cc: Added inline to Tile::IsReadyToDraw
[chromium-blink-merge.git] / sql / connection.h
blob793860642283aa7b70ff5e9a2f641d83eda4defb
1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #ifndef SQL_CONNECTION_H_
6 #define SQL_CONNECTION_H_
8 #include <map>
9 #include <set>
10 #include <string>
11 #include <vector>
13 #include "base/basictypes.h"
14 #include "base/callback.h"
15 #include "base/compiler_specific.h"
16 #include "base/memory/ref_counted.h"
17 #include "base/memory/scoped_ptr.h"
18 #include "base/threading/thread_restrictions.h"
19 #include "base/time/time.h"
20 #include "sql/sql_export.h"
22 struct sqlite3;
23 struct sqlite3_stmt;
25 namespace base {
26 class FilePath;
29 namespace sql {
31 class Recovery;
32 class Statement;
34 // Uniquely identifies a statement. There are two modes of operation:
36 // - In the most common mode, you will use the source file and line number to
37 // identify your statement. This is a convienient way to get uniqueness for
38 // a statement that is only used in one place. Use the SQL_FROM_HERE macro
39 // to generate a StatementID.
41 // - In the "custom" mode you may use the statement from different places or
42 // need to manage it yourself for whatever reason. In this case, you should
43 // make up your own unique name and pass it to the StatementID. This name
44 // must be a static string, since this object only deals with pointers and
45 // assumes the underlying string doesn't change or get deleted.
47 // This object is copyable and assignable using the compiler-generated
48 // operator= and copy constructor.
49 class StatementID {
50 public:
51 // Creates a uniquely named statement with the given file ane line number.
52 // Normally you will use SQL_FROM_HERE instead of calling yourself.
53 StatementID(const char* file, int line)
54 : number_(line),
55 str_(file) {
58 // Creates a uniquely named statement with the given user-defined name.
59 explicit StatementID(const char* unique_name)
60 : number_(-1),
61 str_(unique_name) {
64 // This constructor is unimplemented and will generate a linker error if
65 // called. It is intended to try to catch people dynamically generating
66 // a statement name that will be deallocated and will cause a crash later.
67 // All strings must be static and unchanging!
68 explicit StatementID(const std::string& dont_ever_do_this);
70 // We need this to insert into our map.
71 bool operator<(const StatementID& other) const;
73 private:
74 int number_;
75 const char* str_;
78 #define SQL_FROM_HERE sql::StatementID(__FILE__, __LINE__)
80 class Connection;
82 class SQL_EXPORT Connection {
83 private:
84 class StatementRef; // Forward declaration, see real one below.
86 public:
87 // The database is opened by calling Open[InMemory](). Any uncommitted
88 // transactions will be rolled back when this object is deleted.
89 Connection();
90 ~Connection();
92 // Pre-init configuration ----------------------------------------------------
94 // Sets the page size that will be used when creating a new database. This
95 // must be called before Init(), and will only have an effect on new
96 // databases.
98 // From sqlite.org: "The page size must be a power of two greater than or
99 // equal to 512 and less than or equal to SQLITE_MAX_PAGE_SIZE. The maximum
100 // value for SQLITE_MAX_PAGE_SIZE is 32768."
101 void set_page_size(int page_size) { page_size_ = page_size; }
103 // Sets the number of pages that will be cached in memory by sqlite. The
104 // total cache size in bytes will be page_size * cache_size. This must be
105 // called before Open() to have an effect.
106 void set_cache_size(int cache_size) { cache_size_ = cache_size; }
108 // Call to put the database in exclusive locking mode. There is no "back to
109 // normal" flag because of some additional requirements sqlite puts on this
110 // transaition (requires another access to the DB) and because we don't
111 // actually need it.
113 // Exclusive mode means that the database is not unlocked at the end of each
114 // transaction, which means there may be less time spent initializing the
115 // next transaction because it doesn't have to re-aquire locks.
117 // This must be called before Open() to have an effect.
118 void set_exclusive_locking() { exclusive_locking_ = true; }
120 // Call to cause Open() to restrict access permissions of the
121 // database file to only the owner.
122 // TODO(shess): Currently only supported on OS_POSIX, is a noop on
123 // other platforms.
124 void set_restrict_to_user() { restrict_to_user_ = true; }
126 // Set an error-handling callback. On errors, the error number (and
127 // statement, if available) will be passed to the callback.
129 // If no callback is set, the default action is to crash in debug
130 // mode or return failure in release mode.
131 typedef base::Callback<void(int, Statement*)> ErrorCallback;
132 void set_error_callback(const ErrorCallback& callback) {
133 error_callback_ = callback;
135 bool has_error_callback() const {
136 return !error_callback_.is_null();
138 void reset_error_callback() {
139 error_callback_.Reset();
142 // Set this tag to enable additional connection-type histogramming
143 // for SQLite error codes and database version numbers.
144 void set_histogram_tag(const std::string& tag) {
145 histogram_tag_ = tag;
148 // Record a sparse UMA histogram sample under
149 // |name|+"."+|histogram_tag_|. If |histogram_tag_| is empty, no
150 // histogram is recorded.
151 void AddTaggedHistogram(const std::string& name, size_t sample) const;
153 // Run "PRAGMA integrity_check" and post each line of results into
154 // |messages|. Returns the success of running the statement - per
155 // the SQLite documentation, if no errors are found the call should
156 // succeed, and a single value "ok" should be in messages.
157 bool IntegrityCheck(std::vector<std::string>* messages);
159 // Initialization ------------------------------------------------------------
161 // Initializes the SQL connection for the given file, returning true if the
162 // file could be opened. You can call this or OpenInMemory.
163 bool Open(const base::FilePath& path) WARN_UNUSED_RESULT;
165 // Initializes the SQL connection for a temporary in-memory database. There
166 // will be no associated file on disk, and the initial database will be
167 // empty. You can call this or Open.
168 bool OpenInMemory() WARN_UNUSED_RESULT;
170 // Create a temporary on-disk database. The database will be
171 // deleted after close. This kind of database is similar to
172 // OpenInMemory() for small databases, but can page to disk if the
173 // database becomes large.
174 bool OpenTemporary() WARN_UNUSED_RESULT;
176 // Returns true if the database has been successfully opened.
177 bool is_open() const { return !!db_; }
179 // Closes the database. This is automatically performed on destruction for
180 // you, but this allows you to close the database early. You must not call
181 // any other functions after closing it. It is permissable to call Close on
182 // an uninitialized or already-closed database.
183 void Close();
185 // Pre-loads the first <cache-size> pages into the cache from the file.
186 // If you expect to soon use a substantial portion of the database, this
187 // is much more efficient than allowing the pages to be populated organically
188 // since there is no per-page hard drive seeking. If the file is larger than
189 // the cache, the last part that doesn't fit in the cache will be brought in
190 // organically.
192 // This function assumes your class is using a meta table on the current
193 // database, as it openes a transaction on the meta table to force the
194 // database to be initialized. You should feel free to initialize the meta
195 // table after calling preload since the meta table will already be in the
196 // database if it exists, and if it doesn't exist, the database won't
197 // generally exist either.
198 void Preload();
200 // Try to trim the cache memory used by the database. If |aggressively| is
201 // true, this function will try to free all of the cache memory it can. If
202 // |aggressively| is false, this function will try to cut cache memory
203 // usage by half.
204 void TrimMemory(bool aggressively);
206 // Raze the database to the ground. This approximates creating a
207 // fresh database from scratch, within the constraints of SQLite's
208 // locking protocol (locks and open handles can make doing this with
209 // filesystem operations problematic). Returns true if the database
210 // was razed.
212 // false is returned if the database is locked by some other
213 // process. RazeWithTimeout() may be used if appropriate.
215 // NOTE(shess): Raze() will DCHECK in the following situations:
216 // - database is not open.
217 // - the connection has a transaction open.
218 // - a SQLite issue occurs which is structural in nature (like the
219 // statements used are broken).
220 // Since Raze() is expected to be called in unexpected situations,
221 // these all return false, since it is unlikely that the caller
222 // could fix them.
224 // The database's page size is taken from |page_size_|. The
225 // existing database's |auto_vacuum| setting is lost (the
226 // possibility of corruption makes it unreliable to pull it from the
227 // existing database). To re-enable on the empty database requires
228 // running "PRAGMA auto_vacuum = 1;" then "VACUUM".
230 // NOTE(shess): For Android, SQLITE_DEFAULT_AUTOVACUUM is set to 1,
231 // so Raze() sets auto_vacuum to 1.
233 // TODO(shess): Raze() needs a connection so cannot clear SQLITE_NOTADB.
234 // TODO(shess): Bake auto_vacuum into Connection's API so it can
235 // just pick up the default.
236 bool Raze();
237 bool RazeWithTimout(base::TimeDelta timeout);
239 // Breaks all outstanding transactions (as initiated by
240 // BeginTransaction()), closes the SQLite database, and poisons the
241 // object so that all future operations against the Connection (or
242 // its Statements) fail safely, without side effects.
244 // This is intended as an alternative to Close() in error callbacks.
245 // Close() should still be called at some point.
246 void Poison();
248 // Raze() the database and Poison() the handle. Returns the return
249 // value from Raze().
250 // TODO(shess): Rename to RazeAndPoison().
251 bool RazeAndClose();
253 // Delete the underlying database files associated with |path|.
254 // This should be used on a database which has no existing
255 // connections. If any other connections are open to the same
256 // database, this could cause odd results or corruption (for
257 // instance if a hot journal is deleted but the associated database
258 // is not).
260 // Returns true if the database file and associated journals no
261 // longer exist, false otherwise. If the database has never
262 // existed, this will return true.
263 static bool Delete(const base::FilePath& path);
265 // Transactions --------------------------------------------------------------
267 // Transaction management. We maintain a virtual transaction stack to emulate
268 // nested transactions since sqlite can't do nested transactions. The
269 // limitation is you can't roll back a sub transaction: if any transaction
270 // fails, all transactions open will also be rolled back. Any nested
271 // transactions after one has rolled back will return fail for Begin(). If
272 // Begin() fails, you must not call Commit or Rollback().
274 // Normally you should use sql::Transaction to manage a transaction, which
275 // will scope it to a C++ context.
276 bool BeginTransaction();
277 void RollbackTransaction();
278 bool CommitTransaction();
280 // Rollback all outstanding transactions. Use with care, there may
281 // be scoped transactions on the stack.
282 void RollbackAllTransactions();
284 // Returns the current transaction nesting, which will be 0 if there are
285 // no open transactions.
286 int transaction_nesting() const { return transaction_nesting_; }
288 // Attached databases---------------------------------------------------------
290 // SQLite supports attaching multiple database files to a single
291 // handle. Attach the database in |other_db_path| to the current
292 // handle under |attachment_point|. |attachment_point| should only
293 // contain characters from [a-zA-Z0-9_].
295 // Note that calling attach or detach with an open transaction is an
296 // error.
297 bool AttachDatabase(const base::FilePath& other_db_path,
298 const char* attachment_point);
299 bool DetachDatabase(const char* attachment_point);
301 // Statements ----------------------------------------------------------------
303 // Executes the given SQL string, returning true on success. This is
304 // normally used for simple, 1-off statements that don't take any bound
305 // parameters and don't return any data (e.g. CREATE TABLE).
307 // This will DCHECK if the |sql| contains errors.
309 // Do not use ignore_result() to ignore all errors. Use
310 // ExecuteAndReturnErrorCode() and ignore only specific errors.
311 bool Execute(const char* sql) WARN_UNUSED_RESULT;
313 // Like Execute(), but returns the error code given by SQLite.
314 int ExecuteAndReturnErrorCode(const char* sql) WARN_UNUSED_RESULT;
316 // Returns true if we have a statement with the given identifier already
317 // cached. This is normally not necessary to call, but can be useful if the
318 // caller has to dynamically build up SQL to avoid doing so if it's already
319 // cached.
320 bool HasCachedStatement(const StatementID& id) const;
322 // Returns a statement for the given SQL using the statement cache. It can
323 // take a nontrivial amount of work to parse and compile a statement, so
324 // keeping commonly-used ones around for future use is important for
325 // performance.
327 // If the |sql| has an error, an invalid, inert StatementRef is returned (and
328 // the code will crash in debug). The caller must deal with this eventuality,
329 // either by checking validity of the |sql| before calling, by correctly
330 // handling the return of an inert statement, or both.
332 // The StatementID and the SQL must always correspond to one-another. The
333 // ID is the lookup into the cache, so crazy things will happen if you use
334 // different SQL with the same ID.
336 // You will normally use the SQL_FROM_HERE macro to generate a statement
337 // ID associated with the current line of code. This gives uniqueness without
338 // you having to manage unique names. See StatementID above for more.
340 // Example:
341 // sql::Statement stmt(connection_.GetCachedStatement(
342 // SQL_FROM_HERE, "SELECT * FROM foo"));
343 // if (!stmt)
344 // return false; // Error creating statement.
345 scoped_refptr<StatementRef> GetCachedStatement(const StatementID& id,
346 const char* sql);
348 // Used to check a |sql| statement for syntactic validity. If the statement is
349 // valid SQL, returns true.
350 bool IsSQLValid(const char* sql);
352 // Returns a non-cached statement for the given SQL. Use this for SQL that
353 // is only executed once or only rarely (there is overhead associated with
354 // keeping a statement cached).
356 // See GetCachedStatement above for examples and error information.
357 scoped_refptr<StatementRef> GetUniqueStatement(const char* sql);
359 // Info querying -------------------------------------------------------------
361 // Returns true if the given table exists.
362 bool DoesTableExist(const char* table_name) const;
364 // Returns true if the given index exists.
365 bool DoesIndexExist(const char* index_name) const;
367 // Returns true if a column with the given name exists in the given table.
368 bool DoesColumnExist(const char* table_name, const char* column_name) const;
370 // Returns sqlite's internal ID for the last inserted row. Valid only
371 // immediately after an insert.
372 int64 GetLastInsertRowId() const;
374 // Returns sqlite's count of the number of rows modified by the last
375 // statement executed. Will be 0 if no statement has executed or the database
376 // is closed.
377 int GetLastChangeCount() const;
379 // Errors --------------------------------------------------------------------
381 // Returns the error code associated with the last sqlite operation.
382 int GetErrorCode() const;
384 // Returns the errno associated with GetErrorCode(). See
385 // SQLITE_LAST_ERRNO in SQLite documentation.
386 int GetLastErrno() const;
388 // Returns a pointer to a statically allocated string associated with the
389 // last sqlite operation.
390 const char* GetErrorMessage() const;
392 // Return a reproducible representation of the schema equivalent to
393 // running the following statement at a sqlite3 command-line:
394 // SELECT type, name, tbl_name, sql FROM sqlite_master ORDER BY 1, 2, 3, 4;
395 std::string GetSchema() const;
397 private:
398 // For recovery module.
399 friend class Recovery;
401 // Allow test-support code to set/reset error ignorer.
402 friend class ScopedErrorIgnorer;
404 // Statement accesses StatementRef which we don't want to expose to everybody
405 // (they should go through Statement).
406 friend class Statement;
408 // Internal initialize function used by both Init and InitInMemory. The file
409 // name is always 8 bits since we want to use the 8-bit version of
410 // sqlite3_open. The string can also be sqlite's special ":memory:" string.
412 // |retry_flag| controls retrying the open if the error callback
413 // addressed errors using RazeAndClose().
414 enum Retry {
415 NO_RETRY = 0,
416 RETRY_ON_POISON
418 bool OpenInternal(const std::string& file_name, Retry retry_flag);
420 // Internal close function used by Close() and RazeAndClose().
421 // |forced| indicates that orderly-shutdown checks should not apply.
422 void CloseInternal(bool forced);
424 // Check whether the current thread is allowed to make IO calls, but only
425 // if database wasn't open in memory. Function is inlined to be a no-op in
426 // official build.
427 void AssertIOAllowed() {
428 if (!in_memory_)
429 base::ThreadRestrictions::AssertIOAllowed();
432 // Internal helper for DoesTableExist and DoesIndexExist.
433 bool DoesTableOrIndexExist(const char* name, const char* type) const;
435 // Accessors for global error-ignorer, for injecting behavior during tests.
436 // See test/scoped_error_ignorer.h.
437 typedef base::Callback<bool(int)> ErrorIgnorerCallback;
438 static ErrorIgnorerCallback* current_ignorer_cb_;
439 static bool ShouldIgnore(int error);
440 static void SetErrorIgnorer(ErrorIgnorerCallback* ignorer);
441 static void ResetErrorIgnorer();
443 // A StatementRef is a refcounted wrapper around a sqlite statement pointer.
444 // Refcounting allows us to give these statements out to sql::Statement
445 // objects while also optionally maintaining a cache of compiled statements
446 // by just keeping a refptr to these objects.
448 // A statement ref can be valid, in which case it can be used, or invalid to
449 // indicate that the statement hasn't been created yet, has an error, or has
450 // been destroyed.
452 // The Connection may revoke a StatementRef in some error cases, so callers
453 // should always check validity before using.
454 class SQL_EXPORT StatementRef : public base::RefCounted<StatementRef> {
455 public:
456 // |connection| is the sql::Connection instance associated with
457 // the statement, and is used for tracking outstanding statements
458 // and for error handling. Set to NULL for invalid or untracked
459 // refs. |stmt| is the actual statement, and should only be NULL
460 // to create an invalid ref. |was_valid| indicates whether the
461 // statement should be considered valid for diagnistic purposes.
462 // |was_valid| can be true for NULL |stmt| if the connection has
463 // been forcibly closed by an error handler.
464 StatementRef(Connection* connection, sqlite3_stmt* stmt, bool was_valid);
466 // When true, the statement can be used.
467 bool is_valid() const { return !!stmt_; }
469 // When true, the statement is either currently valid, or was
470 // previously valid but the connection was forcibly closed. Used
471 // for diagnostic checks.
472 bool was_valid() const { return was_valid_; }
474 // If we've not been linked to a connection, this will be NULL.
475 // TODO(shess): connection_ can be NULL in case of GetUntrackedStatement(),
476 // which prevents Statement::OnError() from forwarding errors.
477 Connection* connection() const { return connection_; }
479 // Returns the sqlite statement if any. If the statement is not active,
480 // this will return NULL.
481 sqlite3_stmt* stmt() const { return stmt_; }
483 // Destroys the compiled statement and marks it NULL. The statement will
484 // no longer be active. |forced| is used to indicate if orderly-shutdown
485 // checks should apply (see Connection::RazeAndClose()).
486 void Close(bool forced);
488 // Check whether the current thread is allowed to make IO calls, but only
489 // if database wasn't open in memory.
490 void AssertIOAllowed() { if (connection_) connection_->AssertIOAllowed(); }
492 private:
493 friend class base::RefCounted<StatementRef>;
495 ~StatementRef();
497 Connection* connection_;
498 sqlite3_stmt* stmt_;
499 bool was_valid_;
501 DISALLOW_COPY_AND_ASSIGN(StatementRef);
503 friend class StatementRef;
505 // Executes a rollback statement, ignoring all transaction state. Used
506 // internally in the transaction management code.
507 void DoRollback();
509 // Called by a StatementRef when it's being created or destroyed. See
510 // open_statements_ below.
511 void StatementRefCreated(StatementRef* ref);
512 void StatementRefDeleted(StatementRef* ref);
514 // Called by Statement objects when an sqlite function returns an error.
515 // The return value is the error code reflected back to client code.
516 int OnSqliteError(int err, Statement* stmt);
518 // Like |Execute()|, but retries if the database is locked.
519 bool ExecuteWithTimeout(const char* sql, base::TimeDelta ms_timeout)
520 WARN_UNUSED_RESULT;
522 // Internal helper for const functions. Like GetUniqueStatement(),
523 // except the statement is not entered into open_statements_,
524 // allowing this function to be const. Open statements can block
525 // closing the database, so only use in cases where the last ref is
526 // released before close could be called (which should always be the
527 // case for const functions).
528 scoped_refptr<StatementRef> GetUntrackedStatement(const char* sql) const;
530 // The actual sqlite database. Will be NULL before Init has been called or if
531 // Init resulted in an error.
532 sqlite3* db_;
534 // Parameters we'll configure in sqlite before doing anything else. Zero means
535 // use the default value.
536 int page_size_;
537 int cache_size_;
538 bool exclusive_locking_;
539 bool restrict_to_user_;
541 // All cached statements. Keeping a reference to these statements means that
542 // they'll remain active.
543 typedef std::map<StatementID, scoped_refptr<StatementRef> >
544 CachedStatementMap;
545 CachedStatementMap statement_cache_;
547 // A list of all StatementRefs we've given out. Each ref must register with
548 // us when it's created or destroyed. This allows us to potentially close
549 // any open statements when we encounter an error.
550 typedef std::set<StatementRef*> StatementRefSet;
551 StatementRefSet open_statements_;
553 // Number of currently-nested transactions.
554 int transaction_nesting_;
556 // True if any of the currently nested transactions have been rolled back.
557 // When we get to the outermost transaction, this will determine if we do
558 // a rollback instead of a commit.
559 bool needs_rollback_;
561 // True if database is open with OpenInMemory(), False if database is open
562 // with Open().
563 bool in_memory_;
565 // |true| if the connection was closed using RazeAndClose(). Used
566 // to enable diagnostics to distinguish calls to never-opened
567 // databases (incorrect use of the API) from calls to once-valid
568 // databases.
569 bool poisoned_;
571 ErrorCallback error_callback_;
573 // Tag for auxiliary histograms.
574 std::string histogram_tag_;
576 DISALLOW_COPY_AND_ASSIGN(Connection);
579 } // namespace sql
581 #endif // SQL_CONNECTION_H_