wifi/aware/WifiAwareMetrics.java

/*
 * Copyright (C) 2017 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.wifi.aware;

import android.hardware.wifi.V1_0.NanStatusType;
import android.net.wifi.aware.WifiAwareNetworkSpecifier;
import android.text.TextUtils;
import android.util.Log;
import android.util.SparseArray;
import android.util.SparseIntArray;

import com.android.internal.annotations.VisibleForTesting;
import com.android.server.wifi.Clock;
import com.android.server.wifi.nano.WifiMetricsProto;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * Wi-Fi Aware metric container/processor.
 */
public class WifiAwareMetrics {
    private static final String TAG = "WifiAwareMetrics";
    private static final boolean DBG = false;

    // Histogram: 8 buckets (i=0, ..., 7) of 9 slots in range 10^i -> 10^(i+1)
    // Buckets:
    //    1 -> 10: 9 @ 1
    //    10 -> 100: 9 @ 10
    //    100 -> 1000: 9 @ 10^2
    //    10^3 -> 10^4: 9 @ 10^3
    //    10^4 -> 10^5: 9 @ 10^4
    //    10^5 -> 10^6: 9 @ 10^5
    //    10^6 -> 10^7: 9 @ 10^6
    //    10^7 -> 10^8: 9 @ 10^7 --> 10^8 ms -> 10^5s -> 28 hours
    private static final HistParms DURATION_LOG_HISTOGRAM = new HistParms(0, 1, 10, 9, 8);

    private final Object mLock = new Object();
    private final Clock mClock;

    // enableUsage/disableUsage data
    private long mLastEnableUsageMs = 0;
    private long mLastEnableUsageInThisSampleWindowMs = 0;
    private long mAvailableTimeMs = 0;
    private SparseIntArray mHistogramAwareAvailableDurationMs = new SparseIntArray();

    // enabled data
    private long mLastEnableAwareMs = 0;
    private long mLastEnableAwareInThisSampleWindowMs = 0;
    private long mEnabledTimeMs = 0;
    private SparseIntArray mHistogramAwareEnabledDurationMs = new SparseIntArray();

    // attach data
    private static class AttachData {
        boolean mUsesIdentityCallback; // do any attach sessions of the UID use identity callback
        int mMaxConcurrentAttaches;
    }
    private Map<Integer, AttachData> mAttachDataByUid = new HashMap<>();
    private SparseIntArray mAttachStatusData = new SparseIntArray();
    private SparseIntArray mHistogramAttachDuration = new SparseIntArray();

    // discovery data
    private int mMaxPublishInApp = 0;
    private int mMaxSubscribeInApp = 0;
    private int mMaxDiscoveryInApp = 0;
    private int mMaxPublishInSystem = 0;
    private int mMaxSubscribeInSystem = 0;
    private int mMaxDiscoveryInSystem = 0;
    private SparseIntArray mPublishStatusData = new SparseIntArray();
    private SparseIntArray mSubscribeStatusData = new SparseIntArray();
    private SparseIntArray mHistogramPublishDuration = new SparseIntArray();
    private SparseIntArray mHistogramSubscribeDuration = new SparseIntArray();
    private Set<Integer> mAppsWithDiscoverySessionResourceFailure = new HashSet<>();

    // data-path (NDI/NDP) data
    private int mMaxNdiInApp = 0;
    private int mMaxNdpInApp = 0;
    private int mMaxSecureNdpInApp = 0;
    private int mMaxNdiInSystem = 0;
    private int mMaxNdpInSystem = 0;
    private int mMaxSecureNdpInSystem = 0;
    private int mMaxNdpPerNdi = 0;
    private SparseIntArray mInBandNdpStatusData = new SparseIntArray();
    private SparseIntArray mOutOfBandNdpStatusData = new SparseIntArray();

    public WifiAwareMetrics(Clock clock) {
        mClock = clock;
    }

    /**
     * Push usage stats for WifiAwareStateMachine.enableUsage() to
     * histogram_aware_available_duration_ms.
     */
    public void recordEnableUsage() {
        synchronized (mLock) {
            if (mLastEnableUsageMs != 0) {
                Log.w(TAG, "enableUsage: mLastEnableUsage*Ms initialized!?");
            }
            mLastEnableUsageMs = mClock.getElapsedSinceBootMillis();
            mLastEnableUsageInThisSampleWindowMs = mLastEnableUsageMs;
        }
    }

    /**
     * Push usage stats for WifiAwareStateMachine.disableUsage() to
     * histogram_aware_available_duration_ms.
     */

    public void recordDisableUsage() {
        synchronized (mLock) {
            if (mLastEnableUsageMs == 0) {
                Log.e(TAG, "disableUsage: mLastEnableUsage not initialized!?");
                return;
            }

            long now = mClock.getElapsedSinceBootMillis();
            addLogValueToHistogram(now - mLastEnableUsageMs, mHistogramAwareAvailableDurationMs,
                    DURATION_LOG_HISTOGRAM);
            mAvailableTimeMs += now - mLastEnableUsageInThisSampleWindowMs;
            mLastEnableUsageMs = 0;
            mLastEnableUsageInThisSampleWindowMs = 0;
        }
    }

    /**
     * Push usage stats of Aware actually being enabled on-the-air: start
     */
    public void recordEnableAware() {
        synchronized (mLock) {
            if (mLastEnableAwareMs != 0) {
                return; // already enabled
            }
            mLastEnableAwareMs = mClock.getElapsedSinceBootMillis();
            mLastEnableAwareInThisSampleWindowMs = mLastEnableAwareMs;
        }
    }

    /**
     * Push usage stats of Aware actually being enabled on-the-air: stop (disable)
     */
    public void recordDisableAware() {
        synchronized (mLock) {
            if (mLastEnableAwareMs == 0) {
                return; // already disabled
            }

            long now = mClock.getElapsedSinceBootMillis();
            addLogValueToHistogram(now - mLastEnableAwareMs, mHistogramAwareEnabledDurationMs,
                    DURATION_LOG_HISTOGRAM);
            mEnabledTimeMs += now - mLastEnableAwareInThisSampleWindowMs;
            mLastEnableAwareMs = 0;
            mLastEnableAwareInThisSampleWindowMs = 0;
        }
    }

    /**
     * Push information about a new attach session.
     */
    public void recordAttachSession(int uid, boolean usesIdentityCallback,
            SparseArray<WifiAwareClientState> clients) {
        // count the number of clients with the specific uid
        int currentConcurrentCount = 0;
        for (int i = 0; i < clients.size(); ++i) {
            if (clients.valueAt(i).getUid() == uid) {
                ++currentConcurrentCount;
            }
        }

        synchronized (mLock) {
            AttachData data = mAttachDataByUid.get(uid);
            if (data == null) {
                data = new AttachData();
                mAttachDataByUid.put(uid, data);
            }
            data.mUsesIdentityCallback |= usesIdentityCallback;
            data.mMaxConcurrentAttaches = Math.max(data.mMaxConcurrentAttaches,
                    currentConcurrentCount);
            recordAttachStatus(NanStatusType.SUCCESS);
        }
    }

    /**
     * Push information about a new attach session status (recorded when attach session is created).
     */
    public void recordAttachStatus(int status) {
        synchronized (mLock) {
            mAttachStatusData.put(status, mAttachStatusData.get(status) + 1);
        }
    }

    /**
     * Push duration information of an attach session.
     */
    public void recordAttachSessionDuration(long creationTime) {
        synchronized (mLock) {
            addLogValueToHistogram(mClock.getElapsedSinceBootMillis() - creationTime,
                    mHistogramAttachDuration,
                    DURATION_LOG_HISTOGRAM);
        }
    }

    /**
     * Push information about the new discovery session.
     */
    public void recordDiscoverySession(int uid, boolean isPublish,
            SparseArray<WifiAwareClientState> clients) {
        // count the number of sessions per uid and overall
        int numPublishesInSystem = 0;
        int numSubscribesInSystem = 0;
        int numPublishesOnUid = 0;
        int numSubscribesOnUid = 0;

        for (int i = 0; i < clients.size(); ++i) {
            WifiAwareClientState client = clients.valueAt(i);
            boolean sameUid = client.getUid() == uid;

            SparseArray<WifiAwareDiscoverySessionState> sessions = client.getSessions();
            for (int j = 0; j < sessions.size(); ++j) {
                WifiAwareDiscoverySessionState session = sessions.valueAt(j);

                if (session.isPublishSession()) {
                    numPublishesInSystem += 1;
                    if (sameUid) {
                        numPublishesOnUid += 1;
                    }
                } else {
                    numSubscribesInSystem += 1;
                    if (sameUid) {
                        numSubscribesOnUid += 1;
                    }
                }
            }
        }

        synchronized (mLock) {
            mMaxPublishInApp = Math.max(mMaxPublishInApp, numPublishesOnUid);
            mMaxSubscribeInApp = Math.max(mMaxSubscribeInApp, numSubscribesOnUid);
            mMaxDiscoveryInApp = Math.max(mMaxDiscoveryInApp,
                    numPublishesOnUid + numSubscribesOnUid);
            mMaxPublishInSystem = Math.max(mMaxPublishInSystem, numPublishesInSystem);
            mMaxSubscribeInSystem = Math.max(mMaxSubscribeInSystem, numSubscribesInSystem);
            mMaxDiscoveryInSystem = Math.max(mMaxDiscoveryInSystem,
                    numPublishesInSystem + numSubscribesInSystem);
        }
    }

    /**
     * Push information about a new discovery session status (recorded when the discovery session is
     * created).
     */
    public void recordDiscoveryStatus(int uid, int status, boolean isPublish) {
        synchronized (mLock) {
            if (isPublish) {
                mPublishStatusData.put(status, mPublishStatusData.get(status) + 1);
            } else {
                mSubscribeStatusData.put(status, mSubscribeStatusData.get(status) + 1);
            }

            if (status == NanStatusType.NO_RESOURCES_AVAILABLE) {
                mAppsWithDiscoverySessionResourceFailure.add(uid);
            }
        }
    }

    /**
     * Push duration information of a discovery session.
     */
    public void recordDiscoverySessionDuration(long creationTime, boolean isPublish) {
        synchronized (mLock) {
            addLogValueToHistogram(mClock.getElapsedSinceBootMillis() - creationTime,
                    isPublish ? mHistogramPublishDuration : mHistogramSubscribeDuration,
                    DURATION_LOG_HISTOGRAM);
        }
    }

    /**
     * Record NDP (and by extension NDI) usage - on successful creation of an NDP.
     */
    public void recordNdpCreation(int uid,
            Map<WifiAwareNetworkSpecifier, WifiAwareDataPathStateManager
                    .AwareNetworkRequestInformation> networkRequestCache) {
        int numNdpInApp = 0;
        int numSecureNdpInApp = 0;
        int numNdpInSystem = 0;
        int numSecureNdpInSystem = 0;

        Map<String, Integer> ndpPerNdiMap = new HashMap<>();
        Set<String> ndiInApp = new HashSet<>();
        Set<String> ndiInSystem = new HashSet<>();

        for (WifiAwareDataPathStateManager.AwareNetworkRequestInformation anri :
                networkRequestCache.values()) {
            if (anri.state
                    != WifiAwareDataPathStateManager.AwareNetworkRequestInformation
                    .STATE_INITIATOR_CONFIRMED
                    && anri.state
                    != WifiAwareDataPathStateManager.AwareNetworkRequestInformation
                    .STATE_RESPONDER_CONFIRMED) {
                continue; // only count completed (up-and-running) NDPs
            }

            boolean sameUid = anri.uid == uid;
            boolean isSecure = !TextUtils.isEmpty(anri.networkSpecifier.passphrase) || (
                    anri.networkSpecifier.pmk != null && anri.networkSpecifier.pmk.length != 0);

            // in-app stats
            if (sameUid) {
                numNdpInApp += 1;
                if (isSecure) {
                    numSecureNdpInApp += 1;
                }

                ndiInApp.add(anri.interfaceName);
            }

            // system stats
            numNdpInSystem += 1;
            if (isSecure) {
                numSecureNdpInSystem += 1;
            }

            // ndp/ndi stats
            Integer ndpCount = ndpPerNdiMap.get(anri.interfaceName);
            if (ndpCount == null) {
                ndpPerNdiMap.put(anri.interfaceName, 1);
            } else {
                ndpPerNdiMap.put(anri.interfaceName, ndpCount + 1);
            }

            // ndi stats
            ndiInSystem.add(anri.interfaceName);
        }

        synchronized (mLock) {
            mMaxNdiInApp = Math.max(mMaxNdiInApp, ndiInApp.size());
            mMaxNdpInApp = Math.max(mMaxNdpInApp, numNdpInApp);
            mMaxSecureNdpInApp = Math.max(mMaxSecureNdpInApp, numSecureNdpInApp);
            mMaxNdiInSystem = Math.max(mMaxNdiInSystem, ndiInSystem.size());
            mMaxNdpInSystem = Math.max(mMaxNdpInSystem, numNdpInSystem);
            mMaxSecureNdpInSystem = Math.max(mMaxSecureNdpInSystem, numSecureNdpInSystem);
            mMaxNdpPerNdi = Math.max(mMaxNdpPerNdi, Collections.max(ndpPerNdiMap.values()));
        }
    }

    /**
     * Record the completion status of NDP negotiation. There are multiple steps in NDP negotiation
     * a failure on any aborts the process and is recorded. A success on intermediate stages is
     * not recorded - only the final success.
     */
    public void recordNdpStatus(int status, boolean isOutOfBand) {
        synchronized (mLock) {
            if (isOutOfBand) {
                mOutOfBandNdpStatusData.put(status, mOutOfBandNdpStatusData.get(status) + 1);
            } else {
                mInBandNdpStatusData.put(status, mOutOfBandNdpStatusData.get(status) + 1);
            }
        }
    }

    /**
     * Consolidate all metrics into the proto.
     */
    public WifiMetricsProto.WifiAwareLog consolidateProto() {
        WifiMetricsProto.WifiAwareLog log = new WifiMetricsProto.WifiAwareLog();
        long now = mClock.getElapsedSinceBootMillis();
        synchronized (mLock) {
            log.histogramAwareAvailableDurationMs = histogramToProtoArray(
                    mHistogramAwareAvailableDurationMs, DURATION_LOG_HISTOGRAM);
            log.availableTimeMs = mAvailableTimeMs;
            if (mLastEnableUsageInThisSampleWindowMs != 0) {
                log.availableTimeMs += now - mLastEnableUsageInThisSampleWindowMs;
            }

            log.histogramAwareEnabledDurationMs = histogramToProtoArray(
                    mHistogramAwareEnabledDurationMs, DURATION_LOG_HISTOGRAM);
            log.enabledTimeMs = mEnabledTimeMs;
            if (mLastEnableAwareInThisSampleWindowMs != 0) {
                log.enabledTimeMs += now - mLastEnableAwareInThisSampleWindowMs;
            }

            log.numApps = mAttachDataByUid.size();
            log.numAppsUsingIdentityCallback = 0;
            log.maxConcurrentAttachSessionsInApp = 0;
            for (AttachData ad: mAttachDataByUid.values()) {
                if (ad.mUsesIdentityCallback) {
                    ++log.numAppsUsingIdentityCallback;
                }
                log.maxConcurrentAttachSessionsInApp = Math.max(
                        log.maxConcurrentAttachSessionsInApp, ad.mMaxConcurrentAttaches);
            }
            log.histogramAttachSessionStatus = histogramToProtoArray(mAttachStatusData);
            log.histogramAttachDurationMs = histogramToProtoArray(mHistogramAttachDuration,
                    DURATION_LOG_HISTOGRAM);

            log.maxConcurrentPublishInApp = mMaxPublishInApp;
            log.maxConcurrentSubscribeInApp = mMaxSubscribeInApp;
            log.maxConcurrentDiscoverySessionsInApp = mMaxDiscoveryInApp;
            log.maxConcurrentPublishInSystem = mMaxPublishInSystem;
            log.maxConcurrentSubscribeInSystem = mMaxSubscribeInSystem;
            log.maxConcurrentDiscoverySessionsInSystem = mMaxDiscoveryInSystem;
            log.histogramPublishStatus = histogramToProtoArray(mPublishStatusData);
            log.histogramSubscribeStatus = histogramToProtoArray(mSubscribeStatusData);
            log.numAppsWithDiscoverySessionFailureOutOfResources =
                    mAppsWithDiscoverySessionResourceFailure.size();
            log.histogramPublishSessionDurationMs = histogramToProtoArray(mHistogramPublishDuration,
                    DURATION_LOG_HISTOGRAM);
            log.histogramSubscribeSessionDurationMs = histogramToProtoArray(
                    mHistogramSubscribeDuration, DURATION_LOG_HISTOGRAM);

            log.maxConcurrentNdiInApp = mMaxNdiInApp;
            log.maxConcurrentNdiInSystem = mMaxNdiInSystem;
            log.maxConcurrentNdpInApp = mMaxNdpInApp;
            log.maxConcurrentNdpInSystem = mMaxNdpInSystem;
            log.maxConcurrentSecureNdpInApp = mMaxSecureNdpInApp;
            log.maxConcurrentSecureNdpInSystem = mMaxSecureNdpInSystem;
            log.maxConcurrentNdpPerNdi = mMaxNdpPerNdi;
            log.histogramRequestNdpStatus = histogramToProtoArray(mInBandNdpStatusData);
            log.histogramRequestNdpOobStatus = histogramToProtoArray(mOutOfBandNdpStatusData);
        }
        return log;
    }

    /**
     * clear Wi-Fi Aware metrics
     */
    public void clear() {
        long now = mClock.getElapsedSinceBootMillis();
        synchronized (mLock) {
            // don't clear mLastEnableUsage since could be valid for next measurement period
            mHistogramAwareAvailableDurationMs.clear();
            mAvailableTimeMs = 0;
            if (mLastEnableUsageInThisSampleWindowMs != 0) {
                mLastEnableUsageInThisSampleWindowMs = now;
            }

            // don't clear mLastEnableAware since could be valid for next measurement period
            mHistogramAwareEnabledDurationMs.clear();
            mEnabledTimeMs = 0;
            if (mLastEnableAwareInThisSampleWindowMs != 0) {
                mLastEnableAwareInThisSampleWindowMs = now;
            }

            mAttachDataByUid.clear();
            mAttachStatusData.clear();
            mHistogramAttachDuration.clear();

            mMaxPublishInApp = 0;
            mMaxSubscribeInApp = 0;
            mMaxDiscoveryInApp = 0;
            mMaxPublishInSystem = 0;
            mMaxSubscribeInSystem = 0;
            mMaxDiscoveryInSystem = 0;
            mPublishStatusData.clear();
            mSubscribeStatusData.clear();
            mHistogramPublishDuration.clear();
            mHistogramSubscribeDuration.clear();
            mAppsWithDiscoverySessionResourceFailure.clear();

            mMaxNdiInApp = 0;
            mMaxNdpInApp = 0;
            mMaxSecureNdpInApp = 0;
            mMaxNdiInSystem = 0;
            mMaxNdpInSystem = 0;
            mMaxSecureNdpInSystem = 0;
            mMaxNdpPerNdi = 0;
            mInBandNdpStatusData.clear();
            mOutOfBandNdpStatusData.clear();
        }
    }

    /**
     * Dump all WifiAwareMetrics to console (pw) - this method is never called to dump the
     * serialized metrics (handled by parent WifiMetrics).
     *
     * @param fd   unused
     * @param pw   PrintWriter for writing dump to
     * @param args unused
     */
    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
        synchronized (mLock) {
            pw.println("mLastEnableUsage:" + mLastEnableUsageMs);
            pw.println(
                    "mLastEnableUsageInThisSampleWindow:" + mLastEnableUsageInThisSampleWindowMs);
            pw.println("mAvailableTime:" + mAvailableTimeMs);
            pw.println("mHistogramAwareAvailableDurationMs:");
            for (int i = 0; i < mHistogramAwareAvailableDurationMs.size(); ++i) {
                pw.println("  " + mHistogramAwareAvailableDurationMs.keyAt(i) + ": "
                        + mHistogramAwareAvailableDurationMs.valueAt(i));
            }
            pw.println("mAttachDataByUid:");
            for (Map.Entry<Integer, AttachData> ade: mAttachDataByUid.entrySet()) {
                pw.println("  " + "uid=" + ade.getKey() + ": identity="
                        + ade.getValue().mUsesIdentityCallback + ", maxConcurrent="
                        + ade.getValue().mMaxConcurrentAttaches);
            }
            pw.println("mAttachStatusData:");
            for (int i = 0; i < mAttachStatusData.size(); ++i) {
                pw.println("  " + mAttachStatusData.keyAt(i) + ": "
                        + mAttachStatusData.valueAt(i));
            }
            pw.println("mHistogramAttachDuration:");
            for (int i = 0; i < mHistogramAttachDuration.size(); ++i) {
                pw.println("  " + mHistogramAttachDuration.keyAt(i) + ": "
                        + mHistogramAttachDuration.valueAt(i));
            }
        }
    }

    // histogram utilities

    /**
     * Specifies a ~log histogram consisting of two levels of buckets - a set of N big buckets:
     *
     * Buckets starts at: B + P * M^i, where i=0, ... , N-1 (N big buckets)
     * Each big bucket is divided into S sub-buckets
     *
     * Each (big) bucket is M times bigger than the previous one.
     *
     * The buckets are then:
     * #0: B + P * M^0 with S buckets each of width (P*M^1-P*M^0)/S
     * #1: B + P * M^1 with S buckets each of width (P*M^2-P*M^1)/S
     * ...
     * #N-1: B + P * M^(N-1) with S buckets each of width (P*M^N-P*M^(N-1))/S
     */
    @VisibleForTesting
    public static class HistParms {
        public HistParms(int b, int p, int m, int s, int n) {
            this.b = b;
            this.p = p;
            this.m = m;
            this.s = s;
            this.n = n;

            // derived values
            mLog = Math.log(m);
            bb = new double[n];
            sbw = new double[n];
            bb[0] = b + p;
            sbw[0] = p * (m - 1.0) / (double) s;
            for (int i = 1; i < n; ++i) {
                bb[i] = m * (bb[i - 1] - b) + b;
                sbw[i] = m * sbw[i - 1];
            }
        }

        // spec
        public int b;
        public int p;
        public int m;
        public int s;
        public int n;

        // derived
        public double mLog;
        public double[] bb; // bucket base
        public double[] sbw; // sub-bucket width
    }

    /**
     * Adds the input value to the histogram based on the histogram parameters.
     */
    @VisibleForTesting
    public static int addLogValueToHistogram(long x, SparseIntArray histogram, HistParms hp) {
        double logArg = (double) (x - hp.b) / (double) hp.p;
        int bigBucketIndex = -1;
        if (logArg > 0) {
            bigBucketIndex = (int) (Math.log(logArg) / hp.mLog);
        }
        int subBucketIndex;
        if (bigBucketIndex < 0) {
            bigBucketIndex = 0;
            subBucketIndex = 0;
        } else if (bigBucketIndex >= hp.n) {
            bigBucketIndex = hp.n - 1;
            subBucketIndex = hp.s - 1;
        } else {
            subBucketIndex = (int) ((x - hp.bb[bigBucketIndex]) / hp.sbw[bigBucketIndex]);
            if (subBucketIndex >= hp.s) { // probably a rounding error so move to next big bucket
                bigBucketIndex++;
                if (bigBucketIndex >= hp.n) {
                    bigBucketIndex = hp.n - 1;
                    subBucketIndex = hp.s - 1;
                } else {
                    subBucketIndex = (int) ((x - hp.bb[bigBucketIndex]) / hp.sbw[bigBucketIndex]);
                }
            }
        }
        int key = bigBucketIndex * hp.s + subBucketIndex;

        // note that get() returns 0 if index not there already
        int newValue = histogram.get(key) + 1;
        histogram.put(key, newValue);

        return newValue;
    }

    /**
     * Converts the histogram (with the specified histogram parameters) to an array of proto
     * histogram buckets.
     */
    @VisibleForTesting
    public static WifiMetricsProto.WifiAwareLog.HistogramBucket[] histogramToProtoArray(
            SparseIntArray histogram, HistParms hp) {
        WifiMetricsProto.WifiAwareLog.HistogramBucket[] protoArray =
                new WifiMetricsProto.WifiAwareLog.HistogramBucket[histogram.size()];
        for (int i = 0; i < histogram.size(); ++i) {
            int key = histogram.keyAt(i);

            protoArray[i] = new WifiMetricsProto.WifiAwareLog.HistogramBucket();
            protoArray[i].start = (long) (hp.bb[key / hp.s] + hp.sbw[key / hp.s] * (key % hp.s));
            protoArray[i].end = (long) (protoArray[i].start + hp.sbw[key / hp.s]);
            protoArray[i].count = histogram.valueAt(i);
        }

        return protoArray;
    }

    /**
     * Adds the NanStatusType to the histogram (translating to the proto enumeration of the status).
     */
    public static void addNanHalStatusToHistogram(int halStatus, SparseIntArray histogram) {
        int protoStatus = convertNanStatusTypeToProtoEnum(halStatus);
        int newValue = histogram.get(protoStatus) + 1;
        histogram.put(protoStatus, newValue);
    }

    /**
     * Converts a histogram of proto NanStatusTypeEnum to a raw proto histogram.
     */
    @VisibleForTesting
    public static WifiMetricsProto.WifiAwareLog.NanStatusHistogramBucket[] histogramToProtoArray(
            SparseIntArray histogram) {
        WifiMetricsProto.WifiAwareLog.NanStatusHistogramBucket[] protoArray =
                new WifiMetricsProto.WifiAwareLog.NanStatusHistogramBucket[histogram.size()];

        for (int i = 0; i < histogram.size(); ++i) {
            protoArray[i] = new WifiMetricsProto.WifiAwareLog.NanStatusHistogramBucket();
            protoArray[i].nanStatusType = histogram.keyAt(i);
            protoArray[i].count = histogram.valueAt(i);
        }

        return protoArray;
    }

    /**
     * Convert a HAL NanStatusType enum to a Metrics proto enum NanStatusTypeEnum.
     */
    public static int convertNanStatusTypeToProtoEnum(int nanStatusType) {
        switch (nanStatusType) {
            case NanStatusType.SUCCESS:
                return WifiMetricsProto.WifiAwareLog.SUCCESS;
            case NanStatusType.INTERNAL_FAILURE:
                return WifiMetricsProto.WifiAwareLog.INTERNAL_FAILURE;
            case NanStatusType.PROTOCOL_FAILURE:
                return WifiMetricsProto.WifiAwareLog.PROTOCOL_FAILURE;
            case NanStatusType.INVALID_SESSION_ID:
                return WifiMetricsProto.WifiAwareLog.INVALID_SESSION_ID;
            case NanStatusType.NO_RESOURCES_AVAILABLE:
                return WifiMetricsProto.WifiAwareLog.NO_RESOURCES_AVAILABLE;
            case NanStatusType.INVALID_ARGS:
                return WifiMetricsProto.WifiAwareLog.INVALID_ARGS;
            case NanStatusType.INVALID_PEER_ID:
                return WifiMetricsProto.WifiAwareLog.INVALID_PEER_ID;
            case NanStatusType.INVALID_NDP_ID:
                return WifiMetricsProto.WifiAwareLog.INVALID_NDP_ID;
            case NanStatusType.NAN_NOT_ALLOWED:
                return WifiMetricsProto.WifiAwareLog.NAN_NOT_ALLOWED;
            case NanStatusType.NO_OTA_ACK:
                return WifiMetricsProto.WifiAwareLog.NO_OTA_ACK;
            case NanStatusType.ALREADY_ENABLED:
                return WifiMetricsProto.WifiAwareLog.ALREADY_ENABLED;
            case NanStatusType.FOLLOWUP_TX_QUEUE_FULL:
                return WifiMetricsProto.WifiAwareLog.FOLLOWUP_TX_QUEUE_FULL;
            case NanStatusType.UNSUPPORTED_CONCURRENCY_NAN_DISABLED:
                return WifiMetricsProto.WifiAwareLog.UNSUPPORTED_CONCURRENCY_NAN_DISABLED;
            default:
                Log.e(TAG, "Unrecognized NanStatusType: " + nanStatusType);
                return WifiMetricsProto.WifiAwareLog.UNKNOWN_HAL_STATUS;
        }
    }
}