blob: 9b81804bc1fafb68bac8bfb9a63dff4c6887305c [file] [log] [blame]
// Copyright (c) 2011 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.
#pragma once
#include <map>
#include <set>
#include <string>
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/memory/ref_counted.h"
#include "base/time.h"
#include "sql/sql_export.h"
class FilePath;
struct sqlite3;
struct sqlite3_stmt;
namespace sql {
class Statement;
// Uniquely identifies a statement. There are two modes of operation:
// - In the most common mode, you will use the source file and line number to
// identify your statement. This is a convienient way to get uniqueness for
// a statement that is only used in one place. Use the SQL_FROM_HERE macro
// to generate a StatementID.
// - In the "custom" mode you may use the statement from different places or
// need to manage it yourself for whatever reason. In this case, you should
// make up your own unique name and pass it to the StatementID. This name
// must be a static string, since this object only deals with pointers and
// assumes the underlying string doesn't change or get deleted.
// This object is copyable and assignable using the compiler-generated
// operator= and copy constructor.
class StatementID {
// Creates a uniquely named statement with the given file ane line number.
// Normally you will use SQL_FROM_HERE instead of calling yourself.
StatementID(const char* file, int line)
: number_(line),
str_(file) {
// Creates a uniquely named statement with the given user-defined name.
explicit StatementID(const char* unique_name)
: number_(-1),
str_(unique_name) {
// This constructor is unimplemented and will generate a linker error if
// called. It is intended to try to catch people dynamically generating
// a statement name that will be deallocated and will cause a crash later.
// All strings must be static and unchanging!
explicit StatementID(const std::string& dont_ever_do_this);
// We need this to insert into our map.
bool operator<(const StatementID& other) const;
int number_;
const char* str_;
#define SQL_FROM_HERE sql::StatementID(__FILE__, __LINE__)
class Connection;
// ErrorDelegate defines the interface to implement error handling and recovery
// for sqlite operations. This allows the rest of the classes to return true or
// false while the actual error code and causing statement are delivered using
// the OnError() callback.
// The tipical usage is to centralize the code designed to handle database
// corruption, low-level IO errors or locking violations.
class SQL_EXPORT ErrorDelegate : public base::RefCounted<ErrorDelegate> {
// |error| is an sqlite result code as seen in sqlite\preprocessed\sqlite3.h
// |connection| is db connection where the error happened and |stmt| is
// our best guess at the statement that triggered the error. Do not store
// these pointers.
// |stmt| MAY BE NULL if there is no statement causing the problem (i.e. on
// initialization).
// If the error condition has been fixed an the original statement succesfuly
// re-tried then returning SQLITE_OK is appropiate; otherwise is recomended
// that you return the original |error| or the appropiae error code.
virtual int OnError(int error, Connection* connection, Statement* stmt) = 0;
friend class base::RefCounted<ErrorDelegate>;
virtual ~ErrorDelegate();
class SQL_EXPORT Connection {
class StatementRef; // Forward declaration, see real one below.
// The database is opened by calling Open[InMemory](). Any uncommitted
// transactions will be rolled back when this object is deleted.
// Pre-init configuration ----------------------------------------------------
// Sets the page size that will be used when creating a new database. This
// must be called before Init(), and will only have an effect on new
// databases.
// From "The page size must be a power of two greater than or
// equal to 512 and less than or equal to SQLITE_MAX_PAGE_SIZE. The maximum
// value for SQLITE_MAX_PAGE_SIZE is 32768."
void set_page_size(int page_size) { page_size_ = page_size; }
// Sets the number of pages that will be cached in memory by sqlite. The
// total cache size in bytes will be page_size * cache_size. This must be
// called before Open() to have an effect.
void set_cache_size(int cache_size) { cache_size_ = cache_size; }
// Call to put the database in exclusive locking mode. There is no "back to
// normal" flag because of some additional requirements sqlite puts on this
// transaition (requires another access to the DB) and because we don't
// actually need it.
// Exclusive mode means that the database is not unlocked at the end of each
// transaction, which means there may be less time spent initializing the
// next transaction because it doesn't have to re-aquire locks.
// This must be called before Open() to have an effect.
void set_exclusive_locking() { exclusive_locking_ = true; }
// Sets the object that will handle errors. Recomended that it should be set
// before calling Open(). If not set, the default is to ignore errors on
// release and assert on debug builds.
void set_error_delegate(ErrorDelegate* delegate) {
error_delegate_ = delegate;
// Initialization ------------------------------------------------------------
// Initializes the SQL connection for the given file, returning true if the
// file could be opened. You can call this or OpenInMemory.
bool Open(const FilePath& path) WARN_UNUSED_RESULT;
// Initializes the SQL connection for a temporary in-memory database. There
// will be no associated file on disk, and the initial database will be
// empty. You can call this or Open.
bool OpenInMemory() WARN_UNUSED_RESULT;
// Returns trie if the database has been successfully opened.
bool is_open() const { return !!db_; }
// Closes the database. This is automatically performed on destruction for
// you, but this allows you to close the database early. You must not call
// any other functions after closing it. It is permissable to call Close on
// an uninitialized or already-closed database.
void Close();
// Pre-loads the first <cache-size> pages into the cache from the file.
// If you expect to soon use a substantial portion of the database, this
// is much more efficient than allowing the pages to be populated organically
// since there is no per-page hard drive seeking. If the file is larger than
// the cache, the last part that doesn't fit in the cache will be brought in
// organically.
// This function assumes your class is using a meta table on the current
// database, as it openes a transaction on the meta table to force the
// database to be initialized. You should feel free to initialize the meta
// table after calling preload since the meta table will already be in the
// database if it exists, and if it doesn't exist, the database won't
// generally exist either.
void Preload();
// Transactions --------------------------------------------------------------
// Transaction management. We maintain a virtual transaction stack to emulate
// nested transactions since sqlite can't do nested transactions. The
// limitation is you can't roll back a sub transaction: if any transaction
// fails, all transactions open will also be rolled back. Any nested
// transactions after one has rolled back will return fail for Begin(). If
// Begin() fails, you must not call Commit or Rollback().
// Normally you should use sql::Transaction to manage a transaction, which
// will scope it to a C++ context.
bool BeginTransaction();
void RollbackTransaction();
bool CommitTransaction();
// Returns the current transaction nesting, which will be 0 if there are
// no open transactions.
int transaction_nesting() const { return transaction_nesting_; }
// Statements ----------------------------------------------------------------
// Executes the given SQL string, returning true on success. This is
// normally used for simple, 1-off statements that don't take any bound
// parameters and don't return any data (e.g. CREATE TABLE).
// This will DCHECK if the |sql| contains errors.
// Do not use ignore_result() to ignore all errors. Use
// ExecuteAndReturnErrorCode() and ignore only specific errors.
bool Execute(const char* sql) WARN_UNUSED_RESULT;
// Like Execute(), but returns the error code given by SQLite.
int ExecuteAndReturnErrorCode(const char* sql) WARN_UNUSED_RESULT;
// Returns true if we have a statement with the given identifier already
// cached. This is normally not necessary to call, but can be useful if the
// caller has to dynamically build up SQL to avoid doing so if it's already
// cached.
bool HasCachedStatement(const StatementID& id) const;
// Returns a statement for the given SQL using the statement cache. It can
// take a nontrivial amount of work to parse and compile a statement, so
// keeping commonly-used ones around for future use is important for
// performance.
// If the |sql| has an error, an invalid, inert StatementRef is returned (and
// the code will crash in debug). The caller must deal with this eventuality,
// either by checking validity of the |sql| before calling, by correctly
// handling the return of an inert statement, or both.
// The StatementID and the SQL must always correspond to one-another. The
// ID is the lookup into the cache, so crazy things will happen if you use
// different SQL with the same ID.
// You will normally use the SQL_FROM_HERE macro to generate a statement
// ID associated with the current line of code. This gives uniqueness without
// you having to manage unique names. See StatementID above for more.
// Example:
// sql::Statement stmt(connection_.GetCachedStatement(
// if (!stmt)
// return false; // Error creating statement.
scoped_refptr<StatementRef> GetCachedStatement(const StatementID& id,
const char* sql);
// Used to check a |sql| statement for syntactic validity. If the statement is
// valid SQL, returns true.
bool IsSQLValid(const char* sql);
// Returns a non-cached statement for the given SQL. Use this for SQL that
// is only executed once or only rarely (there is overhead associated with
// keeping a statement cached).
// See GetCachedStatement above for examples and error information.
scoped_refptr<StatementRef> GetUniqueStatement(const char* sql);
// Info querying -------------------------------------------------------------
// Returns true if the given table exists.
bool DoesTableExist(const char* table_name) const;
// Returns true if the given index exists.
bool DoesIndexExist(const char* index_name) const;
// Returns true if a column with the given name exists in the given table.
bool DoesColumnExist(const char* table_name, const char* column_name) const;
// Returns sqlite's internal ID for the last inserted row. Valid only
// immediately after an insert.
int64 GetLastInsertRowId() const;
// Returns sqlite's count of the number of rows modified by the last
// statement executed. Will be 0 if no statement has executed or the database
// is closed.
int GetLastChangeCount() const;
// Errors --------------------------------------------------------------------
// Returns the error code associated with the last sqlite operation.
int GetErrorCode() const;
// Returns the errno associated with GetErrorCode(). See
// SQLITE_LAST_ERRNO in SQLite documentation.
int GetLastErrno() const;
// Returns a pointer to a statically allocated string associated with the
// last sqlite operation.
const char* GetErrorMessage() const;
// Statement accesses StatementRef which we don't want to expose to everybody
// (they should go through Statement).
friend class Statement;
// Internal initialize function used by both Init and InitInMemory. The file
// name is always 8 bits since we want to use the 8-bit version of
// sqlite3_open. The string can also be sqlite's special ":memory:" string.
bool OpenInternal(const std::string& file_name);
// Internal helper for DoesTableExist and DoesIndexExist.
bool DoesTableOrIndexExist(const char* name, const char* type) const;
// A StatementRef is a refcounted wrapper around a sqlite statement pointer.
// Refcounting allows us to give these statements out to sql::Statement
// objects while also optionally maintaining a cache of compiled statements
// by just keeping a refptr to these objects.
// A statement ref can be valid, in which case it can be used, or invalid to
// indicate that the statement hasn't been created yet, has an error, or has
// been destroyed.
// The Connection may revoke a StatementRef in some error cases, so callers
// should always check validity before using.
class SQL_EXPORT StatementRef : public base::RefCounted<StatementRef> {
// Default constructor initializes to an invalid statement.
StatementRef(Connection* connection, sqlite3_stmt* stmt);
// When true, the statement can be used.
bool is_valid() const { return !!stmt_; }
// If we've not been linked to a connection, this will be NULL. Guaranteed
// non-NULL when is_valid().
Connection* connection() const { return connection_; }
// Returns the sqlite statement if any. If the statement is not active,
// this will return NULL.
sqlite3_stmt* stmt() const { return stmt_; }
// Destroys the compiled statement and marks it NULL. The statement will
// no longer be active.
void Close();
friend class base::RefCounted<StatementRef>;
Connection* connection_;
sqlite3_stmt* stmt_;
friend class StatementRef;
// Executes a rollback statement, ignoring all transaction state. Used
// internally in the transaction management code.
void DoRollback();
// Called by a StatementRef when it's being created or destroyed. See
// open_statements_ below.
void StatementRefCreated(StatementRef* ref);
void StatementRefDeleted(StatementRef* ref);
// Frees all cached statements from statement_cache_.
void ClearCache();
// Called by Statement objects when an sqlite function returns an error.
// The return value is the error code reflected back to client code.
int OnSqliteError(int err, Statement* stmt);
// Like |Execute()|, but retries if the database is locked.
bool ExecuteWithTimeout(const char* sql, base::TimeDelta ms_timeout)
// The actual sqlite database. Will be NULL before Init has been called or if
// Init resulted in an error.
sqlite3* db_;
// Parameters we'll configure in sqlite before doing anything else. Zero means
// use the default value.
int page_size_;
int cache_size_;
bool exclusive_locking_;
// All cached statements. Keeping a reference to these statements means that
// they'll remain active.
typedef std::map<StatementID, scoped_refptr<StatementRef> >
CachedStatementMap statement_cache_;
// A list of all StatementRefs we've given out. Each ref must register with
// us when it's created or destroyed. This allows us to potentially close
// any open statements when we encounter an error.
typedef std::set<StatementRef*> StatementRefSet;
StatementRefSet open_statements_;
// Number of currently-nested transactions.
int transaction_nesting_;
// True if any of the currently nested transactions have been rolled back.
// When we get to the outermost transaction, this will determine if we do
// a rollback instead of a commit.
bool needs_rollback_;
// This object handles errors resulting from all forms of executing sqlite
// commands or statements. It can be null which means default handling.
scoped_refptr<ErrorDelegate> error_delegate_;
} // namespace sql