SERVER-65864 Parse $densify step as a NumberLong when using a date unit

(cherry picked from commit 8be84724601090e093d6d7ccfa4536a187c41edc)

3 files changed, 24 insertions, 6 deletions

diff --git a/jstests/aggregation/sources/densify/libs/parse_util.js b/jstests/aggregation/sources/densify/libs/parse_util.js
index 7ccedefd81d..d2e6ba4e489 100644
--- a/jstests/aggregation/sources/densify/libs/parse_util.js
+++ b/jstests/aggregation/sources/densify/libs/parse_util.js
@@ -139,6 +139,20 @@ let parseUtil = (function(db, coll, stageName, options = {}) {
             }),
             5733402,
             "a bounding array must be an ascending array of either two dates or two numbers");
+        // Non-whole number step with date bounds
+        assert.commandFailedWithCode(
+            run({
+                [stageName]: {
+                    field: "a",
+                    range: {
+                        step: 1.1,
+                        bounds: [new ISODate("2020-01-01"), new ISODate("2020-01-03")],
+                        unit: "second"
+                    }
+                }
+            }),
+            6586400,
+            "The step parameter in a range satement must be a whole number when densifying a date range");
 
         // Positive test cases
         assert.commandWorked(run({[stageName]: {field: "a", range: {step: 1.0, bounds: [1, 2]}}}));
diff --git a/src/mongo/db/pipeline/document_source_densify.cpp b/src/mongo/db/pipeline/document_source_densify.cpp
index 0325dbaa775..740ef193431 100644
--- a/src/mongo/db/pipeline/document_source_densify.cpp
+++ b/src/mongo/db/pipeline/document_source_densify.cpp
@@ -56,6 +56,10 @@ RangeStatement RangeStatement::parse(RangeSpec spec) {
 
     optional<TimeUnit> unit = [&]() {
         if (auto unit = spec.getUnit()) {
+            uassert(6586400,
+                    "The step parameter in a range statement must be a whole number when "
+                    "densifying a date range",
+                    step.integral64Bit());
             return optional<TimeUnit>(parseTimeUnit(unit.get()));
         } else {
             return optional<TimeUnit>(boost::none);
@@ -275,8 +279,8 @@ DocumentSourceInternalDensify::DocGenerator::DocGenerator(DensifyValue min,
         // Extra checks for date step + unit.
         tassert(5733501, "Unit must be specified with a date step", _range.getUnit());
         tassert(5733505,
-                "Step must be representable as an integer for date densification",
-                _range.getStep().integral());
+                "Step must be a whole number for date densification",
+                _range.getStep().integral64Bit());
     } else {
         tassert(5733506, "Unit must not be specified with non-date values", !_range.getUnit());
     }
@@ -877,7 +881,7 @@ DensifyValue DensifyValue::increment(const RangeStatement& range) const {
             },
             [&](Date_t date) {
                 return DensifyValue(dateAdd(
-                    date, range.getUnit().value(), range.getStep().getDouble(), timezone()));
+                    date, range.getUnit().value(), range.getStep().coerceToLong(), timezone()));
             }},
         _value);
 }
@@ -891,7 +895,7 @@ DensifyValue DensifyValue::decrement(const RangeStatement& range) const {
             },
             [&](Date_t date) {
                 return DensifyValue(dateAdd(
-                    date, range.getUnit().value(), -range.getStep().getDouble(), timezone()));
+                    date, range.getUnit().value(), -range.getStep().coerceToLong(), timezone()));
             }},
         _value);
 }
@@ -906,7 +910,7 @@ bool DensifyValue::isOnStepRelativeTo(DensifyValue base, RangeStatement range) c
             },
             [&](Date_t date) {
                 auto unit = range.getUnit().value();
-                double step = range.getStep().getDouble();
+                long long step = range.getStep().coerceToLong();
                 auto baseDate = base.getDate();
 
                 // Months, quarters and years have variable lengths depending on leap days
diff --git a/src/mongo/db/pipeline/document_source_densify_test.cpp b/src/mongo/db/pipeline/document_source_densify_test.cpp
index 79b16303eb9..c1a0218e9eb 100644
--- a/src/mongo/db/pipeline/document_source_densify_test.cpp
+++ b/src/mongo/db/pipeline/document_source_densify_test.cpp
@@ -374,7 +374,7 @@ DEATH_TEST(DensifyGeneratorTest, DateMinMustBeLessThanMax, "lower or equal to")
                        5733502);
 }
 
-DEATH_TEST(DensifyGeneratorTest, DateStepMustBeInt, "integer") {
+DEATH_TEST(DensifyGeneratorTest, DateStepMustBeInt, "whole number") {
     size_t counter = 0;
     ASSERT_THROWS_CODE(GenClass(makeDate("2021-01-01T00:00:00.000Z"),
                                 RangeStatement(Value(1.5),