| /* |
| * 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. |
| */ |
| |
| #ifndef COUNT_ANOMALY_TRACKER_H |
| #define COUNT_ANOMALY_TRACKER_H |
| |
| #include <stdlib.h> |
| #include <memory> // unique_ptr |
| |
| namespace android { |
| namespace os { |
| namespace statsd { |
| |
| class CountAnomalyTracker { |
| public: |
| CountAnomalyTracker(size_t numBuckets, int thresholdGt); |
| |
| virtual ~CountAnomalyTracker(); |
| |
| |
| // Adds a new past bucket, holding pastBucketCount, and then advances the |
| // present by numberOfBucketsAgo buckets (filling any intervening buckets |
| // with 0s). |
| // Thus, the newly added bucket (which holds pastBucketCount) is stored |
| // numberOfBucketsAgo buckets ago. |
| void addPastBucket(int pastBucketCount, time_t numberOfBucketsAgo); |
| |
| // Informs the anomaly tracker of the current bucket's count, so that it can |
| // determine whether an anomaly has occurred. This value is not stored. |
| void checkAnomaly(int currentCount); |
| |
| private: |
| // Number of past buckets. One less than the total number of buckets needed |
| // for the anomaly detection (since the current bucket is not in the past). |
| const size_t mNumPastBuckets; |
| |
| // Count values for each of the past mNumPastBuckets buckets. |
| // TODO: Add dimensions. This parallels the type of CountMetricProducer.mCounter. |
| std::unique_ptr<int[]> mPastBuckets; |
| |
| // Sum over all of mPastBuckets (cached). |
| // TODO: Add dimensions. This parallels the type of CountMetricProducer.mCounter. |
| // At that point, mSumPastCounters must never contain entries of 0. |
| int mSumPastCounters; |
| |
| // Index of the oldest bucket (i.e. the next bucket to be overwritten). |
| size_t mOldestBucketIndex = 0; |
| |
| // If mSumPastCounters + currentCount > mThresholdGt --> Anomaly! |
| const int mThresholdGt; |
| |
| void declareAnomaly(); |
| |
| // Calculates the corresponding index within the circular array. |
| size_t index(size_t unsafeIndex) { |
| return unsafeIndex % mNumPastBuckets; |
| } |
| |
| // Resets all data. For use when all the data gets stale. |
| void reset(); |
| }; |
| |
| } // namespace statsd |
| } // namespace os |
| } // namespace android |
| #endif // COUNT_ANOMALY_TRACKER_H |