Use template class for in-memory data. (#1496)

exporters/memory/BUILD

@@ -3,6 +3,7 @@ package(default_visibility = ["//visibility:public"])
 cc_library(
     name = "in_memory_span_data",
     hdrs = [
+        "include/opentelemetry/exporters/memory/in_memory_data.h",
         "include/opentelemetry/exporters/memory/in_memory_span_data.h",
     ],
     strip_include_prefix = "include",

exporters/memory/include/opentelemetry/exporters/memory/in_memory_data.h

@@ -0,0 +1,62 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include "opentelemetry/sdk/common/circular_buffer.h"
+
+#include <vector>
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace exporter
+{
+namespace memory
+{
+/**
+ * A wrapper class holding in memory exporter data
+ */
+template <typename T>
+class InMemoryData
+{
+public:
+  /**
+   * @param buffer_size a required value that sets the size of the CircularBuffer
+   */
+  InMemoryData(size_t buffer_size) : data_(buffer_size) {}
+
+  /**
+   * @param data a required unique pointer to the data to add to the CircularBuffer
+   */
+  void Add(std::unique_ptr<T> data) noexcept { data_.Add(data); }
+
+  /**
+   * @return Returns a vector of unique pointers containing all the data in the
+   * CircularBuffer. This operation will empty the Buffer, which is why the data
+   * is returned as unique pointers
+   */
+  std::vector<std::unique_ptr<T>> Get() noexcept
+  {
+    std::vector<std::unique_ptr<T>> res;
+
+    // Pointer swap is required because the Consume function requires that the
+    // AtomicUniquePointer be set to null
+    data_.Consume(
+        data_.size(), [&](opentelemetry::sdk::common::CircularBufferRange<
+                          opentelemetry::sdk::common::AtomicUniquePtr<T>> range) noexcept {
+          range.ForEach([&](opentelemetry::sdk::common::AtomicUniquePtr<T> &ptr) noexcept {
+            std::unique_ptr<T> swap_ptr = nullptr;
+            ptr.Swap(swap_ptr);
+            res.push_back(std::move(swap_ptr));
+            return true;
+          });
+        });
+
+    return res;
+  }
+
+private:
+  opentelemetry::sdk::common::CircularBuffer<T> data_;
+};
+}  // namespace memory
+}  // namespace exporter
+OPENTELEMETRY_END_NAMESPACE

exporters/memory/include/opentelemetry/exporters/memory/in_memory_span_data.h

@@ -3,7 +3,7 @@
 
 #pragma once
 
-#include "opentelemetry/sdk/common/circular_buffer.h"
+#include "opentelemetry/exporters/memory/in_memory_data.h"
 #include "opentelemetry/sdk/trace/recordable.h"
 #include "opentelemetry/sdk/trace/span_data.h"
 
@@ -14,60 +14,17 @@ namespace exporter
 {
 namespace memory
 {
-/**
- * A wrapper class holding in memory exporter data
- */
-class InMemorySpanData final
+class InMemorySpanData final : public exporter::memory::InMemoryData<sdk::trace::SpanData>
 {
 public:
   /**
    * @param buffer_size a required value that sets the size of the CircularBuffer
    */
-  InMemorySpanData(size_t buffer_size) : spans_received_(buffer_size) {}
+  explicit InMemorySpanData(size_t buffer_size)
+      : exporter::memory::InMemoryData<sdk::trace::SpanData>(buffer_size)
+  {}
 
-  /**
-   * @param data a required unique pointer to the data to add to the CircularBuffer
-   */
-  void Add(std::unique_ptr<opentelemetry::sdk::trace::SpanData> data) noexcept
-  {
-    std::unique_ptr<opentelemetry::sdk::trace::SpanData> span_data(
-        static_cast<opentelemetry::sdk::trace::SpanData *>(data.release()));
-    spans_received_.Add(span_data);
-  }
-
-  /**
-   * @return Returns a vector of unique pointers containing all the span data in the
-   * CircularBuffer. This operation will empty the Buffer, which is why the data
-   * is returned as unique pointers
-   */
-  std::vector<std::unique_ptr<opentelemetry::sdk::trace::SpanData>> GetSpans() noexcept
-  {
-    std::vector<std::unique_ptr<opentelemetry::sdk::trace::SpanData>> res;
-
-    // Pointer swap is required because the Consume function requires that the
-    // AtomicUniquePointer be set to null
-    spans_received_.Consume(
-        spans_received_.size(),
-        [&](opentelemetry::sdk::common::CircularBufferRange<
-            opentelemetry::sdk::common::AtomicUniquePtr<opentelemetry::sdk::trace::SpanData>>
-                range) noexcept {
-          range.ForEach(
-              [&](opentelemetry::sdk::common::AtomicUniquePtr<opentelemetry::sdk::trace::SpanData>
-                      &ptr) noexcept {
-                std::unique_ptr<opentelemetry::sdk::trace::SpanData> swap_ptr =
-                    std::unique_ptr<opentelemetry::sdk::trace::SpanData>(nullptr);
-                ptr.Swap(swap_ptr);
-                res.push_back(
-                    std::unique_ptr<opentelemetry::sdk::trace::SpanData>(swap_ptr.release()));
-                return true;
-              });
-        });
-
-    return res;
-  }
-
-private:
-  opentelemetry::sdk::common::CircularBuffer<opentelemetry::sdk::trace::SpanData> spans_received_;
+  std::vector<std::unique_ptr<sdk::trace::SpanData>> GetSpans() noexcept { return Get(); }
 };
 }  // namespace memory
 }  // namespace exporter

exporters/memory/include/opentelemetry/exporters/memory/in_memory_span_exporter.h

@@ -6,6 +6,7 @@
 #include "opentelemetry/common/spin_lock_mutex.h"
 #include "opentelemetry/exporters/memory/in_memory_span_data.h"
 #include "opentelemetry/sdk/trace/exporter.h"
+#include "opentelemetry/sdk/trace/span_data.h"
 #include "opentelemetry/sdk_config.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -26,7 +27,7 @@ class InMemorySpanExporter final : public opentelemetry::sdk::trace::SpanExporte
    * @param buffer_size an optional value that sets the size of the InMemorySpanData
    */
   InMemorySpanExporter(size_t buffer_size = MAX_BUFFER_SIZE)
-      : data_(new opentelemetry::exporter::memory::InMemorySpanData(buffer_size))
+      : data_(new InMemorySpanData(buffer_size))
   {}
 
   /**
@@ -80,13 +81,10 @@ class InMemorySpanExporter final : public opentelemetry::sdk::trace::SpanExporte
   /**
    * @return Returns a shared pointer to this exporters InMemorySpanData
    */
-  std::shared_ptr<opentelemetry::exporter::memory::InMemorySpanData> GetData() noexcept
-  {
-    return data_;
-  }
+  std::shared_ptr<InMemorySpanData> GetData() noexcept { return data_; }
 
 private:
-  std::shared_ptr<opentelemetry::exporter::memory::InMemorySpanData> data_;
+  std::shared_ptr<InMemorySpanData> data_;
   bool is_shutdown_ = false;
   mutable opentelemetry::common::SpinLockMutex lock_;
   const bool isShutdown() const noexcept