Auto merge of #46 - servo:je2, r=SimonSapin

Fix linking on Rust versions that unprefix jemalloc

Fixes #43, fixes #44.

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Author: bors-servo

.travis.yml

@@ -1,5 +1,13 @@
 language: rust
-rust: nightly
+rust:
+ # Jemalloc prefixing change between these two versions
+ - nightly-2016-02-14
+ - nightly-2016-02-17
+
+ - nightly
+ - beta
+ - stable
+
 notifications:
   webhooks: http://build.servo.org:54856/travis
 

Cargo.toml

@@ -5,6 +5,10 @@ authors = [ "The Servo Project Developers" ]
 description = "Infrastructure for measuring the total runtime size of an object on the heap"
 license = "MPL-2.0"
 repository = "https://github.com/servo/heapsize"
+build = "build.rs"
+
+[build-dependencies]
+regex = "0.1"
 
 [features]
 unstable = []

build.rs

@@ -0,0 +1,26 @@
+extern crate regex;
+
+use std::env::var;
+use std::process::Command;
+use std::str;
+
+fn main() {
+    let version_line = Command::new(var("RUSTC").unwrap_or("rustc".into()))
+        .arg("--version")
+        .output()
+        .unwrap()
+        .stdout;
+    let captures = regex::Regex::new(r"rustc (\d+)\.(\d+)\.(\d+).+(\d{4}-\d{2}-\d{2})\)")
+        .unwrap()
+        .captures(str::from_utf8(&version_line).unwrap())
+        .unwrap();
+    let version = (
+        captures[1].parse::<u32>().unwrap(),
+        captures[2].parse::<u32>().unwrap(),
+        captures[3].parse::<u32>().unwrap(),
+        &captures[4],
+    );
+    if version < (1, 8, 0, "2016-02-14") {
+        println!("cargo:rustc-cfg=prefixed_jemalloc");
+    }
+}

src/lib.rs

@@ -20,6 +20,7 @@ use std::rc::Rc;
 
 #[cfg(not(target_os = "windows"))]
 extern {
+    #[cfg_attr(any(prefixed_jemalloc, target_os = "macos", target_os = "android"), link_name = "je_malloc_usable_size")]
     // Get the size of a heap block.
     //
     // Ideally Rust would expose a function like this in std::rt::heap, which would avoid the
@@ -29,7 +30,7 @@ extern {
     // platforms `JEMALLOC_USABLE_SIZE_CONST` is `const` and on some it is empty. But in practice
     // this function doesn't modify the contents of the block that `ptr` points to, so we use
     // `*const c_void` here.
-    fn je_malloc_usable_size(ptr: *const c_void) -> usize;
+    fn malloc_usable_size(ptr: *const c_void) -> usize;
 }
 
 /// A wrapper for je_malloc_usable_size that handles `EMPTY` and returns `usize`.
@@ -42,7 +43,7 @@ pub unsafe fn heap_size_of(ptr: *const c_void) -> usize {
     if ptr == 0x01 as *const c_void {
         0
     } else {
-        je_malloc_usable_size(ptr)
+        malloc_usable_size(ptr)
     }
 }