#4756: Fix watcher gtest fixture log clearing

tests/tt_metal/tt_metal/unit_tests_common/common/watcher_fixture.hpp

@@ -5,6 +5,7 @@
 #include <chrono>
 #include <thread>
 #include "common_fixture.hpp"
+#include "llrt/watcher.hpp"
 
 // A version of CommonFixture with watcher enabled
 class WatcherFixture: public CommonFixture {
@@ -58,6 +59,6 @@ class WatcherFixture: public CommonFixture {
         CommonFixture::RunTestOnDevice(run_function_no_args, device);
         // Wait for a final watcher poll and then clear the log.
         std::this_thread::sleep_for(std::chrono::milliseconds(interval_ms));
-        std::remove(log_file_name.c_str());
+        tt::llrt::watcher_clear_log();
     }
 };

tt_metal/llrt/watcher.cpp

@@ -57,6 +57,7 @@ constexpr uint16_t DEBUG_SANITIZE_NOC_SENTINEL_OK_16 = 0xbada;
 static bool enabled = false;
 static std::mutex watch_mutex;
 static std::unordered_map<void *, std::shared_ptr<WatcherDevice>> devices;
+static string logfile_path = "";
 static FILE *logfile = nullptr;
 static std::chrono::time_point start_time = std::chrono::system_clock::now();
 static std::vector<string> kernel_names;
@@ -611,6 +612,7 @@ void watcher_attach(void *dev,
 
     if (!watcher::enabled && OptionsG.get_watcher_enabled()) {
 
+        watcher::logfile_path = log_path;
         watcher::logfile = watcher::create_file(log_path);
 
         int sleep_usecs = OptionsG.get_watcher_interval() * 1000;
@@ -665,5 +667,9 @@ int watcher_register_kernel(const string& name) {
     return watcher::kernel_names.size() - 1;
 }
 
+void watcher_clear_log() {
+    watcher::logfile = watcher::create_file(watcher::logfile_path);
+}
+
 } // namespace llrt
 } // namespace tt

tt_metal/llrt/watcher.hpp

@@ -20,5 +20,8 @@ void watcher_sanitize_host_noc_write(const metal_SocDescriptor &soc_d, CoreCoord
 
 int watcher_register_kernel(const string& name);
 
+// Helper function to clear the watcher log file
+void watcher_clear_log();
+
 } // namespace llrt
 } // namespace tt