1// Copyright (c) 2011 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.
4
5#include "app/sql/connection.h"
6
7#include <string.h>
8
9#include "app/sql/statement.h"
10#include "base/file_path.h"
11#include "base/logging.h"
12#include "base/string_util.h"
13#include "base/utf_string_conversions.h"
14#ifdef ANDROID
15#include "sqlite3.h"
16#else
17#include "third_party/sqlite/sqlite3.h"
18#endif
19
20namespace {
21
22// Spin for up to a second waiting for the lock to clear when setting
23// up the database.
24// TODO(shess): Better story on this.  http://crbug.com/56559
25const base::TimeDelta kBusyTimeout = base::TimeDelta::FromSeconds(1);
26
27class ScopedBusyTimeout {
28 public:
29  explicit ScopedBusyTimeout(sqlite3* db)
30      : db_(db) {
31  }
32  ~ScopedBusyTimeout() {
33    sqlite3_busy_timeout(db_, 0);
34  }
35
36  int SetTimeout(base::TimeDelta timeout) {
37    DCHECK_LT(timeout.InMilliseconds(), INT_MAX);
38    return sqlite3_busy_timeout(db_,
39                                static_cast<int>(timeout.InMilliseconds()));
40  }
41
42 private:
43  sqlite3* db_;
44};
45
46}  // namespace
47
48namespace sql {
49
50bool StatementID::operator<(const StatementID& other) const {
51  if (number_ != other.number_)
52    return number_ < other.number_;
53  return strcmp(str_, other.str_) < 0;
54}
55
56ErrorDelegate::ErrorDelegate() {
57}
58
59ErrorDelegate::~ErrorDelegate() {
60}
61
62Connection::StatementRef::StatementRef()
63    : connection_(NULL),
64      stmt_(NULL) {
65}
66
67Connection::StatementRef::StatementRef(Connection* connection,
68                                       sqlite3_stmt* stmt)
69    : connection_(connection),
70      stmt_(stmt) {
71  connection_->StatementRefCreated(this);
72}
73
74Connection::StatementRef::~StatementRef() {
75  if (connection_)
76    connection_->StatementRefDeleted(this);
77  Close();
78}
79
80void Connection::StatementRef::Close() {
81  if (stmt_) {
82    sqlite3_finalize(stmt_);
83    stmt_ = NULL;
84  }
85  connection_ = NULL;  // The connection may be getting deleted.
86}
87
88Connection::Connection()
89    : db_(NULL),
90      page_size_(0),
91      cache_size_(0),
92      exclusive_locking_(false),
93      transaction_nesting_(0),
94      needs_rollback_(false) {
95}
96
97Connection::~Connection() {
98  Close();
99}
100
101bool Connection::Open(const FilePath& path) {
102#if defined(OS_WIN)
103  return OpenInternal(WideToUTF8(path.value()));
104#elif defined(OS_POSIX)
105  return OpenInternal(path.value());
106#endif
107}
108
109bool Connection::OpenInMemory() {
110  return OpenInternal(":memory:");
111}
112
113void Connection::Close() {
114  statement_cache_.clear();
115  DCHECK(open_statements_.empty());
116  if (db_) {
117    sqlite3_close(db_);
118    db_ = NULL;
119  }
120}
121
122void Connection::Preload() {
123  if (!db_) {
124    NOTREACHED();
125    return;
126  }
127
128  // A statement must be open for the preload command to work. If the meta
129  // table doesn't exist, it probably means this is a new database and there
130  // is nothing to preload (so it's OK we do nothing).
131  if (!DoesTableExist("meta"))
132    return;
133  Statement dummy(GetUniqueStatement("SELECT * FROM meta"));
134  if (!dummy || !dummy.Step())
135    return;
136
137#if !defined(USE_SYSTEM_SQLITE)
138  // This function is only defined in Chromium's version of sqlite.
139  // Do not call it when using system sqlite.
140  sqlite3_preload(db_);
141#endif
142}
143
144bool Connection::BeginTransaction() {
145  if (needs_rollback_) {
146    DCHECK_GT(transaction_nesting_, 0);
147
148    // When we're going to rollback, fail on this begin and don't actually
149    // mark us as entering the nested transaction.
150    return false;
151  }
152
153  bool success = true;
154  if (!transaction_nesting_) {
155    needs_rollback_ = false;
156
157    Statement begin(GetCachedStatement(SQL_FROM_HERE, "BEGIN TRANSACTION"));
158    if (!begin || !begin.Run())
159      return false;
160  }
161  transaction_nesting_++;
162  return success;
163}
164
165void Connection::RollbackTransaction() {
166  if (!transaction_nesting_) {
167    NOTREACHED() << "Rolling back a nonexistent transaction";
168    return;
169  }
170
171  transaction_nesting_--;
172
173  if (transaction_nesting_ > 0) {
174    // Mark the outermost transaction as needing rollback.
175    needs_rollback_ = true;
176    return;
177  }
178
179  DoRollback();
180}
181
182bool Connection::CommitTransaction() {
183  if (!transaction_nesting_) {
184    NOTREACHED() << "Rolling back a nonexistent transaction";
185    return false;
186  }
187  transaction_nesting_--;
188
189  if (transaction_nesting_ > 0) {
190    // Mark any nested transactions as failing after we've already got one.
191    return !needs_rollback_;
192  }
193
194  if (needs_rollback_) {
195    DoRollback();
196    return false;
197  }
198
199  Statement commit(GetCachedStatement(SQL_FROM_HERE, "COMMIT"));
200  if (!commit)
201    return false;
202  return commit.Run();
203}
204
205bool Connection::Execute(const char* sql) {
206  if (!db_)
207    return false;
208  return sqlite3_exec(db_, sql, NULL, NULL, NULL) == SQLITE_OK;
209}
210
211bool Connection::ExecuteWithTimeout(const char* sql, base::TimeDelta timeout) {
212  if (!db_)
213    return false;
214
215  ScopedBusyTimeout busy_timeout(db_);
216  busy_timeout.SetTimeout(timeout);
217  return sqlite3_exec(db_, sql, NULL, NULL, NULL) == SQLITE_OK;
218}
219
220bool Connection::HasCachedStatement(const StatementID& id) const {
221  return statement_cache_.find(id) != statement_cache_.end();
222}
223
224scoped_refptr<Connection::StatementRef> Connection::GetCachedStatement(
225    const StatementID& id,
226    const char* sql) {
227  CachedStatementMap::iterator i = statement_cache_.find(id);
228  if (i != statement_cache_.end()) {
229    // Statement is in the cache. It should still be active (we're the only
230    // one invalidating cached statements, and we'll remove it from the cache
231    // if we do that. Make sure we reset it before giving out the cached one in
232    // case it still has some stuff bound.
233    DCHECK(i->second->is_valid());
234    sqlite3_reset(i->second->stmt());
235    return i->second;
236  }
237
238  scoped_refptr<StatementRef> statement = GetUniqueStatement(sql);
239  if (statement->is_valid())
240    statement_cache_[id] = statement;  // Only cache valid statements.
241  return statement;
242}
243
244scoped_refptr<Connection::StatementRef> Connection::GetUniqueStatement(
245    const char* sql) {
246  if (!db_)
247    return new StatementRef(this, NULL);  // Return inactive statement.
248
249  sqlite3_stmt* stmt = NULL;
250  if (sqlite3_prepare_v2(db_, sql, -1, &stmt, NULL) != SQLITE_OK) {
251    // Treat this as non-fatal, it can occur in a number of valid cases, and
252    // callers should be doing their own error handling.
253    DLOG(WARNING) << "SQL compile error " << GetErrorMessage();
254    return new StatementRef(this, NULL);
255  }
256  return new StatementRef(this, stmt);
257}
258
259bool Connection::DoesTableExist(const char* table_name) const {
260  // GetUniqueStatement can't be const since statements may modify the
261  // database, but we know ours doesn't modify it, so the cast is safe.
262  Statement statement(const_cast<Connection*>(this)->GetUniqueStatement(
263      "SELECT name FROM sqlite_master "
264      "WHERE type='table' AND name=?"));
265  if (!statement)
266    return false;
267  statement.BindString(0, table_name);
268  return statement.Step();  // Table exists if any row was returned.
269}
270
271bool Connection::DoesColumnExist(const char* table_name,
272                                 const char* column_name) const {
273  std::string sql("PRAGMA TABLE_INFO(");
274  sql.append(table_name);
275  sql.append(")");
276
277  // Our SQL is non-mutating, so this cast is OK.
278  Statement statement(const_cast<Connection*>(this)->GetUniqueStatement(
279      sql.c_str()));
280  if (!statement)
281    return false;
282
283  while (statement.Step()) {
284    if (!statement.ColumnString(1).compare(column_name))
285      return true;
286  }
287  return false;
288}
289
290int64 Connection::GetLastInsertRowId() const {
291  if (!db_) {
292    NOTREACHED();
293    return 0;
294  }
295  return sqlite3_last_insert_rowid(db_);
296}
297
298int Connection::GetLastChangeCount() const {
299  if (!db_) {
300    NOTREACHED();
301    return 0;
302  }
303  return sqlite3_changes(db_);
304}
305
306int Connection::GetErrorCode() const {
307  if (!db_)
308    return SQLITE_ERROR;
309  return sqlite3_errcode(db_);
310}
311
312int Connection::GetLastErrno() const {
313  if (!db_)
314    return -1;
315
316  int err = 0;
317  if (SQLITE_OK != sqlite3_file_control(db_, NULL, SQLITE_LAST_ERRNO, &err))
318    return -2;
319
320  return err;
321}
322
323const char* Connection::GetErrorMessage() const {
324  if (!db_)
325    return "sql::Connection has no connection.";
326  return sqlite3_errmsg(db_);
327}
328
329bool Connection::OpenInternal(const std::string& file_name) {
330  if (db_) {
331    NOTREACHED() << "sql::Connection is already open.";
332    return false;
333  }
334
335  int err = sqlite3_open(file_name.c_str(), &db_);
336  if (err != SQLITE_OK) {
337    OnSqliteError(err, NULL);
338    db_ = NULL;
339    return false;
340  }
341
342  // Enable extended result codes to provide more color on I/O errors.
343  // Not having extended result codes is not a fatal problem, as
344  // Chromium code does not attempt to handle I/O errors anyhow.  The
345  // current implementation always returns SQLITE_OK, the DCHECK is to
346  // quickly notify someone if SQLite changes.
347  err = sqlite3_extended_result_codes(db_, 1);
348  DCHECK_EQ(err, SQLITE_OK) << "Could not enable extended result codes";
349
350  // If indicated, lock up the database before doing anything else, so
351  // that the following code doesn't have to deal with locking.
352  // TODO(shess): This code is brittle.  Find the cases where code
353  // doesn't request |exclusive_locking_| and audit that it does the
354  // right thing with SQLITE_BUSY, and that it doesn't make
355  // assumptions about who might change things in the database.
356  // http://crbug.com/56559
357  if (exclusive_locking_) {
358    // TODO(shess): This should probably be a full CHECK().  Code
359    // which requests exclusive locking but doesn't get it is almost
360    // certain to be ill-tested.
361    if (!Execute("PRAGMA locking_mode=EXCLUSIVE"))
362      NOTREACHED() << "Could not set locking mode: " << GetErrorMessage();
363  }
364
365  if (page_size_ != 0) {
366    // Enforce SQLite restrictions on |page_size_|.
367    DCHECK(!(page_size_ & (page_size_ - 1)))
368        << " page_size_ " << page_size_ << " is not a power of two.";
369    static const int kSqliteMaxPageSize = 32768;  // from sqliteLimit.h
370    DCHECK_LE(page_size_, kSqliteMaxPageSize);
371    const std::string sql = StringPrintf("PRAGMA page_size=%d", page_size_);
372    if (!ExecuteWithTimeout(sql.c_str(), kBusyTimeout))
373      NOTREACHED() << "Could not set page size: " << GetErrorMessage();
374  }
375
376  if (cache_size_ != 0) {
377    const std::string sql = StringPrintf("PRAGMA cache_size=%d", cache_size_);
378    if (!ExecuteWithTimeout(sql.c_str(), kBusyTimeout))
379      NOTREACHED() << "Could not set cache size: " << GetErrorMessage();
380  }
381
382  return true;
383}
384
385void Connection::DoRollback() {
386  Statement rollback(GetCachedStatement(SQL_FROM_HERE, "ROLLBACK"));
387  if (rollback)
388    rollback.Run();
389}
390
391void Connection::StatementRefCreated(StatementRef* ref) {
392  DCHECK(open_statements_.find(ref) == open_statements_.end());
393  open_statements_.insert(ref);
394}
395
396void Connection::StatementRefDeleted(StatementRef* ref) {
397  StatementRefSet::iterator i = open_statements_.find(ref);
398  if (i == open_statements_.end())
399    NOTREACHED();
400  else
401    open_statements_.erase(i);
402}
403
404void Connection::ClearCache() {
405  statement_cache_.clear();
406
407  // The cache clear will get most statements. There may be still be references
408  // to some statements that are held by others (including one-shot statements).
409  // This will deactivate them so they can't be used again.
410  for (StatementRefSet::iterator i = open_statements_.begin();
411       i != open_statements_.end(); ++i)
412    (*i)->Close();
413}
414
415int Connection::OnSqliteError(int err, sql::Statement *stmt) {
416  if (error_delegate_.get())
417    return error_delegate_->OnError(err, this, stmt);
418  // The default handling is to assert on debug and to ignore on release.
419  NOTREACHED() << GetErrorMessage();
420  return err;
421}
422
423}  // namespace sql
424