1 files changed, 129 insertions, 0 deletions
diff --git a/statsd/src/socket/LogEventFilter.h b/statsd/src/socket/LogEventFilter.h
new file mode 100644
index 00000000..c6f7c935
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+++ b/statsd/src/socket/LogEventFilter.h
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2023 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.
+ */
+
+#pragma once
+
+#include <gtest/gtest_prod.h>
+
+#include <atomic>
+#include <mutex>
+#include <unordered_map>
+#include <unordered_set>
+
+namespace android {
+namespace os {
+namespace statsd {
+
+/**
+ * Templating is for benchmarks only
+ *
+ * Based on benchmarks the more fast container to be used for atom ids filtering
+ * is unordered_set<int>
+ * #BM_LogEventFilterUnorderedSet                       391208 ns     390086 ns         1793
+ * #BM_LogEventFilterUnorderedSet2Consumers            1293527 ns    1289326 ns          543
+ * #BM_LogEventFilterSet                                613362 ns     611259 ns         1146
+ * #BM_LogEventFilterSet2Consumers                     1859397 ns    1854193 ns          378
+ *
+ * See @LogEventFilter definition below
+ */
+template <typename T>
+class LogEventFilterGeneric {
+public:
+    virtual ~LogEventFilterGeneric() = default;
+
+    virtual void setFilteringEnabled(bool isEnabled) {
+        mLogsFilteringEnabled = isEnabled;
+    }
+
+    /**
+     * @brief Tests atom id with list of interesting atoms
+     *        If Logs filtering is disabled - assume all atoms in use
+     *        Most of the time should be non-blocking call - only in case when setAtomIds() was
+     *        called the call will be blocking due to atom list needs to be synced up
+     * @param atomId
+     * @return true if atom is used by any of consumer or filtering is disabled
+     */
+    virtual bool isAtomInUse(int atomId) const {
+        if (!mLogsFilteringEnabled) {
+            return true;
+        }
+
+        // check if there is an updated set of interesting atom ids
+        if (mLocalSetUpdateCounter != mSetUpdateCounter.load(std::memory_order_relaxed)) {
+            std::lock_guard<std::mutex> guard(mTagIdsMutex);
+            mLocalSetUpdateCounter = mSetUpdateCounter.load(std::memory_order_relaxed);
+            mLocalTagIds.swap(mTagIds);
+        }
+        return mLocalTagIds.find(atomId) != mLocalTagIds.end();
+    }
+
+    typedef const void* ConsumerId;
+
+    typedef T AtomIdSet;
+    /**
+     * @brief Set the Atom Ids object
+     *
+     * @param tagIds set of atoms ids
+     * @param consumer used to differentiate the consumers to form proper superset of ids
+     */
+    virtual void setAtomIds(AtomIdSet tagIds, ConsumerId consumer) {
+        std::lock_guard lock(mTagIdsMutex);
+        // update ids list from consumer
+        if (tagIds.size() == 0) {
+            mTagIdsPerConsumer.erase(consumer);
+        } else {
+            mTagIdsPerConsumer[consumer].swap(tagIds);
+        }
+        // populate the superset incorporating list of distinct atom ids from all consumers
+        mTagIds.clear();
+        for (const auto& [_, atomIds] : mTagIdsPerConsumer) {
+            mTagIds.insert(atomIds.begin(), atomIds.end());
+        }
+        mSetUpdateCounter.fetch_add(1, std::memory_order_relaxed);
+    }
+
+private:
+    std::atomic_bool mLogsFilteringEnabled = true;
+    std::atomic_int mSetUpdateCounter;
+    mutable int mLocalSetUpdateCounter;
+
+    mutable std::mutex mTagIdsMutex;
+    std::unordered_map<ConsumerId, AtomIdSet> mTagIdsPerConsumer;
+    mutable AtomIdSet mTagIds;
+    mutable AtomIdSet mLocalTagIds;
+
+    friend class LogEventFilterTest;
+
+    FRIEND_TEST(LogEventFilterTest, TestEmptyFilter);
+    FRIEND_TEST(LogEventFilterTest, TestRemoveNonExistingEmptyFilter);
+    FRIEND_TEST(LogEventFilterTest, TestEmptyFilterDisabled);
+    FRIEND_TEST(LogEventFilterTest, TestEmptyFilterDisabledSetter);
+    FRIEND_TEST(LogEventFilterTest, TestNonEmptyFilterFullOverlap);
+    FRIEND_TEST(LogEventFilterTest, TestNonEmptyFilterPartialOverlap);
+    FRIEND_TEST(LogEventFilterTest, TestNonEmptyFilterDisabled);
+    FRIEND_TEST(LogEventFilterTest, TestNonEmptyFilterDisabledPartialOverlap);
+    FRIEND_TEST(LogEventFilterTest, TestMultipleConsumerOverlapIds);
+    FRIEND_TEST(LogEventFilterTest, TestMultipleConsumerNonOverlapIds);
+    FRIEND_TEST(LogEventFilterTest, TestMultipleConsumerOverlapIdsRemoved);
+    FRIEND_TEST(LogEventFilterTest, TestMultipleConsumerNonOverlapIdsRemoved);
+    FRIEND_TEST(LogEventFilterTest, TestMultipleConsumerEmptyFilter);
+};
+
+typedef LogEventFilterGeneric<std::unordered_set<int>> LogEventFilter;
+
+}  // namespace statsd
+}  // namespace os
+}  // namespace android