Speedup OpamSystem.read

Author: kit-ty-kate

src/core/opamSystem.ml

@@ -216,20 +216,18 @@ let remove_file file =
       internal_error "Cannot remove %s (%s)." file (Printexc.to_string e)
   )
 
-let string_of_channel ic =
-  let n = 32768 in
-  let s = Bytes.create n in
-  let b = Buffer.create 1024 in
-  let rec iter ic b s =
-    let nread =
-      try input ic s 0 n
-      with End_of_file -> 0 in
-    if nread > 0 then (
-      Buffer.add_subbytes b s 0 nread;
-      iter ic b s
-    ) in
-  iter ic b s;
-  Buffer.contents b
+let string_of_channel =
+  let n = 4096 in
+  let b = Buffer.create n in
+  let rec iter ic b =
+    match Buffer.add_channel b ic n with
+    | () -> iter ic b
+    | exception End_of_file -> ()
+  in
+  fun ic ->
+    Buffer.clear b;
+    iter ic b;
+    Buffer.contents b
 
 let read file =
   let ic =