From 3b05417246f4c01d1298049c054e22b431564b2c Mon Sep 17 00:00:00 2001
From: Charles Hall <charles@computer.surgery>
Date: Sat, 27 Apr 2024 16:08:50 -0700
Subject: [PATCH] handle the case where 0 or >1 allocs are enabled

In particular this fixes `cargo build --all-features`.
---
 src/alloc/default.rs  |  7 +++++++
 src/alloc/hardened.rs |  2 --
 src/alloc/je.rs       |  5 -----
 src/alloc/mod.rs      | 37 +++++++++++++++++++++----------------
 src/main.rs           |  2 +-
 5 files changed, 29 insertions(+), 24 deletions(-)
 create mode 100644 src/alloc/default.rs

diff --git a/src/alloc/default.rs b/src/alloc/default.rs
new file mode 100644
index 00000000..1d61682e
--- /dev/null
+++ b/src/alloc/default.rs
@@ -0,0 +1,7 @@
+//! Default allocator with no special features
+
+/// Always returns the empty string
+pub(crate) fn memory_stats() -> String { Default::default() }
+
+/// Always returns the empty string
+pub(crate) fn memory_usage() -> String { Default::default() }
diff --git a/src/alloc/hardened.rs b/src/alloc/hardened.rs
index 023cb487..9ac84f9a 100644
--- a/src/alloc/hardened.rs
+++ b/src/alloc/hardened.rs
@@ -1,5 +1,3 @@
-#![cfg(all(not(target_env = "msvc"), feature = "hardened_malloc", target_os = "linux", not(feature = "jemalloc")))]
-
 #[global_allocator]
 static HMALLOC: hardened_malloc_rs::HardenedMalloc = hardened_malloc_rs::HardenedMalloc;
 
diff --git a/src/alloc/je.rs b/src/alloc/je.rs
index db6a56cf..d17c4f0b 100644
--- a/src/alloc/je.rs
+++ b/src/alloc/je.rs
@@ -1,6 +1,3 @@
-#![cfg(all(not(target_env = "msvc"), feature = "jemalloc", not(feature = "hardened_malloc")))]
-#![allow(dead_code)]
-
 use std::ffi::{c_char, c_void};
 
 use tikv_jemalloc_ctl as mallctl;
@@ -10,8 +7,6 @@ use tikv_jemallocator as jemalloc;
 #[global_allocator]
 static JEMALLOC: jemalloc::Jemalloc = jemalloc::Jemalloc;
 
-pub(crate) fn version() -> &'static str { mallctl::version::read().expect("version string") }
-
 pub(crate) fn memory_usage() -> String {
 	use mallctl::stats;
 	let allocated = stats::allocated::read().unwrap_or_default() as f64 / 1024.0 / 1024.0;
diff --git a/src/alloc/mod.rs b/src/alloc/mod.rs
index 775fe8c2..6b7c89a1 100644
--- a/src/alloc/mod.rs
+++ b/src/alloc/mod.rs
@@ -1,20 +1,25 @@
-pub(crate) mod hardened;
-pub(crate) mod je;
-
-#[cfg(all(not(target_env = "msvc"), feature = "hardened_malloc", target_os = "linux", not(feature = "jemalloc")))]
-pub(crate) fn memory_usage() -> String { hardened::memory_usage() }
+//! Integration with allocators
 
+// jemalloc
 #[cfg(all(not(target_env = "msvc"), feature = "jemalloc", not(feature = "hardened_malloc")))]
-pub(crate) fn memory_usage() -> String { je::memory_usage() }
-
-#[cfg(any(target_env = "msvc", all(not(feature = "jemalloc"), not(feature = "hardened_malloc"))))]
-pub(crate) fn memory_usage() -> String { String::default() }
-
-#[cfg(all(not(target_env = "msvc"), feature = "hardened_malloc", target_os = "linux", not(feature = "jemalloc")))]
-pub(crate) fn memory_stats() -> String { hardened::memory_stats() }
-
+mod je;
 #[cfg(all(not(target_env = "msvc"), feature = "jemalloc", not(feature = "hardened_malloc")))]
-pub(crate) fn memory_stats() -> String { je::memory_stats() }
+pub(crate) use je::{memory_stats, memory_usage};
 
-#[cfg(any(target_env = "msvc", all(not(feature = "jemalloc"), not(feature = "hardened_malloc"))))]
-pub(crate) fn memory_stats() -> String { String::default() }
+// hardened_malloc
+#[cfg(all(not(target_env = "msvc"), feature = "hardened_malloc", target_os = "linux", not(feature = "jemalloc")))]
+mod hardened;
+#[cfg(all(not(target_env = "msvc"), feature = "hardened_malloc", target_os = "linux", not(feature = "jemalloc")))]
+pub(crate) use hardened::{memory_stats, memory_usage};
+
+// default, enabled when none or multiple of the above are enabled
+#[cfg(any(
+	not(any(feature = "jemalloc", feature = "hardened_malloc")),
+	all(feature = "jemalloc", feature = "hardened_malloc"),
+))]
+mod default;
+#[cfg(any(
+	not(any(feature = "jemalloc", feature = "hardened_malloc")),
+	all(feature = "jemalloc", feature = "hardened_malloc"),
+))]
+pub(crate) use default::{memory_stats, memory_usage};
diff --git a/src/main.rs b/src/main.rs
index 3bf77fa1..f5da0f40 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -49,7 +49,7 @@ use utils::{
 	error::{Error, Result},
 };
 
-mod alloc;
+pub(crate) mod alloc;
 mod api;
 mod config;
 mod database;