Enable UMA histogram logger for low memor kill events in ArcMetricsService.

chrome/browser/chromeos/arc/arc_low_memory_killer_monitor.cc

Index: chrome/browser/chromeos/arc/arc_low_memory_killer_monitor.cc
diff --git a/chrome/browser/chromeos/arc/arc_low_memory_killer_monitor.cc b/chrome/browser/chromeos/arc/arc_low_memory_killer_monitor.cc
deleted file mode 100644
index 4976cf085255b745811628f2f831ce7ed3d924b9..0000000000000000000000000000000000000000
--- a/chrome/browser/chromeos/arc/arc_low_memory_killer_monitor.cc
+++ /dev/null
@@ -1,113 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "chrome/browser/chromeos/arc/arc_low_memory_killer_monitor.h"
-
-#include <errno.h>
-#include <fcntl.h>
-#include <stdio.h>
-
-#include <vector>
-
-#include "base/bind.h"
-#include "base/files/file_util.h"
-#include "base/location.h"
-#include "base/logging.h"
-#include "base/metrics/histogram_macros.h"
-#include "base/posix/safe_strerror.h"
-#include "base/sequenced_task_runner.h"
-#include "base/strings/string_number_conversions.h"
-#include "base/strings/string_split.h"
-#include "base/time/time.h"
-#include "third_party/re2/src/re2/re2.h"
-
-namespace arc {
-
-using base::SequencedWorkerPool;
-using base::StringPiece;
-using base::TimeDelta;
-
-#define MAX_LOWMEMORYKILL_TIME_SECS 30
-#define UMA_HISTOGRAM_LOWMEMORYKILL_TIMES(name, sample)   \
-  UMA_HISTOGRAM_CUSTOM_TIMES(                             \
-      name, sample, base::TimeDelta::FromMilliseconds(1), \
-      base::TimeDelta::FromSeconds(MAX_LOWMEMORYKILL_TIME_SECS), 50)
-
-ArcLowMemoryKillerMonitor::ArcLowMemoryKillerMonitor()
-    : worker_pool_(
-          new SequencedWorkerPool(1, "arc_low_memory_killer_monitor")) {}
-
-ArcLowMemoryKillerMonitor::~ArcLowMemoryKillerMonitor() {
-  Stop();
-}
-
-void ArcLowMemoryKillerMonitor::Start() {
-  auto task_runner = worker_pool_->GetTaskRunnerWithShutdownBehavior(
-      SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
-  task_runner->PostTask(
-      FROM_HERE, base::Bind(&ArcLowMemoryKillerMonitor::Run, worker_pool_));
-}
-
-void ArcLowMemoryKillerMonitor::Stop() {
-  worker_pool_->Shutdown();
-}
-
-// static
-void ArcLowMemoryKillerMonitor::Run(
-    scoped_refptr<base::SequencedWorkerPool> worker_pool) {
-  static const int kMaxBufSize = 512;
-
-  FILE* kmsg_handle = base::OpenFile(base::FilePath("/dev/kmsg"), "r");
-  if (!kmsg_handle) {
-    LOG(WARNING) << "Open /dev/kmsg failed: " << base::safe_strerror(errno);
-    return;
-  }
-  // Skip kernel messages prior to the instantiation of this object to avoid
-  // double reporting.
-  fseek(kmsg_handle, 0, SEEK_END);
-
-  char buf[kMaxBufSize];
-  int freed_size;
-  int64_t timestamp, last_timestamp = -1;
-  const TimeDelta kMaxTimeDelta =
-      TimeDelta::FromSeconds(MAX_LOWMEMORYKILL_TIME_SECS);
-
-  while (fgets(buf, kMaxBufSize, kmsg_handle)) {
-    if (worker_pool->IsShutdownInProgress()) {
-      DVLOG(1) << "Chrome is shutting down, exit now.";
-      break;
-    }
-    if (RE2::PartialMatch(buf, "lowmemorykiller: .* to free (\\d+)kB",
-                          &freed_size)) {
-      std::vector<StringPiece> fields = SplitStringPiece(
-          buf, ",", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
-
-      // The time to last kill event. Could be |kMaxTimeDelta| in case of the
-      // first kill event.
-      TimeDelta time_delta(kMaxTimeDelta);
-      // Timestamp is the third field in a line of /dev/kmsg.
-      //
-      // Sample log line:
-      // 6,2302,533604004,-;lowmemorykiller: Killing 'externalstorage' (21742),
-      // adj 1000,\x0a   to free 27320kB on behalf of 'kswapd0' (47) because\x0a
-      // cache 181920kB is below limit 184320kB for oom_score_adj 1000\x0a
-      // Free memory is 1228kB above reserved
-      if (fields.size() >= 3) {
-        base::StringToInt64(fields[2], &timestamp);
-        if (last_timestamp > 0) {
-          time_delta = TimeDelta::FromMicroseconds(timestamp - last_timestamp);
-        }
-        last_timestamp = timestamp;
-
-        UMA_HISTOGRAM_MEMORY_KB("ArcRuntime.LowMemoryKiller.FreedSize",
-                                freed_size);
-        UMA_HISTOGRAM_LOWMEMORYKILL_TIMES(
-            "ArcRuntime.LowMemoryKiller.TimeDelta", time_delta);
-      }
-    }
-  }
-  base::CloseFile(kmsg_handle);
-}
-
-}  // namespace arc