Add UMA for history report

Add the following UMA metrics:
- Search.HistoryReport.DeltaFile.LastSeqNo
- Search.HistoryReport.DeltaFile.LevelDBEntries
- Search.HistoryReport.UsageReportsBuffer.LevelDBEntries

These are health checking signals to see if Icing-related levelDBs
could grow too big.

Bug: 857345
Change-Id: Icfc67b3442864a1c31b15427de40b406ea674ff7
Reviewed-on: https://chromium-review.googlesource.com/1117937Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573559}

chrome/browser/android/history_report/delta_file_backend_leveldb.cc

@@ -8,10 +8,12 @@
 
 #include "base/files/file_util.h"
 #include "base/logging.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/process_memory_dump.h"
 #include "chrome/browser/android/history_report/delta_file_commons.h"
+#include "chrome/browser/android/history_report/usage_report_util.h"
 #include "third_party/leveldatabase/env_chromium.h"
 #include "third_party/leveldatabase/leveldb_chrome.h"
 #include "third_party/leveldatabase/src/include/leveldb/comparator.h"
@@ -109,13 +111,20 @@ bool DeltaFileBackend::Init() {
     }
     status = leveldb_env::OpenDB(options, path, &db_);
   }
-  if (status.ok()) {
-    CHECK(db_);
-    return true;
+  if (!status.ok()) {
+    LOG(WARNING) << "Unable to open " << path_.value() << ": "
+                 << status.ToString();
+    return false;
   }
-  LOG(WARNING) << "Unable to open " << path_.value() << ": "
-               << status.ToString();
-  return false;
+  CHECK(db_);
+
+  UMA_HISTOGRAM_COUNTS_1M("Search.HistoryReport.DeltaFile.LevelDBEntries",
+                          usage_report_util::DatabaseEntries(db_.get()));
+
+  UMA_HISTOGRAM_COUNTS_1M("Search.HistoryReport.DeltaFile.LastSeqNo",
+                          GetLastSeqNo(db_.get()));
+
+  return true;
 }
 
 bool DeltaFileBackend::EnsureInitialized() {

chrome/browser/android/history_report/delta_file_service.h

@@ -32,7 +32,7 @@ class DeltaFileService {
   explicit DeltaFileService(const base::FilePath& dir);
   virtual ~DeltaFileService();
 
-  // Adds new addtion entry to delta file.
+  // Adds new addition entry to delta file.
   virtual void PageAdded(const GURL& url);
   // Adds new deletion entry to delta file.
   void PageDeleted(const GURL& url);

chrome/browser/android/history_report/usage_report_util.cc

-
 // Copyright 2015 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.
@@ -10,6 +9,9 @@
 
 #include "chrome/browser/android/proto/delta_file.pb.h"
 #include "net/base/url_util.h"
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
+#include "third_party/leveldatabase/src/include/leveldb/iterator.h"
+#include "third_party/leveldatabase/src/include/leveldb/options.h"
 #include "url/gurl.h"
 
 namespace history_report {
@@ -46,5 +48,15 @@ bool ShouldIgnoreUrl(const GURL& url) {
   return false;
 }
 
+int DatabaseEntries(leveldb::DB* db) {
+  std::unique_ptr<leveldb::Iterator> db_iter(
+      db->NewIterator(leveldb::ReadOptions()));
+
+  int count = 0;
+  for (db_iter->SeekToFirst(); db_iter->Valid(); db_iter->Next())
+    count++;
+  return count;
+}
+
 }  // namespace usage_report_util
 }  // namespace history_report

chrome/browser/android/history_report/usage_report_util.h

@@ -7,6 +7,7 @@
 
 #include<string>
 
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
 #include "ui/base/page_transition_types.h"
 
 class GURL;
@@ -23,6 +24,8 @@ bool IsTypedVisit(ui::PageTransition visit_transition);
 
 bool ShouldIgnoreUrl(const GURL& url);
 
+int DatabaseEntries(leveldb::DB* db);
+
 }  // namespace usage_report_util
 }  // namespace history_report
 

chrome/browser/android/history_report/usage_reports_buffer_backend.cc

@@ -55,12 +55,17 @@ bool UsageReportsBufferBackend::Init() {
     }
     status = leveldb_env::OpenDB(options, path, &db_);
   }
-  if (status.ok()) {
-    CHECK(db_);
-    return true;
+  if (!status.ok()) {
+    LOG(WARNING) << "Unable to open " << path << ": " << status.ToString();
+    return false;
   }
-  LOG(WARNING) << "Unable to open " << path << ": " << status.ToString();
-  return false;
+  CHECK(db_);
+
+  UMA_HISTOGRAM_COUNTS_1M(
+      "Search.HistoryReport.UsageReportsBuffer.LevelDBEntries",
+      usage_report_util::DatabaseEntries(db_.get()));
+
+  return true;
 }
 
 void UsageReportsBufferBackend::AddVisit(const std::string& id,
@@ -138,11 +143,7 @@ std::string UsageReportsBufferBackend::Dump() {
     return dump;
   }
   dump.append("num pending entries=");
-  leveldb::ReadOptions options;
-  int num_entries = 0;
-  std::unique_ptr<leveldb::Iterator> db_it(db_->NewIterator(options));
-  for (db_it->SeekToFirst(); db_it->Valid(); db_it->Next()) num_entries++;
-  dump.append(base::IntToString(num_entries));
+  dump.append(base::IntToString(usage_report_util::DatabaseEntries(db_.get())));
   dump.append("]");
   return dump;
 }
@@ -171,4 +172,3 @@ bool UsageReportsBufferBackend::OnMemoryDump(
 }
 
 }  // namespace history_report
-

chrome/browser/android/proto/delta_file.proto

@@ -12,14 +12,25 @@ package history_report;
 
 message DeltaFileEntry {
   // Next ID to use: 4
+
+  // |seq_no| is an auto increment sequence number, used as the key.
   optional int64 seq_no = 1;
+
+  // |type| can only be "add" or "del".
   optional string type = 2;
+
   optional string url = 3;
 }
 
 message UsageReport {
   // Next ID to use: 4
+
+  // |id| is derived from the URL, and the length doesn't exceed 256 chars.
+  // DeltaFileEntry and UsageReport can be joined by |id| this way.
   optional string id = 1;
+
   optional int64 timestamp_ms = 2;
+
+  // Whether the navigation is PAGE_TRANSITION_TYPED and not redirected.
   optional bool typed_visit = 3;
 }

tools/metrics/histograms/histograms.xml

@@ -88382,6 +88382,36 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="Search.HistoryReport.DeltaFile.LastSeqNo" units="count"
+    expires_after="M71">
+  <owner>wychen@chromium.org</owner>
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The last sequential number in the delta file for Icing. This is measured on
+    cold start.
+  </summary>
+</histogram>
+
+<histogram name="Search.HistoryReport.DeltaFile.LevelDBEntries" units="entries"
+    expires_after="2019-06-01">
+  <owner>wychen@chromium.org</owner>
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The number of entries in the delta file level DB for Icing. This is measured
+    on cold start.
+  </summary>
+</histogram>
+
+<histogram name="Search.HistoryReport.UsageReportsBuffer.LevelDBEntries"
+    units="entries" expires_after="2019-06-01">
+  <owner>wychen@chromium.org</owner>
+  <owner>yusufo@chromium.org</owner>
+  <summary>
+    The number of entries in the usage report level DB for Icing. This is
+    measured on cold start.
+  </summary>
+</histogram>
+
 <histogram name="Search.IcingContextReportingStatus"
     enum="IcingContextReportingStatus">
   <owner>joaodasilva@chromium.org</owner>