CDRIVER-3775 structured log: floating point durations (#1831)

* Add double() structured log item
* Modify monotonic_time_duration() structured log item to use double-precision floating point milliseconds, instead of two integers

See also DRIVERS-3089

Author: mdbmes

src/libmongoc/src/mongoc/mongoc-structured-log-private.h

@@ -172,6 +172,16 @@ mongoc_structured_log_instance_destroy (mongoc_structured_log_instance_t *instan
 #define _mongoc_structured_log_item_int64(_key_or_null, _value_int64) \
    {.func = _mongoc_structured_log_append_int64, .arg1.utf8 = (_key_or_null), .arg2.int64 = (_value_int64)},
 
+/**
+ * @def double(key, value)
+ * @brief Structured log item, double precision floating point
+ *
+ * @param key Key as a NUL-terminated const char * expression, or NULL to skip this item.
+ * @param value Value as a double expression.
+ */
+#define _mongoc_structured_log_item_double(_key_or_null, _value_double) \
+   {.func = _mongoc_structured_log_append_double, .arg1.utf8 = (_key_or_null), .arg2.double_value = (_value_double)},
+
 /**
  * @def boolean(key, value)
  * @brief Structured log item, boolean
@@ -337,12 +347,9 @@ typedef enum {
  * @def monotonic_time_duration(duration)
  * @brief Structured log item, standard format for a duration in monotonic time.
  * @param duration Duration in microseconds, as an int64_t expression.
- *
- * Includes milliseconds for consistency across drivers, and microseconds as the highest available resolution.
  */
-#define _mongoc_structured_log_item_monotonic_time_duration(_duration)              \
-   _mongoc_structured_log_item_int32 ("durationMS", (int32_t) ((_duration) / 1000)) \
-      _mongoc_structured_log_item_int64 ("durationMicros", (_duration))
+#define _mongoc_structured_log_item_monotonic_time_duration(_duration) \
+   _mongoc_structured_log_item_double ("durationMS", (_duration) * 1e-3)
 
 typedef struct mongoc_structured_log_builder_stage_t mongoc_structured_log_builder_stage_t;
 
@@ -371,6 +378,7 @@ struct mongoc_structured_log_builder_stage_t {
       const char *utf8;
       const mongoc_read_prefs_t *read_prefs;
       const struct _mongoc_topology_t *topology;
+      double double_value;
       int32_t int32;
       int64_t int64;
       mongoc_error_content_flags_t error_flags;
@@ -428,6 +436,11 @@ _mongoc_structured_log_append_int64 (bson_t *bson,
                                      const mongoc_structured_log_builder_stage_t *stage,
                                      const mongoc_structured_log_opts_t *opts);
 
+const mongoc_structured_log_builder_stage_t *
+_mongoc_structured_log_append_double (bson_t *bson,
+                                      const mongoc_structured_log_builder_stage_t *stage,
+                                      const mongoc_structured_log_opts_t *opts);
+
 const mongoc_structured_log_builder_stage_t *
 _mongoc_structured_log_append_boolean (bson_t *bson,
                                        const mongoc_structured_log_builder_stage_t *stage,

src/libmongoc/src/mongoc/mongoc-structured-log.c

@@ -716,6 +716,19 @@ _mongoc_structured_log_append_int64 (bson_t *bson,
    return stage + 1;
 }
 
+const mongoc_structured_log_builder_stage_t *
+_mongoc_structured_log_append_double (bson_t *bson,
+                                      const mongoc_structured_log_builder_stage_t *stage,
+                                      const mongoc_structured_log_opts_t *opts)
+{
+   BSON_UNUSED (opts);
+   const char *key_or_null = stage->arg1.utf8;
+   if (key_or_null) {
+      bson_append_double (bson, key_or_null, -1, stage->arg2.double_value);
+   }
+   return stage + 1;
+}
+
 const mongoc_structured_log_builder_stage_t *
 _mongoc_structured_log_append_boolean (bson_t *bson,
                                        const mongoc_structured_log_builder_stage_t *stage,

src/libmongoc/tests/test-mongoc-structured-log.c

@@ -221,6 +221,8 @@ test_structured_log_basic_data_types (void)
                                  BCON_INT32 (-12345),
                                  "kInt64",
                                  BCON_INT64 (0x76543210aabbccdd),
+                                 "kDouble",
+                                 BCON_DOUBLE (3.14159265358979323846),
                                  "kTrue",
                                  BCON_BOOL (true),
                                  "kFalse",
@@ -253,6 +255,8 @@ test_structured_log_basic_data_types (void)
                           int32 (NULL, 9999),
                           int64 ("kInt64", 0x76543210aabbccdd),
                           int64 (NULL, -1),
+                          double ("kDouble", 3.14159265358979323846),
+                          double (NULL, 1),
                           boolean ("kTrue", true),
                           boolean ("kFalse", false),
                           boolean (NULL, true));
@@ -626,17 +630,11 @@ test_structured_log_duration (void)
       .expected_bson = BCON_NEW ("message",
                                  BCON_UTF8 ("Log entry with duration"),
                                  "durationMS",
-                                 BCON_INT32 (1),
-                                 "durationMicros",
-                                 BCON_INT64 (1999),
+                                 BCON_DOUBLE (1.999),
                                  "durationMS",
-                                 BCON_INT32 (0),
-                                 "durationMicros",
-                                 BCON_INT64 (10),
+                                 BCON_DOUBLE (0.01),
                                  "durationMS",
-                                 BCON_INT32 (10000000),
-                                 "durationMicros",
-                                 BCON_INT64 (10000000999)),
+                                 BCON_DOUBLE (10000000.999)),
       .expected_calls = 1,
    };