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

[James Henderson via llvm-commits]

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@@ -0,0 +1,132 @@
+//===- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides the basic framework for Telemetry
+/// Refer to its documentation at llvm/docs/Telemetry.rst for more details.
+//===---------------------------------------------------------------------===//
+
+#ifndef LLVM_TELEMETRY_TELEMETRY_H
+#define LLVM_TELEMETRY_TELEMETRY_H
+
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/JSON.h"
+#include <memory>
+#include <optional>
+#include <string>
+
+namespace llvm {
+namespace telemetry {
+
+class Serializer {
+public:
+  virtual llvm::Error init() = 0;
+  virtual void write(StringRef KeyName, bool Value) = 0;
+  virtual void write(StringRef KeyName, int Value) = 0;
+  virtual void write(StringRef KeyName, size_t Value) = 0;
+  virtual void write(StringRef KeyName, StringRef Value) = 0;
+  virtual void write(StringRef KeyName,
+                     const std::map<std::string, std::string> &Value) = 0;
+  virtual llvm::Error finalize() = 0;
+};
+
+/// Configuration for the Manager class.
+/// This stores configurations from both users and vendors and is passed
+/// to the Manager upon construction. (Any changes to the config after
+/// the Manager's construction will not have any effect on it).
+///
+/// This struct can be extended as needed to add additional configuration
+/// points specific to a vendor's implementation.
+struct Config {
+  // If true, telemetry will be enabled.
+  const bool EnableTelemetry;
+  Config(bool E) : EnableTelemetry(E) {}
+
+  virtual std::string makeSessionId() { return "0"; }
+};
+
+/// For isa, dyn_cast, etc operations on TelemetryInfo.
+typedef unsigned KindType;
+/// This struct is used by TelemetryInfo to support isa<>, dyn_cast<>
+/// operations.
+/// It is defined as a struct (rather than an enum) because it is
+/// expected to be extended by subclasses which may have
+/// additional TelemetryInfo types defined to describe different events.
+struct EntryKind {
+  static const KindType Base = 0;
+};
+
+/// TelemetryInfo is the data courier, used to move instrumented data
+/// from the tool being monitored to the Telemetry framework.
+///
+/// This base class contains only the basic set of telemetry data.
+/// Downstream implementations can define more subclasses with
+/// additional fields to describe different events and concepts.
+///
+/// For example, The LLDB debugger can define a DebugCommandInfo subclass
+/// which has additional fields about the debug-command being instrumented,
+/// such as `CommandArguments` or `CommandName`.
+struct TelemetryInfo {
+  // This represents a unique-id, conventionally corresponding to
+  // a tool's session - i.e., every time the tool starts until it exits.
+  //
+  // Note: a tool could have multiple sessions running at once, in which
+  // case, these shall be multiple sets of TelemetryInfo with multiple unique
+  // ids.
----------------
jh7370 wrote:

```suggestion
  // IDs.
```

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