[llvm] [llvm]Add a simple Telemetry framework (PR #102323)

[James Henderson via llvm-commits]

================
@@ -0,0 +1,107 @@
+//===- llvm/Telemetry/Telemetry.h - Telemetry -------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TELEMETRY_TELEMETRY_H
+#define LLVM_TELEMETRY_TELEMETRY_H
+
+#include <chrono>
+#include <ctime>
+#include <memory>
+#include <optional>
+#include <string>
+
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/JSON.h"
+
+namespace llvm {
+namespace telemetry {
+
+using SteadyTimePoint = std::chrono::time_point<std::chrono::steady_clock>;
+
+struct TelemetryConfig {
+  // If true, telemetry will be enabled.
+  bool enable_telemetry;
+
+  // Additional destinations to send the logged entries.
+  // Could be stdout, stderr, or some local paths.
+  // Note: these are destinations are __in addition to__ whatever the default
+  // destination(s) are, as implemented by vendors.
+  std::vector<std::string> additional_destinations;
+};
+
+struct TelemetryEventStats {
+  // REQUIRED: Start time of event
+  SteadyTimePoint m_start;
+  // OPTIONAL: End time of event - may be empty if not meaningful.
+  std::optional<SteadyTimePoint> m_end;
+  // TBD: could add some memory stats here too?
+
+  TelemetryEventStats() = default;
+  TelemetryEventStats(SteadyTimePoint start) : m_start(start) {}
+  TelemetryEventStats(SteadyTimePoint start, SteadyTimePoint end)
+      : m_start(start), m_end(end) {}
+
+  std::string ToString() const;
----------------
jh7370 wrote:

Not sure I see what's wrong with that? The destination and serialization are pretty tied together, at least in this kind of design. You could split them, in theory, but not all destinations will accept the same kind of serialization output, e.g. a file or stdout will take strings, whatever format they're in, but a dictionary class won't take arbitrary strings - it needs to know the types of the source data.

https://github.com/llvm/llvm-project/pull/102323