v1.1.4 の ExposureSummary.HighestRiskScore の部分の差分解説 #31
Comments
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現象としては、
なので、「接触可能性アリ」の通知は出るが、アプリでは「陽性者との接触確認する」と 0 という現象と思われる。 ExposureSummary.HighestRiskScore >= config.MinimumRiskScore のチェックを入れると
ってことになるけど、iOS 側で EN の履歴を見れば「1件あります」という現象は続くと思われる。 EN API
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v1.1.4 の修正解析以下は、Exposure Notification - Apple Developer の Source Code から、EN api 関係のコードをダウンロードしてチェック。 コードを引用して解説します。 ポイントin ENExposureDetectionDaemonSession.m
これにより、TEKとの接触はあったが、すべてのリスク値が最小リスク値を下回る場合に、以下の現象となる。
これを v1.1.4 では以下のように修正する。
これにより、通知で接触可能性アリと出るが、アプリでは陽性者数がゼロ件である、という現象はなくなる。 原因detectExposures が返す summary.matchedKeyCount がリスク計算を考慮したもの、と勘違いが原因である。 v1.1.3 以前の現象
v1.1.4 以降の現象
おそらく「接触チェックの記録」のカウントは、addFile の _matchedKeyCount のままのため、最小リスク値は考慮されずカウントは「1」になると考えられる。
という現象が発生すると思う。 ENExposureDetectionDaemonSession.m より抜粋/*
* Find matches for an the TEKs contained with the provided ENFile.
* Returnes NO if the matching process encounters an error, else returns YES.
*/
- (BOOL)addFile:(ENFile *)mainFile
{
__block NSError *error = nil;
uint64_t fileMatchCount = 0;
for( ;; )
{
@autoreleasepool
{
NSMutableArray<ENTemporaryExposureKey *> *tekArray = [[NSMutableArray <ENTemporaryExposureKey *> alloc] init];
check_compile_time_code( TEKBatchSize > 0 );
uint32_t tekCount = 0;
// Match the TEKs in batches to reduce the peak memory usage
for( ; tekCount < TEKBatchSize; ++tekCount )
{
ENTemporaryExposureKey *key = [mainFile readTEKAndReturnError:&error];
if( !key ) break;
[tekArray addObject:key];
}
if( tekCount == 0 ) break;
// マッチした数を返す。リスク値は考慮されない
fileMatchCount += [_databaseQuerySession matchCountForKeys:tekArray attenuationThreshold:0xFF error:&error];
if( error ) break;
}
}
// 単純に、TEK がマッチした値を _matchedKeyCount に保存しておく
_matchedKeyCount += fileMatchCount;
if( error )
{
return NO;
}
return YES;
}- (ENExposureDetectionSummary *)generateSummary
{
// Process all the cached info to create the summary.
__block uint32_t attenuationDurationSums[ 3 ] = { 0, 0, 0 };
__block uint32_t *attenuationDurationSumsPtr = attenuationDurationSums;
__block uint64_t minimumRiskScoreSkipped = 0;
ENRiskScore minimumRiskScore = _configuration.minimumRiskScore;
double minimumRiskScoreFullRange = _configuration.minimumRiskScoreFullRange;
__block ENRiskScore maximumRiskScore = 0;
__block double maximumRiskScoreFullRange = 0;
__block CFAbsoluteTime mostRecentExposureTime = 0;
__block double riskScoreSumFullRange = 0;
CFAbsoluteTime nowTime = CFAbsoluteTimeGetCurrent();
[_databaseQuerySession enumerateCachedExposureInfo:
^( NSArray <ENExposureInfo *> * _Nullable inExposureInfoBatch, NSError * _Nullable __unused inError )
{
for( ENExposureInfo *exposureInfo in inExposureInfoBatch )
{
// Determine if this exposure is the most recent exposure
NSTimeInterval exposureTime = exposureInfo.date.timeIntervalSinceReferenceDate;
if( exposureTime > mostRecentExposureTime ) mostRecentExposureTime = exposureTime;
// Filter out any exposures with a risk score below the configured minimum
double riskScoreFullRange = [self estimateRiskWithExposureInfo:exposureInfo referenceTime:nowTime
transmissionRiskLevel:nil];
ENRiskScore clampedRiskScore = (ENRiskScore) Clamp( riskScoreFullRange, ENRiskScoreMin, ENRiskScoreMax );
// 最小リスク値以下のものは、戻り値に含めない
if( ( clampedRiskScore < minimumRiskScore ) || ( riskScoreFullRange < minimumRiskScoreFullRange ) )
{
// 最小リスク値を下回る場合は、スキップする
++minimumRiskScoreSkipped;
continue;
}
// Update the maximum seen risk score
if( clampedRiskScore > maximumRiskScore ) maximumRiskScore = clampedRiskScore;
if( riskScoreFullRange > maximumRiskScoreFullRange ) maximumRiskScoreFullRange = riskScoreFullRange;
riskScoreSumFullRange += riskScoreFullRange;
// Accumulate the calculated attenuation durations
NSArray <NSNumber *> *attenuationDurations = exposureInfo.attenuationDurations;
if( attenuationDurations.count >= countof( attenuationDurationSums ) )
{
for( size_t i = 0; i < countof( attenuationDurationSums ); ++i )
{
uint32_t durationSum = attenuationDurationSumsPtr[ i ];
if( durationSum >= ENDurationMaxSeconds ) continue;
durationSum += attenuationDurations[ i ].unsignedIntValue;
if( durationSum > ENDurationMaxSeconds ) durationSum = ENDurationMaxSeconds;
attenuationDurationSumsPtr[ i ] = durationSum;
}
}
}
}];
// Round the attenuation durations
NSInteger daysSinceLastExposure = ( mostRecentExposureTime > 0 )
? ( (NSInteger)( ( nowTime - mostRecentExposureTime ) / kSecondsPerDay ) )
: 0;
attenuationDurationSums[ 0 ] = RoundUp( attenuationDurationSums[ 0 ], ENDurationIncrement );
attenuationDurationSums[ 1 ] = RoundUp( attenuationDurationSums[ 1 ], ENDurationIncrement );
attenuationDurationSums[ 2 ] = RoundUp( attenuationDurationSums[ 2 ], ENDurationIncrement );
// Generate the summary
ENExposureDetectionSummary *summary = [[ENExposureDetectionSummary alloc] init];
summary.attenuationDurations =
@[
@(attenuationDurationSums[ 0 ]),
@(attenuationDurationSums[ 1 ]),
@(attenuationDurationSums[ 2 ])
];
summary.daysSinceLastExposure = daysSinceLastExposure;
// マッチカウントは、addFile で保持している _matchedKeyCount を返す
// ゆえに全てのTEKで最小リスク値を
summary.matchedKeyCount = _matchedKeyCount;
summary.maximumRiskScore = maximumRiskScore;
summary.maximumRiskScoreFullRange = maximumRiskScoreFullRange;
summary.riskScoreSumFullRange = riskScoreSumFullRange;
return summary;
}- (NSArray<ENExposureInfo *> *)exposureInfo
{
// Get the ENExposureInfo objects from the database.
__block NSInteger databaseTotal = 0;
__block ENRiskScore minimumRiskScore = _configuration.minimumRiskScore;
double minimumRiskScoreFullRange = _configuration.minimumRiskScoreFullRange;
__block uint64_t minimumRiskScoreSkipped = 0;
CFAbsoluteTime nowTime = CFAbsoluteTimeGetCurrent();
NSMutableArray <ENExposureInfo *> *exposureInfoArray = [[NSMutableArray <ENExposureInfo *> alloc] init];
[_databaseQuerySession enumerateCachedExposureInfo:
^( NSArray <ENExposureInfo *> * _Nullable inExposureInfoBatch, NSError * _Nullable __unused inError )
{
databaseTotal += inExposureInfoBatch.count;
for( ENExposureInfo *exposureInfo in inExposureInfoBatch )
{
// Filter out any exposures with a risk score below the configured minimum
ENRiskLevel transmissionRiskLevel = 0;
double riskScoreFullRange = [self estimateRiskWithExposureInfo:exposureInfo referenceTime:nowTime
transmissionRiskLevel:&transmissionRiskLevel];
ENRiskScore clampedRiskScore = (ENRiskScore) Clamp( riskScoreFullRange, ENRiskScoreMin, ENRiskScoreMax );
// ここの条件式は、generateSummary と全く同じ
if( ( clampedRiskScore < minimumRiskScore ) || ( riskScoreFullRange < minimumRiskScoreFullRange ) )
{
// 最小リスク値であればスキップする
++minimumRiskScoreSkipped;
continue;
}
// Round the attenuation durations
uint32_t duration = (uint32_t) exposureInfo.duration;
duration = RoundUp( duration, ENDurationIncrement );
exposureInfo.duration = Min( duration, ENDurationMaxSeconds );
NSMutableArray <NSNumber *> *filteredAttenuationDurations = [[NSMutableArray <NSNumber *> alloc] init];
for( NSNumber *attenuationDuration in exposureInfo.attenuationDurations )
{
duration = attenuationDuration.unsignedIntValue;
duration = RoundUp( duration, ENDurationIncrement );
duration = Min( duration, ENDurationMaxSeconds );
[filteredAttenuationDurations addObject:@(duration)];
}
// Populate the final ENExposureInfo
exposureInfo.attenuationDurations = filteredAttenuationDurations;
exposureInfo.totalRiskScore = clampedRiskScore;
exposureInfo.totalRiskScoreFullRange = riskScoreFullRange;
exposureInfo.transmissionRiskLevel = transmissionRiskLevel;
// exposureInfoArray に保存しておく
[exposureInfoArray addObject:exposureInfo];
}
}];
// exposureInfoArray を返す
return exposureInfoArray;
}BuildingAnAppToNotifyUsersOfCOVID19Exposure の readme よりServer.shared.getExposureConfiguration { result in
switch result {
case let .success(configuration):
ExposureManager.shared.manager.detectExposures(configuration: configuration, diagnosisKeyURLs: localURLs) { summary, error in
if let error = error {
finish(.failure(error))
return
}
// ここで Summary.HighestRiskScore をチェックせずに、
// getExposureInfo を使うのが、ミスリード？
let userExplanation = NSLocalizedString("USER_NOTIFICATION_EXPLANATION", comment: "User notification")
ExposureManager.shared.manager.getExposureInfo(summary: summary!, userExplanation: userExplanation) { exposures, error in
if let error = error {
finish(.failure(error))
return
}
let newExposures = exposures!.map { exposure in
Exposure(date: exposure.date,
duration: exposure.duration,
totalRiskScore: exposure.totalRiskScore,
transmissionRiskLevel: exposure.transmissionRiskLevel)
}
finish(.success((newExposures, nextDiagnosisKeyFileIndex + localURLs.count)))
}
}
case let .failure(error):
finish(.failure(error))
}
} |
の予定であるが、v1.1.4 でも出るらしい。ぐぬぬ。 |
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ちょっと謎な
if (userData.ExposureSummary.HighestRiskScore >= config.MinimumRiskScore)なところを推測するための記録として。The text was updated successfully, but these errors were encountered: