Revert CL 117933003. Re-add resource speculative prefetching code.

chrome/browser/predictors/resource_prefetch_predictor_tables.cc

Index: chrome/browser/predictors/resource_prefetch_predictor_tables.cc
diff --git a/chrome/browser/predictors/resource_prefetch_predictor_tables.cc b/chrome/browser/predictors/resource_prefetch_predictor_tables.cc
new file mode 100644
index 0000000000000000000000000000000000000000..89ebd7dce7f5aa989bf5af19651660c736c7d43a
--- /dev/null
+++ b/chrome/browser/predictors/resource_prefetch_predictor_tables.cc
@@ -0,0 +1,513 @@
+// Copyright 2014 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/predictors/resource_prefetch_predictor_tables.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "base/strings/stringprintf.h"
+#include "content/public/browser/browser_thread.h"
+#include "sql/statement.h"
+
+using content::BrowserThread;
+using sql::Statement;
+
+namespace {
+
+const char kUrlResourceTableName[] = "resource_prefetch_predictor_url";
+const char kUrlMetadataTableName[] = "resource_prefetch_predictor_url_metadata";
+const char kHostResourceTableName[] = "resource_prefetch_predictor_host";
+const char kHostMetadataTableName[] =
+    "resource_prefetch_predictor_host_metadata";
+
+void BindResourceRowToStatement(
+    const predictors::ResourcePrefetchPredictorTables::ResourceRow& row,
+    const std::string& primary_key,
+    Statement* statement) {
+  statement->BindString(0, primary_key);
+  statement->BindString(1, row.resource_url.spec());
+  statement->BindInt(2, static_cast<int>(row.resource_type));
+  statement->BindInt(3, row.number_of_hits);
+  statement->BindInt(4, row.number_of_misses);
+  statement->BindInt(5, row.consecutive_misses);
+  statement->BindDouble(6, row.average_position);
+}
+
+bool StepAndInitializeResourceRow(
+    Statement* statement,
+    predictors::ResourcePrefetchPredictorTables::ResourceRow* row) {
+  if (!statement->Step())
+    return false;
+
+  row->primary_key = statement->ColumnString(0);
+  row->resource_url = GURL(statement->ColumnString(1));
+  row->resource_type = static_cast<content::ResourceType>(
+      statement->ColumnInt(2));
+  row->number_of_hits = statement->ColumnInt(3);
+  row->number_of_misses = statement->ColumnInt(4);
+  row->consecutive_misses = statement->ColumnInt(5);
+  row->average_position = statement->ColumnDouble(6);
+  return true;
+}
+
+}  // namespace
+
+namespace predictors {
+
+// static
+const size_t ResourcePrefetchPredictorTables::kMaxStringLength = 1024;
+
+ResourcePrefetchPredictorTables::ResourceRow::ResourceRow()
+    : resource_type(content::RESOURCE_TYPE_LAST_TYPE),
+      number_of_hits(0),
+      number_of_misses(0),
+      consecutive_misses(0),
+      average_position(0.0),
+      score(0.0) {
+}
+
+ResourcePrefetchPredictorTables::ResourceRow::ResourceRow(
+    const ResourceRow& other)
+        : primary_key(other.primary_key),
+          resource_url(other.resource_url),
+          resource_type(other.resource_type),
+          number_of_hits(other.number_of_hits),
+          number_of_misses(other.number_of_misses),
+          consecutive_misses(other.consecutive_misses),
+          average_position(other.average_position),
+          score(other.score) {
+}
+
+ResourcePrefetchPredictorTables::ResourceRow::ResourceRow(
+    const std::string& i_primary_key,
+    const std::string& i_resource_url,
+    content::ResourceType i_resource_type,
+    int i_number_of_hits,
+    int i_number_of_misses,
+    int i_consecutive_misses,
+    double i_average_position)
+        : primary_key(i_primary_key),
+          resource_url(i_resource_url),
+          resource_type(i_resource_type),
+          number_of_hits(i_number_of_hits),
+          number_of_misses(i_number_of_misses),
+          consecutive_misses(i_consecutive_misses),
+          average_position(i_average_position) {
+  UpdateScore();
+}
+
+void ResourcePrefetchPredictorTables::ResourceRow::UpdateScore() {
+  // The score is calculated so that when the rows are sorted, the stylesheets
+  // and scripts appear first, sorted by position(ascending) and then the rest
+  // of the resources sorted by position(ascending).
+  static const int kMaxResourcesPerType = 100;
+  switch (resource_type) {
+    case content::RESOURCE_TYPE_STYLESHEET:
+    case content::RESOURCE_TYPE_SCRIPT:
+      score = (2 * kMaxResourcesPerType) - average_position;
+      break;
+
+    case content::RESOURCE_TYPE_IMAGE:
+    default:
+      score = kMaxResourcesPerType - average_position;
+      break;
+  }
+}
+
+bool ResourcePrefetchPredictorTables::ResourceRow::operator==(
+    const ResourceRow& rhs) const {
+  return primary_key == rhs.primary_key &&
+      resource_url == rhs.resource_url &&
+      resource_type == rhs.resource_type &&
+      number_of_hits == rhs.number_of_hits &&
+      number_of_misses == rhs.number_of_misses &&
+      consecutive_misses == rhs.consecutive_misses &&
+      average_position == rhs.average_position &&
+      score == rhs.score;
+}
+
+bool ResourcePrefetchPredictorTables::ResourceRowSorter::operator()(
+    const ResourceRow& x, const ResourceRow& y) const {
+  return x.score > y.score;
+}
+
+ResourcePrefetchPredictorTables::PrefetchData::PrefetchData(
+    PrefetchKeyType i_key_type,
+    const std::string& i_primary_key)
+    : key_type(i_key_type),
+      primary_key(i_primary_key) {
+}
+
+ResourcePrefetchPredictorTables::PrefetchData::PrefetchData(
+    const PrefetchData& other)
+    : key_type(other.key_type),
+      primary_key(other.primary_key),
+      last_visit(other.last_visit),
+      resources(other.resources) {
+}
+
+ResourcePrefetchPredictorTables::PrefetchData::~PrefetchData() {
+}
+
+bool ResourcePrefetchPredictorTables::PrefetchData::operator==(
+    const PrefetchData& rhs) const {
+  return key_type == rhs.key_type && primary_key == rhs.primary_key &&
+      resources == rhs.resources;
+}
+
+void ResourcePrefetchPredictorTables::GetAllData(
+    PrefetchDataMap* url_data_map,
+    PrefetchDataMap* host_data_map) {
+  DCHECK_CURRENTLY_ON(BrowserThread::DB);
+  if (CantAccessDatabase())
+    return;
+
+  DCHECK(url_data_map);
+  DCHECK(host_data_map);
+  url_data_map->clear();
+  host_data_map->clear();
+
+  std::vector<std::string> urls_to_delete, hosts_to_delete;
+  GetAllDataHelper(PREFETCH_KEY_TYPE_URL, url_data_map, &urls_to_delete);
+  GetAllDataHelper(PREFETCH_KEY_TYPE_HOST, host_data_map, &hosts_to_delete);
+
+  if (!urls_to_delete.empty() || !hosts_to_delete.empty())
+    DeleteData(urls_to_delete, hosts_to_delete);
+}
+
+void ResourcePrefetchPredictorTables::UpdateData(
+    const PrefetchData& url_data,
+    const PrefetchData& host_data) {
+  DCHECK_CURRENTLY_ON(BrowserThread::DB);
+  if (CantAccessDatabase())
+    return;
+
+  DCHECK(!url_data.is_host() && host_data.is_host());
+  DCHECK(!url_data.primary_key.empty() || !host_data.primary_key.empty());
+
+  DB()->BeginTransaction();
+
+  bool success = (url_data.primary_key.empty() || UpdateDataHelper(url_data)) &&
+      (host_data.primary_key.empty() || UpdateDataHelper(host_data));
+  if (!success)
+    DB()->RollbackTransaction();
+
+  DB()->CommitTransaction();
+}
+
+void ResourcePrefetchPredictorTables::DeleteData(
+    const std::vector<std::string>& urls,
+    const std::vector<std::string>& hosts) {
+  DCHECK_CURRENTLY_ON(BrowserThread::DB);
+  if (CantAccessDatabase())
+    return;
+
+  DCHECK(!urls.empty() || !hosts.empty());
+
+  if (!urls.empty())
+    DeleteDataHelper(PREFETCH_KEY_TYPE_URL, urls);
+  if (!hosts.empty())
+    DeleteDataHelper(PREFETCH_KEY_TYPE_HOST, hosts);
+}
+
+void ResourcePrefetchPredictorTables::DeleteSingleDataPoint(
+    const std::string& key,
+    PrefetchKeyType key_type) {
+  DCHECK_CURRENTLY_ON(BrowserThread::DB);
+  if (CantAccessDatabase())
+    return;
+
+  DeleteDataHelper(key_type, std::vector<std::string>(1, key));
+}
+
+void ResourcePrefetchPredictorTables::DeleteAllData() {
+  if (CantAccessDatabase())
+    return;
+
+  Statement deleter(DB()->GetUniqueStatement(
+      base::StringPrintf("DELETE FROM %s", kUrlResourceTableName).c_str()));
+  deleter.Run();
+  deleter.Assign(DB()->GetUniqueStatement(
+      base::StringPrintf("DELETE FROM %s", kUrlMetadataTableName).c_str()));
+  deleter.Run();
+  deleter.Assign(DB()->GetUniqueStatement(
+      base::StringPrintf("DELETE FROM %s", kHostResourceTableName).c_str()));
+  deleter.Run();
+  deleter.Assign(DB()->GetUniqueStatement(
+      base::StringPrintf("DELETE FROM %s", kHostMetadataTableName).c_str()));
+  deleter.Run();
+}
+
+ResourcePrefetchPredictorTables::ResourcePrefetchPredictorTables()
+    : PredictorTableBase() {
+}
+
+ResourcePrefetchPredictorTables::~ResourcePrefetchPredictorTables() {
+}
+
+void ResourcePrefetchPredictorTables::GetAllDataHelper(
+    PrefetchKeyType key_type,
+    PrefetchDataMap* data_map,
+    std::vector<std::string>* to_delete) {
+  bool is_host = key_type == PREFETCH_KEY_TYPE_HOST;
+
+  // Read the resources table and organize it per primary key.
+  const char* resource_table_name = is_host ? kHostResourceTableName :
+      kUrlResourceTableName;
+  Statement resource_reader(DB()->GetUniqueStatement(
+      base::StringPrintf("SELECT * FROM %s", resource_table_name).c_str()));
+
+  ResourceRow row;
+  while (StepAndInitializeResourceRow(&resource_reader, &row)) {
+    row.UpdateScore();
+    std::string primary_key = row.primary_key;
+    // Don't need to store primary key since the data is grouped by primary key.
+    row.primary_key.clear();
+
+    PrefetchDataMap::iterator it = data_map->find(primary_key);
+    if (it == data_map->end()) {
+      it = data_map->insert(std::make_pair(
+          primary_key, PrefetchData(key_type, primary_key))).first;
+    }
+    it->second.resources.push_back(row);
+  }
+
+  // Sort each of the resource row vectors by score.
+  for (PrefetchDataMap::iterator it = data_map->begin(); it != data_map->end();
+       ++it) {
+    std::sort(it->second.resources.begin(),
+              it->second.resources.end(),
+              ResourceRowSorter());
+  }
+
+  // Read the metadata and keep track of entries that have metadata, but no
+  // resource entries, so they can be deleted.
+  const char* metadata_table_name = is_host ? kHostMetadataTableName :
+      kUrlMetadataTableName;
+  Statement metadata_reader(DB()->GetUniqueStatement(
+      base::StringPrintf("SELECT * FROM %s", metadata_table_name).c_str()));
+
+  while (metadata_reader.Step()) {
+    std::string primary_key = metadata_reader.ColumnString(0);
+
+    PrefetchDataMap::iterator it = data_map->find(primary_key);
+    if (it != data_map->end()) {
+      int64 last_visit = metadata_reader.ColumnInt64(1);
+      it->second.last_visit = base::Time::FromInternalValue(last_visit);
+    } else {
+      to_delete->push_back(primary_key);
+    }
+  }
+}
+
+bool ResourcePrefetchPredictorTables::UpdateDataHelper(
+    const PrefetchData& data) {
+  DCHECK(!data.primary_key.empty());
+
+  if (!StringsAreSmallerThanDBLimit(data)) {
+    UMA_HISTOGRAM_BOOLEAN("ResourcePrefetchPredictor.DbStringTooLong", true);
+    return false;
+  }
+
+  // Delete the older data from both the tables.
+  scoped_ptr<Statement> deleter(data.is_host() ?
+      GetHostResourceDeleteStatement() : GetUrlResourceDeleteStatement());
+  deleter->BindString(0, data.primary_key);
+  if (!deleter->Run())
+    return false;
+
+  deleter.reset(data.is_host() ? GetHostMetadataDeleteStatement() :
+      GetUrlMetadataDeleteStatement());
+  deleter->BindString(0, data.primary_key);
+  if (!deleter->Run())
+    return false;
+
+  // Add the new data to the tables.
+  const ResourceRows& resources = data.resources;
+  for (ResourceRows::const_iterator it = resources.begin();
+       it != resources.end(); ++it) {
+    scoped_ptr<Statement> resource_inserter(data.is_host() ?
+        GetHostResourceUpdateStatement() : GetUrlResourceUpdateStatement());
+    BindResourceRowToStatement(*it, data.primary_key, resource_inserter.get());
+    if (!resource_inserter->Run())
+      return false;
+  }
+
+  scoped_ptr<Statement> metadata_inserter(data.is_host() ?
+      GetHostMetadataUpdateStatement() : GetUrlMetadataUpdateStatement());
+  metadata_inserter->BindString(0, data.primary_key);
+  metadata_inserter->BindInt64(1, data.last_visit.ToInternalValue());
+  if (!metadata_inserter->Run())
+    return false;
+
+  return true;
+}
+
+void ResourcePrefetchPredictorTables::DeleteDataHelper(
+    PrefetchKeyType key_type,
+    const std::vector<std::string>& keys) {
+  bool is_host = key_type == PREFETCH_KEY_TYPE_HOST;
+
+  for (std::vector<std::string>::const_iterator it = keys.begin();
+       it != keys.end(); ++it) {
+    scoped_ptr<Statement> deleter(is_host ? GetHostResourceDeleteStatement() :
+        GetUrlResourceDeleteStatement());
+    deleter->BindString(0, *it);
+    deleter->Run();
+
+    deleter.reset(is_host ? GetHostMetadataDeleteStatement() :
+        GetUrlMetadataDeleteStatement());
+    deleter->BindString(0, *it);
+    deleter->Run();
+  }
+}
+
+bool ResourcePrefetchPredictorTables::StringsAreSmallerThanDBLimit(
+    const PrefetchData& data) const {
+  if (data.primary_key.length() > kMaxStringLength)
+    return false;
+
+  for (ResourceRows::const_iterator it = data.resources.begin();
+       it != data.resources.end(); ++it) {
+    if (it->resource_url.spec().length() > kMaxStringLength)
+      return false;
+  }
+  return true;
+}
+
+void ResourcePrefetchPredictorTables::CreateTableIfNonExistent() {
+  DCHECK_CURRENTLY_ON(BrowserThread::DB);
+  if (CantAccessDatabase())
+    return;
+
+  const char resource_table_creator[] =
+      "CREATE TABLE %s ( "
+      "main_page_url TEXT, "
+      "resource_url TEXT, "
+      "resource_type INTEGER, "
+      "number_of_hits INTEGER, "
+      "number_of_misses INTEGER, "
+      "consecutive_misses INTEGER, "
+      "average_position DOUBLE, "
+      "PRIMARY KEY(main_page_url, resource_url))";
+  const char* metadata_table_creator =
+      "CREATE TABLE %s ( "
+      "main_page_url TEXT, "
+      "last_visit_time INTEGER, "
+      "PRIMARY KEY(main_page_url))";
+
+  sql::Connection* db = DB();
+  bool success =
+      (db->DoesTableExist(kUrlResourceTableName) ||
+       db->Execute(base::StringPrintf(resource_table_creator,
+                                      kUrlResourceTableName).c_str())) &&
+      (db->DoesTableExist(kUrlMetadataTableName) ||
+       db->Execute(base::StringPrintf(metadata_table_creator,
+                                      kUrlMetadataTableName).c_str())) &&
+      (db->DoesTableExist(kHostResourceTableName) ||
+       db->Execute(base::StringPrintf(resource_table_creator,
+                                      kHostResourceTableName).c_str())) &&
+      (db->DoesTableExist(kHostMetadataTableName) ||
+       db->Execute(base::StringPrintf(metadata_table_creator,
+                                      kHostMetadataTableName).c_str()));
+
+  if (!success)
+    ResetDB();
+}
+
+void ResourcePrefetchPredictorTables::LogDatabaseStats()  {
+  DCHECK_CURRENTLY_ON(BrowserThread::DB);
+  if (CantAccessDatabase())
+    return;
+
+  Statement statement(DB()->GetUniqueStatement(
+      base::StringPrintf("SELECT count(*) FROM %s",
+                         kUrlResourceTableName).c_str()));
+  if (statement.Step())
+    UMA_HISTOGRAM_COUNTS("ResourcePrefetchPredictor.UrlTableRowCount",
+                         statement.ColumnInt(0));
+
+  statement.Assign(DB()->GetUniqueStatement(
+      base::StringPrintf("SELECT count(*) FROM %s",
+                         kHostResourceTableName).c_str()));
+  if (statement.Step())
+    UMA_HISTOGRAM_COUNTS("ResourcePrefetchPredictor.HostTableRowCount",
+                         statement.ColumnInt(0));
+}
+
+Statement*
+    ResourcePrefetchPredictorTables::GetUrlResourceDeleteStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf("DELETE FROM %s WHERE main_page_url=?",
+                         kUrlResourceTableName).c_str()));
+}
+
+Statement*
+    ResourcePrefetchPredictorTables::GetUrlResourceUpdateStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf(
+          "INSERT INTO %s "
+          "(main_page_url, resource_url, resource_type, number_of_hits, "
+          "number_of_misses, consecutive_misses, average_position) "
+          "VALUES (?,?,?,?,?,?,?)", kUrlResourceTableName).c_str()));
+}
+
+Statement*
+    ResourcePrefetchPredictorTables::GetUrlMetadataDeleteStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf("DELETE FROM %s WHERE main_page_url=?",
+                         kUrlMetadataTableName).c_str()));
+}
+
+Statement*
+    ResourcePrefetchPredictorTables::GetUrlMetadataUpdateStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf(
+          "INSERT INTO %s (main_page_url, last_visit_time) VALUES (?,?)",
+          kUrlMetadataTableName).c_str()));
+}
+
+Statement*
+    ResourcePrefetchPredictorTables::GetHostResourceDeleteStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf("DELETE FROM %s WHERE main_page_url=?",
+                         kHostResourceTableName).c_str()));
+}
+
+Statement*
+    ResourcePrefetchPredictorTables::GetHostResourceUpdateStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf(
+          "INSERT INTO %s "
+          "(main_page_url, resource_url, resource_type, number_of_hits, "
+          "number_of_misses, consecutive_misses, average_position) "
+          "VALUES (?,?,?,?,?,?,?)", kHostResourceTableName).c_str()));
+}
+
+Statement*
+    ResourcePrefetchPredictorTables::GetHostMetadataDeleteStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf("DELETE FROM %s WHERE main_page_url=?",
+                         kHostMetadataTableName).c_str()));
+}
+
+Statement* ResourcePrefetchPredictorTables::GetHostMetadataUpdateStatement() {
+  return new Statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf(
+          "INSERT INTO %s (main_page_url, last_visit_time) VALUES (?,?)",
+          kHostMetadataTableName).c_str()));
+}
+
+}  // namespace predictors