Use `mmap` to map in task stacks and guard page

Also implement caching of stacks.

1 files changed, 13 insertions, 2 deletions

diff --git a/src/libstd/rt/env.rs b/src/libstd/rt/env.rs
index f3fa482b18c..729e377e1af 100644
--- a/src/libstd/rt/env.rs
+++ b/src/libstd/rt/env.rs
@@ -10,7 +10,7 @@
 
 //! Runtime environment settings
 
-use from_str::FromStr;
+use from_str::from_str;
 use option::{Some, None};
 use os;
 
@@ -18,18 +18,25 @@ use os;
 // They are expected to be initialized once then left alone.
 
 static mut MIN_STACK: uint = 2 * 1024 * 1024;
+/// This default corresponds to 20M of cache per scheduler (at the default size).
+static mut MAX_CACHED_STACKS: uint = 10;
 static mut DEBUG_BORROW: bool = false;
 static mut POISON_ON_FREE: bool = false;
 
 pub fn init() {
     unsafe {
         match os::getenv("RUST_MIN_STACK") {
-            Some(s) => match FromStr::from_str(s) {
+            Some(s) => match from_str(s) {
                 Some(i) => MIN_STACK = i,
                 None => ()
             },
             None => ()
         }
+        match os::getenv("RUST_MAX_CACHED_STACKS") {
+            Some(max) => MAX_CACHED_STACKS = from_str(max).expect("expected positive integer in \
+                                                                   RUST_MAX_CACHED_STACKS"),
+            None => ()
+        }
         match os::getenv("RUST_DEBUG_BORROW") {
             Some(_) => DEBUG_BORROW = true,
             None => ()
@@ -45,6 +52,10 @@ pub fn min_stack() -> uint {
     unsafe { MIN_STACK }
 }
 
+pub fn max_cached_stacks() -> uint {
+    unsafe { MAX_CACHED_STACKS }
+}
+
 pub fn debug_borrow() -> bool {
     unsafe { DEBUG_BORROW }
 }