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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.
#ifndef SQL_DATABASE_H_
#define SQL_DATABASE_H_
#include <stddef.h>
#include <stdint.h>
#include <memory>
#include <set>
#include <string>
#include <utility>
#include <vector>
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/component_export.h"
#include "base/containers/flat_map.h"
#include "base/feature_list.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "base/threading/scoped_blocking_call.h"
#include "sql/internal_api_token.h"
#include "sql/sql_features.h"
#include "sql/statement_id.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
struct sqlite3;
struct sqlite3_stmt;
namespace base {
class FilePath;
namespace trace_event {
class ProcessMemoryDump;
} // namespace trace_event
} // namespace base
namespace sql {
class DatabaseMemoryDumpProvider;
class Statement;
namespace test {
class ScopedErrorExpecter;
} // namespace test
struct COMPONENT_EXPORT(SQL) DatabaseOptions {
// Default page size for newly created databases.
//
// Guaranteed to match SQLITE_DEFAULT_PAGE_SIZE.
static constexpr int kDefaultPageSize = 4096;
// If true, the database can only be opened by one process at a time.
//
// SQLite supports a locking protocol that allows multiple processes to safely
// operate on the same database at the same time. The locking protocol is used
// on every transaction, and comes with a small performance penalty.
//
// Setting this to true causes the locking protocol to be used once, when the
// database is opened. No other process will be able to access the database at
// the same time.
//
// More details at https://www.sqlite.org/pragma.html#pragma_locking_mode
//
// SQLite's locking protocol is summarized at
// https://www.sqlite.org/c3ref/io_methods.html
//
// Exclusive mode is strongly recommended. It reduces the I/O cost of setting
// up a transaction. It also removes the need of handling transaction failures
// due to lock contention.
bool exclusive_locking = true;
// If true, enables SQLite's Write-Ahead Logging (WAL).
//
// WAL integration is under development, and should not be used in shipping
// Chrome features yet. In particular, our custom database recovery code does
// not support the WAL log file.
//
// WAL mode is currently not fully supported on FuchsiaOS. It will only be
// turned on if the database is also using exclusive locking mode.
// (https://crbug.com/1082059)
//
// Note: Changing page size is not supported when in WAL mode. So running
// 'PRAGMA page_size = <new-size>' will result in no-ops.
//
// More details at https://www.sqlite.org/wal.html
bool wal_mode =
base::FeatureList::IsEnabled(sql::features::kEnableWALModeByDefault);
// Database page size.
//
// Larger page sizes result in shallower B-trees, because they allow an inner
// page to hold more keys. On the flip side, larger page sizes may result in
// more I/O when making small changes to existing records.
//
// Must be a power of two between 512 and 65536 inclusive.
int page_size = kDefaultPageSize;
// The size of in-memory cache, in pages.
//
// SQLite's database cache will take up at most (`page_size` * `cache_size`)
// bytes of RAM.
//
// 0 invokes SQLite's default, which is currently to size up the cache to use
// exactly 2,048,000 bytes of RAM.
int cache_size = 0;
};
// Handle to an open SQLite database.
//
// Instances of this class are thread-unsafe and DCHECK that they are accessed
// on the same sequence.
class COMPONENT_EXPORT(SQL) Database {
private:
class StatementRef; // Forward declaration, see real one below.
public:
// The database is opened by calling Open[InMemory](). Any uncommitted
// transactions will be rolled back when this object is deleted.
//
// This constructor is deprecated.
// TODO(crbug.com/1126968): Remove this constructor after migrating all
// uses to the explicit constructor below.
Database();
// |options| only affects newly created databases.
explicit Database(DatabaseOptions options);
~Database();
// Allows mmapping to be disabled globally by default in the calling process.
// Must be called before any threads attempt to create a Database.
//
// TODO(crbug.com/1117049): Remove this global configuration.
static void DisableMmapByDefault();
// Pre-init configuration ----------------------------------------------------
// The page size that will be used when creating a new database.
int page_size() const { return options_.page_size; }
// Returns whether a database will be opened in WAL mode.
bool UseWALMode() const;
// Call to use alternative status-tracking for mmap. Usually this is tracked
// in the meta table, but some databases have no meta table.
// TODO(shess): Maybe just have all databases use the alt option?
void set_mmap_alt_status() { mmap_alt_status_ = true; }
// Opt out of memory-mapped file I/O.
void set_mmap_disabled() { mmap_disabled_ = true; }
// Set an error-handling callback. On errors, the error number (and
// statement, if available) will be passed to the callback.
//
// If no callback is set, the default action is to crash in debug
// mode or return failure in release mode.
using ErrorCallback = base::RepeatingCallback<void(int, Statement*)>;
void set_error_callback(const ErrorCallback& callback) {
error_callback_ = callback;
}
bool has_error_callback() const { return !error_callback_.is_null(); }
void reset_error_callback() { error_callback_.Reset(); }
// Developer-friendly database ID used in logging output and memory dumps.
void set_histogram_tag(const std::string& tag);
// Run "PRAGMA integrity_check" and post each line of
// results into |messages|. Returns the success of running the
// statement - per the SQLite documentation, if no errors are found the
// call should succeed, and a single value "ok" should be in messages.
bool FullIntegrityCheck(std::vector<std::string>* messages);
// Runs "PRAGMA quick_check" and, unlike the FullIntegrityCheck method,
// interprets the results returning true if the the statement executes
// without error and results in a single "ok" value.
bool QuickIntegrityCheck() WARN_UNUSED_RESULT;
// Meant to be called from a client error callback so that it's able to
// get diagnostic information about the database.
std::string GetDiagnosticInfo(int extended_error, Statement* statement);
// Reports memory usage into provided memory dump with the given name.
bool ReportMemoryUsage(base::trace_event::ProcessMemoryDump* pmd,
const std::string& dump_name);
// Initialization ------------------------------------------------------------
// Initializes the SQL database for the given file, returning true if the
// file could be opened. You can call this or OpenInMemory.
bool Open(const base::FilePath& path) WARN_UNUSED_RESULT;
// Initializes the SQL database 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;
// Create a temporary on-disk database. The database will be
// deleted after close. This kind of database is similar to
// OpenInMemory() for small databases, but can page to disk if the
// database becomes large.
bool OpenTemporary() WARN_UNUSED_RESULT;
// Returns true if the database has been successfully opened.
bool is_open() const { return static_cast<bool>(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();
// Reads the first <cache-size>*<page-size> bytes of the file to prime the
// filesystem cache. This can be more efficient than faulting pages
// individually. Since this involves blocking I/O, it should only be used if
// the caller will immediately read a substantial amount of data from the
// database.
//
// TODO(shess): Design a set of histograms or an experiment to inform this
// decision. Preloading should almost always improve later performance
// numbers for this database simply because it pulls operations forward, but
// if the data isn't actually used soon then preloading just slows down
// everything else.
void Preload();
// Release all non-essential memory associated with this database connection.
void TrimMemory();
// Raze the database to the ground. This approximates creating a
// fresh database from scratch, within the constraints of SQLite's
// locking protocol (locks and open handles can make doing this with
// filesystem operations problematic). Returns true if the database
// was razed.
//
// false is returned if the database is locked by some other
// process.
//
// NOTE(shess): Raze() will DCHECK in the following situations:
// - database is not open.
// - the database has a transaction open.
// - a SQLite issue occurs which is structural in nature (like the
// statements used are broken).
// Since Raze() is expected to be called in unexpected situations,
// these all return false, since it is unlikely that the caller
// could fix them.
//
// The database's page size is taken from |options_.page_size|. The
// existing database's |auto_vacuum| setting is lost (the
// possibility of corruption makes it unreliable to pull it from the
// existing database). To re-enable on the empty database requires
// running "PRAGMA auto_vacuum = 1;" then "VACUUM".
//
// NOTE(shess): For Android, SQLITE_DEFAULT_AUTOVACUUM is set to 1,
// so Raze() sets auto_vacuum to 1.
//
// TODO(shess): Raze() needs a database so cannot clear SQLITE_NOTADB.
// TODO(shess): Bake auto_vacuum into Database's API so it can
// just pick up the default.
bool Raze();
// Breaks all outstanding transactions (as initiated by
// BeginTransaction()), closes the SQLite database, and poisons the
// object so that all future operations against the Database (or
// its Statements) fail safely, without side effects.
//
// This is intended as an alternative to Close() in error callbacks.
// Close() should still be called at some point.
void Poison();
// Raze() the database and Poison() the handle. Returns the return
// value from Raze().
// TODO(shess): Rename to RazeAndPoison().
bool RazeAndClose();
// Delete the underlying database files associated with |path|. This should be
// used on a database which is not opened by any Database instance. Open
// Database instances pointing to the database can cause odd results or
// corruption (for instance if a hot journal is deleted but the associated
// database is not).
//
// Returns true if the database file and associated journals no
// longer exist, false otherwise. If the database has never
// existed, this will return true.
static bool Delete(const base::FilePath& path);
// 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();
// Rollback all outstanding transactions. Use with care, there may
// be scoped transactions on the stack.
void RollbackAllTransactions();
// Returns the current transaction nesting, which will be 0 if there are
// no open transactions.
int transaction_nesting() const { return transaction_nesting_; }
// Attached databases---------------------------------------------------------
// SQLite supports attaching multiple database files to a single connection.
//
// Attach the database in |other_db_path| to the current connection under
// |attachment_point|. |attachment_point| must only contain characters from
// [a-zA-Z0-9_].
//
// On the SQLite version shipped with Chrome (3.21+, Oct 2017), databases can
// be attached while a transaction is opened. However, these databases cannot
// be detached until the transaction is committed or aborted.
//
// These APIs are only exposed for use in recovery. They are extremely subtle
// and are not useful for features built on top of //sql.
bool AttachDatabase(const base::FilePath& other_db_path,
const char* attachment_point,
InternalApiToken);
bool DetachDatabase(const char* attachment_point, InternalApiToken);
// 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 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.
//
// The SQL_FROM_HERE macro is the recommended way of generating a StatementID.
// Code that generates custom IDs must ensure that a StatementID is never used
// for different SQL statements. Failing to meet this requirement results in
// incorrect behavior, and should be caught by a DCHECK.
//
// The SQL statement passed in |sql| must match the SQL statement reported
// back by SQLite. Mismatches are caught by a DCHECK, so any code that has
// automated test coverage or that was manually tested on a DCHECK build will
// not exhibit this problem. Mismatches generally imply that the statement
// passed in has extra whitespace or comments surrounding it, which waste
// storage and CPU cycles.
//
// 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.
//
// Example:
// sql::Statement stmt(database_.GetCachedStatement(
// SQL_FROM_HERE, "SELECT * FROM foo"));
// if (!stmt)
// return false; // Error creating statement.
scoped_refptr<StatementRef> GetCachedStatement(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);
// Performs a passive checkpoint on the main attached database if it is in
// WAL mode. Returns true if the checkpoint was successful and false in case
// of an error. It is a no-op if the database is not in WAL mode.
//
// Note: Checkpointing is a very slow operation and will block any writes
// until it is finished. Please use with care.
bool CheckpointDatabase();
// Info querying -------------------------------------------------------------
// Returns true if the given structure exists. Instead of test-then-create,
// callers should almost always prefer the "IF NOT EXISTS" version of the
// CREATE statement.
bool DoesIndexExist(const char* index_name) const;
bool DoesTableExist(const char* table_name) const;
bool DoesViewExist(const char* table_name) const;
// Returns true if a column with the given name exists in the given table.
//
// Calling this method on a VIEW returns an unspecified result.
//
// This should only be used by migration code for legacy features that do not
// use MetaTable, and need an alternative way of figuring out the database's
// current version.
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_t 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;
// Approximates the amount of memory used by SQLite for this database.
//
// This measures the memory used for the page cache (most likely the biggest
// consumer), database schema, and prepared statements.
//
// The memory used by the page cache can be recovered by calling TrimMemory(),
// which will cause SQLite to drop the page cache.
int GetMemoryUsage();
// 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;
// Return a reproducible representation of the schema equivalent to
// running the following statement at a sqlite3 command-line:
// SELECT type, name, tbl_name, sql FROM sqlite_master ORDER BY 1, 2, 3, 4;
std::string GetSchema() const;
// Returns |true| if there is an error expecter (see SetErrorExpecter), and
// that expecter returns |true| when passed |error|. Clients which provide an
// |error_callback| should use IsExpectedSqliteError() to check for unexpected
// errors; if one is detected, DLOG(DCHECK) is generally appropriate (see
// OnSqliteError implementation).
static bool IsExpectedSqliteError(int error);
// Computes the path of a database's rollback journal.
//
// The journal file is created at the beginning of the database's first
// transaction. The file may be removed and re-created between transactions,
// depending on whether the database is opened in exclusive mode, and on
// configuration options. The journal file does not exist when the database
// operates in WAL mode.
//
// This is intended for internal use and tests. To preserve our ability to
// iterate on our SQLite configuration, features must avoid relying on
// the existence of specific files.
static base::FilePath JournalPath(const base::FilePath& db_path);
// Computes the path of a database's write-ahead log (WAL).
//
// The WAL file exists while a database is opened in WAL mode.
//
// This is intended for internal use and tests. To preserve our ability to
// iterate on our SQLite configuration, features must avoid relying on
// the existence of specific files.
static base::FilePath WriteAheadLogPath(const base::FilePath& db_path);
// Computes the path of a database's shared memory (SHM) file.
//
// The SHM file is used to coordinate between multiple processes using the
// same database in WAL mode. Thus, this file only exists for databases using
// WAL and not opened in exclusive mode.
//
// This is intended for internal use and tests. To preserve our ability to
// iterate on our SQLite configuration, features must avoid relying on
// the existence of specific files.
static base::FilePath SharedMemoryFilePath(const base::FilePath& db_path);
// Internal state accessed by other classes in //sql.
sqlite3* db(InternalApiToken) const { return db_; }
bool poisoned(InternalApiToken) const { return poisoned_; }
private:
// Allow test-support code to set/reset error expecter.
friend class test::ScopedErrorExpecter;
// Statement accesses StatementRef which we don't want to expose to everybody
// (they should go through Statement).
friend class Statement;
FRIEND_TEST_ALL_PREFIXES(SQLDatabaseTest, CachedStatement);
FRIEND_TEST_ALL_PREFIXES(SQLDatabaseTest, CollectDiagnosticInfo);
FRIEND_TEST_ALL_PREFIXES(SQLDatabaseTest, GetAppropriateMmapSize);
FRIEND_TEST_ALL_PREFIXES(SQLDatabaseTest, GetAppropriateMmapSizeAltStatus);
FRIEND_TEST_ALL_PREFIXES(SQLDatabaseTest, OnMemoryDump);
FRIEND_TEST_ALL_PREFIXES(SQLDatabaseTest, RegisterIntentToUpload);
FRIEND_TEST_ALL_PREFIXES(SQLiteFeaturesTest, WALNoClose);
// 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.
//
// |retry_flag| controls retrying the open if the error callback
// addressed errors using RazeAndClose().
enum Retry { NO_RETRY = 0, RETRY_ON_POISON };
bool OpenInternal(const std::string& file_name, Retry retry_flag);
// Internal close function used by Close() and RazeAndClose().
// |forced| indicates that orderly-shutdown checks should not apply.
void CloseInternal(bool forced);
// Construct a ScopedBlockingCall to annotate IO calls, but only if
// database wasn't open in memory. ScopedBlockingCall uses |from_here| to
// declare its blocking execution scope (see https://www.crbug/934302).
void InitScopedBlockingCall(
const base::Location& from_here,
absl::optional<base::ScopedBlockingCall>* scoped_blocking_call) const {
if (!in_memory_)
scoped_blocking_call->emplace(from_here, base::BlockingType::MAY_BLOCK);
}
// Internal helper for Does*Exist() functions.
bool DoesSchemaItemExist(const char* name, const char* type) const;
// Accessors for global error-expecter, for injecting behavior during tests.
// See test/scoped_error_expecter.h.
using ErrorExpecterCallback = base::RepeatingCallback<bool(int)>;
static ErrorExpecterCallback* current_expecter_cb_;
static void SetErrorExpecter(ErrorExpecterCallback* expecter);
static void ResetErrorExpecter();
// 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 Database may revoke a StatementRef in some error cases, so callers
// should always check validity before using.
class COMPONENT_EXPORT(SQL) StatementRef
: public base::RefCounted<StatementRef> {
public:
REQUIRE_ADOPTION_FOR_REFCOUNTED_TYPE();
// |database| is the sql::Database instance associated with
// the statement, and is used for tracking outstanding statements
// and for error handling. Set to nullptr for invalid or untracked
// refs. |stmt| is the actual statement, and should only be null
// to create an invalid ref. |was_valid| indicates whether the
// statement should be considered valid for diagnostic purposes.
// |was_valid| can be true for a null |stmt| if the Database has
// been forcibly closed by an error handler.
StatementRef(Database* database, sqlite3_stmt* stmt, bool was_valid);
// When true, the statement can be used.
bool is_valid() const { return !!stmt_; }
// When true, the statement is either currently valid, or was
// previously valid but the database was forcibly closed. Used
// for diagnostic checks.
bool was_valid() const { return was_valid_; }
// If we've not been linked to a database, this will be null.
//
// TODO(shess): database_ can be nullptr in case of
// GetUntrackedStatement(), which prevents Statement::OnError() from
// forwarding errors.
Database* database() const { return database_; }
// Returns the sqlite statement if any. If the statement is not active,
// this will return nullptr.
sqlite3_stmt* stmt() const { return stmt_; }
// Destroys the compiled statement and sets it to nullptr. The statement
// will no longer be active. |forced| is used to indicate if
// orderly-shutdown checks should apply (see Database::RazeAndClose()).
void Close(bool forced);
// Construct a ScopedBlockingCall to annotate IO calls, but only if
// database wasn't open in memory. ScopedBlockingCall uses |from_here| to
// declare its blocking execution scope (see https://www.crbug/934302).
void InitScopedBlockingCall(
const base::Location& from_here,
absl::optional<base::ScopedBlockingCall>* scoped_blocking_call) const {
if (database_)
database_->InitScopedBlockingCall(from_here, scoped_blocking_call);
}
private:
friend class base::RefCounted<StatementRef>;
~StatementRef();
Database* database_;
sqlite3_stmt* stmt_;
bool was_valid_;
DISALLOW_COPY_AND_ASSIGN(StatementRef);
};
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);
// Called when a sqlite function returns an error, which is passed
// as |err|. The return value is the error code to be reflected
// back to client code. |stmt| is non-null if the error relates to
// an sql::Statement instance. |sql| is non-nullptr if the error
// relates to non-statement sql code (Execute, for instance). Both
// can be null, but both should never be set.
// NOTE(shess): Originally, the return value was intended to allow
// error handlers to transparently convert errors into success.
// Unfortunately, transactions are not generally restartable, so
// this did not work out.
int OnSqliteError(int err, Statement* stmt, const char* sql) const;
// Like |Execute()|, but retries if the database is locked.
bool ExecuteWithTimeout(const char* sql,
base::TimeDelta ms_timeout) WARN_UNUSED_RESULT;
// Implementation helper for GetUniqueStatement() and GetUntrackedStatement().
// |tracking_db| is the db the resulting ref should register with for
// outstanding statement tracking, which should be |this| to track or null to
// not track.
scoped_refptr<StatementRef> GetStatementImpl(sql::Database* tracking_db,
const char* sql) const;
// Helper for implementing const member functions. Like GetUniqueStatement(),
// except the StatementRef is not entered into |open_statements_|, so an
// outstanding StatementRef from this function can block closing the database.
// The StatementRef will not call OnSqliteError(), because that can call
// |error_callback_| which can close the database.
scoped_refptr<StatementRef> GetUntrackedStatement(const char* sql) const;
bool IntegrityCheckHelper(const char* pragma_sql,
std::vector<std::string>* messages)
WARN_UNUSED_RESULT;
// Release page-cache memory if memory-mapped I/O is enabled and the database
// was changed. Passing true for |implicit_change_performed| allows
// overriding the change detection for cases like DDL (CREATE, DROP, etc),
// which do not participate in the total-rows-changed tracking.
void ReleaseCacheMemoryIfNeeded(bool implicit_change_performed);
// Returns the results of sqlite3_db_filename(), which should match the path
// passed to Open().
base::FilePath DbPath() const;
// Helper to collect diagnostic info for a corrupt database.
std::string CollectCorruptionInfo();
// Helper to collect diagnostic info for errors.
std::string CollectErrorInfo(int error, Statement* stmt) const;
// Calculates a value appropriate to pass to "PRAGMA mmap_size = ". So errors
// can make it unsafe to map a file, so the file is read using regular I/O,
// with any errors causing 0 (don't map anything) to be returned. If the
// entire file is read without error, a large value is returned which will
// allow the entire file to be mapped in most cases.
//
// Results are recorded in the database's meta table for future reference, so
// the file should only be read through once.
size_t GetAppropriateMmapSize();
// Helpers for GetAppropriateMmapSize().
bool GetMmapAltStatus(int64_t* status);
bool SetMmapAltStatus(int64_t status);
// The actual sqlite database. Will be null before Init has been called or if
// Init resulted in an error.
sqlite3* db_ = nullptr;
// TODO(shuagga@microsoft.com): Make `options_` const after removing all
// setters.
DatabaseOptions options_;
// Holds references to all cached statements so they remain active.
//
// flat_map is appropriate here because the codebase has ~400 cached
// statements, and each statement is at most one insertion in the map
// throughout a process' lifetime.
base::flat_map<StatementID, scoped_refptr<StatementRef>> 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.
std::set<StatementRef*> open_statements_;
// Number of currently-nested transactions.
int transaction_nesting_ = 0;
// 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_ = false;
// True if database is open with OpenInMemory(), False if database is open
// with Open().
bool in_memory_ = false;
// |true| if the Database was closed using RazeAndClose(). Used
// to enable diagnostics to distinguish calls to never-opened
// databases (incorrect use of the API) from calls to once-valid
// databases.
bool poisoned_ = false;
// |true| to use alternate storage for tracking mmap status.
bool mmap_alt_status_ = false;
// |true| if SQLite memory-mapped I/O is not desired for this database.
bool mmap_disabled_;
// |true| if SQLite memory-mapped I/O was enabled for this database.
// Used by ReleaseCacheMemoryIfNeeded().
bool mmap_enabled_ = false;
// Used by ReleaseCacheMemoryIfNeeded() to track if new changes have happened
// since memory was last released.
int total_changes_at_last_release_ = 0;
ErrorCallback error_callback_;
// Developer-friendly database ID used in logging output and memory dumps.
std::string histogram_tag_;
// Stores the dump provider object when db is open.
std::unique_ptr<DatabaseMemoryDumpProvider> memory_dump_provider_;
DISALLOW_COPY_AND_ASSIGN(Database);
};
} // namespace sql
#endif // SQL_DATABASE_H_