DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Implementation

Mercurial (dcc6d7a0dc00)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414
/* -*- 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 "nsAutoPtr.h"
#include "nsCOMPtr.h"
#include "mozilla/Mutex.h"
#include "nsProxyRelease.h"
#include "nsThreadUtils.h"
#include "nsIInterfaceRequestor.h"

#include "nsDataHashtable.h"
#include "mozIStorageProgressHandler.h"
#include "SQLiteMutex.h"
#include "mozIStorageConnection.h"
#include "mozStorageService.h"
#include "mozIStorageAsyncConnection.h"
#include "mozIStorageCompletionCallback.h"

#include "nsIMutableArray.h"
#include "mozilla/Attributes.h"

#include "sqlite3.h"

class nsIFile;
class nsIFileURL;
class nsIEventTarget;
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

  /**
   * Structure used to describe user functions on the database connection.
   */
  struct FunctionInfo {
    enum FunctionType {
      SIMPLE,
      AGGREGATE
    };

    nsCOMPtr<nsISupports> function;
    FunctionType type;
    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 aAsyncOnly
   *        If |true|, the Connection only implements asynchronous interface:
   *        - |mozIStorageAsyncConnection|;
   *        If |false|, the result also implements synchronous interface:
   *        - |mozIStorageConnection|.
   */
  Connection(Service *aService, int aFlags, bool aAsyncOnly);

  /**
   * Creates the connection to an in-memory database.
   */
  nsresult initialize();

  /**
   * 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);

  /**
   * 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.
   *
   * @returns an event target suitable for asynchronous statement execution.
   */
  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.mAsyncExecutionThread
   *  - Connection.mConnectionClosed
   *  - AsyncExecuteStatements.mCancelRequested
   */
  Mutex sharedAsyncExecutionMutex;

  /**
   * 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 thread this database was opened on.  This MUST be thread it is
   * closed on.
   */
  const nsCOMPtr<nsIThread> threadOpenedOn;

  /**
   * Closes the SQLite database, and warns about any non-finalized statements.
   */
  nsresult internalClose(sqlite3 *aDBConn);

  /**
   * Shuts down the passed-in async thread.
   */
  void shutdownAsyncThread(nsIThread *aAsyncThread);

  /**
   * 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(sqlite3 *aNativeConnection,
                                    int32_t aTransactionType=TRANSACTION_DEFERRED);
  nsresult commitTransactionInternal(sqlite3 *aNativeConnection);
  nsresult rollbackTransactionInternal(sqlite3 *aNativeConnection);

  bool connectionReady();

  /**
   * True if this connection is shutting down but not yet closed.
   */
  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.
   */
  bool isClosed();

  nsresult initializeClone(Connection *aClone, bool aReadOnly);

private:
  ~Connection();
  nsresult initializeInternal();

  /**
   * 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(nsISupports *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();

  sqlite3 *mDBConn;
  nsCOMPtr<nsIFileURL> mFileURL;
  nsCOMPtr<nsIFile> mDatabaseFile;

  /**
   * 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;

  /**
   * Lazily created thread for asynchronous statement execution.  Consumers
   * should use getAsyncExecutionTarget rather than directly accessing this
   * field.
   */
  nsCOMPtr<nsIThread> mAsyncExecutionThread;

  /**
   * 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;

  /**
   * Tracks whether the async thread has been initialized and Shutdown() has
   * not yet been invoked on it.
   */
  DebugOnly<bool> mAsyncExecutionThreadIsAlive;

  /**
   * Set to true just prior to calling sqlite3_close on the
   * connection.
   *
   * This variable should be accessed while holding the
   * sharedAsyncExecutionMutex.
   */
  bool mConnectionClosed;

  /**
   * Tracks if we have a transaction in progress or not.  Access protected by
   * sharedDBMutex.
   */
  bool mTransactionInProgress;

  /**
   * Stores the mapping of a given function by name to its instance.  Access is
   * protected by sharedDBMutex.
   */
  nsDataHashtable<nsCStringHashKey, FunctionInfo> mFunctions;

  /**
   * Stores the registered progress handler for the database connection.  Access
   * is protected by sharedDBMutex.
   */
  nsCOMPtr<mozIStorageProgressHandler> mProgressHandler;

  /**
   * Stores the flags we passed to sqlite3_open_v2.
   */
  const int mFlags;

  // 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;

  /**
   * If |false|, this instance supports synchronous operations
   * and it can be cast to |mozIStorageConnection|.
   */
  const bool mAsyncOnly;
};


/**
 * A Runnable designed to call a mozIStorageCompletionCallback on
 * the appropriate thread.
 */
class CallbackComplete final : public nsRunnable
{
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)
    : mStatus(aStatus)
    , mValue(aValue)
    , mCallback(aCallback)
  {
  }

  NS_IMETHOD Run() {
    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

#endif // mozilla_storage_Connection_h