chrome/browser/history/thumbnail_database.cc - chromium/src - Git at Google

 // Copyright (c) 2006-2008 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/history/thumbnail_database.h"

 #include "base/file_util.h"
 #include "base/gfx/jpeg_codec.h"
 #include "base/time.h"
 #include "base/string_util.h"
 #include "chrome/browser/history/history_publisher.h"
 #include "chrome/browser/history/url_database.h"
 #include "chrome/common/sqlite_utils.h"
 #include "chrome/common/thumbnail_score.h"
 #include "third_party/skia/include/core/SkBitmap.h"

 using base::Time;

 namespace history {

 // Version number of the database.
 static const int kCurrentVersionNumber = 3;
 static const int kCompatibleVersionNumber = 3;

 ThumbnailDatabase::ThumbnailDatabase()
     : db_(NULL),
       statement_cache_(NULL),
       transaction_nesting_(0),
       history_publisher_(NULL) {
 }

 ThumbnailDatabase::~ThumbnailDatabase() {
   // The DBCloseScoper will delete the DB and the cache.
 }

 InitStatus ThumbnailDatabase::Init(const FilePath& db_name,
                                    const HistoryPublisher* history_publisher) {
   history_publisher_ = history_publisher;

   // OpenSqliteDb uses the narrow version of open, so the resulting DB is in
   // UTF-8.
   if (OpenSqliteDb(db_name, &db_) != SQLITE_OK)
     return INIT_FAILURE;

   // Set the database page size to something  larger to give us
   // better performance (we're typically seek rather than bandwidth limited).
   // This only has an effect before any tables have been created, otherwise
   // this is a NOP. Must be a power of 2 and a max of 8192. We use a bigger
   // one because we're storing larger data (4-16K) in it, so we want a few
   // blocks per element.
   sqlite3_exec(db_, "PRAGMA page_size=4096", NULL, NULL, NULL);

   // The UI is generally designed to work well when the thumbnail database is
   // slow, so we can tolerate much less caching. The file is also very large
   // and so caching won't save a significant percentage of it for us,
   // reducing the benefit of caching in the first place. With the default cache
   // size of 2000 pages, it will take >8MB of memory, so reducing it can be a
   // big savings.
   sqlite3_exec(db_, "PRAGMA cache_size=64", NULL, NULL, NULL);

   // Run the database in exclusive mode. Nobody else should be accessing the
   // database while we're running, and this will give somewhat improved perf.
   sqlite3_exec(db_, "PRAGMA locking_mode=EXCLUSIVE", NULL, NULL, NULL);

   statement_cache_ = new SqliteStatementCache;
   DBCloseScoper scoper(&db_, &statement_cache_);

   // Scope initialization in a transaction so we can't be partially initialized.
   SQLTransaction transaction(db_);
   transaction.Begin();

   // Create the tables.
   if (!meta_table_.Init(std::string(), kCurrentVersionNumber,
                         kCompatibleVersionNumber, db_) ||
       !InitThumbnailTable() ||
       !InitFavIconsTable(false))
     return INIT_FAILURE;
   InitFavIconsIndex();

   // Version check. We should not encounter a database too old for us to handle
   // in the wild, so we try to continue in that case.
   if (meta_table_.GetCompatibleVersionNumber() > kCurrentVersionNumber) {
     LOG(WARNING) << "Thumbnail database is too new.";
     return INIT_TOO_NEW;
   }

   int cur_version = meta_table_.GetVersionNumber();
   if (cur_version == 2) {
     if (!UpgradeToVersion3()) {
       LOG(WARNING) << "Unable to update to thumbnail database to version 3.";
       return INIT_FAILURE;
     }
     ++cur_version;
   }

   LOG_IF(WARNING, cur_version < kCurrentVersionNumber) <<
       "Thumbnail database version " << cur_version << " is too old to handle.";

   // Initialization is complete.
   if (transaction.Commit() != SQLITE_OK)
     return INIT_FAILURE;

   // Initialize the statement cache and the scoper to automatically close it.
   statement_cache_->set_db(db_);
   scoper.Detach();
   close_scoper_.Attach(&db_, &statement_cache_);

   // The following code is useful in debugging the thumbnail database. Upon
   // startup, it will spit out a file for each thumbnail in the database so you
   // can open them in an external viewer. Insert the path name on your system
   // into the string below (I recommend using a blank directory since there may
   // be a lot of files).
 #if 0
   SQLStatement statement;
   statement.prepare(db_, "SELECT id, image_data FROM favicons");
   while (statement.step() == SQLITE_ROW) {
     int idx = statement.column_int(0);
     std::vector<unsigned char> data;
     statement.column_blob_as_vector(1, &data);

     char filename[256];
     sprintf(filename, "<<< YOUR PATH HERE >>>\\%d.png", idx);
     if (!data.empty()) {
       file_util::WriteFile(ASCIIToWide(std::string(filename)),
                            reinterpret_cast<char*>(&data[0]),
                            data.size());
     }
   }
 #endif

   return INIT_OK;
 }

 bool ThumbnailDatabase::InitThumbnailTable() {
   if (!DoesSqliteTableExist(db_, "thumbnails")) {
     if (sqlite3_exec(db_, "CREATE TABLE thumbnails ("
         "url_id INTEGER PRIMARY KEY,"
         "boring_score DOUBLE DEFAULT 1.0,"
         "good_clipping INTEGER DEFAULT 0,"
         "at_top INTEGER DEFAULT 0,"
         "last_updated INTEGER DEFAULT 0,"
         "data BLOB)", NULL, NULL, NULL) != SQLITE_OK)
       return false;
   }
   return true;
 }

 bool ThumbnailDatabase::UpgradeToVersion3() {
   // sqlite doesn't like the "ALTER TABLE xxx ADD (column_one, two,
   // three)" syntax, so list out the commands we need to execute:
   const char* alterations[] = {
     "ALTER TABLE thumbnails ADD boring_score DOUBLE DEFAULT 1.0",
     "ALTER TABLE thumbnails ADD good_clipping INTEGER DEFAULT 0",
     "ALTER TABLE thumbnails ADD at_top INTEGER DEFAULT 0",
     "ALTER TABLE thumbnails ADD last_updated INTEGER DEFAULT 0",
     NULL
   };

   for (int i = 0; alterations[i] != NULL; ++i) {
     if (sqlite3_exec(db_, alterations[i],
                      NULL, NULL, NULL) != SQLITE_OK) {
       NOTREACHED();
       return false;
     }
   }

   meta_table_.SetVersionNumber(3);
   meta_table_.SetCompatibleVersionNumber(std::min(3, kCompatibleVersionNumber));
   return true;
 }

 bool ThumbnailDatabase::RecreateThumbnailTable() {
   if (sqlite3_exec(db_, "DROP TABLE thumbnails", NULL, NULL, NULL) != SQLITE_OK)
     return false;
   return InitThumbnailTable();
 }

 bool ThumbnailDatabase::InitFavIconsTable(bool is_temporary) {
   // Note: if you update the schema, don't forget to update
   // CopyToTemporaryFaviconTable as well.
   const char* name = is_temporary ? "temp_favicons" : "favicons";
   if (!DoesSqliteTableExist(db_, name)) {
     std::string sql;
     sql.append("CREATE TABLE ");
     sql.append(name);
     sql.append("("
                "id INTEGER PRIMARY KEY,"
                "url LONGVARCHAR NOT NULL,"
                "last_updated INTEGER DEFAULT 0,"
                "image_data BLOB)");
     if (sqlite3_exec(db_, sql.c_str(), NULL, NULL, NULL) != SQLITE_OK)
       return false;
   }
   return true;
 }

 void ThumbnailDatabase::InitFavIconsIndex() {
   // Add an index on the url column. We ignore errors. Since this is always
   // called during startup, the index will normally already exist.
   sqlite3_exec(db_, "CREATE INDEX favicons_url ON favicons(url)",
                NULL, NULL, NULL);
 }

 void ThumbnailDatabase::BeginTransaction() {
   DCHECK(db_);
   if (transaction_nesting_ == 0) {
     int rv = sqlite3_exec(db_, "BEGIN TRANSACTION", NULL, NULL, NULL);
     DCHECK(rv == SQLITE_OK) << "Failed to begin transaction";
   }
   transaction_nesting_++;
 }

 void ThumbnailDatabase::CommitTransaction() {
   DCHECK(db_);
   DCHECK(transaction_nesting_ > 0) << "Committing too many transaction";
   transaction_nesting_--;
   if (transaction_nesting_ == 0) {
     int rv = sqlite3_exec(db_, "COMMIT", NULL, NULL, NULL);
     DCHECK(rv == SQLITE_OK) << "Failed to commit transaction";
   }
 }

 void ThumbnailDatabase::Vacuum() {
   DCHECK(transaction_nesting_ == 0) <<
       "Can not have a transaction when vacuuming.";
   sqlite3_exec(db_, "VACUUM", NULL, NULL, NULL);
 }

 void ThumbnailDatabase::SetPageThumbnail(
     const GURL& url,
     URLID id,
     const SkBitmap& thumbnail,
     const ThumbnailScore& score,
     const Time& time) {
   if (!thumbnail.isNull()) {
     bool add_thumbnail = true;
     ThumbnailScore current_score;
     if (ThumbnailScoreForId(id, &current_score)) {
       add_thumbnail = ShouldReplaceThumbnailWith(current_score, score);
     }

     if (add_thumbnail) {
       SQLITE_UNIQUE_STATEMENT(
           statement, *statement_cache_,
           "INSERT OR REPLACE INTO thumbnails "
           "(url_id, boring_score, good_clipping, at_top, last_updated, data) "
           "VALUES (?,?,?,?,?,?)");
       if (!statement.is_valid())
         return;

       // We use 90 quality (out of 100) which is pretty high, because
       // we're very sensitive to artifacts for these small sized,
       // highly detailed images.
       std::vector<unsigned char> jpeg_data;
       SkAutoLockPixels thumbnail_lock(thumbnail);
       bool encoded = JPEGCodec::Encode(
           reinterpret_cast<unsigned char*>(thumbnail.getAddr32(0, 0)),
           JPEGCodec::FORMAT_BGRA, thumbnail.width(),
           thumbnail.height(),
           static_cast<int>(thumbnail.rowBytes()), 90,
           &jpeg_data);

       if (encoded) {
         statement->bind_int64(0, id);
         statement->bind_double(1, score.boring_score);
         statement->bind_bool(2, score.good_clipping);
         statement->bind_bool(3, score.at_top);
         statement->bind_int64(4, score.time_at_snapshot.ToTimeT());
         statement->bind_blob(5, &jpeg_data[0],
                              static_cast<int>(jpeg_data.size()));
         if (statement->step() != SQLITE_DONE)
           DLOG(WARNING) << "Unable to insert thumbnail";
       }

       // Publish the thumbnail to any indexers listening to us.
       // The tests may send an invalid url. Hence avoid publishing those.
       if (url.is_valid() && history_publisher_ != NULL)
         history_publisher_->PublishPageThumbnail(jpeg_data, url, time);
     }
   } else {
     if ( !DeleteThumbnail(id) )
       DLOG(WARNING) << "Unable to delete thumbnail";
   }
 }

 bool ThumbnailDatabase::GetPageThumbnail(URLID id,
                                          std::vector<unsigned char>* data) {
   SQLITE_UNIQUE_STATEMENT(
       statement, *statement_cache_,
       "SELECT data FROM thumbnails WHERE url_id=?");
   if (!statement.is_valid())
     return false;

   statement->bind_int64(0, id);
   if (statement->step() != SQLITE_ROW)
     return false;  // don't have a thumbnail for this ID

   return statement->column_blob_as_vector(0, data);
 }

 bool ThumbnailDatabase::DeleteThumbnail(URLID id) {
   SQLITE_UNIQUE_STATEMENT(
       statement, *statement_cache_,
       "DELETE FROM thumbnails WHERE url_id = ?");
   if (!statement.is_valid())
     return false;

   statement->bind_int64(0, id);
   return statement->step() == SQLITE_DONE;
 }

 bool ThumbnailDatabase::ThumbnailScoreForId(
     URLID id,
     ThumbnailScore* score) {
   // Fetch the current thumbnail's information to make sure we
   // aren't replacing a good thumbnail with one that's worse.
   SQLITE_UNIQUE_STATEMENT(
       select_statement, *statement_cache_,
       "SELECT boring_score, good_clipping, at_top, last_updated "
       "FROM thumbnails WHERE url_id=?");
   if (!select_statement.is_valid()) {
     NOTREACHED() << "Couldn't build select statement!";
   } else {
     select_statement->bind_int64(0, id);
     if (select_statement->step() == SQLITE_ROW) {
       double current_boring_score = select_statement->column_double(0);
       bool current_clipping = select_statement->column_bool(1);
       bool current_at_top = select_statement->column_bool(2);
       Time last_updated = Time::FromTimeT(select_statement->column_int64(3));
       *score = ThumbnailScore(current_boring_score, current_clipping,
                               current_at_top, last_updated);
       return true;
     }
   }

   return false;
 }

 bool ThumbnailDatabase::SetFavIcon(URLID icon_id,
                                    const std::vector<unsigned char>& icon_data,
                                    Time time) {
   DCHECK(icon_id);
   if (icon_data.size()) {
     SQLITE_UNIQUE_STATEMENT(
         statement, *statement_cache_,
         "UPDATE favicons SET image_data=?, last_updated=? WHERE id=?");
     if (!statement.is_valid())
       return 0;

     statement->bind_blob(0, &icon_data.front(),
                         static_cast<int>(icon_data.size()));
     statement->bind_int64(1, time.ToTimeT());
     statement->bind_int64(2, icon_id);
     return statement->step() == SQLITE_DONE;
   } else {
     SQLITE_UNIQUE_STATEMENT(
         statement, *statement_cache_,
         "UPDATE favicons SET image_data=NULL, last_updated=? WHERE id=?");
     if (!statement.is_valid())
       return 0;

     statement->bind_int64(0, time.ToTimeT());
     statement->bind_int64(1, icon_id);
     return statement->step() == SQLITE_DONE;
   }
 }

 bool ThumbnailDatabase::SetFavIconLastUpdateTime(FavIconID icon_id,
                                                  const Time& time) {
   SQLITE_UNIQUE_STATEMENT(
       statement, *statement_cache_,
       "UPDATE favicons SET last_updated=? WHERE id=?");
   if (!statement.is_valid())
     return 0;

   statement->bind_int64(0, time.ToTimeT());
   statement->bind_int64(1, icon_id);
   return statement->step() == SQLITE_DONE;
 }

 FavIconID ThumbnailDatabase::GetFavIconIDForFavIconURL(const GURL& icon_url) {
   SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
                           "SELECT id FROM favicons WHERE url=?");
   if (!statement.is_valid())
     return 0;

   statement->bind_string(0, URLDatabase::GURLToDatabaseURL(icon_url));
   if (statement->step() != SQLITE_ROW)
     return 0;  // not cached

   return statement->column_int64(0);
 }

 bool ThumbnailDatabase::GetFavIcon(
     FavIconID icon_id,
     Time* last_updated,
     std::vector<unsigned char>* png_icon_data,
     GURL* icon_url) {
   DCHECK(icon_id);

   SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
       "SELECT last_updated, image_data, url FROM favicons WHERE id=?");
   if (!statement.is_valid())
     return 0;

   statement->bind_int64(0, icon_id);

   if (statement->step() != SQLITE_ROW) {
     // No entry for the id.
     return false;
   }

   *last_updated = Time::FromTimeT(statement->column_int64(0));
   if (statement->column_bytes(1) > 0)
     statement->column_blob_as_vector(1, png_icon_data);
   if (icon_url)
     *icon_url = GURL(statement->column_string(2));

   return true;
 }

 FavIconID ThumbnailDatabase::AddFavIcon(const GURL& icon_url) {
   SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
                           "INSERT INTO favicons (url) VALUES (?)");
   if (!statement.is_valid())
     return 0;

   statement->bind_string(0, URLDatabase::GURLToDatabaseURL(icon_url));
   if (statement->step() != SQLITE_DONE)
     return 0;
   return sqlite3_last_insert_rowid(db_);
 }

 bool ThumbnailDatabase::DeleteFavIcon(FavIconID id) {
   SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
                           "DELETE FROM favicons WHERE id = ?");
   if (!statement.is_valid())
     return false;
   statement->bind_int64(0, id);
   return statement->step() == SQLITE_DONE;
 }

 FavIconID ThumbnailDatabase::CopyToTemporaryFavIconTable(FavIconID source) {
   SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
       "INSERT INTO temp_favicons (url, last_updated, image_data)"
       "SELECT url, last_updated, image_data "
       "FROM favicons WHERE id = ?");
   if (!statement.is_valid())
     return 0;
   statement->bind_int64(0, source);
   if (statement->step() != SQLITE_DONE)
     return 0;

   // We return the ID of the newly inserted favicon.
   return sqlite3_last_insert_rowid(db_);
 }

 bool ThumbnailDatabase::CommitTemporaryFavIconTable() {
   // Delete the old favicons table.
   if (sqlite3_exec(db_, "DROP TABLE favicons", NULL, NULL, NULL) != SQLITE_OK)
     return false;

   // Rename the temporary one.
   if (sqlite3_exec(db_, "ALTER TABLE temp_favicons RENAME TO favicons",
                    NULL, NULL, NULL) != SQLITE_OK)
     return false;

   // The renamed table needs the index (the temporary table doesn't have one).
   InitFavIconsIndex();
   return true;
 }

 }  // namespace history
	// Copyright (c) 2006-2008 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/history/thumbnail_database.h"

	#include "base/file_util.h"
	#include "base/gfx/jpeg_codec.h"
	#include "base/time.h"
	#include "base/string_util.h"
	#include "chrome/browser/history/history_publisher.h"
	#include "chrome/browser/history/url_database.h"
	#include "chrome/common/sqlite_utils.h"
	#include "chrome/common/thumbnail_score.h"
	#include "third_party/skia/include/core/SkBitmap.h"

	using base::Time;

	namespace history {

	// Version number of the database.
	static const int kCurrentVersionNumber = 3;
	static const int kCompatibleVersionNumber = 3;

	ThumbnailDatabase::ThumbnailDatabase()
	: db_(NULL),
	statement_cache_(NULL),
	transaction_nesting_(0),
	history_publisher_(NULL) {
	}

	ThumbnailDatabase::~ThumbnailDatabase() {
	// The DBCloseScoper will delete the DB and the cache.
	}

	InitStatus ThumbnailDatabase::Init(const FilePath& db_name,
	const HistoryPublisher* history_publisher) {
	history_publisher_ = history_publisher;

	// OpenSqliteDb uses the narrow version of open, so the resulting DB is in
	// UTF-8.
	if (OpenSqliteDb(db_name, &db_) != SQLITE_OK)
	return INIT_FAILURE;

	// Set the database page size to something larger to give us
	// better performance (we're typically seek rather than bandwidth limited).
	// This only has an effect before any tables have been created, otherwise
	// this is a NOP. Must be a power of 2 and a max of 8192. We use a bigger
	// one because we're storing larger data (4-16K) in it, so we want a few
	// blocks per element.
	sqlite3_exec(db_, "PRAGMA page_size=4096", NULL, NULL, NULL);

	// The UI is generally designed to work well when the thumbnail database is
	// slow, so we can tolerate much less caching. The file is also very large
	// and so caching won't save a significant percentage of it for us,
	// reducing the benefit of caching in the first place. With the default cache
	// size of 2000 pages, it will take >8MB of memory, so reducing it can be a
	// big savings.
	sqlite3_exec(db_, "PRAGMA cache_size=64", NULL, NULL, NULL);

	// Run the database in exclusive mode. Nobody else should be accessing the
	// database while we're running, and this will give somewhat improved perf.
	sqlite3_exec(db_, "PRAGMA locking_mode=EXCLUSIVE", NULL, NULL, NULL);

	statement_cache_ = new SqliteStatementCache;
	DBCloseScoper scoper(&db_, &statement_cache_);

	// Scope initialization in a transaction so we can't be partially initialized.
	SQLTransaction transaction(db_);
	transaction.Begin();

	// Create the tables.
	if (!meta_table_.Init(std::string(), kCurrentVersionNumber,
	kCompatibleVersionNumber, db_) \|\|
	!InitThumbnailTable() \|\|
	!InitFavIconsTable(false))
	return INIT_FAILURE;
	InitFavIconsIndex();

	// Version check. We should not encounter a database too old for us to handle
	// in the wild, so we try to continue in that case.
	if (meta_table_.GetCompatibleVersionNumber() > kCurrentVersionNumber) {
	LOG(WARNING) << "Thumbnail database is too new.";
	return INIT_TOO_NEW;
	}

	int cur_version = meta_table_.GetVersionNumber();
	if (cur_version == 2) {
	if (!UpgradeToVersion3()) {
	LOG(WARNING) << "Unable to update to thumbnail database to version 3.";
	return INIT_FAILURE;
	}
	++cur_version;
	}

	LOG_IF(WARNING, cur_version < kCurrentVersionNumber) <<
	"Thumbnail database version " << cur_version << " is too old to handle.";

	// Initialization is complete.
	if (transaction.Commit() != SQLITE_OK)
	return INIT_FAILURE;

	// Initialize the statement cache and the scoper to automatically close it.
	statement_cache_->set_db(db_);
	scoper.Detach();
	close_scoper_.Attach(&db_, &statement_cache_);

	// The following code is useful in debugging the thumbnail database. Upon
	// startup, it will spit out a file for each thumbnail in the database so you
	// can open them in an external viewer. Insert the path name on your system
	// into the string below (I recommend using a blank directory since there may
	// be a lot of files).
	#if 0
	SQLStatement statement;
	statement.prepare(db_, "SELECT id, image_data FROM favicons");
	while (statement.step() == SQLITE_ROW) {
	int idx = statement.column_int(0);
	std::vector<unsigned char> data;
	statement.column_blob_as_vector(1, &data);

	char filename[256];
	sprintf(filename, "<<< YOUR PATH HERE >>>\\%d.png", idx);
	if (!data.empty()) {
	file_util::WriteFile(ASCIIToWide(std::string(filename)),
	reinterpret_cast<char*>(&data[0]),
	data.size());
	}
	}
	#endif

	return INIT_OK;
	}

	bool ThumbnailDatabase::InitThumbnailTable() {
	if (!DoesSqliteTableExist(db_, "thumbnails")) {
	if (sqlite3_exec(db_, "CREATE TABLE thumbnails ("
	"url_id INTEGER PRIMARY KEY,"
	"boring_score DOUBLE DEFAULT 1.0,"
	"good_clipping INTEGER DEFAULT 0,"
	"at_top INTEGER DEFAULT 0,"
	"last_updated INTEGER DEFAULT 0,"
	"data BLOB)", NULL, NULL, NULL) != SQLITE_OK)
	return false;
	}
	return true;
	}

	bool ThumbnailDatabase::UpgradeToVersion3() {
	// sqlite doesn't like the "ALTER TABLE xxx ADD (column_one, two,
	// three)" syntax, so list out the commands we need to execute:
	const char* alterations[] = {
	"ALTER TABLE thumbnails ADD boring_score DOUBLE DEFAULT 1.0",
	"ALTER TABLE thumbnails ADD good_clipping INTEGER DEFAULT 0",
	"ALTER TABLE thumbnails ADD at_top INTEGER DEFAULT 0",
	"ALTER TABLE thumbnails ADD last_updated INTEGER DEFAULT 0",
	NULL
	};

	for (int i = 0; alterations[i] != NULL; ++i) {
	if (sqlite3_exec(db_, alterations[i],
	NULL, NULL, NULL) != SQLITE_OK) {
	NOTREACHED();
	return false;
	}
	}

	meta_table_.SetVersionNumber(3);
	meta_table_.SetCompatibleVersionNumber(std::min(3, kCompatibleVersionNumber));
	return true;
	}

	bool ThumbnailDatabase::RecreateThumbnailTable() {
	if (sqlite3_exec(db_, "DROP TABLE thumbnails", NULL, NULL, NULL) != SQLITE_OK)
	return false;
	return InitThumbnailTable();
	}

	bool ThumbnailDatabase::InitFavIconsTable(bool is_temporary) {
	// Note: if you update the schema, don't forget to update
	// CopyToTemporaryFaviconTable as well.
	const char* name = is_temporary ? "temp_favicons" : "favicons";
	if (!DoesSqliteTableExist(db_, name)) {
	std::string sql;
	sql.append("CREATE TABLE ");
	sql.append(name);
	sql.append("("
	"id INTEGER PRIMARY KEY,"
	"url LONGVARCHAR NOT NULL,"
	"last_updated INTEGER DEFAULT 0,"
	"image_data BLOB)");
	if (sqlite3_exec(db_, sql.c_str(), NULL, NULL, NULL) != SQLITE_OK)
	return false;
	}
	return true;
	}

	void ThumbnailDatabase::InitFavIconsIndex() {
	// Add an index on the url column. We ignore errors. Since this is always
	// called during startup, the index will normally already exist.
	sqlite3_exec(db_, "CREATE INDEX favicons_url ON favicons(url)",
	NULL, NULL, NULL);
	}

	void ThumbnailDatabase::BeginTransaction() {
	DCHECK(db_);
	if (transaction_nesting_ == 0) {
	int rv = sqlite3_exec(db_, "BEGIN TRANSACTION", NULL, NULL, NULL);
	DCHECK(rv == SQLITE_OK) << "Failed to begin transaction";
	}
	transaction_nesting_++;
	}

	void ThumbnailDatabase::CommitTransaction() {
	DCHECK(db_);
	DCHECK(transaction_nesting_ > 0) << "Committing too many transaction";
	transaction_nesting_--;
	if (transaction_nesting_ == 0) {
	int rv = sqlite3_exec(db_, "COMMIT", NULL, NULL, NULL);
	DCHECK(rv == SQLITE_OK) << "Failed to commit transaction";
	}
	}

	void ThumbnailDatabase::Vacuum() {
	DCHECK(transaction_nesting_ == 0) <<
	"Can not have a transaction when vacuuming.";
	sqlite3_exec(db_, "VACUUM", NULL, NULL, NULL);
	}

	void ThumbnailDatabase::SetPageThumbnail(
	const GURL& url,
	URLID id,
	const SkBitmap& thumbnail,
	const ThumbnailScore& score,
	const Time& time) {
	if (!thumbnail.isNull()) {
	bool add_thumbnail = true;
	ThumbnailScore current_score;
	if (ThumbnailScoreForId(id, &current_score)) {
	add_thumbnail = ShouldReplaceThumbnailWith(current_score, score);
	}

	if (add_thumbnail) {
	SQLITE_UNIQUE_STATEMENT(
	statement, *statement_cache_,
	"INSERT OR REPLACE INTO thumbnails "
	"(url_id, boring_score, good_clipping, at_top, last_updated, data) "
	"VALUES (?,?,?,?,?,?)");
	if (!statement.is_valid())
	return;

	// We use 90 quality (out of 100) which is pretty high, because
	// we're very sensitive to artifacts for these small sized,
	// highly detailed images.
	std::vector<unsigned char> jpeg_data;
	SkAutoLockPixels thumbnail_lock(thumbnail);
	bool encoded = JPEGCodec::Encode(
	reinterpret_cast<unsigned char*>(thumbnail.getAddr32(0, 0)),
	JPEGCodec::FORMAT_BGRA, thumbnail.width(),
	thumbnail.height(),
	static_cast<int>(thumbnail.rowBytes()), 90,
	&jpeg_data);

	if (encoded) {
	statement->bind_int64(0, id);
	statement->bind_double(1, score.boring_score);
	statement->bind_bool(2, score.good_clipping);
	statement->bind_bool(3, score.at_top);
	statement->bind_int64(4, score.time_at_snapshot.ToTimeT());
	statement->bind_blob(5, &jpeg_data[0],
	static_cast<int>(jpeg_data.size()));
	if (statement->step() != SQLITE_DONE)
	DLOG(WARNING) << "Unable to insert thumbnail";
	}

	// Publish the thumbnail to any indexers listening to us.
	// The tests may send an invalid url. Hence avoid publishing those.
	if (url.is_valid() && history_publisher_ != NULL)
	history_publisher_->PublishPageThumbnail(jpeg_data, url, time);
	}
	} else {
	if ( !DeleteThumbnail(id) )
	DLOG(WARNING) << "Unable to delete thumbnail";
	}
	}

	bool ThumbnailDatabase::GetPageThumbnail(URLID id,
	std::vector<unsigned char>* data) {
	SQLITE_UNIQUE_STATEMENT(
	statement, *statement_cache_,
	"SELECT data FROM thumbnails WHERE url_id=?");
	if (!statement.is_valid())
	return false;

	statement->bind_int64(0, id);
	if (statement->step() != SQLITE_ROW)
	return false; // don't have a thumbnail for this ID

	return statement->column_blob_as_vector(0, data);
	}

	bool ThumbnailDatabase::DeleteThumbnail(URLID id) {
	SQLITE_UNIQUE_STATEMENT(
	statement, *statement_cache_,
	"DELETE FROM thumbnails WHERE url_id = ?");
	if (!statement.is_valid())
	return false;

	statement->bind_int64(0, id);
	return statement->step() == SQLITE_DONE;
	}

	bool ThumbnailDatabase::ThumbnailScoreForId(
	URLID id,
	ThumbnailScore* score) {
	// Fetch the current thumbnail's information to make sure we
	// aren't replacing a good thumbnail with one that's worse.
	SQLITE_UNIQUE_STATEMENT(
	select_statement, *statement_cache_,
	"SELECT boring_score, good_clipping, at_top, last_updated "
	"FROM thumbnails WHERE url_id=?");
	if (!select_statement.is_valid()) {
	NOTREACHED() << "Couldn't build select statement!";
	} else {
	select_statement->bind_int64(0, id);
	if (select_statement->step() == SQLITE_ROW) {
	double current_boring_score = select_statement->column_double(0);
	bool current_clipping = select_statement->column_bool(1);
	bool current_at_top = select_statement->column_bool(2);
	Time last_updated = Time::FromTimeT(select_statement->column_int64(3));
	*score = ThumbnailScore(current_boring_score, current_clipping,
	current_at_top, last_updated);
	return true;
	}
	}

	return false;
	}

	bool ThumbnailDatabase::SetFavIcon(URLID icon_id,
	const std::vector<unsigned char>& icon_data,
	Time time) {
	DCHECK(icon_id);
	if (icon_data.size()) {
	SQLITE_UNIQUE_STATEMENT(
	statement, *statement_cache_,
	"UPDATE favicons SET image_data=?, last_updated=? WHERE id=?");
	if (!statement.is_valid())
	return 0;

	statement->bind_blob(0, &icon_data.front(),
	static_cast<int>(icon_data.size()));
	statement->bind_int64(1, time.ToTimeT());
	statement->bind_int64(2, icon_id);
	return statement->step() == SQLITE_DONE;
	} else {
	SQLITE_UNIQUE_STATEMENT(
	statement, *statement_cache_,
	"UPDATE favicons SET image_data=NULL, last_updated=? WHERE id=?");
	if (!statement.is_valid())
	return 0;

	statement->bind_int64(0, time.ToTimeT());
	statement->bind_int64(1, icon_id);
	return statement->step() == SQLITE_DONE;
	}
	}

	bool ThumbnailDatabase::SetFavIconLastUpdateTime(FavIconID icon_id,
	const Time& time) {
	SQLITE_UNIQUE_STATEMENT(
	statement, *statement_cache_,
	"UPDATE favicons SET last_updated=? WHERE id=?");
	if (!statement.is_valid())
	return 0;

	statement->bind_int64(0, time.ToTimeT());
	statement->bind_int64(1, icon_id);
	return statement->step() == SQLITE_DONE;
	}

	FavIconID ThumbnailDatabase::GetFavIconIDForFavIconURL(const GURL& icon_url) {
	SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
	"SELECT id FROM favicons WHERE url=?");
	if (!statement.is_valid())
	return 0;

	statement->bind_string(0, URLDatabase::GURLToDatabaseURL(icon_url));
	if (statement->step() != SQLITE_ROW)
	return 0; // not cached

	return statement->column_int64(0);
	}

	bool ThumbnailDatabase::GetFavIcon(
	FavIconID icon_id,
	Time* last_updated,
	std::vector<unsigned char>* png_icon_data,
	GURL* icon_url) {
	DCHECK(icon_id);

	SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
	"SELECT last_updated, image_data, url FROM favicons WHERE id=?");
	if (!statement.is_valid())
	return 0;

	statement->bind_int64(0, icon_id);

	if (statement->step() != SQLITE_ROW) {
	// No entry for the id.
	return false;
	}

	*last_updated = Time::FromTimeT(statement->column_int64(0));
	if (statement->column_bytes(1) > 0)
	statement->column_blob_as_vector(1, png_icon_data);
	if (icon_url)
	*icon_url = GURL(statement->column_string(2));

	return true;
	}

	FavIconID ThumbnailDatabase::AddFavIcon(const GURL& icon_url) {
	SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
	"INSERT INTO favicons (url) VALUES (?)");
	if (!statement.is_valid())
	return 0;

	statement->bind_string(0, URLDatabase::GURLToDatabaseURL(icon_url));
	if (statement->step() != SQLITE_DONE)
	return 0;
	return sqlite3_last_insert_rowid(db_);
	}

	bool ThumbnailDatabase::DeleteFavIcon(FavIconID id) {
	SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
	"DELETE FROM favicons WHERE id = ?");
	if (!statement.is_valid())
	return false;
	statement->bind_int64(0, id);
	return statement->step() == SQLITE_DONE;
	}

	FavIconID ThumbnailDatabase::CopyToTemporaryFavIconTable(FavIconID source) {
	SQLITE_UNIQUE_STATEMENT(statement, *statement_cache_,
	"INSERT INTO temp_favicons (url, last_updated, image_data)"
	"SELECT url, last_updated, image_data "
	"FROM favicons WHERE id = ?");
	if (!statement.is_valid())
	return 0;
	statement->bind_int64(0, source);
	if (statement->step() != SQLITE_DONE)
	return 0;

	// We return the ID of the newly inserted favicon.
	return sqlite3_last_insert_rowid(db_);
	}

	bool ThumbnailDatabase::CommitTemporaryFavIconTable() {
	// Delete the old favicons table.
	if (sqlite3_exec(db_, "DROP TABLE favicons", NULL, NULL, NULL) != SQLITE_OK)
	return false;

	// Rename the temporary one.
	if (sqlite3_exec(db_, "ALTER TABLE temp_favicons RENAME TO favicons",
	NULL, NULL, NULL) != SQLITE_OK)
	return false;

	// The renamed table needs the index (the temporary table doesn't have one).
	InitFavIconsIndex();
	return true;
	}

	} // namespace history