Add libtimeinstate for reading uid time-in-state BPF map

Add a library to simplify reading the per-UID time_in_state data
collected using eBPF.

Also add some basic gtests to test the provided interface

Bug: 78498733
Test: gtests pass on crosshatch after loading time_in_state bpf
program
Change-Id: I997e0fd2faad398c7b427084a08edacb9405f089
Signed-off-by: Connor O'Brien <connoro@google.com>
diff --git a/libs/cputimeinstate/testtimeinstate.cpp b/libs/cputimeinstate/testtimeinstate.cpp
new file mode 100644
index 0000000..9837865
--- /dev/null
+++ b/libs/cputimeinstate/testtimeinstate.cpp
@@ -0,0 +1,58 @@
+
+#include <unordered_map>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include <cputimeinstate.h>
+
+namespace android {
+namespace bpf {
+
+using std::vector;
+
+TEST(TimeInStateTest, SingleUid) {
+    vector<vector<uint64_t>> times;
+    ASSERT_TRUE(getUidCpuFreqTimes(0, &times));
+    EXPECT_FALSE(times.empty());
+}
+
+TEST(TimeInStateTest, AllUid) {
+    vector<size_t> sizes;
+    std::unordered_map<uint32_t, vector<vector<uint64_t>>> map;
+    ASSERT_TRUE(getUidsCpuFreqTimes(&map));
+
+    ASSERT_FALSE(map.empty());
+
+    auto firstEntry = map.begin()->second;
+    for (const auto &subEntry : firstEntry) sizes.emplace_back(subEntry.size());
+
+    for (const auto &vec : map) {
+        ASSERT_EQ(vec.second.size(), sizes.size());
+        for (size_t i = 0; i < vec.second.size(); ++i) ASSERT_EQ(vec.second[i].size(), sizes[i]);
+    }
+}
+
+TEST(TimeInStateTest, RemoveUid) {
+    vector<vector<uint64_t>> times, times2;
+    ASSERT_TRUE(getUidCpuFreqTimes(0, &times));
+    ASSERT_FALSE(times.empty());
+
+    uint64_t sum = 0;
+    for (size_t i = 0; i < times.size(); ++i) {
+        for (auto x : times[i]) sum += x;
+    }
+    ASSERT_GT(sum, (uint64_t)0);
+
+    ASSERT_TRUE(clearUidCpuFreqTimes(0));
+
+    ASSERT_TRUE(getUidCpuFreqTimes(0, &times2));
+    ASSERT_EQ(times2.size(), times.size());
+    for (size_t i = 0; i < times.size(); ++i) {
+        ASSERT_EQ(times2[i].size(), times[i].size());
+        for (size_t j = 0; j < times[i].size(); ++j) ASSERT_LE(times2[i][j], times[i][j]);
+    }
+}
+
+} // namespace bpf
+} // namespace android