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// 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 "sql/connection.h"
#include <string.h>
#include "base/file_path.h"
#include "base/logging.h"
#include "base/string_util.h"
#include "base/stringprintf.h"
#include "base/utf_string_conversions.h"
#include "sql/statement.h"
#include "third_party/sqlite/sqlite3.h"
namespace {
// Spin for up to a second waiting for the lock to clear when setting
// up the database.
// TODO(shess): Better story on this. http://crbug.com/56559
const int kBusyTimeoutSeconds = 1;
class ScopedBusyTimeout {
public:
explicit ScopedBusyTimeout(sqlite3* db)
: db_(db) {
}
~ScopedBusyTimeout() {
sqlite3_busy_timeout(db_, 0);
}
int SetTimeout(base::TimeDelta timeout) {
DCHECK_LT(timeout.InMilliseconds(), INT_MAX);
return sqlite3_busy_timeout(db_,
static_cast<int>(timeout.InMilliseconds()));
}
private:
sqlite3* db_;
};
} // namespace
namespace sql {
bool StatementID::operator<(const StatementID& other) const {
if (number_ != other.number_)
return number_ < other.number_;
return strcmp(str_, other.str_) < 0;
}
ErrorDelegate::ErrorDelegate() {
}
ErrorDelegate::~ErrorDelegate() {
}
Connection::StatementRef::StatementRef()
: connection_(NULL),
stmt_(NULL) {
}
Connection::StatementRef::StatementRef(Connection* connection,
sqlite3_stmt* stmt)
: connection_(connection),
stmt_(stmt) {
connection_->StatementRefCreated(this);
}
Connection::StatementRef::~StatementRef() {
if (connection_)
connection_->StatementRefDeleted(this);
Close();
}
void Connection::StatementRef::Close() {
if (stmt_) {
sqlite3_finalize(stmt_);
stmt_ = NULL;
}
connection_ = NULL; // The connection may be getting deleted.
}
Connection::Connection()
: db_(NULL),
page_size_(0),
cache_size_(0),
exclusive_locking_(false),
transaction_nesting_(0),
needs_rollback_(false) {
}
Connection::~Connection() {
Close();
}
bool Connection::Open(const FilePath& path) {
#if defined(OS_WIN)
return OpenInternal(WideToUTF8(path.value()));
#elif defined(OS_POSIX)
return OpenInternal(path.value());
#endif
}
bool Connection::OpenInMemory() {
return OpenInternal(":memory:");
}
void Connection::Close() {
// TODO(shess): Calling "PRAGMA journal_mode = DELETE" at this point
// will delete the -journal file. For ChromiumOS or other more
// embedded systems, this is probably not appropriate, whereas on
// desktop it might make some sense.
// sqlite3_close() needs all prepared statements to be finalized.
// Release all cached statements, then assert that the client has
// released all statements.
statement_cache_.clear();
DCHECK(open_statements_.empty());
// Additionally clear the prepared statements, because they contain
// weak references to this connection. This case has come up when
// error-handling code is hit in production.
ClearCache();
if (db_) {
// TODO(shess): Some additional code to debug http://crbug.com/95527 .
// If you are reading this due to link errors or something, it can
// be safely removed.
#if defined(HAS_SQLITE3_95527)
unsigned int nTouched = 0;
sqlite3_95527(db_, &nTouched);
// If a VERY large amount of memory was touched, crash. This
// should never happen.
// TODO(shess): Pull this in. It should be page_size * page_cache
// or something like that, 4M or 16M. For now it's just to
// prevent optimization.
CHECK_LT(nTouched, 1000*1000*1000U);
#endif
// TODO(shess): Histogram for failure.
sqlite3_close(db_);
db_ = NULL;
}
}
void Connection::Preload() {
if (!db_) {
DLOG(FATAL) << "Cannot preload null db";
return;
}
// A statement must be open for the preload command to work. If the meta
// table doesn't exist, it probably means this is a new database and there
// is nothing to preload (so it's OK we do nothing).
if (!DoesTableExist("meta"))
return;
Statement dummy(GetUniqueStatement("SELECT * FROM meta"));
if (!dummy.Step())
return;
#if !defined(USE_SYSTEM_SQLITE)
// This function is only defined in Chromium's version of sqlite.
// Do not call it when using system sqlite.
sqlite3_preload(db_);
#endif
}
bool Connection::BeginTransaction() {
if (needs_rollback_) {
DCHECK_GT(transaction_nesting_, 0);
// When we're going to rollback, fail on this begin and don't actually
// mark us as entering the nested transaction.
return false;
}
bool success = true;
if (!transaction_nesting_) {
needs_rollback_ = false;
Statement begin(GetCachedStatement(SQL_FROM_HERE, "BEGIN TRANSACTION"));
if (!begin.Run())
return false;
}
transaction_nesting_++;
return success;
}
void Connection::RollbackTransaction() {
if (!transaction_nesting_) {
DLOG(FATAL) << "Rolling back a nonexistent transaction";
return;
}
transaction_nesting_--;
if (transaction_nesting_ > 0) {
// Mark the outermost transaction as needing rollback.
needs_rollback_ = true;
return;
}
DoRollback();
}
bool Connection::CommitTransaction() {
if (!transaction_nesting_) {
DLOG(FATAL) << "Rolling back a nonexistent transaction";
return false;
}
transaction_nesting_--;
if (transaction_nesting_ > 0) {
// Mark any nested transactions as failing after we've already got one.
return !needs_rollback_;
}
if (needs_rollback_) {
DoRollback();
return false;
}
Statement commit(GetCachedStatement(SQL_FROM_HERE, "COMMIT"));
return commit.Run();
}
int Connection::ExecuteAndReturnErrorCode(const char* sql) {
if (!db_)
return false;
return sqlite3_exec(db_, sql, NULL, NULL, NULL);
}
bool Connection::Execute(const char* sql) {
int error = ExecuteAndReturnErrorCode(sql);
// This needs to be a FATAL log because the error case of arriving here is
// that there's a malformed SQL statement. This can arise in development if
// a change alters the schema but not all queries adjust.
if (error == SQLITE_ERROR)
DLOG(FATAL) << "SQL Error in " << sql << ", " << GetErrorMessage();
return error == SQLITE_OK;
}
bool Connection::ExecuteWithTimeout(const char* sql, base::TimeDelta timeout) {
if (!db_)
return false;
ScopedBusyTimeout busy_timeout(db_);
busy_timeout.SetTimeout(timeout);
return Execute(sql);
}
bool Connection::HasCachedStatement(const StatementID& id) const {
return statement_cache_.find(id) != statement_cache_.end();
}
scoped_refptr<Connection::StatementRef> Connection::GetCachedStatement(
const StatementID& id,
const char* sql) {
CachedStatementMap::iterator i = statement_cache_.find(id);
if (i != statement_cache_.end()) {
// Statement is in the cache. It should still be active (we're the only
// one invalidating cached statements, and we'll remove it from the cache
// if we do that. Make sure we reset it before giving out the cached one in
// case it still has some stuff bound.
DCHECK(i->second->is_valid());
sqlite3_reset(i->second->stmt());
return i->second;
}
scoped_refptr<StatementRef> statement = GetUniqueStatement(sql);
if (statement->is_valid())
statement_cache_[id] = statement; // Only cache valid statements.
return statement;
}
scoped_refptr<Connection::StatementRef> Connection::GetUniqueStatement(
const char* sql) {
if (!db_)
return new StatementRef(this, NULL); // Return inactive statement.
sqlite3_stmt* stmt = NULL;
if (sqlite3_prepare_v2(db_, sql, -1, &stmt, NULL) != SQLITE_OK) {
// This is evidence of a syntax error in the incoming SQL.
DLOG(FATAL) << "SQL compile error " << GetErrorMessage();
return new StatementRef(this, NULL);
}
return new StatementRef(this, stmt);
}
bool Connection::IsSQLValid(const char* sql) {
sqlite3_stmt* stmt = NULL;
if (sqlite3_prepare_v2(db_, sql, -1, &stmt, NULL) != SQLITE_OK)
return false;
sqlite3_finalize(stmt);
return true;
}
bool Connection::DoesTableExist(const char* table_name) const {
return DoesTableOrIndexExist(table_name, "table");
}
bool Connection::DoesIndexExist(const char* index_name) const {
return DoesTableOrIndexExist(index_name, "index");
}
bool Connection::DoesTableOrIndexExist(
const char* name, const char* type) const {
// GetUniqueStatement can't be const since statements may modify the
// database, but we know ours doesn't modify it, so the cast is safe.
Statement statement(const_cast<Connection*>(this)->GetUniqueStatement(
"SELECT name FROM sqlite_master "
"WHERE type=? AND name=?"));
statement.BindString(0, type);
statement.BindString(1, name);
return statement.Step(); // Table exists if any row was returned.
}
bool Connection::DoesColumnExist(const char* table_name,
const char* column_name) const {
std::string sql("PRAGMA TABLE_INFO(");
sql.append(table_name);
sql.append(")");
// Our SQL is non-mutating, so this cast is OK.
Statement statement(const_cast<Connection*>(this)->GetUniqueStatement(
sql.c_str()));
while (statement.Step()) {
if (!statement.ColumnString(1).compare(column_name))
return true;
}
return false;
}
int64 Connection::GetLastInsertRowId() const {
if (!db_) {
DLOG(FATAL) << "Illegal use of connection without a db";
return 0;
}
return sqlite3_last_insert_rowid(db_);
}
int Connection::GetLastChangeCount() const {
if (!db_) {
DLOG(FATAL) << "Illegal use of connection without a db";
return 0;
}
return sqlite3_changes(db_);
}
int Connection::GetErrorCode() const {
if (!db_)
return SQLITE_ERROR;
return sqlite3_errcode(db_);
}
int Connection::GetLastErrno() const {
if (!db_)
return -1;
int err = 0;
if (SQLITE_OK != sqlite3_file_control(db_, NULL, SQLITE_LAST_ERRNO, &err))
return -2;
return err;
}
const char* Connection::GetErrorMessage() const {
if (!db_)
return "sql::Connection has no connection.";
return sqlite3_errmsg(db_);
}
bool Connection::OpenInternal(const std::string& file_name) {
if (db_) {
DLOG(FATAL) << "sql::Connection is already open.";
return false;
}
int err = sqlite3_open(file_name.c_str(), &db_);
if (err != SQLITE_OK) {
OnSqliteError(err, NULL);
Close();
db_ = NULL;
return false;
}
// Enable extended result codes to provide more color on I/O errors.
// Not having extended result codes is not a fatal problem, as
// Chromium code does not attempt to handle I/O errors anyhow. The
// current implementation always returns SQLITE_OK, the DCHECK is to
// quickly notify someone if SQLite changes.
err = sqlite3_extended_result_codes(db_, 1);
DCHECK_EQ(err, SQLITE_OK) << "Could not enable extended result codes";
// If indicated, lock up the database before doing anything else, so
// that the following code doesn't have to deal with locking.
// TODO(shess): This code is brittle. Find the cases where code
// doesn't request |exclusive_locking_| and audit that it does the
// right thing with SQLITE_BUSY, and that it doesn't make
// assumptions about who might change things in the database.
// http://crbug.com/56559
if (exclusive_locking_) {
// TODO(shess): This should probably be a full CHECK(). Code
// which requests exclusive locking but doesn't get it is almost
// certain to be ill-tested.
if (!Execute("PRAGMA locking_mode=EXCLUSIVE"))
DLOG(FATAL) << "Could not set locking mode: " << GetErrorMessage();
}
// http://www.sqlite.org/pragma.html#pragma_journal_mode
// DELETE (default) - delete -journal file to commit.
// TRUNCATE - truncate -journal file to commit.
// PERSIST - zero out header of -journal file to commit.
// journal_size_limit provides size to trim to in PERSIST.
// TODO(shess): Figure out if PERSIST and journal_size_limit really
// matter. In theory, it keeps pages pre-allocated, so if
// transactions usually fit, it should be faster.
ignore_result(Execute("PRAGMA journal_mode = PERSIST"));
ignore_result(Execute("PRAGMA journal_size_limit = 16384"));
const base::TimeDelta kBusyTimeout =
base::TimeDelta::FromSeconds(kBusyTimeoutSeconds);
if (page_size_ != 0) {
// Enforce SQLite restrictions on |page_size_|.
DCHECK(!(page_size_ & (page_size_ - 1)))
<< " page_size_ " << page_size_ << " is not a power of two.";
static const int kSqliteMaxPageSize = 32768; // from sqliteLimit.h
DCHECK_LE(page_size_, kSqliteMaxPageSize);
const std::string sql = StringPrintf("PRAGMA page_size=%d", page_size_);
if (!ExecuteWithTimeout(sql.c_str(), kBusyTimeout))
DLOG(FATAL) << "Could not set page size: " << GetErrorMessage();
}
if (cache_size_ != 0) {
const std::string sql = StringPrintf("PRAGMA cache_size=%d", cache_size_);
if (!ExecuteWithTimeout(sql.c_str(), kBusyTimeout))
DLOG(FATAL) << "Could not set cache size: " << GetErrorMessage();
}
if (!ExecuteWithTimeout("PRAGMA secure_delete=ON", kBusyTimeout)) {
DLOG(FATAL) << "Could not enable secure_delete: " << GetErrorMessage();
Close();
return false;
}
return true;
}
void Connection::DoRollback() {
Statement rollback(GetCachedStatement(SQL_FROM_HERE, "ROLLBACK"));
rollback.Run();
needs_rollback_ = false;
}
void Connection::StatementRefCreated(StatementRef* ref) {
DCHECK(open_statements_.find(ref) == open_statements_.end());
open_statements_.insert(ref);
}
void Connection::StatementRefDeleted(StatementRef* ref) {
StatementRefSet::iterator i = open_statements_.find(ref);
if (i == open_statements_.end())
DLOG(FATAL) << "Could not find statement";
else
open_statements_.erase(i);
}
void Connection::ClearCache() {
statement_cache_.clear();
// The cache clear will get most statements. There may be still be references
// to some statements that are held by others (including one-shot statements).
// This will deactivate them so they can't be used again.
for (StatementRefSet::iterator i = open_statements_.begin();
i != open_statements_.end(); ++i)
(*i)->Close();
}
int Connection::OnSqliteError(int err, sql::Statement *stmt) {
if (error_delegate_.get())
return error_delegate_->OnError(err, this, stmt);
// The default handling is to assert on debug and to ignore on release.
DLOG(FATAL) << GetErrorMessage();
return err;
}
} // namespace sql
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