cpusensor: Search in peci-0 directory

The code was searching /sys/bus/peci/devices for PECI sensors.
This results in below directories to be searched on typical 2 socket
x86 systems.
* peci-0
* 0-30
* 0-31
Where 0-30 and 0-31 exist in peci-0 as well.
It is unnecessary, and the files in 0-30 and 0-31 will be searched twice
because they exist in peci-0.

Change the code to search in /sys/bus/peci/devices/peci-0 to make sure
it only search the files within the expected directory.
Note that the current peci driver only create peci-0, this code could be
easily extended to support peci-1/2/3 in the future.

Tested: The time for cpusensor to search the peci sensors reduces from
        0.5s to about 0.3s.

Signed-off-by: Lei YU <[email protected]>
Change-Id: I7b0f3ad7bea7a3dced13a985f0ad19ffda33f6d2

Author: leiyu-bytedance

Diff for: src/CPUSensorMain.cpp

@@ -168,9 +168,8 @@ bool createSensors(boost::asio::io_service& io,
     }
 
     std::vector<fs::path> hwmonNamePaths;
-    if (!findFiles(fs::path(R"(/sys/bus/peci/devices)"),
-                   R"(peci-\d+/\d+-.+/peci-.+/hwmon/hwmon\d+/name$)",
-                   hwmonNamePaths, 6))
+    if (!findFiles(fs::path(R"(/sys/bus/peci/devices/peci-0)"),
+                   R"(\d+-.+/peci-.+/hwmon/hwmon\d+/name$)", hwmonNamePaths, 5))
     {
         std::cerr << "No CPU sensors in system\n";
         return true;

Diff for: tests/test_Utils.cpp

@@ -145,3 +145,21 @@ TEST_F(TestUtils, findFiles_peciPath_end_with_slash)
     EXPECT_TRUE(ret);
     EXPECT_EQ(foundPaths.size(), 3u);
 }
+
+TEST_F(TestUtils, findFiles_in_sub_peci_match)
+{
+    std::vector<fs::path> foundPaths;
+    auto ret =
+        findFiles(peciDir / "peci-0", R"(\d+-.+/peci-.+/hwmon/hwmon\d+/name$)",
+                  foundPaths, 5);
+    EXPECT_TRUE(ret);
+    EXPECT_EQ(foundPaths.size(), 1u);
+
+    foundPaths.clear();
+
+    ret = findFiles(peciDir / "peci-0",
+                    R"(\d+-.+/peci-.+/hwmon/hwmon\d+/temp\d+_input)",
+                    foundPaths, 5);
+    EXPECT_TRUE(ret);
+    EXPECT_EQ(foundPaths.size(), 3u);
+}