ACTUAL_WORK_DURATION)
        public static final int GPU_LOAD_UP = 5;

        /**
         * This hint indicates a decrease in GPU workload intensity. It means that
         * this hint session can reduce GPU resources and still meet the target duration.
         *
         * @hide
         */
        @TestApi
        @FlaggedApi(Flags.FLAG_ADPF_GPU_REPORT_ACTUAL_WORK_DURATION)
        public static final int GPU_LOAD_DOWN = 6;

        /**
        * This hint indicates an upcoming GPU workload that is completely changed and
        * unknown. It means that the hint session should reset GPU resources to a known
        * baseline to prepare for an arbitrary load, and must wake up if inactive.
         *
         * @hide
         */
        @TestApi
        @FlaggedApi(Flags.FLAG_ADPF_GPU_REPORT_ACTUAL_WORK_DURATION)
        public static final int GPU_LOAD_RESET = 7;

        /** @hide */
        @Retention(RetentionPolicy.SOURCE)
        @IntDef(prefix = {"CPU_LOAD_", "GPU_LOAD_"}, value = {
            CPU_LOAD_UP,
            CPU_LOAD_DOWN,
            CPU_LOAD_RESET,
            CPU_LOAD_RESUME,
            GPU_LOAD_UP,
            GPU_LOAD_DOWN,
            GPU_LOAD_RESET
        })
        public @interface Hint {}

        /** @hide */
        @Override
        protected void finalize() throws Throwable {
            try {
                close();
            } finally {
                super.finalize();
            }
        }

        /**
         * Updates this session's target total duration for each cycle of work.
         *
         * @param targetDurationNanos the new desired duration in nanoseconds
         */
        public void updateTargetWorkDuration(long targetDurationNanos) {
            Preconditions.checkArgumentPositive(targetDurationNanos, "the hint target duration"
                    + " should be positive.");
            nativeUpdateTargetWorkDuration(mNativeSessionPtr, targetDurationNanos);
        }

        /**
         * Reports the actual duration for the last cycle of work.
         *
         * The system will attempt to adjust the core placement of the threads within the thread
         * group and/or the frequency of the core on which they are run to bring the actual duration
         * close to the target duration.
         *
         * @param actualDurationNanos how long the thread group took to complete its last task in
         *     nanoseconds
         */
        public void reportActualWorkDuration(long actualDurationNanos) {
            Preconditions.checkArgumentPositive(actualDurationNanos, "the actual duration should"
                    + " be positive.");
            nativeReportActualWorkDuration(mNativeSessionPtr, actualDurationNanos);
        }

        /**
         * Ends the current hint session.
         *
         * Once called, you should not call anything else on this object.
         */
        public void close() {
            if (mNativeSessionPtr != 0) {
                nativeCloseSession(mNativeSessionPtr);
                mNativeSessionPtr = 0;
            }
        }

        /**
         * Sends performance hints to inform the hint session of changes in the workload.
         *
         * @param hint The hint to send to the session
         *
         * @hide
         */
        @TestApi
        public void sendHint(@Hint int hint) {
            Preconditions.checkArgumentNonNegative(hint, "the hint ID should be at least"
                    + " zero.");
            try {
                nativeSendHint(mNativeSessionPtr, hint);
            } finally {
                Reference.reachabilityFence(this);
            }
        }

        /**
         * This tells the session that these threads can be
         * safely scheduled to prefer power efficiency over performance.
         *
         * @param enabled The flag that sets whether this session uses power-efficient scheduling.
         */
        @FlaggedApi(Flags.FLAG_ADPF_PREFER_POWER_EFFICIENCY)
        public void setPreferPowerEfficiency(boolean enabled) {
            nativeSetPreferPowerEfficiency(mNativeSessionPtr, enabled);
        }

        /**
         * Set a list of threads to the performance hint session. This operation will replace
         * the current list of threads with the given list of threads.
         * Note that this is not an oneway method.
         *
         * @param tids The list of threads to be associated with this session. They must be
         *     part of this app's thread group
         *
         * @throws IllegalStateException if the hint session is not in the foreground
         * @throws IllegalArgumentException if the thread id list is empty
         * @throws SecurityException if any thread id doesn't belong to the application
         */
        public void setThreads(@NonNull int[] tids) {
            if (mNativeSessionPtr == 0) {
                return;
            }
            Objects.requireNonNull(tids, "tids cannot be null");
            if (tids.length == 0) {
                throw new IllegalArgumentException("Thread id list can't be empty.");
            }
            nativeSetThreads(mNativeSessionPtr, tids);
        }

        /**
         * Returns the list of thread ids.
         *
         * @hide
         */
        @TestApi
        public @Nullable int[] getThreadIds() {
            return nativeGetThreadIds(mNativeSessionPtr);
        }

        /**
         * Reports the work duration for the last cycle of work.
         *
         * The system will attempt to adjust the core placement of the threads within the thread
         * group and/or the frequency of the core on which they are run to bring the actual duration
         * close to the target duration.
         *
         * @param workDuration the work duration of each component.
         * @throws IllegalArgumentException if
         * the work period start timestamp or the total duration are less than or equal to zero,
         * if either the actual CPU duration or actual GPU duration is less than zero,
         * or if both the CPU and GPU durations are zero.
         */
        @FlaggedApi(Flags.FLAG_ADPF_GPU_REPORT_ACTUAL_WORK_DURATION)
        public void reportActualWorkDuration(@NonNull WorkDuration workDuration) {
            if (workDuration.mWorkPeriodStartTimestampNanos <= 0) {
                throw new IllegalArgumentException(
                    "the work period start timestamp should be greater than zero.");
            }
            if (workDuration.mActualTotalDurationNanos <= 0) {
                throw new IllegalArgumentException(
                    "the actual total duration should be greater than zero.");
            }
            if (workDuration.mActualCpuDurationNanos < 0) {
                throw new IllegalArgumentException(
                    "the actual CPU duration should be greater than or equal to zero.");
            }
            if (workDuration.mActualGpuDurationNanos < 0) {
                throw new IllegalArgumentException(
                    "the actual GPU duration should be greater than or equal to zero.");
            }
            if (workDuration.mActualCpuDurationNanos + workDuration.mActualGpuDurationNanos <= 0) {
                throw new IllegalArgumentException(
                    "either the actual CPU duration or the actual GPU duration should be greater"
                    + "than zero.");
            }
            nativeReportActualWorkDuration(mNativeSessionPtr,
                    workDuration.mWorkPeriodStartTimestampNanos,
                    workDuration.mActualTotalDurationNanos,
                    workDuration.mActualCpuDurationNanos, workDuration.mActualGpuDurationNanos);
        }
    }

    private static native long nativeAcquireManager();
    private static native long nativeGetPreferredUpdateRateNanos(long nativeManagerPtr);
    private static native long nativeCreateSession(long nativeManagerPtr,
            int[] tids, long initialTargetWorkDurationNanos);
    private static native int[] nativeGetThreadIds(long nativeSessionPtr);
    private static native void nativeUpdateTargetWorkDuration(long nativeSessionPtr,
            long targetDurationNanos);
    private static native void nativeReportActualWorkDuration(long nativeSessionPtr,
            long actualDurationNanos);
    private static native void nativeCloseSession(long nativeSessionPtr);
    private static native void nativeSendHint(long nativeSessionPtr, int hint);
    private static native void nativeSetThreads(long nativeSessionPtr, int[] tids);
    private static native void nativeSetPreferPowerEfficiency(long nativeSessionPtr,
            boolean enabled);
    private static native void nativeReportActualWorkDuration(long nativeSessionPtr,
            long workPeriodStartTimestampNanos, long actualTotalDurationNanos,
            long actualCpuDurationNanos, long actualGpuDurationNanos);
}