[dart:io] Adds ProcessInfo.{max,current}Rss. Adds OS::MaxRSS on Fuchsia.

sdk/lib/io/process.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 // TODO(ager): The only reason for this class is that we
 // cannot patch a top-level at this point.
 class _ProcessUtils {
   external static void _exit(int status);
@@ skipping 82 matching lines @@
   }
   _ProcessUtils._sleep(milliseconds);
 }
 
 /**
  * Returns the PID of the current process.
  */
 int get pid => _ProcessUtils._pid(null);
 
 /**
+ * [ProcessInfo] provides methods for retrieving information about the
+ * current process.
+ */
+class ProcessInfo {
+  /**
+   * The current resident set size of memory for the process.
+   *
+   * Note that the meaning of this field is platform dependent. For example,
+   * some memory acounted for here may be shared with other processes, or if
+   * the same page is mapped into a process's address space, it may be counted
+   * twice.
+   */
+  external static int get currentRss;
+
+  /**
+   * The high-watermark in bytes for the resident set size of memory for the
+   * process.
+   *
+   * Note that the meaning of this field is platform dependent. For example,
+   * some memory acounted for here may be shared with other processes, or if
+   * the same page is mapped into a process's address space, it may be counted
+   * twice.
+   */
+  external static int get maxRss;
+}
+
+/**
  * Modes for running a new process.
  */
 enum ProcessStartMode {
   /// Normal child process.
   NORMAL,
 
   /// Detached child process with no open communication channel.
   DETACHED,
 
   /// Detached child process with stdin, stdout and stderr still open
@@ skipping 453 matching lines @@
   final int errorCode;
 
   const ProcessException(this.executable, this.arguments,
       [this.message = "", this.errorCode = 0]);
   String toString() {
     var msg = (message == null) ? 'OS error code: $errorCode' : message;
     var args = arguments.join(' ');
     return "ProcessException: $msg\n  Command: $executable $args";
   }
 }