Add method to parse date from null-terminated string

Author: projjal

cpp/src/arrow/util/value_parsing.h

@@ -23,6 +23,7 @@
 #include <chrono>
 #include <cstddef>
 #include <cstdint>
+#include <cstring>
 #include <limits>
 #include <memory>
 #include <string>
@@ -561,6 +562,38 @@ static inline bool ParseTimestampStrptime(const char* buf, size_t length,
   return true;
 }
 
+/// \brief Returns time since the UNIX epoch in the requested unit. Takes null terminated
+/// buffer as argument
+static inline bool ParseTimestampStrptime(const char* buf,
+                                          const char* format, bool ignore_time_in_day,
+                                          bool allow_trailing_chars, TimeUnit::type unit,
+                                          int64_t* out) {
+  // NOTE: strptime() is more than 10x faster than arrow_vendored::date::parse().
+  struct tm result;
+  memset(&result, 0, sizeof(struct tm));
+#ifdef _WIN32
+  char* ret = arrow_strptime(buf, format, &result);
+#else
+  char* ret = strptime(buf, format, &result);
+#endif
+  if (ret == NULLPTR) {
+    return false;
+  }
+  if (!allow_trailing_chars && static_cast<size_t>(ret - buf) != strlen(buf)) {
+    return false;
+  }
+  // ignore the time part
+  arrow_vendored::date::sys_seconds secs =
+      arrow_vendored::date::sys_days(arrow_vendored::date::year(result.tm_year + 1900) /
+                                     (result.tm_mon + 1) / result.tm_mday);
+  if (!ignore_time_in_day) {
+    secs += (std::chrono::hours(result.tm_hour) + std::chrono::minutes(result.tm_min) +
+             std::chrono::seconds(result.tm_sec));
+  }
+  *out = detail::ConvertTimePoint(secs, unit);
+  return true;
+}
+
 /// \brief Parsing options for timestamps
 struct ParseTimestampContext {
   TimeUnit::type unit;

cpp/src/gandiva/tests/generate_data.h

@@ -129,4 +129,15 @@ class FastUtf8DataGenerator : public DataGenerator<std::string> {
   char cur_char_;
 };
 
+class Utf8DateDataGenerator : public DataGenerator<std::string> {
+ public:
+  Utf8DateDataGenerator() {}
+
+  std::string GenerateData() {
+    return "1990-0" + std::to_string(random_.next() / 9 + 1) + "-1" + std::to_string(random_.next() / 9 + 1);
+  }
+
+  private:
+  Random random_;
+};
 }  // namespace gandiva

cpp/src/gandiva/tests/micro_benchmarks.cc

@@ -277,6 +277,30 @@ static void TimedTestInExpr(benchmark::State& state) {
   ASSERT_OK(status);
 }
 
+static void TimedTestToDate(benchmark::State& state) {
+  auto field_a = field("a", utf8());
+  auto schema = arrow::schema({field_a});
+  auto pool = arrow::default_memory_pool();
+
+  auto field_result = field("res", arrow::date64());
+
+  auto node_a = TreeExprBuilder::MakeField(field_a);
+  auto date_pattern = TreeExprBuilder::MakeStringLiteral("YYYY-MM-DD");
+  auto suppress_literal = TreeExprBuilder::MakeLiteral(1);
+  auto fn = TreeExprBuilder::MakeFunction("to_date", {node_a, date_pattern, suppress_literal}, arrow::date64());
+  auto expr = TreeExprBuilder::MakeExpression(fn, field_result);
+
+  std::shared_ptr<Projector> projector;
+  ASSERT_OK(Projector::Make(schema, {expr}, TestConfiguration(), &projector));
+
+  Utf8DateDataGenerator data_generator;
+  ProjectEvaluator evaluator(projector);
+
+  Status status = TimedEvaluate<arrow::StringType, std::string>(
+      schema, evaluator, data_generator, pool, 1 * MILLION, 16 * THOUSAND, state);
+  ASSERT_TRUE(status.ok());
+}
+
 static void DoDecimalAdd3(benchmark::State& state, int32_t precision, int32_t scale,
                           bool large = false) {
   // schema for input fields
@@ -398,6 +422,7 @@ BENCHMARK(TimedTestFilterLike)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(TimedTestAllocs)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(TimedTestMultiOr)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(TimedTestInExpr)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
+BENCHMARK(TimedTestToDate)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(DecimalAdd2Fast)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(DecimalAdd2LeadingZeroes)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(DecimalAdd2LeadingZeroesWithDiv)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
@@ -406,5 +431,4 @@ BENCHMARK(DecimalAdd3Fast)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(DecimalAdd3LeadingZeroes)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(DecimalAdd3LeadingZeroesWithDiv)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
 BENCHMARK(DecimalAdd3Large)->MinTime(1.0)->Unit(benchmark::kMicrosecond);
-
 }  // namespace gandiva

cpp/src/gandiva/to_date_holder.cc

@@ -84,7 +84,7 @@ int64_t ToDateHolder::operator()(ExecutionContext* context, const std::string& d
   // 2. does not process time in format +08:00 (or) id.
   int64_t seconds_since_epoch = 0;
   if (!::arrow::internal::ParseTimestampStrptime(
-          data.c_str(), data.length(), pattern_.c_str(),
+          data.c_str(), pattern_.c_str(),
           /*ignore_time_in_day=*/true, /*allow_trailing_chars=*/true,
           ::arrow::TimeUnit::SECOND, &seconds_since_epoch)) {
     return_error(context, data);