Mapping PG interval type

pgx-tests/src/tests/datetime_tests.rs

@@ -100,6 +100,17 @@ fn timestamptz_to_i64(tstz: pg_sys::TimestampTz) -> i64 {
     tstz
 }
 
+#[pg_extern]
+fn accept_interval(interval: Interval) -> Interval {
+    interval
+}
+
+#[pg_extern]
+fn accept_interval_round_trip(interval: Interval) -> Interval {
+    let duration: time::Duration = interval.into();
+    duration.try_into().expect("Error converting Duration to PgInterval")
+}
+
 #[cfg(any(test, feature = "pg_test"))]
 #[pgx::pg_schema]
 mod tests {
@@ -442,4 +453,63 @@ mod tests {
         assert!(ts.is_neg_infinity());
         Ok(())
     }
+
+    #[pg_test]
+    fn test_accept_interval_random() {
+        let result = Spi::get_one::<bool>("SELECT accept_interval(interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds') = interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds';")
+            .expect("failed to get SPI result");
+        assert_eq!(result, Some(true));
+    }
+
+    #[pg_test]
+    fn test_accept_interval_neg_random() {
+        let result = Spi::get_one::<bool>("SELECT accept_interval(interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds ago') = interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds ago';")
+            .expect("failed to get SPI result");
+        assert_eq!(result, Some(true));
+    }
+
+    #[pg_test]
+    fn test_accept_interval_round_trip_random() {
+        let result = Spi::get_one::<bool>("SELECT accept_interval_round_trip(interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds') = interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds';")
+            .expect("failed to get SPI result");
+        assert_eq!(result, Some(true));
+    }
+
+    #[pg_test]
+    fn test_accept_interval_round_trip_neg_random() {
+        let result = Spi::get_one::<bool>("SELECT accept_interval_round_trip(interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds ago') = interval'1 year 2 months 3 days 4 hours 5 minutes 6 seconds ago';")
+            .expect("failed to get SPI result");
+        assert_eq!(result, Some(true));
+    }
+
+    #[pg_test]
+    fn test_interval_serialization() {
+        let interval = Interval::try_from_months_days_usecs(3, 4, 5_000_000).unwrap();
+        let json = json!({ "interval test": interval });
+
+        assert_eq!(json!({"interval test":"3 mons 4 days 00:00:05"}), json);
+    }
+
+    #[pg_test]
+    fn test_duration_to_interval_err() {
+        use pgx::IntervalConversionError;
+        // normal limit of i32::MAX months
+        let duration = time::Duration::days(pg_sys::DAYS_PER_MONTH as i64 * i32::MAX as i64);
+
+        let result = TryInto::<Interval>::try_into(duration);
+        match result {
+            Ok(_) => (),
+            _ => panic!("failed duration -> interval conversion"),
+        };
+
+        // one month too many, expect error
+        let duration =
+            time::Duration::days(pg_sys::DAYS_PER_MONTH as i64 * (i32::MAX as i64 + 1i64));
+
+        let result = TryInto::<Interval>::try_into(duration);
+        match result {
+            Err(IntervalConversionError::DurationMonthsOutOfBounds) => (),
+            _ => panic!("invalid duration -> interval conversion succeeded"),
+        };
+    }
 }

pgx/src/datum/interval.rs

@@ -0,0 +1,189 @@
+/*
+Portions Copyright 2019-2021 ZomboDB, LLC.
+Portions Copyright 2021-2022 Technology Concepts & Design, Inc. <[email protected]>
+
+All rights reserved.
+
+Use of this source code is governed by the MIT license that can be found in the LICENSE file.
+*/
+
+use std::ops::{Mul, Sub};
+use std::ptr::NonNull;
+
+use crate::datum::time::USECS_PER_SEC;
+use crate::{direct_function_call, pg_sys, FromDatum, IntoDatum, PgBox};
+use pg_sys::{DAYS_PER_MONTH, SECS_PER_DAY};
+use pgx_sql_entity_graph::metadata::{
+    ArgumentError, Returns, ReturnsError, SqlMapping, SqlTranslatable,
+};
+
+#[cfg(feature = "time-crate")]
+const MONTH_DURATION: time::Duration = time::Duration::days(DAYS_PER_MONTH as i64);
+
+/// From the PG docs  https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-INTERVAL-INPUT
+/// Internally interval values are stored as months, days, and microseconds. This is done because the number of days in a month varies,
+/// and a day can have 23 or 25hours if a daylight savings time adjustment is involved. The months and days fields are integers while
+/// the microseconds field can store fractional seconds. Because intervals are usually created from constant strings or timestamp
+/// subtraction, this storage method works well in most cases...
+#[derive(Debug)]
+#[repr(transparent)]
+pub struct Interval(NonNull<pg_sys::Interval>);
+
+impl Interval {
+    /// This function takes `months`/`days`/`usecs` as input to convert directly to the internal PG storage struct `pg_sys::Interval`
+    /// - the sign of all units must be all matching in the positive or all matching in the negative direction
+    pub fn try_from_months_days_usecs(
+        months: i32,
+        days: i32,
+        usecs: i64,
+    ) -> Result<Self, IntervalConversionError> {
+        // SAFETY: `pg_sys::Interval` will be uninitialized, set all fields
+        let mut interval = unsafe { PgBox::<pg_sys::Interval>::alloc() };
+        interval.day = days;
+        interval.month = months;
+        interval.time = usecs;
+        let ptr = interval.into_pg();
+        let non_null = NonNull::new(ptr).expect("pointer is null");
+        Ok(Interval::from_ptr(non_null))
+    }
+
+    pub fn from_ptr(ptr: NonNull<pg_sys::Interval>) -> Self {
+        Interval(ptr)
+    }
+
+    pub fn as_ptr(&self) -> NonNull<pg_sys::Interval> {
+        self.0
+    }
+
+    /// Total number of months before/after 2000-01-01
+    pub fn months(&self) -> i32 {
+        // SAFETY: Validity asserted on construction
+        unsafe { (*self.0.as_ptr()).month }
+    }
+
+    /// Total number of days before/after the `months()` offset (sign must match `months`)
+    pub fn days(&self) -> i32 {
+        // SAFETY: Validity asserted on construction
+        unsafe { (*self.0.as_ptr()).day }
+    }
+
+    /// Total number of usecs before/after the `days()` offset (sign must match `months`/`days`)
+    pub fn usecs(&self) -> i64 {
+        // SAFETY: Validity asserted on construction
+        unsafe { (*self.0.as_ptr()).time }
+    }
+}
+
+impl FromDatum for Interval {
+    unsafe fn from_polymorphic_datum(
+        datum: pg_sys::Datum,
+        is_null: bool,
+        _typoid: pg_sys::Oid,
+    ) -> Option<Self>
+    where
+        Self: Sized,
+    {
+        if is_null {
+            None
+        } else {
+            let ptr = datum.cast_mut_ptr::<pg_sys::Interval>();
+            let non_null = NonNull::new(ptr).expect("ptr was null");
+            Some(Interval(non_null))
+        }
+    }
+}
+
+impl IntoDatum for Interval {
+    fn into_datum(self) -> Option<pg_sys::Datum> {
+        let interval = self.0.as_ptr();
+        Some(interval.into())
+    }
+    fn type_oid() -> pg_sys::Oid {
+        pg_sys::INTERVALOID
+    }
+}
+
+#[cfg(feature = "time-crate")]
+impl TryFrom<time::Duration> for Interval {
+    type Error = IntervalConversionError;
+    fn try_from(duration: time::Duration) -> Result<Interval, Self::Error> {
+        let total_months = duration.whole_days() / (pg_sys::DAYS_PER_MONTH as i64);
+
+        if total_months >= (i32::MIN as i64) && total_months <= (i32::MAX as i64) {
+            let mut month = 0;
+            let mut d = duration;
+
+            if time::Duration::abs(d) >= MONTH_DURATION {
+                month = total_months as i32;
+                d = d.sub(MONTH_DURATION.mul(month));
+            }
+
+            let time = d.whole_microseconds() as i64;
+
+            Interval::try_from_months_days_usecs(month, 0, time)
+        } else {
+            Err(IntervalConversionError::DurationMonthsOutOfBounds)
+        }
+    }
+}
+
+#[cfg(feature = "time-crate")]
+impl From<Interval> for time::Duration {
+    fn from(interval: Interval) -> time::Duration {
+        // SAFETY: Validity of interval's ptr asserted on construction
+        unsafe {
+            let interval = *interval.0.as_ptr(); // internal interval
+            let sec = interval.time / USECS_PER_SEC as i64;
+            let fsec = ((interval.time - (sec * USECS_PER_SEC as i64)) * 1000) as i32; // convert usec to nsec
+
+            let mut duration = time::Duration::new(sec, fsec);
+
+            if interval.month != 0 {
+                duration = duration.saturating_add(MONTH_DURATION.mul(interval.month));
+            }
+
+            if interval.day != 0 {
+                duration = duration.saturating_add(time::Duration::new(
+                    (interval.day * SECS_PER_DAY as i32) as i64,
+                    0,
+                ));
+            }
+
+            duration
+        }
+    }
+}
+
+impl serde::Serialize for Interval {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        unsafe {
+            // SAFETY: Validity of ptr asserted on construction
+            let interval = self.0.as_ptr();
+            let cstr = direct_function_call::<&std::ffi::CStr>(
+                pg_sys::interval_out,
+                vec![Some(pg_sys::Datum::from(interval as *const _))],
+            )
+            .expect("failed to convert interval to a cstring");
+
+            serializer.serialize_str(cstr.to_str().unwrap())
+        }
+    }
+}
+
+unsafe impl SqlTranslatable for Interval {
+    fn argument_sql() -> Result<SqlMapping, ArgumentError> {
+        Ok(SqlMapping::literal("interval"))
+    }
+    fn return_sql() -> Result<Returns, ReturnsError> {
+        Ok(Returns::One(SqlMapping::literal("interval")))
+    }
+}
+
+#[derive(thiserror::Error, Debug, Clone, Copy)]
+pub enum IntervalConversionError {
+    #[error("duration's total month count outside of valid i32::MIN..=i32::MAX range")]
+    DurationMonthsOutOfBounds,
+}

pgx/src/datum/mod.rs

@@ -17,6 +17,7 @@ mod from;
 mod geo;
 mod inet;
 mod internal;
+mod interval;
 mod into;
 mod item_pointer_data;
 mod json;
@@ -42,6 +43,7 @@ pub use from::*;
 pub use geo::*;
 pub use inet::*;
 pub use internal::*;
+pub use interval::*;
 pub use into::*;
 pub use item_pointer_data::*;
 pub use json::*;

pgx/src/prelude.rs

@@ -17,9 +17,10 @@ pub use crate::pgbox::{AllocatedByPostgres, AllocatedByRust, PgBox, WhoAllocated
 
 // These could be factored into a temporal type module that could be easily imported for code which works with them.
 // However, reexporting them seems fine for now.
+
 pub use crate::datum::{
-    AnyNumeric, Array, Date, FromDatum, IntoDatum, Numeric, PgVarlena, PostgresType, Range,
-    RangeData, RangeSubType, Time, TimeWithTimeZone, Timestamp, TimestampWithTimeZone,
+    AnyNumeric, Array, Date, FromDatum, Interval, IntoDatum, Numeric, PgVarlena, PostgresType,
+    Range, RangeData, RangeSubType, Time, TimeWithTimeZone, Timestamp, TimestampWithTimeZone,
     VariadicArray,
 };
 pub use crate::inoutfuncs::{InOutFuncs, JsonInOutFuncs, PgVarlenaInOutFuncs};