make the runtime client's user agent overrideable (#106)

* make the runtime client's user agent overrideable

* remove extra empty string

* clang-format -i src/*

Author: bmoffatt

Diff for: include/aws/lambda-runtime/runtime.h

@@ -137,6 +137,7 @@ class runtime {
     using next_outcome = aws::lambda_runtime::outcome<invocation_request, aws::http::response_code>;
     using post_outcome = aws::lambda_runtime::outcome<no_result, aws::http::response_code>;
 
+    runtime(std::string const& endpoint, std::string const& user_agent);
     runtime(std::string const& endpoint);
     ~runtime();
 
@@ -164,6 +165,7 @@ class runtime {
         invocation_response const& handler_response);
 
 private:
+    std::string const m_user_agent_header;
     std::array<std::string const, 3> const m_endpoints;
     CURL* const m_curl_handle;
 };

Diff for: src/runtime.cpp

@@ -124,12 +124,6 @@ static size_t write_header(char* ptr, size_t size, size_t nmemb, void* userdata)
     return size * nmemb;
 }
 
-static std::string const& get_user_agent_header()
-{
-    static std::string user_agent = std::string("User-Agent: AWS_Lambda_Cpp/") + get_version();
-    return user_agent;
-}
-
 static size_t read_data(char* buffer, size_t size, size_t nitems, void* userdata)
 {
     auto const limit = size * nitems;
@@ -163,10 +157,12 @@ static int rt_curl_debug_callback(CURL* handle, curl_infotype type, char* data,
 }
 #endif
 
-runtime::runtime(std::string const& endpoint)
-    : m_endpoints{{endpoint + "/2018-06-01/runtime/init/error",
-                   endpoint + "/2018-06-01/runtime/invocation/next",
-                   endpoint + "/2018-06-01/runtime/invocation/"}},
+runtime::runtime(std::string const& endpoint) : runtime(endpoint, "AWS_Lambda_Cpp/" + std::string(get_version())) {}
+
+runtime::runtime(std::string const& endpoint, std::string const& user_agent)
+    : m_user_agent_header("User-Agent: " + user_agent), m_endpoints{{endpoint + "/2018-06-01/runtime/init/error",
+                                                                     endpoint + "/2018-06-01/runtime/invocation/next",
+                                                                     endpoint + "/2018-06-01/runtime/invocation/"}},
       m_curl_handle(curl_easy_init())
 {
     if (!m_curl_handle) {
@@ -234,7 +230,7 @@ runtime::next_outcome runtime::get_next()
     curl_easy_setopt(m_curl_handle, CURLOPT_HEADERDATA, &resp);
 
     curl_slist* headers = nullptr;
-    headers = curl_slist_append(headers, get_user_agent_header().c_str());
+    headers = curl_slist_append(headers, m_user_agent_header.c_str());
     curl_easy_setopt(m_curl_handle, CURLOPT_HTTPHEADER, headers);
 
     logging::log_debug(LOG_TAG, "Making request to %s", m_endpoints[Endpoints::NEXT].c_str());
@@ -339,7 +335,7 @@ runtime::post_outcome runtime::do_post(
 
     headers = curl_slist_append(headers, "Expect:");
     headers = curl_slist_append(headers, "transfer-encoding:");
-    headers = curl_slist_append(headers, get_user_agent_header().c_str());
+    headers = curl_slist_append(headers, m_user_agent_header.c_str());
     auto const& payload = handler_response.get_payload();
     logging::log_debug(
         LOG_TAG, "calculating content length... %s", ("content-length: " + std::to_string(payload.length())).c_str());