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| -rw-r--r-- | storage/mozStorageConnection.h | 561 |
1 files changed, 561 insertions, 0 deletions
diff --git a/storage/mozStorageConnection.h b/storage/mozStorageConnection.h new file mode 100644 index 0000000000..b511e8d2c2 --- /dev/null +++ b/storage/mozStorageConnection.h @@ -0,0 +1,561 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ : + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef mozilla_storage_Connection_h +#define mozilla_storage_Connection_h + +#include "nsCOMPtr.h" +#include "mozilla/Atomics.h" +#include "mozilla/Mutex.h" +#include "nsProxyRelease.h" +#include "nsThreadUtils.h" +#include "nsIInterfaceRequestor.h" + +#include "nsTHashMap.h" +#include "mozIStorageProgressHandler.h" +#include "SQLiteMutex.h" +#include "mozIStorageConnection.h" +#include "mozStorageService.h" +#include "mozIStorageAsyncConnection.h" +#include "mozIStorageCompletionCallback.h" + +#include "mozilla/Attributes.h" + +#include "sqlite3.h" + +class nsIFile; +class nsIFileURL; +class nsIEventTarget; +class nsISerialEventTarget; +class nsIThread; + +namespace mozilla { +namespace storage { + +class Connection final : public mozIStorageConnection, + public nsIInterfaceRequestor { + public: + NS_DECL_THREADSAFE_ISUPPORTS + NS_DECL_MOZISTORAGEASYNCCONNECTION + NS_DECL_MOZISTORAGECONNECTION + NS_DECL_NSIINTERFACEREQUESTOR + + /** + * Indicates if a database operation is synchronous or asynchronous. + * + * - Async operations may be called from any thread for all connections. + * - Sync operations may be called from any thread for sync connections, and + * from background threads for async connections. + */ + enum ConnectionOperation { ASYNCHRONOUS, SYNCHRONOUS }; + + /** + * Structure used to describe user functions on the database connection. + */ + struct FunctionInfo { + nsCOMPtr<mozIStorageFunction> function; + int32_t numArgs; + }; + + /** + * @param aService + * Pointer to the storage service. Held onto for the lifetime of the + * connection. + * @param aFlags + * The flags to pass to sqlite3_open_v2. + * @param aSupportedOperations + * The operation types supported on this connection. All connections + * implement both the async (`mozIStorageAsyncConnection`) and sync + * (`mozIStorageConnection`) interfaces, but async connections may not + * call sync operations from the main thread. + * @param aInterruptible + * If |true|, the pending operations can be interrupted by invokind the + * Interrupt() method. + * If |false|, method Interrupt() must not be used. + * @param aIgnoreLockingMode + * If |true|, ignore locks in force on the file. Only usable with + * read-only connections. Defaults to false. + * Use with extreme caution. If sqlite ignores locks, reads may fail + * indicating database corruption (the database won't actually be + * corrupt) or produce wrong results without any indication that has + * happened. + */ + Connection(Service* aService, int aFlags, + ConnectionOperation aSupportedOperations, + bool aInterruptible = false, bool aIgnoreLockingMode = false); + + /** + * Creates the connection to an in-memory database. + */ + nsresult initialize(const nsACString& aStorageKey, const nsACString& aName); + + /** + * Creates the connection to the database. + * + * @param aDatabaseFile + * The nsIFile of the location of the database to open, or create if it + * does not exist. + */ + nsresult initialize(nsIFile* aDatabaseFile); + + /** + * Creates the connection to the database. + * + * @param aFileURL + * The nsIFileURL of the location of the database to open, or create if + * it does not exist. + */ + nsresult initialize(nsIFileURL* aFileURL, + const nsACString& aTelemetryFilename); + + /** + * Same as initialize, but to be used on the async thread. + */ + nsresult initializeOnAsyncThread(nsIFile* aStorageFile); + + /** + * Fetches runtime status information for this connection. + * + * @param aStatusOption One of the SQLITE_DBSTATUS options defined at + * http://www.sqlite.org/c3ref/c_dbstatus_options.html + * @param [optional] aMaxValue if provided, will be set to the highest + * istantaneous value. + * @return the current value for the specified option. + */ + int32_t getSqliteRuntimeStatus(int32_t aStatusOption, + int32_t* aMaxValue = nullptr); + /** + * Registers/unregisters a commit hook callback. + * + * @param aCallbackFn a callback function to be invoked on transactions + * commit. Pass nullptr to unregister the current callback. + * @param [optional] aData if provided, will be passed to the callback. + * @see http://sqlite.org/c3ref/commit_hook.html + */ + void setCommitHook(int (*aCallbackFn)(void*), void* aData = nullptr) { + MOZ_ASSERT(mDBConn, "A connection must exist at this point"); + ::sqlite3_commit_hook(mDBConn, aCallbackFn, aData); + }; + + /** + * Gets autocommit status. + */ + bool getAutocommit() { + return mDBConn && static_cast<bool>(::sqlite3_get_autocommit(mDBConn)); + }; + + /** + * Lazily creates and returns a background execution thread. In the future, + * the thread may be re-claimed if left idle, so you should call this + * method just before you dispatch and not save the reference. + * + * This must be called from the opener thread. + * + * @return an event target suitable for asynchronous statement execution. + * @note This method will return null once AsyncClose() has been called. + */ + nsIEventTarget* getAsyncExecutionTarget(); + + /** + * Mutex used by asynchronous statements to protect state. The mutex is + * declared on the connection object because there is no contention between + * asynchronous statements (they are serialized on mAsyncExecutionThread). + * Currently protects: + * - Connection.mAsyncExecutionThreadShuttingDown + * - Connection.mConnectionClosed + * - AsyncExecuteStatements.mCancelRequested + */ + Mutex sharedAsyncExecutionMutex MOZ_UNANNOTATED; + + /** + * Wraps the mutex that SQLite gives us from sqlite3_db_mutex. This is public + * because we already expose the sqlite3* native connection and proper + * operation of the deadlock detector requires everyone to use the same single + * SQLiteMutex instance for correctness. + */ + SQLiteMutex sharedDBMutex; + + /** + * References the event target this database was opened on. + */ + const nsCOMPtr<nsISerialEventTarget> eventTargetOpenedOn; + + /** + * Closes the SQLite database, and warns about any non-finalized statements. + */ + nsresult internalClose(sqlite3* aDBConn); + + /** + * Shuts down the passed-in async thread. + */ + void shutdownAsyncThread(); + + /** + * Obtains the filename of the connection. Useful for logging. + */ + nsCString getFilename(); + + /** + * Creates an sqlite3 prepared statement object from an SQL string. + * + * @param aNativeConnection + * The underlying Sqlite connection to prepare the statement with. + * @param aSQL + * The SQL statement string to compile. + * @param _stmt + * New sqlite3_stmt object. + * @return the result from sqlite3_prepare_v2. + */ + int prepareStatement(sqlite3* aNativeConnection, const nsCString& aSQL, + sqlite3_stmt** _stmt); + + /** + * Performs a sqlite3_step on aStatement, while properly handling + * SQLITE_LOCKED when not on the main thread by waiting until we are notified. + * + * @param aNativeConnection + * The underlying Sqlite connection to step the statement with. + * @param aStatement + * A pointer to a sqlite3_stmt object. + * @return the result from sqlite3_step. + */ + int stepStatement(sqlite3* aNativeConnection, sqlite3_stmt* aStatement); + + /** + * Raw connection transaction management. + * + * @see BeginTransactionAs, CommitTransaction, RollbackTransaction. + */ + nsresult beginTransactionInternal( + const SQLiteMutexAutoLock& aProofOfLock, sqlite3* aNativeConnection, + int32_t aTransactionType = TRANSACTION_DEFERRED); + nsresult commitTransactionInternal(const SQLiteMutexAutoLock& aProofOfLock, + sqlite3* aNativeConnection); + nsresult rollbackTransactionInternal(const SQLiteMutexAutoLock& aProofOfLock, + sqlite3* aNativeConnection); + + /** + * Indicates if this database connection is open. + */ + inline bool connectionReady() { return mDBConn != nullptr; } + + /** + * Indicates if this database connection has an open transaction. Because + * multiple threads can execute statements on the same connection, this method + * requires proof that the caller is holding `sharedDBMutex`. + * + * Per the SQLite docs, `sqlite3_get_autocommit` returns 0 if autocommit mode + * is disabled. `BEGIN` disables autocommit mode, and `COMMIT`, `ROLLBACK`, or + * an automatic rollback re-enables it. + */ + inline bool transactionInProgress(const SQLiteMutexAutoLock& aProofOfLock) { + return !getAutocommit(); + } + + /** + * Indicates if this database connection supports the given operation. + * + * @param aOperationType + * The operation type, sync or async. + * @return `true` if the operation is supported, `false` otherwise. + */ + bool operationSupported(ConnectionOperation aOperationType); + + /** + * Thread-aware version of connectionReady, results per caller's thread are: + * - owner thread: Same as connectionReady(). True means we have a valid, + * un-closed database connection and it's not going away until you invoke + * Close() or AsyncClose(). + * - async thread: Returns true at all times because you can't schedule + * runnables against the async thread after AsyncClose() has been called. + * Therefore, the connection is still around if your code is running. + * - any other thread: Race-prone Lies! If you are main-thread code in + * mozStorageService iterating over the list of connections, you need to + * acquire the sharedAsyncExecutionMutex for the connection, invoke + * connectionReady() while holding it, and then continue to hold it while + * you do whatever you need to do. This is because of off-main-thread + * consumers like dom/cache and IndexedDB and other QuotaManager clients. + */ + bool isConnectionReadyOnThisThread(); + + /** + * True if this connection has inited shutdown. + */ + bool isClosing(); + + /** + * True if the underlying connection is closed. + * Any sqlite resources may be lost when this returns true, so nothing should + * try to use them. + * This locks on sharedAsyncExecutionMutex. + */ + bool isClosed(); + + /** + * Same as isClosed(), but takes a proof-of-lock instead of locking + * internally. + */ + bool isClosed(MutexAutoLock& lock); + + /** + * True if the async execution thread is alive and able to be used (i.e., it + * is not in the process of shutting down.) + * + * This must be called from the opener thread. + */ + bool isAsyncExecutionThreadAvailable(); + + nsresult initializeClone(Connection* aClone, bool aReadOnly); + + /** + * Records a status from a sqlite statement. + * + * @param srv The sqlite result for the failure or SQLITE_OK. + */ + void RecordQueryStatus(int srv); + + /** + * Returns the number of pages in the free list that can be removed. + * + * A database may use chunked growth to reduce filesystem fragmentation, then + * Sqlite will allocate and release multiple pages in chunks. We want to + * preserve the chunked space to reduce the likelihood of fragmentation, + * releasing free pages only when there's a large amount of them. This can be + * used to decide if it's worth vacuuming the database and how many pages can + * be vacuumed in case of incremental vacuum. + * Note this returns 0, and asserts, in case of errors. + */ + int32_t RemovablePagesInFreeList(const nsACString& aSchemaName); + + /** + * Whether the statement currently running on the helper thread can be + * interrupted. + */ + Atomic<bool> mIsStatementOnHelperThreadInterruptible; + + private: + ~Connection(); + nsresult initializeInternal(); + void initializeFailed(); + + /** + * Records the status of an attempt to load a sqlite database to telemetry. + * + * @param rv The state of the load, success or failure. + */ + void RecordOpenStatus(nsresult rv); + + /** + * Sets the database into a closed state so no further actions can be + * performed. + * + * @note mDBConn is set to nullptr in this method. + */ + nsresult setClosedState(); + + /** + * Helper for calls to sqlite3_exec. Reports long delays to Telemetry. + * + * @param aNativeConnection + * The underlying Sqlite connection to execute the query with. + * @param aSqlString + * SQL string to execute + * @return the result from sqlite3_exec. + */ + int executeSql(sqlite3* aNativeConnection, const char* aSqlString); + + /** + * Describes a certain primitive type in the database. + * + * Possible Values Are: + * INDEX - To check for the existence of an index + * TABLE - To check for the existence of a table + */ + enum DatabaseElementType { INDEX, TABLE }; + + /** + * Determines if the specified primitive exists. + * + * @param aElementType + * The type of element to check the existence of + * @param aElementName + * The name of the element to check for + * @returns true if element exists, false otherwise + */ + nsresult databaseElementExists(enum DatabaseElementType aElementType, + const nsACString& aElementName, bool* _exists); + + bool findFunctionByInstance(mozIStorageFunction* aInstance); + + static int sProgressHelper(void* aArg); + // Generic progress handler + // Dispatch call to registered progress handler, + // if there is one. Do nothing in other cases. + int progressHandler(); + + /** + * Like `operationSupported`, but throws (and, in a debug build, asserts) if + * the operation is unsupported. + */ + nsresult ensureOperationSupported(ConnectionOperation aOperationType); + + sqlite3* mDBConn; + nsCString mStorageKey; + nsCString mName; + nsCOMPtr<nsIFileURL> mFileURL; + nsCOMPtr<nsIFile> mDatabaseFile; + + /** + * Lazily created thread for asynchronous statement execution. Consumers + * should use getAsyncExecutionTarget rather than directly accessing this + * field. + * + * This must be modified only on the opener thread. + */ + nsCOMPtr<nsIThread> mAsyncExecutionThread; + + /** + * The filename that will be reported to telemetry for this connection. By + * default this will be the leaf of the path to the database file. + */ + nsCString mTelemetryFilename; + + /** + * Stores the default behavior for all transactions run on this connection. + */ + mozilla::Atomic<int32_t> mDefaultTransactionType; + + /** + * Used to trigger cleanup logic only the first time our refcount hits 1. We + * may trigger a failsafe Close() that invokes SpinningSynchronousClose() + * which invokes AsyncClose() which may bump our refcount back up to 2 (and + * which will then fall back down to 1 again). It's also possible that the + * Service may bump our refcount back above 1 if getConnections() runs before + * we invoke unregisterConnection(). + */ + mozilla::Atomic<bool> mDestroying; + + /** + * Stores the mapping of a given function by name to its instance. Access is + * protected by sharedDBMutex. + */ + nsTHashMap<nsCStringHashKey, FunctionInfo> mFunctions; + + /** + * Stores the registered progress handler for the database connection. Access + * is protected by sharedDBMutex. + */ + nsCOMPtr<mozIStorageProgressHandler> mProgressHandler; + + // This is here for two reasons: 1) It's used to make sure that the + // connections do not outlive the service. 2) Our custom collating functions + // call its localeCompareStrings() method. + RefPtr<Service> mStorageService; + + nsresult synchronousClose(); + + /** + * Stores the flags we passed to sqlite3_open_v2. + */ + const int mFlags; + + uint32_t mTransactionNestingLevel; + + /** + * Indicates which operations are supported on this connection. + */ + const ConnectionOperation mSupportedOperations; + + /** + * Stores whether this connection is interruptible. + */ + const bool mInterruptible; + + /** + * Stores whether we should ask sqlite3_open_v2 to ignore locking. + */ + const bool mIgnoreLockingMode; + + /** + * Set to true by Close() or AsyncClose() prior to shutdown. + * + * If false, we guarantee both that the underlying sqlite3 database + * connection is still open and that getAsyncExecutionTarget() can + * return a thread. Once true, either the sqlite3 database + * connection is being shutdown or it has been + * shutdown. Additionally, once true, getAsyncExecutionTarget() + * returns null. + * + * This variable should be accessed while holding the + * sharedAsyncExecutionMutex. + */ + bool mAsyncExecutionThreadShuttingDown; + + /** + * Set to true just prior to calling sqlite3_close on the + * connection. + * + * This variable should be accessed while holding the + * sharedAsyncExecutionMutex. + */ + bool mConnectionClosed; + + /** + * Stores the growth increment chunk size, set through SetGrowthIncrement(). + */ + Atomic<int32_t> mGrowthChunkSize; +}; + +/** + * A Runnable designed to call a mozIStorageCompletionCallback on + * the appropriate thread. + */ +class CallbackComplete final : public Runnable { + public: + /** + * @param aValue The result to pass to the callback. It must + * already be owned by the main thread. + * @param aCallback The callback. It must already be owned by the + * main thread. + */ + CallbackComplete(nsresult aStatus, nsISupports* aValue, + already_AddRefed<mozIStorageCompletionCallback> aCallback) + : Runnable("storage::CallbackComplete"), + mStatus(aStatus), + mValue(aValue), + mCallback(aCallback) {} + + NS_IMETHOD Run() override { + MOZ_ASSERT(NS_IsMainThread()); + nsresult rv = mCallback->Complete(mStatus, mValue); + + // Ensure that we release on the main thread + mValue = nullptr; + mCallback = nullptr; + return rv; + } + + private: + nsresult mStatus; + nsCOMPtr<nsISupports> mValue; + // This is a RefPtr<T> and not a nsCOMPtr<T> because + // nsCOMP<T> would cause an off-main thread QI, which + // is not a good idea (and crashes XPConnect). + RefPtr<mozIStorageCompletionCallback> mCallback; +}; + +} // namespace storage +} // namespace mozilla + +/** + * Casting Connection to nsISupports is ambiguous. + * This method handles that. + */ +inline nsISupports* ToSupports(mozilla::storage::Connection* p) { + return NS_ISUPPORTS_CAST(mozIStorageAsyncConnection*, p); +} + +#endif // mozilla_storage_Connection_h |