From 45c10db41f2af5919621ff69f5dc090cc917c1d3 Mon Sep 17 00:00:00 2001
From: bcoopers <coopersmithbrian@gmail.com>
Date: Sun, 29 Mar 2015 19:08:53 -0400
Subject: [PATCH 1/4] Clarified and simplified algorithm for increasing size of
 buffer in read_to_end()

---
 src/libstd/io/mod.rs | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 830a88bb6c95b..3de9a06892627 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -101,15 +101,14 @@ fn append_to_string<F>(buf: &mut String, f: F) -> Result<usize>
 fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize> {
     let start_len = buf.len();
     let mut len = start_len;
-    let mut cap_bump = 16;
+    let min_cap_bump = 16;
     let ret;
     loop {
         if len == buf.len() {
             if buf.capacity() == buf.len() {
-                if cap_bump < DEFAULT_BUF_SIZE {
-                    cap_bump *= 2;
-                }
-                buf.reserve(cap_bump);
+                // reserve() rounds up our request to the nearest power of two, so after the first
+                // time the capacity is exceeded, we double our capacity at each call to reserve. 
+                buf.reserve(min_cap_bump);
             }
             let new_area = buf.capacity() - buf.len();
             buf.extend(iter::repeat(0).take(new_area));

From 2982fe39ad93e29709a2e1414a4228718c8de28a Mon Sep 17 00:00:00 2001
From: bcoopers <coopersmithbrian@gmail.com>
Date: Sun, 29 Mar 2015 19:23:46 -0400
Subject: [PATCH 2/4] 80 character line limit

---
 src/libstd/io/mod.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 3de9a06892627..bc3791b99d07a 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -106,8 +106,9 @@ fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize>
     loop {
         if len == buf.len() {
             if buf.capacity() == buf.len() {
-                // reserve() rounds up our request to the nearest power of two, so after the first
-                // time the capacity is exceeded, we double our capacity at each call to reserve. 
+                // reserve() rounds up our request to the nearest power of two,
+                // so after the first time the capacity is exceeded, we double
+                // our capacity at each call to reserve. 
                 buf.reserve(min_cap_bump);
             }
             let new_area = buf.capacity() - buf.len();

From 8d3e55908ae0e51f04c170133c9f9739886b8e2e Mon Sep 17 00:00:00 2001
From: bcoopers <coopersmithbrian@gmail.com>
Date: Sun, 29 Mar 2015 19:29:11 -0400
Subject: [PATCH 3/4] Clearer wording

---
 src/libstd/io/mod.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index bc3791b99d07a..c4ec2a7ca17f9 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -106,9 +106,9 @@ fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize>
     loop {
         if len == buf.len() {
             if buf.capacity() == buf.len() {
-                // reserve() rounds up our request to the nearest power of two,
-                // so after the first time the capacity is exceeded, we double
-                // our capacity at each call to reserve. 
+                // reserve() rounds up our request such that every request
+                // (with maybe the exception of the first request) for the
+                // same amount of space doubles our capacity.
                 buf.reserve(min_cap_bump);
             }
             let new_area = buf.capacity() - buf.len();

From 240734c31e529557583a0dc8e97abf858b4a375d Mon Sep 17 00:00:00 2001
From: bcoopers <coopersmithbrian@gmail.com>
Date: Mon, 30 Mar 2015 13:59:32 -0400
Subject: [PATCH 4/4] Only zero at most 64k at a time.  We still use the
 doubling reallocation strategy since extend() calls reserve() and/or push()
 for us.

---
 src/libstd/io/mod.rs | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index c4ec2a7ca17f9..6b03fb45c779d 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -101,18 +101,14 @@ fn append_to_string<F>(buf: &mut String, f: F) -> Result<usize>
 fn read_to_end<R: Read + ?Sized>(r: &mut R, buf: &mut Vec<u8>) -> Result<usize> {
     let start_len = buf.len();
     let mut len = start_len;
-    let min_cap_bump = 16;
+    let mut new_write_size = 16;
     let ret;
     loop {
         if len == buf.len() {
-            if buf.capacity() == buf.len() {
-                // reserve() rounds up our request such that every request
-                // (with maybe the exception of the first request) for the
-                // same amount of space doubles our capacity.
-                buf.reserve(min_cap_bump);
+            if new_write_size < DEFAULT_BUF_SIZE {
+                new_write_size *= 2;
             }
-            let new_area = buf.capacity() - buf.len();
-            buf.extend(iter::repeat(0).take(new_area));
+            buf.extend(iter::repeat(0).take(new_write_size));
         }
 
         match r.read(&mut buf[len..]) {