Remove the speculative resource prefetching code. This was experimental code added 1.5 years ago an…

chrome/browser/predictors/resource_prefetch_predictor_tables.cc

Index: chrome/browser/predictors/resource_prefetch_predictor_tables.cc
===================================================================
--- chrome/browser/predictors/resource_prefetch_predictor_tables.cc	(revision 243063)
+++ chrome/browser/predictors/resource_prefetch_predictor_tables.cc	(working copy)
@@ -1,514 +0,0 @@
-// Copyright (c) 2012 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 = ResourceType::FromInt(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(ResourceType::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,
-    ResourceType::Type 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 ResourceType::STYLESHEET:
-    case ResourceType::SCRIPT:
-      score = (2 * kMaxResourcesPerType) - average_position;
-      break;
-
-    case ResourceType::IMAGE:
-      score = kMaxResourcesPerType - average_position;
-      break;
-
-    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) {
-  CHECK(BrowserThread::CurrentlyOn(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) {
-  CHECK(BrowserThread::CurrentlyOn(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) {
-  CHECK(BrowserThread::CurrentlyOn(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) {
-  CHECK(BrowserThread::CurrentlyOn(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() {
-  CHECK(BrowserThread::CurrentlyOn(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()  {
-  CHECK(BrowserThread::CurrentlyOn(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