thermal: Optimize uevent monitor timeout mechanism

If non-thermal uevents keep triggered, thermalhal will
not hit uevent timeout to update temperature.

Bug: 138257706
Test: pts-tradefed run pts -m PtsThermalHalTestCases

Change-Id: I8470b95f34ff3867e1a9c677e3712d8c8deb3a3c
Signed-off-by: TeYuan Wang <kamewang@google.com>

hidl/thermal/utils/thermal_watcher.cpp

@@ -67,6 +67,7 @@ void ThermalWatcher::registerFilesToWatch(const std::set<std::string> &sensors_t
     looper_->addFd(uevent_fd_.get(), 0, Looper::EVENT_INPUT, nullptr, nullptr);
     is_polling_ = false;
     thermal_triggered_ = true;
+    last_update_time_ = boot_clock::now();
 }
 
 bool ThermalWatcher::startWatchingDeviceFiles() {
@@ -147,8 +148,11 @@ bool ThermalWatcher::threadLoop() {
     int fd;
     std::set<std::string> sensors;
 
+    auto time_elapsed_ms = std::chrono::duration_cast<std::chrono::milliseconds>(boot_clock::now() -
+                                                                                 last_update_time_)
+                                   .count();
     int timeout = (thermal_triggered_ || is_polling_) ? kMinPollIntervalMs : kUeventPollTimeoutMs;
-    if (looper_->pollOnce(timeout, &fd, nullptr, nullptr) >= 0) {
+    if (time_elapsed_ms < timeout && looper_->pollOnce(timeout, &fd, nullptr, nullptr) >= 0) {
         if (fd != uevent_fd_.get()) {
             return true;
         }
@@ -159,6 +163,7 @@ bool ThermalWatcher::threadLoop() {
         }
     }
     thermal_triggered_ = cb_(sensors);
+    last_update_time_ = boot_clock::now();
     return true;
 }
 

hidl/thermal/utils/thermal_watcher.h

@@ -27,6 +27,7 @@
 #include <unordered_map>
 #include <vector>
 
+#include <android-base/chrono_utils.h>
 #include <android-base/unique_fd.h>
 #include <utils/Looper.h>
 #include <utils/Thread.h>
@@ -37,6 +38,7 @@ namespace thermal {
 namespace V2_0 {
 namespace implementation {
 
+using android::base::boot_clock;
 using android::base::unique_fd;
 using WatcherCallback = std::function<bool(const std::set<std::string> &name)>;
 
@@ -92,6 +94,8 @@ class ThermalWatcher : public ::android::Thread {
     bool thermal_triggered_;
     // Flag to point out if device can support uevent notify.
     bool is_polling_;
+    // Timestamp for last thermal update
+    boot_clock::time_point last_update_time_;
 };
 
 }  // namespace implementation