gh-141645: Add a TUI mode to the new tachyon profiler

Author: pablogsal

Lib/profiling/sampling/_trace.py

@@ -0,0 +1,51 @@
+"""Tracing utility for live profiler debugging.
+
+Usage:
+    export SAMPLING_LIVE_TRACE=/tmp/live_trace.log
+    ./python -m profiling.sampling --live -p <PID>
+"""
+
+import os
+import sys
+import time
+
+trace_file = None
+if trace_filename := os.environ.get("SAMPLING_LIVE_TRACE"):
+    trace_file = open(trace_filename, "a")
+    trace_file.write(f"\n{'='*80}\n")
+    trace_file.write(f"Live Profiler Trace Session Started: {time.strftime('%Y-%m-%d %H:%M:%S')}\n")
+    trace_file.write(f"{'='*80}\n")
+    trace_file.flush()
+
+
+def trace(line: str, *args, **kwargs) -> None:
+    if trace_file is None:
+        return
+
+    if args or kwargs:
+        line = line.format(*args, **kwargs)
+
+    timestamp = time.strftime("%H:%M:%S")
+    trace_file.write(f"[{timestamp}] {line}\n")
+    trace_file.flush()
+
+
+def trace_exception(msg: str, exc: Exception) -> None:
+    if trace_file is None:
+        return
+
+    import traceback
+    timestamp = time.strftime("%H:%M:%S")
+    trace_file.write(f"[{timestamp}] EXCEPTION: {msg}\n")
+    traceback.print_exc(file=trace_file)
+    trace_file.flush()
+
+
+def close_trace() -> None:
+    global trace_file
+    if trace_file is not None:
+        trace_file.write(f"\n{'='*80}\n")
+        trace_file.write(f"Trace Session Ended: {time.strftime('%Y-%m-%d %H:%M:%S')}\n")
+        trace_file.write(f"{'='*80}\n\n")
+        trace_file.close()
+        trace_file = None