1 /* 2 * Copyright (C) 2008 Apple Inc. All Rights Reserved. 3 * Copyright (C) 2011 Google, Inc. All Rights Reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 */ 27 28 #include "config.h" 29 #include "modules/webdatabase/DatabaseContext.h" 30 31 #include "core/dom/Document.h" 32 #include "core/dom/ExecutionContext.h" 33 #include "modules/webdatabase/Database.h" 34 #include "modules/webdatabase/DatabaseManager.h" 35 #include "modules/webdatabase/DatabaseTask.h" 36 #include "modules/webdatabase/DatabaseThread.h" 37 #include "platform/weborigin/SchemeRegistry.h" 38 #include "platform/weborigin/SecurityOrigin.h" 39 #include "wtf/Assertions.h" 40 41 namespace WebCore { 42 43 // How the DatabaseContext Life-Cycle works? 44 // ======================================== 45 // ... in other words, who's keeping the DatabaseContext alive and how long does 46 // it need to stay alive? 47 // 48 // The DatabaseContext is referenced from RefPtrs in: 49 // 1. ExecutionContext 50 // 2. Database 51 // 52 // At Birth: 53 // ======== 54 // We create a DatabaseContext only when there is a need i.e. the script tries to 55 // open a Database via DatabaseManager::openDatabase(). 56 // 57 // The DatabaseContext constructor will call ref(). This lets DatabaseContext keep itself alive. 58 // Note that paired deref() is called from contextDestroyed(). 59 // 60 // Once a DatabaseContext is associated with a ExecutionContext, it will 61 // live until after the ExecutionContext destructs. This is true even if 62 // we don't succeed in opening any Databases for that context. When we do 63 // succeed in opening Databases for this ExecutionContext, the Database 64 // will re-use the same DatabaseContext. 65 // 66 // At Shutdown: 67 // =========== 68 // During shutdown, the DatabaseContext needs to: 69 // 1. "outlive" the ExecutionContext. 70 // - This is needed because the DatabaseContext needs to remove itself from the 71 // ExecutionContext's ActiveDOMObject list and ContextLifecycleObserver 72 // list. This removal needs to be executed on the script's thread. Hence, we 73 // rely on the ExecutionContext's shutdown process to call 74 // stop() and contextDestroyed() to give us a chance to clean these up from 75 // the script thread. 76 // 77 // 2. "outlive" the Databases. 78 // - This is because they may make use of the DatabaseContext to execute a close 79 // task and shutdown in an orderly manner. When the Databases are destructed, 80 // they will deref the DatabaseContext from the DatabaseThread. 81 // 82 // During shutdown, the ExecutionContext is shutting down on the script thread 83 // while the Databases are shutting down on the DatabaseThread. Hence, there can be 84 // a race condition as to whether the ExecutionContext or the Databases 85 // destruct first. 86 // 87 // The RefPtrs in the Databases and ExecutionContext will ensure that the 88 // DatabaseContext will outlive both regardless of which of the 2 destructs first. 89 90 PassRefPtrWillBeRawPtr<DatabaseContext> DatabaseContext::create(ExecutionContext* context) 91 { 92 RefPtrWillBeRawPtr<DatabaseContext> self = adoptRefWillBeNoop(new DatabaseContext(context)); 93 DatabaseManager::manager().registerDatabaseContext(self.get()); 94 return self.release(); 95 } 96 97 DatabaseContext::DatabaseContext(ExecutionContext* context) 98 : ActiveDOMObject(context) 99 , m_hasOpenDatabases(false) 100 , m_hasRequestedTermination(false) 101 { 102 // ActiveDOMObject expects this to be called to set internal flags. 103 suspendIfNeeded(); 104 105 // For debug accounting only. We must do this before we register the 106 // instance. The assertions assume this. 107 DatabaseManager::manager().didConstructDatabaseContext(); 108 if (context->isWorkerGlobalScope()) 109 toWorkerGlobalScope(context)->registerTerminationObserver(this); 110 } 111 112 DatabaseContext::~DatabaseContext() 113 { 114 // For debug accounting only. We must call this last. The assertions assume 115 // this. 116 DatabaseManager::manager().didDestructDatabaseContext(); 117 } 118 119 void DatabaseContext::trace(Visitor* visitor) 120 { 121 visitor->trace(m_databaseThread); 122 visitor->trace(m_openSyncDatabases); 123 } 124 125 // This is called if the associated ExecutionContext is destructing while 126 // we're still associated with it. That's our cue to disassociate and shutdown. 127 // To do this, we stop the database and let everything shutdown naturally 128 // because the database closing process may still make use of this context. 129 // It is not safe to just delete the context here. 130 void DatabaseContext::contextDestroyed() 131 { 132 RefPtrWillBeRawPtr<DatabaseContext> protector(this); 133 stopDatabases(); 134 if (executionContext()->isWorkerGlobalScope()) 135 toWorkerGlobalScope(executionContext())->unregisterTerminationObserver(this); 136 DatabaseManager::manager().unregisterDatabaseContext(this); 137 ActiveDOMObject::contextDestroyed(); 138 } 139 140 void DatabaseContext::wasRequestedToTerminate() 141 { 142 DatabaseManager::manager().interruptAllDatabasesForContext(this); 143 } 144 145 // stop() is from stopActiveDOMObjects() which indicates that the owner LocalFrame 146 // or WorkerThread is shutting down. Initiate the orderly shutdown by stopping 147 // the associated databases. 148 void DatabaseContext::stop() 149 { 150 stopDatabases(); 151 } 152 153 DatabaseContext* DatabaseContext::backend() 154 { 155 return this; 156 } 157 158 DatabaseThread* DatabaseContext::databaseThread() 159 { 160 if (!m_databaseThread && !m_hasOpenDatabases) { 161 // It's OK to ask for the m_databaseThread after we've requested 162 // termination because we're still using it to execute the closing 163 // of the database. However, it is NOT OK to create a new thread 164 // after we've requested termination. 165 ASSERT(!m_hasRequestedTermination); 166 167 // Create the database thread on first request - but not if at least one database was already opened, 168 // because in that case we already had a database thread and terminated it and should not create another. 169 m_databaseThread = DatabaseThread::create(); 170 m_databaseThread->start(); 171 } 172 173 return m_databaseThread.get(); 174 } 175 176 void DatabaseContext::didOpenDatabase(DatabaseBackendBase& database) 177 { 178 if (!database.isSyncDatabase()) 179 return; 180 ASSERT(isContextThread()); 181 #if ENABLE(OILPAN) 182 m_openSyncDatabases.add(&database, adoptPtr(new DatabaseCloser(database))); 183 #else 184 m_openSyncDatabases.add(&database); 185 #endif 186 } 187 188 void DatabaseContext::didCloseDatabase(DatabaseBackendBase& database) 189 { 190 #if !ENABLE(OILPAN) 191 if (!database.isSyncDatabase()) 192 return; 193 ASSERT(isContextThread()); 194 m_openSyncDatabases.remove(&database); 195 #endif 196 } 197 198 #if ENABLE(OILPAN) 199 DatabaseContext::DatabaseCloser::~DatabaseCloser() 200 { 201 m_database.closeImmediately(); 202 } 203 #endif 204 205 void DatabaseContext::stopSyncDatabases() 206 { 207 // SQLite is "multi-thread safe", but each database handle can only be used 208 // on a single thread at a time. 209 // 210 // For DatabaseBackendSync, we open the SQLite database on the script 211 // context thread. And hence we should also close it on that same 212 // thread. This means that the SQLite database need to be closed here in the 213 // destructor. 214 ASSERT(isContextThread()); 215 #if ENABLE(OILPAN) 216 m_openSyncDatabases.clear(); 217 #else 218 Vector<DatabaseBackendBase*> syncDatabases; 219 copyToVector(m_openSyncDatabases, syncDatabases); 220 m_openSyncDatabases.clear(); 221 for (size_t i = 0; i < syncDatabases.size(); ++i) 222 syncDatabases[i]->closeImmediately(); 223 #endif 224 } 225 226 void DatabaseContext::stopDatabases() 227 { 228 stopSyncDatabases(); 229 230 // Though we initiate termination of the DatabaseThread here in 231 // stopDatabases(), we can't clear the m_databaseThread ref till we get to 232 // the destructor. This is because the Databases that are managed by 233 // DatabaseThread still rely on this ref between the context and the thread 234 // to execute the task for closing the database. By the time we get to the 235 // destructor, we're guaranteed that the databases are destructed (which is 236 // why our ref count is 0 then and we're destructing). Then, the 237 // m_databaseThread RefPtr destructor will deref and delete the 238 // DatabaseThread. 239 240 if (m_databaseThread && !m_hasRequestedTermination) { 241 TaskSynchronizer sync; 242 m_databaseThread->requestTermination(&sync); 243 m_hasRequestedTermination = true; 244 sync.waitForTaskCompletion(); 245 } 246 } 247 248 bool DatabaseContext::allowDatabaseAccess() const 249 { 250 if (executionContext()->isDocument()) 251 return toDocument(executionContext())->isActive(); 252 ASSERT(executionContext()->isWorkerGlobalScope()); 253 // allowDatabaseAccess is not yet implemented for workers. 254 return true; 255 } 256 257 SecurityOrigin* DatabaseContext::securityOrigin() const 258 { 259 return executionContext()->securityOrigin(); 260 } 261 262 bool DatabaseContext::isContextThread() const 263 { 264 return executionContext()->isContextThread(); 265 } 266 267 } // namespace WebCore 268
