Cleanup SIGINT handling to terminate tuning

At the moment, sending a SIGINT (Ctrl + C) is utterly useless:
1. it can take a long time to finish a tuning iteration
2. SIGINT results in 2 successive thread join calls which always
crash the program

This PR fixes these broken behaviors by shortcircuiting those
compilations and evaluations that have not yet started at the time
SIGINT was sent. We still need to flush the pipe so when multiple
threads are compiling, we need to wait for the last one to finish.

Tested and works from both python and C++

Author: nicolasvasilache

tc/autotuner/autotuner-inl.h

@@ -89,24 +89,28 @@ void TuningHarness<Backend>::doCompile(SearchStrategy& searchStrategy) {
     }
     std::unique_ptr<typename Backend::ExecutorType> pExecutor(nullptr);
     auto pConf = searchStrategy.population.at(current).get();
-    auto options = makeOptions<Backend>(baseMapping_, *pConf);
-    try {
-      if (FLAGS_debug_tuner) {
-        std::stringstream ssInfo;
-        typename Backend::MappingOptionsCppPrinter infoPrinter(ssInfo);
-        infoPrinter << options;
-        LOG(INFO) << "[COMPILE] Start compilation @:" << current;
-        LOG_LINE_BY_LINE(INFO, ssInfo);
+    if (not stopRequested_) {
+      auto options = makeOptions<Backend>(baseMapping_, *pConf);
+      try {
+        if (FLAGS_debug_tuner) {
+          std::stringstream ssInfo;
+          typename Backend::MappingOptionsCppPrinter infoPrinter(ssInfo);
+          infoPrinter << options;
+          LOG(INFO) << "[COMPILE] Start compilation @:" << current;
+          LOG_LINE_BY_LINE(INFO, ssInfo);
+        }
+        pExecutor =
+            tc::compile<Backend>(tcTree_, inputs_.begin()->second, options);
+        LOG_IF(INFO, FLAGS_debug_tuner) << "[COMPILE] Done compilation";
+      } catch (const std::exception& e) {
+        LOG(WARNING) << "[TUNER][COMPILE] failed compilation: " << e.what();
+        std::stringstream ssWarning;
+        typename Backend::MappingOptionsCppPrinter warningPrinter(ssWarning);
+        warningPrinter << options;
+        LOG_LINE_BY_LINE(WARNING, ssWarning);
+        pConf->invalid = true;
       }
-      pExecutor =
-          tc::compile<Backend>(tcTree_, inputs_.begin()->second, options);
-      LOG_IF(INFO, FLAGS_debug_tuner) << "[COMPILE] Done compilation";
-    } catch (const std::exception& e) {
-      LOG(WARNING) << "[TUNER][COMPILE] failed compilation: " << e.what();
-      std::stringstream ssWarning;
-      typename Backend::MappingOptionsCppPrinter warningPrinter(ssWarning);
-      warningPrinter << options;
-      LOG_LINE_BY_LINE(WARNING, ssWarning);
+    } else {
       pConf->invalid = true;
     }
 
@@ -158,6 +162,11 @@ void TuningHarness<Backend>::doEvaluate(
       continue;
     }
 
+    if (stopRequested_) {
+      pConf->invalid = true;
+      continue;
+    }
+
     auto options = makeOptions<Backend>(baseMapping_, *pConf);
     if (FLAGS_debug_tuner) {
       // Always log option to INFO so we can correlate to timing offline
@@ -497,8 +506,7 @@ Autotuner<Backend, SearchStrategy>::tune(
     } catch (const std::exception& e) {
       std::cerr << "Exception during autotuning: " << e.what()
                 << "\n dumping cache to "
-                << tc::makeOptionsFilename(cacheFileName) << "/"
-                << Backend::makeDeviceFilename(cacheFileName) << std::endl;
+                << tc::makeOptionsFilename(cacheFileName) << std::endl;
       storeTopKInCache<Backend>(optionsCache_, cacheFileName);
       tuningHarnessThreadEx = std::current_exception();
     }
@@ -507,11 +515,7 @@ Autotuner<Backend, SearchStrategy>::tune(
   while (not tuningHarnessFinished) {
     std::this_thread::sleep_for(std::chrono::milliseconds(100));
     if (sigint_) {
-      std::cerr
-          << "Autotuning will stop after the current iteration has finished."
-          << std::endl;
       tuningHarness.stopAfterCurrentIteration();
-      tuningHarnessThread.join();
       storeTopKInCache<Backend>(optionsCache_, cacheFileName);
     }
     if (sigterm_) {