metricsd: Only collect metrics over a short period.

Instead of reporting the metrics over both a long and a short period,
collect and report only over a short period. This makes the code simpler
and the metrics easier to understand.

Also move the collection out of metrics_daemon and into a separate
collector to make it simpler to understand.

BUG: 24464945

Change-Id: I17e52536aaa75321a5e34f42ed488545c2c3efde

metricsd/Android.mk

@@ -26,6 +26,7 @@ metrics_client_sources := \
   metrics_client.cc
 
 metrics_daemon_sources := \
+  collectors/averaged_statistics_collector.cc \
   collectors/disk_usage_collector.cc \
   metrics_daemon.cc \
   metrics_daemon_main.cc \
@@ -40,6 +41,8 @@ metrics_daemon_sources := \
   serialization/serialization_utils.cc
 
 metrics_tests_sources := \
+  collectors/averaged_statistics_collector.cc \
+  collectors/averaged_statistics_collector_test.cc \
   collectors/disk_usage_collector.cc \
   metrics_daemon.cc \
   metrics_daemon_test.cc \
@@ -146,6 +149,7 @@ include $(BUILD_EXECUTABLE)
 # ========================================================
 include $(CLEAR_VARS)
 LOCAL_MODULE := metrics_tests
+LOCAL_CLANG := true
 LOCAL_CFLAGS := $(metrics_CFLAGS)
 LOCAL_CPP_EXTENSION := $(metrics_cpp_extension)
 LOCAL_CPPFLAGS := $(metrics_CPPFLAGS) -Wno-sign-compare

metricsd/collectors/averaged_statistics_collector.cc

@@ -0,0 +1,216 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "averaged_statistics_collector.h"
+
+#include <base/files/file_util.h>
+#include <base/files/file_path.h>
+#include <base/strings/string_number_conversions.h>
+#include <base/strings/string_split.h>
+
+#include "metrics_daemon.h"
+
+namespace {
+
+// disk stats metrics
+
+// The {Read,Write}Sectors numbers are in sectors/second.
+// A sector is usually 512 bytes.
+const char kReadSectorsHistogramName[] = "Platform.ReadSectors";
+const char kWriteSectorsHistogramName[] = "Platform.WriteSectors";
+const int kDiskMetricsStatItemCount = 11;
+
+// Assume a max rate of 250Mb/s for reads (worse for writes) and 512 byte
+// sectors.
+const int kSectorsIOMax = 500000;  // sectors/second
+const int kSectorsBuckets = 50;    // buckets
+
+// Page size is 4k, sector size is 0.5k.  We're not interested in page fault
+// rates that the disk cannot sustain.
+const int kPageFaultsMax = kSectorsIOMax / 8;  // Page faults/second
+const int kPageFaultsBuckets = 50;
+
+// Major page faults, i.e. the ones that require data to be read from disk.
+const char kPageFaultsHistogramName[] = "Platform.PageFaults";
+
+// Swap in and Swap out
+const char kSwapInHistogramName[] = "Platform.SwapIn";
+const char kSwapOutHistogramName[] = "Platform.SwapOut";
+
+const int kIntervalBetweenCollection = 60;  // seconds
+const int kCollectionDuration = 1;  // seconds
+
+}  // namespace
+
+AveragedStatisticsCollector::AveragedStatisticsCollector(
+    MetricsLibraryInterface* metrics_library,
+    const std::string& diskstats_path,
+    const std::string& vmstats_path) :
+  metrics_lib_(metrics_library),
+  diskstats_path_(diskstats_path),
+  vmstats_path_(vmstats_path) {
+}
+
+void AveragedStatisticsCollector::ScheduleWait() {
+  base::MessageLoop::current()->PostDelayedTask(FROM_HERE,
+      base::Bind(&AveragedStatisticsCollector::WaitCallback,
+                 base::Unretained(this)),
+      base::TimeDelta::FromSeconds(
+          kIntervalBetweenCollection - kCollectionDuration));
+}
+
+void AveragedStatisticsCollector::ScheduleCollect() {
+  base::MessageLoop::current()->PostDelayedTask(FROM_HERE,
+      base::Bind(&AveragedStatisticsCollector::CollectCallback,
+                 base::Unretained(this)),
+      base::TimeDelta::FromSeconds(kCollectionDuration));
+}
+
+void AveragedStatisticsCollector::WaitCallback() {
+  ReadInitialValues();
+  ScheduleCollect();
+}
+
+void AveragedStatisticsCollector::CollectCallback() {
+  Collect();
+  ScheduleWait();
+}
+
+void AveragedStatisticsCollector::ReadInitialValues() {
+  stats_start_time_ = MetricsDaemon::GetActiveTime();
+  DiskStatsReadStats(&read_sectors_, &write_sectors_);
+  VmStatsReadStats(&vmstats_);
+}
+
+bool AveragedStatisticsCollector::DiskStatsReadStats(
+    uint64_t* read_sectors, uint64_t* write_sectors) {
+  CHECK(read_sectors);
+  CHECK(write_sectors);
+  std::string line;
+  if (diskstats_path_.empty()) {
+    return false;
+  }
+
+  if (!base::ReadFileToString(base::FilePath(diskstats_path_), &line)) {
+    PLOG(WARNING) << "Could not read disk stats from "
+                  << diskstats_path_.value();
+    return false;
+  }
+
+  std::vector<std::string> parts = base::SplitString(
+      line, " ", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+  if (parts.size() != kDiskMetricsStatItemCount) {
+    LOG(ERROR) << "Could not parse disk stat correctly. Expected "
+               << kDiskMetricsStatItemCount << " elements but got "
+               << parts.size();
+    return false;
+  }
+  if (!base::StringToUint64(parts[2], read_sectors)) {
+    LOG(ERROR) << "Couldn't convert read sectors " << parts[2] << " to uint64";
+    return false;
+  }
+  if (!base::StringToUint64(parts[6], write_sectors)) {
+    LOG(ERROR) << "Couldn't convert write sectors " << parts[6] << " to uint64";
+    return false;
+  }
+
+  return true;
+}
+
+bool AveragedStatisticsCollector::VmStatsParseStats(
+    const char* stats, struct VmstatRecord* record) {
+  CHECK(stats);
+  CHECK(record);
+  base::StringPairs pairs;
+  base::SplitStringIntoKeyValuePairs(stats, ' ', '\n', &pairs);
+
+  for (base::StringPairs::iterator it = pairs.begin();
+       it != pairs.end(); ++it) {
+    if (it->first == "pgmajfault" &&
+        !base::StringToUint64(it->second, &record->page_faults)) {
+      return false;
+    }
+    if (it->first == "pswpin" &&
+        !base::StringToUint64(it->second, &record->swap_in)) {
+      return false;
+    }
+    if (it->first == "pswpout" &&
+        !base::StringToUint64(it->second, &record->swap_out)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool AveragedStatisticsCollector::VmStatsReadStats(struct VmstatRecord* stats) {
+  CHECK(stats);
+  std::string value_string;
+  if (!base::ReadFileToString(vmstats_path_, &value_string)) {
+    LOG(WARNING) << "cannot read " << vmstats_path_.value();
+    return false;
+  }
+  return VmStatsParseStats(value_string.c_str(), stats);
+}
+
+void AveragedStatisticsCollector::Collect() {
+  uint64_t read_sectors_now, write_sectors_now;
+  struct VmstatRecord vmstats_now;
+  double time_now = MetricsDaemon::GetActiveTime();
+  double delta_time = time_now - stats_start_time_;
+  bool diskstats_success = DiskStatsReadStats(&read_sectors_now,
+                                              &write_sectors_now);
+
+  int delta_read = read_sectors_now - read_sectors_;
+  int delta_write = write_sectors_now - write_sectors_;
+  int read_sectors_per_second = delta_read / delta_time;
+  int write_sectors_per_second = delta_write / delta_time;
+  bool vmstats_success = VmStatsReadStats(&vmstats_now);
+  uint64_t delta_faults = vmstats_now.page_faults - vmstats_.page_faults;
+  uint64_t delta_swap_in = vmstats_now.swap_in - vmstats_.swap_in;
+  uint64_t delta_swap_out = vmstats_now.swap_out - vmstats_.swap_out;
+  uint64_t page_faults_per_second = delta_faults / delta_time;
+  uint64_t swap_in_per_second = delta_swap_in / delta_time;
+  uint64_t swap_out_per_second = delta_swap_out / delta_time;
+  if (diskstats_success) {
+    metrics_lib_->SendToUMA(kReadSectorsHistogramName,
+                            read_sectors_per_second,
+                            1,
+                            kSectorsIOMax,
+                            kSectorsBuckets);
+    metrics_lib_->SendToUMA(kWriteSectorsHistogramName,
+                            write_sectors_per_second,
+                            1,
+                            kSectorsIOMax,
+                            kSectorsBuckets);
+  }
+  if (vmstats_success) {
+    metrics_lib_->SendToUMA(kPageFaultsHistogramName,
+                            page_faults_per_second,
+                            1,
+                            kPageFaultsMax,
+                            kPageFaultsBuckets);
+    metrics_lib_->SendToUMA(kSwapInHistogramName,
+                            swap_in_per_second,
+                            1,
+                            kPageFaultsMax,
+                            kPageFaultsBuckets);
+    metrics_lib_->SendToUMA(kSwapOutHistogramName,
+                            swap_out_per_second,
+                            1,
+                            kPageFaultsMax,
+                            kPageFaultsBuckets);
+  }
+}

metricsd/collectors/averaged_statistics_collector.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef METRICSD_COLLECTORS_AVERAGED_STATISTICS_COLLECTOR_H_
+#define METRICSD_COLLECTORS_AVERAGED_STATISTICS_COLLECTOR_H_
+
+#include "metrics/metrics_library.h"
+
+class AveragedStatisticsCollector {
+ public:
+  AveragedStatisticsCollector(MetricsLibraryInterface* metrics_library,
+                              const std::string& diskstats_path,
+                              const std::string& vmstat_path);
+
+  // Schedule a wait period.
+  void ScheduleWait();
+
+  // Schedule a collection period.
+  void ScheduleCollect();
+
+  // Callback used by the main loop.
+  void CollectCallback();
+
+  // Callback used by the main loop.
+  void WaitCallback();
+
+  // Read and store the initial values at the beginning of a collection cycle.
+  void ReadInitialValues();
+
+  // Collect the disk usage statistics and report them.
+  void Collect();
+
+ private:
+  friend class AveragedStatisticsTest;
+  FRIEND_TEST(AveragedStatisticsTest, ParseDiskStats);
+  FRIEND_TEST(AveragedStatisticsTest, ParseVmStats);
+
+  // Record for retrieving and reporting values from /proc/vmstat
+  struct VmstatRecord {
+    uint64_t page_faults;    // major faults
+    uint64_t swap_in;        // pages swapped in
+    uint64_t swap_out;       // pages swapped out
+  };
+
+  // Read the disk read/write statistics for the main disk.
+  bool DiskStatsReadStats(uint64_t* read_sectors, uint64_t* write_sectors);
+
+  // Parse the content of the vmstats file into |record|.
+  bool VmStatsParseStats(const char* stats, struct VmstatRecord* record);
+
+  // Read the vmstats into |stats|.
+  bool VmStatsReadStats(struct VmstatRecord* stats);
+
+  MetricsLibraryInterface* metrics_lib_;
+  base::FilePath diskstats_path_;
+  base::FilePath vmstats_path_;
+
+  // Values observed at the beginning of the collection period.
+  uint64_t read_sectors_;
+  uint64_t write_sectors_;
+  struct VmstatRecord vmstats_;
+
+  double stats_start_time_;
+};
+
+#endif  // METRICSD_COLLECTORS_AVERAGED_STATISTICS_COLLECTOR_H_