1 files changed, 126 insertions, 0 deletions
diff --git a/src/cpp/ext/filters/census/context.h b/src/cpp/ext/filters/census/context.h
new file mode 100644
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+++ b/src/cpp/ext/filters/census/context.h
@@ -0,0 +1,126 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CPP_EXT_FILTERS_CENSUS_CONTEXT_H
+#define GRPC_INTERNAL_CPP_EXT_FILTERS_CENSUS_CONTEXT_H
+
+#include <grpc/support/port_platform.h>
+
+#include <grpc/status.h>
+#include "absl/memory/memory.h"
+#include "absl/strings/string_view.h"
+#include "absl/strings/strip.h"
+#include "opencensus/trace/span.h"
+#include "opencensus/trace/span_context.h"
+#include "opencensus/trace/trace_params.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/cpp/common/channel_filter.h"
+#include "src/cpp/ext/filters/census/rpc_encoding.h"
+
+// This is needed because grpc has hardcoded CensusContext with a
+// forward declaration of 'struct census_context;'
+struct census_context;
+
+namespace grpc {
+
+// Thread compatible.
+class CensusContext {
+ public:
+  CensusContext() : span_(::opencensus::trace::Span::BlankSpan()) {}
+
+  explicit CensusContext(absl::string_view name)
+      : span_(::opencensus::trace::Span::StartSpan(name)) {}
+
+  CensusContext(absl::string_view name, const ::opencensus::trace::Span* parent)
+      : span_(::opencensus::trace::Span::StartSpan(name, parent)) {}
+
+  CensusContext(absl::string_view name,
+                const ::opencensus::trace::SpanContext& parent_ctxt)
+      : span_(::opencensus::trace::Span::StartSpanWithRemoteParent(
+            name, parent_ctxt)) {}
+
+  ::opencensus::trace::SpanContext Context() const { return span_.context(); }
+  ::opencensus::trace::Span Span() const { return span_; }
+  void EndSpan() { span_.End(); }
+
+ private:
+  ::opencensus::trace::Span span_;
+};
+
+// Serializes the outgoing trace context. Field IDs are 1 byte followed by
+// field data. A 1 byte version ID is always encoded first.
+size_t TraceContextSerialize(const ::opencensus::trace::SpanContext& context,
+                             char* tracing_buf, size_t tracing_buf_size);
+
+// Serializes the outgoing stats context.  Field IDs are 1 byte followed by
+// field data. A 1 byte version ID is always encoded first. Tags are directly
+// serialized into the given grpc_slice.
+size_t StatsContextSerialize(size_t max_tags_len, grpc_slice* tags);
+
+// Serialize outgoing server stats. Returns the number of bytes serialized.
+size_t ServerStatsSerialize(uint64_t server_elapsed_time, char* buf,
+                            size_t buf_size);
+
+// Deserialize incoming server stats. Returns the number of bytes deserialized.
+size_t ServerStatsDeserialize(const char* buf, size_t buf_size,
+                              uint64_t* server_elapsed_time);
+
+// Deserialize the incoming SpanContext and generate a new server context based
+// on that. This new span will never be a root span. This should only be called
+// with a blank CensusContext as it overwrites it.
+void GenerateServerContext(absl::string_view tracing, absl::string_view stats,
+                           absl::string_view primary_role,
+                           absl::string_view method, CensusContext* context);
+
+// Creates a new client context that is by default a new root context.
+// If the current context is the default context then the newly created
+// span automatically becomes a root span. This should only be called with a
+// blank CensusContext as it overwrites it.
+void GenerateClientContext(absl::string_view method, CensusContext* ctxt,
+                           CensusContext* parent_ctx);
+
+// Returns the incoming data size from the grpc call final info.
+uint64_t GetIncomingDataSize(const grpc_call_final_info* final_info);
+
+// Returns the outgoing data size from the grpc call final info.
+uint64_t GetOutgoingDataSize(const grpc_call_final_info* final_info);
+
+// These helper functions return the SpanContext and Span, respectively
+// associated with the census_context* stored by grpc. The user will need to
+// call this for manual propagation of tracing data.
+::opencensus::trace::SpanContext SpanContextFromCensusContext(
+    const census_context* ctxt);
+::opencensus::trace::Span SpanFromCensusContext(const census_context* ctxt);
+
+// Returns a string representation of the StatusCode enum.
+absl::string_view StatusCodeToString(grpc_status_code code);
+
+inline absl::string_view GetMethod(const grpc_slice* path) {
+  if (GRPC_SLICE_IS_EMPTY(*path)) {
+    return "";
+  }
+  // Check for leading '/' and trim it if present.
+  return absl::StripPrefix(absl::string_view(reinterpret_cast<const char*>(
+                                                 GRPC_SLICE_START_PTR(*path)),
+                                             GRPC_SLICE_LENGTH(*path)),
+                           "/");
+}
+
+}  // namespace grpc
+
+#endif /* GRPC_INTERNAL_CPP_EXT_FILTERS_CENSUS_CONTEXT_H */