feat(config): Add new helper function for parsing human readable durations

Signed-off-by: Steffen Vogel <[email protected]>

Author: stv0g

common/include/villas/timing.hpp

@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <cstdint>
+#include <chrono>
 #include <cstdio>
 #include <ctime>
 
@@ -33,3 +33,14 @@ double time_to_double(const struct timespec *ts);
 
 // Convert double containing seconds after 1970 to timespec.
 struct timespec time_from_double(double secs);
+
+// Convert timespec to an std::chrono::time_point.
+template <typename Duration = std::chrono::nanoseconds>
+std::chrono::time_point<std::chrono::system_clock, Duration>
+time_to_timepoint(const struct timespec *ts) {
+  auto dur =
+      std::chrono::seconds(ts->tv_sec) + std::chrono::nanoseconds(ts->tv_nsec);
+
+  return std::chrono::time_point<std::chrono::system_clock, Duration>(
+      std::chrono::duration_cast<Duration>(dur));
+}

include/villas/config_helper.hpp

@@ -7,11 +7,17 @@
 
 #pragma once
 
+#include <chrono>
+#include <regex>
+#include <stdexcept>
+
 #include <jansson.h>
 
 #include <villas/node/config.hpp>
 #include <villas/sample.hpp>
 
+#include "villas/exceptions.hpp"
+
 #ifdef WITH_CONFIG
 #include <libconfig.h>
 #endif
@@ -42,5 +48,93 @@ int json_object_extend(json_t *orig, json_t *merge);
 
 json_t *json_load_cli(int argc, const char *argv[]);
 
+template <typename Duration = std::chrono::nanoseconds>
+Duration parse_duration(std::string_view input) {
+  using namespace std::literals::chrono_literals;
+
+  // Map unit strings to their corresponding chrono durations
+  static const std::unordered_map<std::string, std::chrono::nanoseconds>
+      unit_map = {
+          {"d", 24h},  // days
+          {"h", 1h},   // hours
+          {"m", 1min}, // minutes
+          {"s", 1s},   // seconds
+          {"ms", 1ms}, // milliseconds
+          {"us", 1us}, // microseconds
+          {"ns", 1ns}  // nanoseconds
+      };
+
+  std::regex token_re(R"((\d+)([a-z]+))");
+  auto begin = std::regex_iterator(input.begin(), input.end(), token_re);
+  auto end = std::regex_iterator<std::string_view::const_iterator>();
+
+  std::chrono::nanoseconds total_duration{0};
+
+  for (auto i = begin; i != end; ++i) {
+    auto match = *i;
+    auto number_str = match[1];
+    auto unit_str = match[2];
+
+    auto it = unit_map.find(unit_str);
+    if (it == unit_map.end()) {
+      throw RuntimeError("Unknown duration unit: {}", unit_str.str());
+    }
+
+    auto unit = it->second;
+
+    int64_t number;
+    try {
+      number = std::stoul(number_str);
+    } catch (const std::invalid_argument &e) {
+      throw RuntimeError("Invalid number in duration: {}", match.str());
+    } catch (const std::out_of_range &e) {
+      throw RuntimeError("Duration overflows maximum representable value: {}",
+                         match.str());
+    }
+
+    auto duration = unit * number;
+
+    if (duration > Duration::zero() && duration < Duration(1))
+      throw RuntimeError("Duration underflows minimum representable value");
+
+    if (unit.count() != 0 &&
+        duration.count() / unit.count() != number) // Check for overflow.
+      throw RuntimeError("Duration overflows maximum representable value: {}",
+                         match.str());
+    ;
+
+    total_duration += duration;
+  }
+
+  return std::chrono::duration_cast<Duration>(total_duration);
+}
+
+template <typename Duration = std::chrono::nanoseconds>
+Duration parse_duration(json_t *json) {
+  switch (json_typeof(json)) {
+  case JSON_INTEGER: {
+    int64_t value = json_integer_value(json);
+    if (value < 0) {
+      throw ConfigError(json, "duration-negative", "Negative duration value");
+    }
+
+    return Duration(value);
+  }
+
+  case JSON_STRING: {
+    try {
+      return parse_duration<Duration>(
+          std::string_view(json_string_value(json), json_string_length(json)));
+    } catch (const RuntimeError &e) {
+      throw ConfigError(json, "duration", "{}", e.what());
+    }
+  }
+
+  default:
+    throw ConfigError(json, "duration",
+                      "Expected a string or integer for duration");
+  }
+}
+
 } // namespace node
 } // namespace villas