improve example (#29)

* improve example

* client example

* lvalue

Author: Shikugawa

cpp2sky/segment_context.h

@@ -181,6 +181,9 @@ class SegmentContext {
   virtual std::string createSW8HeaderValue(CurrentSegmentSpanPtr parent,
                                            std::string& target_address,
                                            bool sample = true) = 0;
+  virtual std::string createSW8HeaderValue(CurrentSegmentSpanPtr parent,
+                                           std::string&& target_address,
+                                           bool sample = true) = 0;
 
   /**
    * Generate Apache SkyWalking native segment object.

example/BUILD

@@ -5,6 +5,17 @@ cc_binary(
   srcs = ["sample.cc"],
   deps = [
     "//cpp2sky:cpp2sky_interface",
-    "//source:cpp2sky_lib"
+    "//source:cpp2sky_lib",
+    "@com_github_httplib//:httplib",
+  ],
+)
+
+cc_binary(
+  name = "tracer_client_example",
+  srcs = ["sample_client.cc"],
+  deps = [
+    "//cpp2sky:cpp2sky_interface",
+    "//source:cpp2sky_lib",
+    "@com_github_httplib//:httplib",
   ],
 )

example/sample.cc

@@ -12,4 +12,50 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-int main(void) { return 0; }
+#include <chrono>
+#include <string>
+
+#include "cpp2sky/propagation.h"
+#include "cpp2sky/segment_context.h"
+#include "cpp2sky/tracer.h"
+#include "httplib.h"
+
+using namespace cpp2sky;
+
+static const std::string service_name = "";
+static const std::string instance_name = "node_0";
+static const std::string address = "0.0.0.0:11800";
+
+SegmentConfig seg_config(service_name, instance_name);
+TracerConfig tracer_config(address);
+
+uint64_t now() {
+  using namespace std::chrono;
+  return duration_cast<milliseconds>(system_clock::now().time_since_epoch())
+      .count();
+}
+
+int main() {
+  httplib::Server svr;
+  // 1. Create tracer object to send span data to OAP.
+  auto tracer = createInsecureGrpcTracer(tracer_config);
+
+  svr.Get("/ping", [&](const httplib::Request& req, httplib::Response& res) {
+    // 2. Create segment context
+    auto current_segment = createSegmentContext(seg_config);
+
+    // 3. Initialize span data to track root workload on current service.
+    auto current_span = current_segment->createCurrentSegmentRootSpan();
+
+    // 4. Set info
+    current_span->setOperationName("/ping");
+    current_span->setStartTime(now());
+    current_span->setEndTime(now());
+
+    // 5. Send span data
+    tracer->sendSegment(std::move(current_segment));
+  });
+
+  svr.listen("0.0.0.0", 8081);
+  return 0;
+}

example/sample_client.cc

@@ -0,0 +1,62 @@
+// Copyright 2020 SkyAPM
+
+// 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.
+
+#include <chrono>
+#include <string>
+
+#include "cpp2sky/propagation.h"
+#include "cpp2sky/segment_context.h"
+#include "cpp2sky/tracer.h"
+#include "httplib.h"
+
+using namespace cpp2sky;
+
+static const std::string service_name = "";
+static const std::string instance_name = "client_0";
+static const std::string address = "0.0.0.0:11800";
+
+SegmentConfig seg_config(service_name, instance_name);
+TracerConfig tracer_config(address);
+
+uint64_t now() {
+  using namespace std::chrono;
+  return duration_cast<milliseconds>(system_clock::now().time_since_epoch())
+      .count();
+}
+
+int main() {
+  // 1. Create tracer object to send span data to OAP.
+  auto tracer = createInsecureGrpcTracer(tracer_config);
+  // 2. Create segment context
+  auto current_segment = createSegmentContext(seg_config);
+
+  // 3. Initialize span data to track root workload on current service.
+  auto current_span = current_segment->createCurrentSegmentRootSpan();
+
+  // 4. Set info
+  current_span->setOperationName("/ping");
+  current_span->setStartTime(now());
+
+  httplib::Client cli("remote", 8082);
+  httplib::Headers headers = {{"sw8", current_segment->createSW8HeaderValue(
+                                          current_span, "remote:8082")}};
+  auto res = cli.Get("/ping", headers);
+
+  current_span->setEndTime(now());
+
+  // 5. Send span data
+  tracer->sendSegment(std::move(current_segment));
+
+  return 0;
+}

source/grpc_async_client_impl.cc

@@ -69,6 +69,11 @@ GrpcAsyncSegmentReporterStream::GrpcAsyncSegmentReporterStream(
     : client_(client) {}
 
 GrpcAsyncSegmentReporterStream::~GrpcAsyncSegmentReporterStream() {
+  {
+    std::unique_lock<std::mutex> lck_(mux_);
+    cond_.wait(lck_, [this] { return pending_messages_.empty(); });
+  }
+
   ctx_.TryCancel();
   request_writer_->Finish(&status_, toTag(&finish_));
 }
@@ -117,6 +122,12 @@ bool GrpcAsyncSegmentReporterStream::handleOperation(Operation incoming_op) {
     // Release pending messages which are inserted when stream is not ready
     // to write.
     clearPendingMessages();
+
+    // Release if lock with condition variable has been acquired.
+    // It will blocked if stream has notified to be closed.
+    if (pending_messages_.empty()) {
+      cond_.notify_all();
+    }
     return true;
   } else if (state_ == Operation::Finished) {
     gpr_log(GPR_INFO, "Stream closed with http status: %d",

source/grpc_async_client_impl.h

@@ -16,7 +16,9 @@
 
 #include <grpcpp/grpcpp.h>
 
+#include <condition_variable>
 #include <memory>
+#include <mutex>
 #include <queue>
 
 #include "cpp2sky/internal/async_client.h"
@@ -103,6 +105,9 @@ class GrpcAsyncSegmentReporterStream final
   TaggedStream connected_{Operation::Connected, this};
   TaggedStream write_done_{Operation::WriteDone, this};
   TaggedStream finish_{Operation::Finished, this};
+
+  std::mutex mux_;
+  std::condition_variable cond_;
 };
 
 class GrpcAsyncSegmentReporterStreamFactory final

source/segment_context_impl.cc

@@ -156,6 +156,12 @@ std::string SegmentContextImpl::createSW8HeaderValue(
   return header_value;
 }
 
+std::string SegmentContextImpl::createSW8HeaderValue(
+    CurrentSegmentSpanPtr parent_span, std::string&& target_address,
+    bool sample) {
+  return createSW8HeaderValue(parent_span, target_address, sample);
+}
+
 SegmentObject SegmentContextImpl::createSegmentObject() {
   SegmentObject obj;
   obj.set_traceid(trace_id_);

source/segment_context_impl.h

@@ -122,6 +122,9 @@ class SegmentContextImpl : public SegmentContext {
   std::string createSW8HeaderValue(CurrentSegmentSpanPtr parent_span,
                                    std::string& target_address,
                                    bool sample) override;
+  std::string createSW8HeaderValue(CurrentSegmentSpanPtr parent,
+                                   std::string&& target_address,
+                                   bool sample = true) override;
   SegmentObject createSegmentObject() override;
 
  private: