Make number of stubs per channel configurable and expose metrics from
client
diff --git a/test/cpp/util/metrics_server.cc b/test/cpp/util/metrics_server.cc
new file mode 100644
index 0000000..42a8911
--- /dev/null
+++ b/test/cpp/util/metrics_server.cc
@@ -0,0 +1,118 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *is % allowed in string
+ */
+
+#include "test/cpp/util/metrics_server.h"
+
+#include <vector>
+
+#include <grpc++/server_builder.h>
+
+#include "test/proto/metrics.grpc.pb.h"
+#include "test/proto/metrics.pb.h"
+
+namespace grpc {
+namespace testing {
+
+using std::vector;
+
+Guage::Guage(long initial_val) : val_(initial_val) {}
+
+void Guage::Set(long new_val) {
+  val_.store(new_val, std::memory_order_relaxed);
+}
+
+long Guage::Get() { return val_.load(std::memory_order_relaxed); }
+
+grpc::Status MetricsServiceImpl::GetAllGuages(
+    ServerContext* context, const EmptyMessage* request,
+    ServerWriter<GuageResponse>* writer) {
+  gpr_log(GPR_INFO, "GetAllGuages called");
+
+  std::lock_guard<std::mutex> lock(mu_);
+  for (auto it = guages_.begin(); it != guages_.end(); it++) {
+    GuageResponse resp;
+    resp.set_name(it->first);           // Guage name
+    resp.set_value(it->second->Get());  // Guage value
+    writer->Write(resp);
+  }
+
+  return Status::OK;
+}
+
+grpc::Status MetricsServiceImpl::GetGuage(ServerContext* context,
+                                          const GuageRequest* request,
+                                          GuageResponse* response) {
+  std::lock_guard<std::mutex> lock(mu_);
+
+  auto it = guages_.find(request->name());
+  if (it != guages_.end()) {
+    response->set_name(it->first);
+    response->set_value(it->second->Get());
+  }
+
+  return Status::OK;
+}
+
+std::shared_ptr<Guage> MetricsServiceImpl::CreateGuage(string name,
+                                                       bool& already_present) {
+  std::lock_guard<std::mutex> lock(mu_);
+
+  std::shared_ptr<Guage> guage(new Guage(0));
+  auto p = guages_.emplace(name, guage);
+
+  // p.first is an iterator pointing to <name, shared_ptr<Guage>> pair. p.second
+  // is a boolean indicating if the Guage is already present in the map
+  already_present = !p.second;
+  return p.first->second;
+}
+
+// Starts the metrics server and returns the grpc::Server instance. Call
+// wait() on the returned server instance.
+std::unique_ptr<grpc::Server> MetricsServiceImpl::StartServer(int port) {
+  gpr_log(GPR_INFO, "Building metrics server..");
+
+  grpc::string address = "0.0.0.0:" + std::to_string(port);
+
+  ServerBuilder builder;
+  builder.AddListeningPort(address, grpc::InsecureServerCredentials());
+  builder.RegisterService(this);
+
+  std::unique_ptr<grpc::Server> server(builder.BuildAndStart());
+  gpr_log(GPR_INFO, "Metrics server %s started. Ready to receive requests..",
+          address.c_str());
+
+  return server;
+}
+
+}  // namespace testing
+}  // namespace grpc
diff --git a/test/cpp/util/metrics_server.h b/test/cpp/util/metrics_server.h
new file mode 100644
index 0000000..c33d40e
--- /dev/null
+++ b/test/cpp/util/metrics_server.h
@@ -0,0 +1,101 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *is % allowed in string
+ */
+#ifndef GRPC_TEST_CPP_METRICS_SERVER_H
+#define GRPC_TEST_CPP_METRICS_SERVER_H
+
+#include <atomic>
+#include <map>
+#include <mutex>
+#include <vector>
+
+#include "test/proto/metrics.grpc.pb.h"
+#include "test/proto/metrics.pb.h"
+
+/*
+ * This implements a Metrics server defined in test/proto/metrics.proto. Any
+ * test service can use this to export Metrics (TODO (sreek): Only Guages for
+ * now).
+ *
+ * Example:
+ *    MetricsServiceImpl metricsImpl;
+ *    ..
+ *    // Create Guage(s). Note: Guages can be created even after calling
+ *    // 'StartServer'.
+ *    Guage guage1 = metricsImpl.CreateGuage("foo",is_present);
+ *    // guage1 can now be used anywhere in the program to set values.
+ *    ...
+ *    // Create the metrics server
+ *    std::unique_ptr<grpc::Server> server = metricsImpl.StartServer(port);
+ *    server->Wait(); // Note: This is blocking.
+ */
+namespace grpc {
+namespace testing {
+
+using std::map;
+using std::vector;
+
+class Guage {
+ public:
+  Guage(long initial_val);
+  void Set(long new_val);
+  long Get();
+
+ private:
+  std::atomic_long val_;
+};
+
+class MetricsServiceImpl GRPC_FINAL : public MetricsService::Service {
+ public:
+  grpc::Status GetAllGuages(ServerContext* context, const EmptyMessage* request,
+                            ServerWriter<GuageResponse>* writer) GRPC_OVERRIDE;
+
+  grpc::Status GetGuage(ServerContext* context, const GuageRequest* request,
+                        GuageResponse* response) GRPC_OVERRIDE;
+
+  // Create a Guage with name 'name'. is_present is set to true if the Guage
+  // is already present in the map.
+  // NOTE: CreateGuage can be called anytime (i.e before or after calling
+  // StartServer).
+  std::shared_ptr<Guage> CreateGuage(string name, bool& is_present);
+
+  std::unique_ptr<grpc::Server> StartServer(int port);
+
+ private:
+  std::map<string, std::shared_ptr<Guage>> guages_;
+  std::mutex mu_;
+};
+
+}  // namespace testing
+}  // namespace grpc
+
+#endif  // GRPC_TEST_CPP_METRICS_SERVER_H