1 files changed, 94 insertions, 0 deletions
diff --git a/toolkit/components/telemetry/core/ScalarInfo.h b/toolkit/components/telemetry/core/ScalarInfo.h
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+++ b/toolkit/components/telemetry/core/ScalarInfo.h
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef TelemetryScalarInfo_h__
+#define TelemetryScalarInfo_h__
+
+#include "TelemetryCommon.h"
+
+// This module is internal to Telemetry. It defines a structure that holds the
+// scalar info. It should only be used by TelemetryScalarData.h automatically
+// generated file and TelemetryScalar.cpp. This should not be used anywhere
+// else. For the public interface to Telemetry functionality, see Telemetry.h.
+
+namespace {
+
+/**
+ * Base scalar information, common to both "static" and dynamic scalars.
+ */
+struct BaseScalarInfo {
+  uint32_t kind;
+  uint32_t dataset;
+  mozilla::Telemetry::Common::RecordedProcessType record_in_processes;
+  bool keyed;
+  uint32_t key_count;
+  uint32_t key_offset;
+  mozilla::Telemetry::Common::SupportedProduct products;
+  bool builtin;
+
+  constexpr BaseScalarInfo(
+      uint32_t aKind, uint32_t aDataset,
+      mozilla::Telemetry::Common::RecordedProcessType aRecordInProcess,
+      bool aKeyed, uint32_t aKeyCount, uint32_t aKeyOffset,
+      mozilla::Telemetry::Common::SupportedProduct aProducts,
+      bool aBuiltin = true)
+      : kind(aKind),
+        dataset(aDataset),
+        record_in_processes(aRecordInProcess),
+        keyed(aKeyed),
+        key_count(aKeyCount),
+        key_offset(aKeyOffset),
+        products(aProducts),
+        builtin(aBuiltin) {}
+  virtual ~BaseScalarInfo() = default;
+
+  virtual const char* name() const = 0;
+  virtual const char* expiration() const = 0;
+
+  virtual uint32_t storeOffset() const = 0;
+  virtual uint32_t storeCount() const = 0;
+};
+
+/**
+ * "Static" scalar definition: these are the ones riding
+ * the trains.
+ */
+struct ScalarInfo : BaseScalarInfo {
+  uint32_t name_offset;
+  uint32_t expiration_offset;
+  uint32_t store_count;
+  uint16_t store_offset;
+
+  // In order to cleanly support dynamic scalars in TelemetryScalar.cpp, we need
+  // to use virtual functions for |name| and |expiration|, as they won't be
+  // looked up in the static tables in that case. However, using virtual
+  // functions makes |ScalarInfo| non-aggregate and prevents from using
+  // aggregate initialization (curly brackets) in the generated
+  // TelemetryScalarData.h. To work around this problem we define a constructor
+  // that takes the exact number of parameters we need.
+  constexpr ScalarInfo(
+      uint32_t aKind, uint32_t aNameOffset, uint32_t aExpirationOffset,
+      uint32_t aDataset,
+      mozilla::Telemetry::Common::RecordedProcessType aRecordInProcess,
+      bool aKeyed, uint32_t aKeyCount, uint32_t aKeyOffset,
+      mozilla::Telemetry::Common::SupportedProduct aProducts,
+      uint32_t aStoreCount, uint32_t aStoreOffset)
+      : BaseScalarInfo(aKind, aDataset, aRecordInProcess, aKeyed, aKeyCount,
+                       aKeyOffset, aProducts),
+        name_offset(aNameOffset),
+        expiration_offset(aExpirationOffset),
+        store_count(aStoreCount),
+        store_offset(aStoreOffset) {}
+
+  const char* name() const override;
+  const char* expiration() const override;
+
+  uint32_t storeOffset() const override { return store_offset; };
+  uint32_t storeCount() const override { return store_count; };
+};
+
+}  // namespace
+
+#endif  // TelemetryScalarInfo_h__