[NETD-BPF#1] Move libnetdutils to frameworks/libs/net/...

libnetdutils is referenced by netd.c and TrafficController.cpp, which
are going to be mainlined. Therefore, move libnetdutils to a common
place where both mainline module and platform code (Netd) can refer to.

Bug: 202086915
Test: build; flash; cd system/netd; atest
Ignore-AOSP-First: the netd change(same topic) would not automerge from
aosp.
No-Typo-Check: Clean code move with no other changes.
BYPASS_INCLUSIVE_LANGUAGE_REASON=Clean code move with no other changes.
Change-Id: I645bfe35f6543149c9a9f894cd4158d27a481abe

staticlibs/netd/libnetdutils/ThreadUtilTest.cpp

@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#include <string>
+
+#include <android-base/expected.h>
+#include <gtest/gtest.h>
+#include <netdutils/ThreadUtil.h>
+
+namespace android::netdutils {
+
+namespace {
+
+android::base::expected<std::string, int> getThreadName() {
+    char name[16] = {};
+    if (const int ret = pthread_getname_np(pthread_self(), name, sizeof(name)); ret != 0) {
+        return android::base::unexpected(ret);
+    }
+    return std::string(name);
+}
+
+class NoopRun {
+  public:
+    explicit NoopRun(const std::string& name = "") : mName(name) { instanceNum++; }
+
+    // Destructor happens in the thread.
+    ~NoopRun() {
+        if (checkName) {
+            auto expected = getThreadName();
+            EXPECT_TRUE(expected.has_value());
+            EXPECT_EQ(mExpectedName, expected.value());
+        }
+        instanceNum--;
+    }
+
+    void run() {}
+
+    std::string threadName() { return mName; }
+
+    // Set the expected thread name which will be used to check if it matches the actual thread
+    // name which is returned from the system call. The check will happen in the destructor.
+    void setExpectedName(const std::string& expectedName) {
+        checkName = true;
+        mExpectedName = expectedName;
+    }
+
+    static bool waitForAllReleased(int timeoutMs) {
+        constexpr int intervalMs = 20;
+        int limit = timeoutMs / intervalMs;
+        for (int i = 1; i < limit; i++) {
+            if (instanceNum == 0) {
+                return true;
+            }
+            usleep(intervalMs * 1000);
+        }
+        return false;
+    }
+
+    // To track how many instances are alive.
+    static std::atomic<int> instanceNum;
+
+  private:
+    std::string mName;
+    std::string mExpectedName;
+    bool checkName = false;
+};
+
+std::atomic<int> NoopRun::instanceNum;
+
+}  // namespace
+
+TEST(ThreadUtilTest, objectReleased) {
+    NoopRun::instanceNum = 0;
+    NoopRun* obj = new NoopRun();
+    EXPECT_EQ(1, NoopRun::instanceNum);
+    threadLaunch(obj);
+
+    // Wait for the object released along with the thread exited.
+    EXPECT_TRUE(NoopRun::waitForAllReleased(1000));
+    EXPECT_EQ(0, NoopRun::instanceNum);
+}
+
+TEST(ThreadUtilTest, SetThreadName) {
+    NoopRun::instanceNum = 0;
+
+    // Test thread name empty.
+    NoopRun* obj1 = new NoopRun();
+    obj1->setExpectedName("");
+
+    // Test normal case.
+    NoopRun* obj2 = new NoopRun("TestName");
+    obj2->setExpectedName("TestName");
+
+    // Test thread name too long.
+    std::string name("TestNameTooooLong");
+    NoopRun* obj3 = new NoopRun(name);
+    obj3->setExpectedName(name.substr(0, 15));
+
+    // Thread names are examined in their destructors.
+    EXPECT_EQ(3, NoopRun::instanceNum);
+    threadLaunch(obj1);
+    threadLaunch(obj2);
+    threadLaunch(obj3);
+
+    EXPECT_TRUE(NoopRun::waitForAllReleased(1000));
+    EXPECT_EQ(0, NoopRun::instanceNum);
+}
+
+}  // namespace android::netdutils