[metrics] Add file output support

Adds a new command line option, -Xwrite-metrics-to-file=_, which
specifies a file for writing metrics to. This can be used in conjunction
with -Xwrite-metrics-to-log, which will cause the output to go to both
logcat and the file.

Writing metrics to a file can be helpful for testing or benchmarking
environments.

Access to the file is protected using advisory locking, so it is safe to
have multiple processes write metrics to the same file.

Test: test/run-test --host test/2234-write-metrics-to-file
Bug: 175025360, 170149255
Change-Id: I83a4f959cbb96847dc71188035c050a73b915064

14 files changed, 150 insertions, 16 deletions

diff --git a/libartbase/base/variant_map.h b/libartbase/base/variant_map.h
index 581bc234cc..7349bbc046 100644
--- a/libartbase/base/variant_map.h
+++ b/libartbase/base/variant_map.h
@@ -229,6 +229,14 @@ struct VariantMap {
     return GetValuePtr(key);
   }
 
+  // Look up the value from the key and return the value wrapped in a std::optional. If it was not
+  // set in the map, return an empty std::optional.
+  template <typename TValue>
+  std::optional<TValue> GetOptional(const TKey<TValue>& key) const {
+    auto* ptr = Get(key);
+    return (ptr == nullptr) ? std::optional<TValue>{} : std::make_optional(*ptr);
+  }
+
   // Lookup the value from the key. If it was not set in the map, return the default value.
   // The default value is either the key's default, or TValue{} if the key doesn't have a default.
   template <typename TValue>
diff --git a/runtime/metrics/metrics.cc b/runtime/metrics/metrics.cc
index 81ae2b4dab..e85897b19e 100644
--- a/runtime/metrics/metrics.cc
+++ b/runtime/metrics/metrics.cc
@@ -16,12 +16,20 @@
 
 #include "metrics.h"
 
+#include <sstream>
+
+#include "android-base/file.h"
 #include "android-base/logging.h"
 #include "base/macros.h"
+#include "base/scoped_flock.h"
+#include "runtime.h"
+#include "runtime_options.h"
 
 #pragma clang diagnostic push
 #pragma clang diagnostic error "-Wconversion"
 
+using android::base::WriteStringToFd;
+
 namespace art {
 namespace metrics {
 
@@ -116,15 +124,15 @@ std::unique_ptr<MetricsReporter> MetricsReporter::Create(ReportingConfig config,
   std::unique_ptr<MetricsBackend> backend;
 
   // We can't use std::make_unique here because the MetricsReporter constructor is private.
-  return std::unique_ptr<MetricsReporter>{new MetricsReporter{config, metrics}};
+  return std::unique_ptr<MetricsReporter>{new MetricsReporter{std::move(config), metrics}};
 }
 
 MetricsReporter::MetricsReporter(ReportingConfig config, const ArtMetrics* metrics)
-    : config_{config}, metrics_{metrics} {}
+    : config_{std::move(config)}, metrics_{metrics} {}
 
 MetricsReporter::~MetricsReporter() {
   // If we are configured to report metrics, do one final report at the end.
-  if (config_.dump_to_logcat) {
+  if (config_.ReportingEnabled()) {
     LOG_STREAM(INFO) << "\n*** ART internal metrics ***\n\n";
     // LOG_STREAM(INFO) destroys the stream at the end of the statement, which makes it tricky pass
     // it to store as a field in StreamBackend. To get around this, we use an immediately-invoked
@@ -136,6 +144,31 @@ MetricsReporter::~MetricsReporter() {
     }(LOG_STREAM(INFO));
     LOG_STREAM(INFO) << "\n*** Done dumping ART internal metrics ***\n";
   }
+  if (config_.dump_to_file.has_value()) {
+    const auto& filename = config_.dump_to_file.value();
+    std::ostringstream stream;
+    StreamBackend backend{stream};
+    metrics_->ReportAllMetrics(&backend);
+
+    std::string error_message;
+    auto file{
+        LockedFile::Open(filename.c_str(), O_CREAT | O_WRONLY | O_APPEND, true, &error_message)};
+    if (file.get() == nullptr) {
+      LOG(WARNING) << "Could open metrics file '" << filename << "': " << error_message;
+    } else {
+      if (!WriteStringToFd(stream.str(), file.get()->Fd())) {
+        PLOG(WARNING) << "Error writing metrics to file";
+      }
+    }
+  }
+}
+
+ReportingConfig ReportingConfig::FromRuntimeArguments(const RuntimeArgumentMap& args) {
+  using M = RuntimeArgumentMap;
+  return {
+      .dump_to_logcat = args.Exists(M::WriteMetricsToLog),
+      .dump_to_file = args.GetOptional(M::WriteMetricsToFile),
+  };
 }
 
 }  // namespace metrics
diff --git a/runtime/metrics/metrics.h b/runtime/metrics/metrics.h
index 7156d576e0..a6e395559a 100644
--- a/runtime/metrics/metrics.h
+++ b/runtime/metrics/metrics.h
@@ -21,6 +21,7 @@
 
 #include <array>
 #include <atomic>
+#include <optional>
 #include <ostream>
 #include <string_view>
 #include <vector>
@@ -58,6 +59,10 @@
 // per metric.
 
 namespace art {
+
+class Runtime;
+struct RuntimeArgumentMap;
+
 namespace metrics {
 
 /**
@@ -340,9 +345,16 @@ class ArtMetrics {
 std::string DatumName(DatumId datum);
 
 struct ReportingConfig {
-  bool dump_to_logcat;
-  // TODO(eholk): this will grow to support other configurations, such as logging to a file, or
-  // statsd. There will also be options for reporting after a period of time, or at certain events.
+  static ReportingConfig FromRuntimeArguments(const RuntimeArgumentMap& args);
+
+  // Causes metrics to be written to the log, which makes them show up in logcat.
+  bool dump_to_logcat{false};
+
+  // If set, provides a file name to enable metrics logging to a file.
+  std::optional<std::string> dump_to_file;
+
+  // Returns whether any options are set that enables metrics reporting.
+  constexpr bool ReportingEnabled() const { return dump_to_logcat || dump_to_file.has_value(); }
 };
 
 // MetricsReporter handles periodically reporting ART metrics.
diff --git a/runtime/parsed_options.cc b/runtime/parsed_options.cc
index 508e697f7f..5b8c9d3bc1 100644
--- a/runtime/parsed_options.cc
+++ b/runtime/parsed_options.cc
@@ -395,7 +395,12 @@ std::unique_ptr<RuntimeParser> ParsedOptions::MakeParser(bool ignore_unrecognize
       .Define("-Xuse-stderr-logger")
           .IntoKey(M::UseStderrLogger)
       .Define("-Xwrite-metrics-to-log")
+          .WithHelp("Enables writing ART metrics to logcat")
           .IntoKey(M::WriteMetricsToLog)
+      .Define("-Xwrite-metrics-to-file=_")
+          .WithHelp("Enables writing ART metrics to the given file")
+          .WithType<std::string>()
+          .IntoKey(M::WriteMetricsToFile)
       .Define("-Xonly-use-system-oat-files")
           .IntoKey(M::OnlyUseSystemOatFiles)
       .Define("-Xverifier-logging-threshold=_")
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index ac3c39219e..568d500563 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -223,13 +223,6 @@ void CheckConstants() {
   CHECK_EQ(mirror::Array::kFirstElementOffset, mirror::Array::FirstElementOffset());
 }
 
-metrics::ReportingConfig ParseMetricsReportingConfig(const RuntimeArgumentMap& args) {
-  using M = RuntimeArgumentMap;
-  return {
-      .dump_to_logcat = args.Exists(M::WriteMetricsToLog),
-  };
-}
-
 }  // namespace
 
 Runtime::Runtime()
@@ -1716,8 +1709,7 @@ bool Runtime::Init(RuntimeArgumentMap&& runtime_options_in) {
   // Class-roots are setup, we can now finish initializing the JniIdManager.
   GetJniIdManager()->Init(self);
 
-  metrics_reporter_ =
-      metrics::MetricsReporter::Create(ParseMetricsReportingConfig(runtime_options), &metrics_);
+  InitMetrics(runtime_options);
 
   // Runtime initialization is largely done now.
   // We load plugins first since that can modify the runtime state slightly.
@@ -1817,6 +1809,13 @@ bool Runtime::Init(RuntimeArgumentMap&& runtime_options_in) {
   return true;
 }
 
+void Runtime::InitMetrics(const RuntimeArgumentMap& runtime_options) {
+  auto metrics_config = metrics::ReportingConfig::FromRuntimeArguments(runtime_options);
+  if (metrics_config.ReportingEnabled()) {
+    metrics_reporter_ = metrics::MetricsReporter::Create(metrics_config, GetMetrics());
+  }
+}
+
 bool Runtime::EnsurePluginLoaded(const char* plugin_name, std::string* error_msg) {
   // Is the plugin already loaded?
   for (const Plugin& p : plugins_) {
diff --git a/runtime/runtime.h b/runtime/runtime.h
index 7fd731eb0d..06f05a177e 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -980,6 +980,7 @@ class Runtime {
       SHARED_TRYLOCK_FUNCTION(true, Locks::mutator_lock_);
   void InitNativeMethods() REQUIRES(!Locks::mutator_lock_);
   void RegisterRuntimeNativeMethods(JNIEnv* env);
+  void InitMetrics(const RuntimeArgumentMap& runtime_options);
 
   void StartDaemonThreads();
   void StartSignalCatcher();
diff --git a/runtime/runtime_options.def b/runtime/runtime_options.def
index 4462de22f5..80ec30833f 100644
--- a/runtime/runtime_options.def
+++ b/runtime/runtime_options.def
@@ -185,5 +185,6 @@ RUNTIME_OPTIONS_KEY (bool,                PerfettoHprof,                  false)
 
 // Whether to dump ART metrics to logcat
 RUNTIME_OPTIONS_KEY (Unit,                WriteMetricsToLog)
+RUNTIME_OPTIONS_KEY (std::string,         WriteMetricsToFile)
 
 #undef RUNTIME_OPTIONS_KEY
diff --git a/test/2234-write-metrics-to-file/check b/test/2234-write-metrics-to-file/check
new file mode 100755
index 0000000000..b9040957f6
--- /dev/null
+++ b/test/2234-write-metrics-to-file/check
@@ -0,0 +1,34 @@
+#!/bin/bash
+#
+# Copyright (C) 2020 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.
+
+# Inputs:
+# $1: Test's expected standard output
+# $2: Test's actual standard output
+# $3: Test's expected standard error
+# $4: Test's actual standard error
+
+# Check that one of the metrics appears in stderr.
+grep 'ClassVerificationTotalTime' "$2" >/dev/null
+MSG_FOUND=$?
+
+if [[ $MSG_FOUND -ne 0 ]] ; then
+  # Print out the log and return with error.
+  cat "$2"
+  exit 1
+fi
+
+# Success.
+exit 0
diff --git a/test/2234-write-metrics-to-file/expected-stderr.txt b/test/2234-write-metrics-to-file/expected-stderr.txt
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/test/2234-write-metrics-to-file/expected-stderr.txt
diff --git a/test/2234-write-metrics-to-file/expected-stdout.txt b/test/2234-write-metrics-to-file/expected-stdout.txt
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/test/2234-write-metrics-to-file/expected-stdout.txt
diff --git a/test/2234-write-metrics-to-file/info.txt b/test/2234-write-metrics-to-file/info.txt
new file mode 100644
index 0000000000..d2e50dfde0
--- /dev/null
+++ b/test/2234-write-metrics-to-file/info.txt
@@ -0,0 +1 @@
+Checks that metrics can be written to a file.
diff --git a/test/2234-write-metrics-to-file/run b/test/2234-write-metrics-to-file/run
new file mode 100755
index 0000000000..d2ff292100
--- /dev/null
+++ b/test/2234-write-metrics-to-file/run
@@ -0,0 +1,19 @@
+#!/bin/bash
+#
+# Copyright (C) 2020 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.
+
+# Use /dev/stdout as the file so that buildbot can automatically grab the output for the check
+# script.
+exec ${RUN} $@ --runtime-option -Xwrite-metrics-to-file=/dev/stdout
diff --git a/test/2234-write-metrics-to-file/src/Main.java b/test/2234-write-metrics-to-file/src/Main.java
new file mode 100644
index 0000000000..0426192ab2
--- /dev/null
+++ b/test/2234-write-metrics-to-file/src/Main.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+public class Main {
+  public static void main(String[] args) {
+  }
+}
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 385db458a9..4c6976258b 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1351,7 +1351,8 @@
         "description": ["Failing on RI. Needs further investigating."]
     },
     {
-        "tests": ["2232-write-metrics-to-log"],
+        "tests": ["2232-write-metrics-to-log",
+                  "2234-write-metrics-to-file"],
         "variant": "jvm",
         "description": ["RI does not support ART metrics."]
     },