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

runtime/bin/process_fuchsia.cc

 // Copyright (c) 2016, 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.
 
 #if !defined(DART_IO_DISABLED)
 
 #include "platform/globals.h"
 #if defined(HOST_OS_FUCHSIA)
 
 #include "bin/process.h"
@@ skipping 413 matching lines @@
 void Process::TerminateExitCodeHandler() {
   ExitCodeHandler::Terminate();
 }
 
 
 intptr_t Process::CurrentProcessId() {
   return static_cast<intptr_t>(getpid());
 }
 
 
+int64_t Process::CurrentRSS() {
+  mx_info_task_stats_t task_stats;
+  mx_handle_t process = mx_process_self();
+  mx_status_t status = mx_object_get_info(
+      process, MX_INFO_TASK_STATS, &task_stats, sizeof(task_stats), NULL, NULL);
+  if (status != NO_ERROR) {
+    // TODO(zra): Translate this to a Unix errno.
+    errno = status;
+    return -1;
+  }
+  return task_stats.mem_committed_bytes;
+}
+
+
+int64_t Process::MaxRSS() {
+  // There is currently no way to get the high watermark value on Fuchsia, so
+  // just return the current RSS value.
+  return CurrentRSS();
+}
+
+
 static bool ProcessWaitCleanup(intptr_t out,
                                intptr_t err,
                                intptr_t exit_event,
                                intptr_t epoll_fd) {
   int e = errno;
   VOID_NO_RETRY_EXPECTED(close(out));
   VOID_NO_RETRY_EXPECTED(close(err));
   VOID_NO_RETRY_EXPECTED(close(exit_event));
   VOID_NO_RETRY_EXPECTED(close(epoll_fd));
   errno = e;
@@ skipping 371 matching lines @@
 
 void Process::ClearSignalHandler(intptr_t signal) {
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(HOST_OS_FUCHSIA)
 
 #endif  // !defined(DART_IO_DISABLED)