util: Added convenient ISO 8061 UTC datetime str helper

Author: AndreasAakesson

api/isotime

@@ -0,0 +1,25 @@
+// -*-C++-*-
+// This file is a part of the IncludeOS unikernel - www.includeos.org
+//
+// Copyright 2017 Oslo and Akershus University College of Applied Sciences
+// and Alfred Bratterud
+//
+// 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.
+
+#pragma once
+#ifndef API_ISOTIME_HEADER
+#define API_ISOTIME_HEADER
+
+#include "util/isotime.hpp"
+
+#endif

api/util/isotime.hpp

@@ -0,0 +1,46 @@
+// This file is a part of the IncludeOS unikernel - www.includeos.org
+//
+// Copyright 2017 Oslo and Akershus University College of Applied Sciences
+// and Alfred Bratterud
+//
+// 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.
+
+#pragma once
+#ifndef UTIL_ISOTIME_HPP
+#define UTIL_ISOTIME_HPP
+
+#include <ctime>
+#include <string>
+
+namespace isotime
+{
+  /**
+   * @brief      Returns a ISO 8601 UTC datetime string.
+   *             Example: 2017-04-10T13:37:00Z
+   *
+   * @param[in]  ts    A timestamp
+   *
+   * @return     An ISO datetime string, formatted as "YYYY-MM-DDThh:mm:ssZ"
+   */
+  std::string to_datetime_string(time_t ts)
+  {
+    char buf[sizeof "2017-04-10T13:37:00Z"];
+    strftime(buf, sizeof buf, "%FT%TZ", gmtime(&ts));
+    return buf;
+  }
+}
+
+#endif
+
+
+

examples/acorn/service.cpp

@@ -39,17 +39,11 @@ Disk_ptr disk;
 
 #include <time.h>
 
-// Get current date/time, format is [YYYY-MM-DD.HH:mm:ss]
+#include <isotime>
+// Get current date/time, format is [YYYY-MM-DDTHH:mm:ssZ]
 const std::string timestamp() {
-    time_t     now = time(0);
-    struct tm  tstruct;
-    char       buf[80];
-    tstruct = *localtime(&now);
-    // Visit http://en.cppreference.com/w/cpp/chrono/c/strftime
-    // for more information about date/time format
-    strftime(buf, sizeof(buf), "[%Y-%m-%d.%X] ", &tstruct);
-
-    return buf;
+  time_t     now = time(0);
+  return "[" + isotime::to_datetime_string(now) + "] ";
 }
 
 #include <net/inet4>
@@ -153,7 +147,7 @@ void Service::start(const std::string&) {
       router.use("/api/dashboard", dashboard_->router());
 
       // Fallback route for angular application - serve index.html if route is not found
-      router.on_get("/app/.*", 
+      router.on_get("/app/.*",
       [&fs](auto, auto res) {
         #ifdef VERBOSE_WEBSERVER
         printf("[@GET:/app/*] Fallback route - try to serve index.html\n");

test/CMakeLists.txt

@@ -93,6 +93,7 @@ set(TEST_SOURCES
   ${TEST}/util/unit/delegate.cpp
   ${TEST}/util/unit/fixed_queue.cpp
   ${TEST}/util/unit/fixed_vector.cpp
+  ${TEST}/util/unit/isotime.cpp
   ${TEST}/util/unit/logger_test.cpp
   ${TEST}/util/unit/membitmap.cpp
   ${TEST}/util/unit/path_to_regex_no_options.cpp

test/util/unit/isotime.cpp

@@ -0,0 +1,39 @@
+// This file is a part of the IncludeOS unikernel - www.includeos.org
+//
+// Copyright 2017 Oslo and Akershus University College of Applied Sciences
+// and Alfred Bratterud
+//
+// 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 <common.cxx>
+#include <isotime>
+
+CASE("A timestamp can be converted into a ISO UTC datetime string")
+{
+  uint64_t beginning = 0;
+  auto str = isotime::to_datetime_string(beginning);
+
+  EXPECT(str == "1970-01-01T00:00:00Z");
+
+  uint64_t one_minute_later = 60;
+  str = isotime::to_datetime_string(one_minute_later);
+
+  EXPECT(str == "1970-01-01T00:01:00Z");
+
+  uint64_t five_hours_later = 3600*5;
+  str = isotime::to_datetime_string(five_hours_later);
+
+  EXPECT(str == "1970-01-01T05:00:00Z");
+
+  // Not gonna bother more due to leap seconds and calendars etc...
+}