tor-memquota: moved auto calc into separate function (9fcfda8f) · Commits · Moumen Alaoui / Arti

crates/tor-memquota/src/config.rs

+112 −49

Original line number	Diff line number	Diff line
		@@ -169,18 +169,56 @@ impl ConfigBuilder {
		// but we have no way of knowing whether we are a relay or not here.
		let max = match max {
		ExplicitOrAuto::Explicit(x) => x,
		ExplicitOrAuto::Auto => 'auto: {
		ExplicitOrAuto::Auto => compute_max_from_total_system_mem(total_available_memory()),
		};

		let low_water = match low_water {
		ExplicitOrAuto::Explicit(x) => x,
		ExplicitOrAuto::Auto => Qty((max as f32 0.75) as _),
		};

		let config = ConfigInner { max, low_water };

		/// Minimum low water. `const` so that overflows are compile-time.
		const MIN_LOW_WATER: usize = crate::mtracker::MAX_CACHE.as_usize() * MIN_MAX_PARTICIPANTS;
		let min_low_water = MIN_LOW_WATER;
		if *config.low_water < min_low_water {
		return Err(ConfigBuildError::Invalid {
		field: "low_water".into(),
		problem: format!("must be at least {min_low_water}"),
		});
		}

		let ratio: f32 = config.low_water as f32 / config.max as f32;
		if ratio > MAX_LOW_WATER_RATIO {
		return Err(ConfigBuildError::Inconsistent {
		fields: vec!["low_water".into(), "max".into()],
		problem: format!(
		"low_water / max = {ratio}; must be <= {MAX_LOW_WATER_RATIO}, ideally considerably lower"
		),
		});
		}

		Ok(Config(IfEnabled::Enabled(config, enabled)))
		}
		}

		/// Determine a max given the system's total available memory.
		///
		/// This is used when `max` is configured as "auto".
		/// It takes a `Result` so that we can handle the case where the total memory isn't available.
		fn compute_max_from_total_system_mem(mem: Result<usize, MemQueryError>) -> Qty {
		const MIB: usize = 1024 * 1024;
		const GIB: usize = 1024 * 1024 * 1024;

		let mem = match total_available_memory() {
		let mem = match mem {
		Ok(x) => x,
		Err(e) => {
		warn!("Unable to get the total available memory. Using a constant max instead: {e}");

		// Can't get the total available memory,
		// so we return a max depending on whether the architecture is 32-bit or 64-bit.
		break 'auto Qty({
		return Qty({
		cfg_if::cfg_if! {
		if #[cfg(target_pointer_width = "64")] {
		8 * GIB
		@@ -218,38 +256,6 @@ impl ConfigBuilder {

		Qty(mem)
		}
		};

		let low_water = match low_water {
		ExplicitOrAuto::Explicit(x) => x,
		ExplicitOrAuto::Auto => Qty((max as f32 0.75) as _),
		};

		let config = ConfigInner { max, low_water };

		/// Minimum low water. `const` so that overflows are compile-time.
		const MIN_LOW_WATER: usize = crate::mtracker::MAX_CACHE.as_usize() * MIN_MAX_PARTICIPANTS;
		let min_low_water = MIN_LOW_WATER;
		if *config.low_water < min_low_water {
		return Err(ConfigBuildError::Invalid {
		field: "low_water".into(),
		problem: format!("must be at least {min_low_water}"),
		});
		}

		let ratio: f32 = config.low_water as f32 / config.max as f32;
		if ratio > MAX_LOW_WATER_RATIO {
		return Err(ConfigBuildError::Inconsistent {
		fields: vec!["low_water".into(), "max".into()],
		problem: format!(
		"low_water / max = {ratio}; must be <= {MAX_LOW_WATER_RATIO}, ideally considerably lower"
		),
		});
		}

		Ok(Config(IfEnabled::Enabled(config, enabled)))
		}
		}

		/// The total available memory in bytes.
		///
		@@ -443,4 +449,61 @@ mod test {
		b.build().unwrap();
		}
		}

		/// Test the logic that computes the `max` when configured as "auto".
		#[test]
		// We do some `1 * X` operations below for readability.
		#[allow(clippy::identity_op)]
		fn auto_max() {
		#[allow(unused)]
		fn check_helper(val: Qty, expected_32: Qty, expected_64: Qty) {
		assert_eq!(val, {
		cfg_if::cfg_if! {
		if #[cfg(target_pointer_width = "64")] {
		expected_64
		} else if #[cfg(target_pointer_width = "32")] {
		expected_32
		} else {
		panic!("Unsupported architecture :(");
		}
		}
		});
		}

		check_helper(
		compute_max_from_total_system_mem(Err(MemQueryError::Unavailable)),
		/* 32-bit / Qty(1 1024 * 1024 * 1024),
		/* 64-bit / Qty(8 1024 * 1024 * 1024),
		);
		check_helper(
		compute_max_from_total_system_mem(Ok(8 * 1024 * 1024 * 1024)),
		/* 32-bit / Qty(2 1024 * 1024 * 1024),
		/* 64-bit */ Qty(3435973836),
		);
		check_helper(
		compute_max_from_total_system_mem(Ok(7 * 1024 * 1024 * 1024)),
		/* 32-bit / Qty(2 1024 * 1024 * 1024),
		/* 64-bit */ Qty(5637144576),
		);
		check_helper(
		compute_max_from_total_system_mem(Ok(1 * 1024 * 1024 * 1024)),
		/* 32-bit */ Qty(805306368),
		/* 64-bit */ Qty(805306368),
		);
		check_helper(
		compute_max_from_total_system_mem(Ok(7 * 1024)),
		/* 32-bit / Qty(256 1024 * 1024),
		/* 64-bit / Qty(256 1024 * 1024),
		);
		check_helper(
		compute_max_from_total_system_mem(Ok(0)),
		/* 32-bit / Qty(256 1024 * 1024),
		/* 64-bit / Qty(256 1024 * 1024),
		);
		check_helper(
		compute_max_from_total_system_mem(Ok(usize::MAX)),
		/* 32-bit / Qty(2 1024 * 1024 * 1024),
		/* 64-bit / Qty(8 1024 * 1024 * 1024),
		);
		}
		}