start rand utils suite

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/mod.rs

@@ -6,6 +6,7 @@ pub mod hash;
 pub mod html;
 pub mod json;
 pub mod mutex_map;
+pub mod rand;
 pub mod string;
 pub mod sys;
 mod tests;
@@ -19,7 +20,8 @@ pub use hash::calculate_hash;
 pub use html::Escape as HtmlEscape;
 pub use json::{deserialize_from_str, to_canonical_object};
 pub use mutex_map::MutexMap;
-pub use string::{random_string, str_from_bytes, string_from_bytes};
+pub use rand::string as random_string;
+pub use string::{str_from_bytes, string_from_bytes};
 pub use sys::available_parallelism;
 pub use time::millis_since_unix_epoch;
 
@@ -41,7 +43,7 @@ pub fn unwrap_infallible<T>(result: Result<T, std::convert::Infallible>) -> T {
 
 #[must_use]
 pub fn generate_keypair() -> Vec<u8> {
-	let mut value = random_string(8).as_bytes().to_vec();
+	let mut value = rand::string(8).as_bytes().to_vec();
 	value.push(0xFF);
 	value.extend_from_slice(
 		&ruma::signatures::Ed25519KeyPair::generate().expect("Ed25519KeyPair generation always works (?)"),

src/core/utils/rand.rs

@@ -0,0 +1,24 @@
+use std::{
+	ops::Range,
+	time::{Duration, SystemTime},
+};
+
+use rand::{thread_rng, Rng};
+
+pub fn string(length: usize) -> String {
+	thread_rng()
+		.sample_iter(&rand::distributions::Alphanumeric)
+		.take(length)
+		.map(char::from)
+		.collect()
+}
+
+#[inline]
+#[must_use]
+pub fn timepoint_secs(range: Range<u64>) -> SystemTime { SystemTime::now() + secs(range) }
+
+#[must_use]
+pub fn secs(range: Range<u64>) -> Duration {
+	let mut rng = thread_rng();
+	Duration::from_secs(rng.gen_range(range))
+}

src/core/utils/string.rs

@@ -1,15 +1,5 @@
-use rand::prelude::*;
-
 use crate::Result;
 
-pub fn random_string(length: usize) -> String {
-	thread_rng()
-		.sample_iter(&rand::distributions::Alphanumeric)
-		.take(length)
-		.map(char::from)
-		.collect()
-}
-
 /// Parses the bytes into a string.
 #[inline]
 pub fn string_from_bytes(bytes: &[u8]) -> Result<String> {