Seculative resource prefetching for URLs CL.

chrome/browser/predictors/resource_prefetch_predictor_tables.cc

+// 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 "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "base/stringprintf.h"
+#include "content/public/browser/browser_thread.h"
+#include "sql/statement.h"
+
+using content::BrowserThread;
+
+namespace {
+
+const char kResourcePredictorUrlTableName[] = "resource_prefetch_predictor_url";
+
+// The maximum length allowed for strings in the database.
+const size_t kMaxURLLength = 2048;
+
+void BindUrlTableRowToStatement(
+    const predictors::ResourcePrefetchPredictorTables::UrlTableRow& row,
+    sql::Statement* statement) {
+  statement->BindString(0, row.main_frame_url.spec().substr(0, kMaxURLLength));
+  statement->BindString(1, row.resource_url.spec().substr(0, kMaxURLLength));
+  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 StepAndInitializeUrlTableRow(
+    sql::Statement* statement,
+    predictors::ResourcePrefetchPredictorTables::UrlTableRow* row) {
+  if (!statement->Step())
+    return false;
+
+  row->main_frame_url = GURL(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 {
+
+ResourcePrefetchPredictorTables::UrlTableRow::UrlTableRow()
+    : resource_type(ResourceType::LAST_TYPE),
+      number_of_hits(0),
+      number_of_misses(0),
+      consecutive_misses(0),
+      average_position(0.0),
+      score(0.0) {
+}
+
+ResourcePrefetchPredictorTables::UrlTableRow::UrlTableRow(
+    const UrlTableRow& other)
+        : main_frame_url(other.main_frame_url),
+          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) {
+}
+
+void ResourcePrefetchPredictorTables::UrlTableRow::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::UrlTableRowSorter::operator()(
+    const UrlTableRow& x,
+    const UrlTableRow& y) const {
+  return x.score > y.score;
+}
+
+ResourcePrefetchPredictorTables::ResourcePrefetchPredictorTables()
+    : PredictorTableBase() {
+}
+
+ResourcePrefetchPredictorTables::~ResourcePrefetchPredictorTables() {
+}
+
+void ResourcePrefetchPredictorTables::GetAllRows(UrlTableRows* url_row_buffer) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (CantAccessDatabase())
+    return;
+
+  CHECK(url_row_buffer && url_row_buffer->empty());
+  sql::Statement url_statement(DB()->GetCachedStatement(SQL_FROM_HERE,
+      base::StringPrintf("SELECT * FROM %s",
+                         kResourcePredictorUrlTableName).c_str()));
+
+  UrlTableRow url_row;
+  while (StepAndInitializeUrlTableRow(&url_statement, &url_row)) {
+    url_row.UpdateScore();
+    url_row_buffer->push_back(url_row);
+  }
+}
+
+void ResourcePrefetchPredictorTables::UpdateRowsForUrl(
+    const GURL& main_page_url,
+    const UrlTableRows& row_buffer) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (CantAccessDatabase())
+    return;
+
+  DB()->BeginTransaction();
+
+  sql::Statement delete_statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf("DELETE FROM %s WHERE main_page_url=?",
+                         kResourcePredictorUrlTableName).c_str()));
+  delete_statement.BindString(0, main_page_url.spec());
+  if (!delete_statement.Run()) {
+    DB()->RollbackTransaction();
+    return;
+  }
+
+  for (UrlTableRows::const_iterator it = row_buffer.begin();
+       it != row_buffer.end(); ++it) {
+    sql::Statement add_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 (?,?,?,?,?,?,?)",
+                kResourcePredictorUrlTableName).c_str()));
+    BindUrlTableRowToStatement(*it, &add_statement);
+    if (!add_statement.Run()) {
+      DB()->RollbackTransaction();
+      return;
+    }
+  }
+
+  DB()->CommitTransaction();
+}
+
+void ResourcePrefetchPredictorTables::DeleteRowsForUrls(
+    const std::vector<GURL>& urls) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (CantAccessDatabase())
+    return;
+
+  // These do not need to be a transaction.
+  for (std::vector<GURL>::const_iterator it = urls.begin(); it != urls.end();
+       ++it) {
+    sql::Statement delete_statement(DB()->GetCachedStatement(
+        SQL_FROM_HERE,
+        base::StringPrintf("DELETE FROM %s WHERE main_page_url=?",
+                           kResourcePredictorUrlTableName).c_str()));
+    delete_statement.BindString(0, it->spec());
+    delete_statement.Run();
+  }
+}
+
+void ResourcePrefetchPredictorTables::DeleteAllRows() {
+  if (CantAccessDatabase())
+    return;
+
+  sql::Statement statement(DB()->GetCachedStatement(
+      SQL_FROM_HERE,
+      base::StringPrintf("DELETE FROM %s",
+                         kResourcePredictorUrlTableName).c_str()));
+  statement.Run();
+}
+
+void ResourcePrefetchPredictorTables::CreateTableIfNonExistent() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (CantAccessDatabase())
+    return;
+
+  std::string url_table_creation_statement = base::StringPrintf(
+      "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))",
+      kResourcePredictorUrlTableName);
+
+  if (!DB()->DoesTableExist(kResourcePredictorUrlTableName) &&
+      !DB()->Execute(url_table_creation_statement.c_str()))
+    ResetDB();
+}
+
+void ResourcePrefetchPredictorTables::LogDatabaseStats()  {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (CantAccessDatabase())
+    return;
+
+  sql::Statement url_statement(DB()->GetUniqueStatement(
+      base::StringPrintf("SELECT count(*) FROM %s",
+                         kResourcePredictorUrlTableName).c_str()));
+  if (url_statement.Step())
+    UMA_HISTOGRAM_COUNTS("ResourcePrefetchPredictor.UrlTableRowCount",
+                         url_statement.ColumnInt(0));
+}
+
+}  // namespace predictors