add memory usage to the diagnostics page

pkg/analysis_server/lib/src/utilities/profiling.dart

Index: pkg/analysis_server/lib/src/utilities/profiling.dart
diff --git a/pkg/analysis_server/lib/src/utilities/profiling.dart b/pkg/analysis_server/lib/src/utilities/profiling.dart
new file mode 100644
index 0000000000000000000000000000000000000000..aa3335f6019d96329b771d6b80cdf2740e2f080c
--- /dev/null
+++ b/pkg/analysis_server/lib/src/utilities/profiling.dart
@@ -0,0 +1,85 @@
+// Copyright (c) 2017, 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.
+
+import 'dart:async';
+import 'dart:io';
+
+/// A class that can return memory and cpu usage information for a given
+/// process.
+abstract class ProcessProfiler {
+  ProcessProfiler._();
+
+  Future<UsageInfo> getProcessUsage(int processId);
+
+  UsageInfo getProcessUsageSync(int processId);
+
+  /// Return a [ProcessProfiler] instance suitable for the current host
+  /// platform. This can return `null` if we're not able to gather memory and
+  /// cpu information for the current platform.
+  static ProcessProfiler getProfilerForPlatform() {
+    if (Platform.isLinux || Platform.isMacOS) {
+      return new _PosixProcessProfiler();
+    }
+
+    // Not a supported platform.
+    return null;
+  }
+}
+
+class UsageInfo {
+  /// A number between 0.0 and 100.0 * the number of host CPUs (but typically
+  /// never more than slightly above 100.0).
+  final double cpuPercentage;
+
+  /// The process memory usage in bytes.
+  final int memoryKB;
+
+  UsageInfo(this.cpuPercentage, this.memoryKB);
+
+  double get memoryMB => memoryKB / 1024;
+}
+
+class _PosixProcessProfiler extends ProcessProfiler {
+  _PosixProcessProfiler() : super._();
+
+  @override
+  Future<UsageInfo> getProcessUsage(int processId) {
+    try {
+      // Execution time is typically 2-4ms.
+      Future<ProcessResult> future =
+          Process.run('ps', ['-o', '%cpu=,rss=', processId.toString()]);
+      return future.then((ProcessResult result) {
+        if (result.exitCode != 0) {
+          return new Future.value(null);
+        }
+
+        return new Future.value(_parse(result.stdout));
+      });
+    } catch (e) {
+      return new Future.error(e);
+    }
+  }
+
+  UsageInfo getProcessUsageSync(int processId) {
+    try {
+      // Execution time is typically 2-4ms.
+      ProcessResult result =
+          Process.runSync('ps', ['-o', '%cpu=,rss=', processId.toString()]);
+      return result.exitCode == 0 ? _parse(result.stdout) : null;
+    } catch (e) {
+      return null;
+    }
+  }
+
+  UsageInfo _parse(String psResults) {
+    try {
+      // "  0.0 378940"
+      String line = psResults.split('\n').first.trim();
+      List<String> values = line.split(' ');
+      return new UsageInfo(double.parse(values[0]), int.parse(values[1]));
+    } catch (e) {
+      return null;
+    }
+  }
+}