Optimise HAMT inner representation to use Box instead of Vec

imhamt/Cargo.toml

@@ -11,7 +11,15 @@ license = "MIT OR Apache-2.0"
 quickcheck = "0.8"
 quickcheck_macros = "0.8"
 
+[target.'cfg(unix)'.dev-dependencies]
+jemalloc-ctl = "*"
+jemallocator = "*"
+
 [features]
 default = []
 with-bench = []
 optimized-node = []
+
+[[example]]
+name = "memdump"
+path = "examples/memdump/main.rs"

imhamt/examples/memdump/main.rs

@@ -0,0 +1,14 @@
+#[cfg(unix)]
+mod unix;
+
+#[cfg(unix)]
+use unix::run;
+
+#[cfg(not(unix))]
+fn run() {
+    println!("example not supported on this platform")
+}
+
+fn main() {
+    run()
+}

imhamt/examples/memdump/unix.rs

@@ -0,0 +1,51 @@
+extern crate imhamt;
+extern crate jemalloc_ctl;
+extern crate jemallocator;
+
+use jemalloc_ctl::{epoch, stats};
+use std::collections::hash_map::DefaultHasher;
+use std::thread;
+use std::time::Duration;
+
+#[global_allocator]
+static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
+
+use imhamt::Hamt;
+
+fn statprint() {
+    let allocated = stats::allocated::read().unwrap();
+    let resident = stats::resident::read().unwrap();
+    println!("{} bytes allocated/{} bytes resident", allocated, resident);
+}
+
+pub fn run() {
+    let mut h: Hamt<DefaultHasher, u32, u32> = Hamt::new();
+
+    println!("adding 100000 entries");
+
+    for i in 0..100000 {
+        h = h.insert(i, i).unwrap();
+    }
+
+    let mut h2 = h.clone();
+
+    epoch::advance().unwrap();
+
+    statprint();
+    thread::sleep(Duration::from_secs(10));
+
+    println!("adding 100000 entries");
+
+    for i in 100000..200000 {
+        h2 = h2.insert(i, i).unwrap();
+    }
+
+    epoch::advance().unwrap();
+
+    statprint();
+    thread::sleep(Duration::from_secs(10));
+
+    epoch::advance().unwrap();
+
+    statprint();
+}

imhamt/src/bitmap.rs

@@ -80,7 +80,7 @@ impl SmallBitmap {
 
     #[inline]
     /// Create a new bitmap with 1 element set
-    pub fn once(b: LevelIndex) -> Self {
+    pub const fn once(b: LevelIndex) -> Self {
         SmallBitmap(b.mask())
     }