gecko-dev/toolkit/modules/Sqlite.jsm
Blair McBride 494c507329 Bug 1073358 - Sqlite.jsm should return some measure of what happened regardless of whether a row handler was used. r=mak
--HG--
extra : transplant_source : %09%E7%2B%D3%9F%93Qzw%C4IL%EC%23g%B9o%DB%0D%DE
2014-09-27 01:17:00 +12:00

1264 lines
43 KiB
JavaScript

/* 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/. */
"use strict";
this.EXPORTED_SYMBOLS = [
"Sqlite",
];
const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
XPCOMUtils.defineLazyModuleGetter(this, "AsyncShutdown",
"resource://gre/modules/AsyncShutdown.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Promise",
"resource://gre/modules/Promise.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Services",
"resource://gre/modules/Services.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "OS",
"resource://gre/modules/osfile.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Log",
"resource://gre/modules/Log.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "CommonUtils",
"resource://services-common/utils.js");
XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
"resource://gre/modules/FileUtils.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "Task",
"resource://gre/modules/Task.jsm");
XPCOMUtils.defineLazyServiceGetter(this, "FinalizationWitnessService",
"@mozilla.org/toolkit/finalizationwitness;1",
"nsIFinalizationWitnessService");
// Counts the number of created connections per database basename(). This is
// used for logging to distinguish connection instances.
let connectionCounters = new Map();
// Tracks identifiers of wrapped connections, that are Storage connections
// opened through mozStorage and then wrapped by Sqlite.jsm to use its syntactic
// sugar API. Since these connections have an unknown origin, we use this set
// to differentiate their behavior.
let wrappedConnections = new Set();
/**
* Once `true`, reject any attempt to open or close a database.
*/
let isClosed = false;
let Debugging = {
// Tests should fail if a connection auto closes. The exception is
// when finalization itself is tested, in which case this flag
// should be set to false.
failTestsOnAutoClose: true
};
// Displays a script error message
function logScriptError(message) {
let consoleMessage = Cc["@mozilla.org/scripterror;1"].
createInstance(Ci.nsIScriptError);
let stack = new Error();
consoleMessage.init(message, stack.fileName, null, stack.lineNumber, 0,
Ci.nsIScriptError.errorFlag, "component javascript");
Services.console.logMessage(consoleMessage);
// This `Promise.reject` will cause tests to fail. The debugging
// flag can be used to suppress this for tests that explicitly
// test auto closes.
if (Debugging.failTestsOnAutoClose) {
Promise.reject(new Error(message));
}
}
/**
* Gets connection identifier from its database file path.
*
* @param path
* A file string path pointing to a database file.
* @return the connection identifier.
*/
function getIdentifierByPath(path) {
let basename = OS.Path.basename(path);
let number = connectionCounters.get(basename) || 0;
connectionCounters.set(basename, number + 1);
return basename + "#" + number;
}
/**
* Barriers used to ensure that Sqlite.jsm is shutdown after all
* its clients.
*/
XPCOMUtils.defineLazyGetter(this, "Barriers", () => {
let Barriers = {
/**
* Public barrier that clients may use to add blockers to the
* shutdown of Sqlite.jsm. Triggered by profile-before-change.
* Once all blockers of this barrier are lifted, we close the
* ability to open new connections.
*/
shutdown: new AsyncShutdown.Barrier("Sqlite.jsm: wait until all clients have completed their task"),
/**
* Private barrier blocked by connections that are still open.
* Triggered after Barriers.shutdown is lifted and `isClosed` is
* set to `true`.
*/
connections: new AsyncShutdown.Barrier("Sqlite.jsm: wait until all connections are closed"),
};
/**
* Observer for the event which is broadcasted when the finalization
* witness `_witness` of `OpenedConnection` is garbage collected.
*
* The observer is passed the connection identifier of the database
* connection that is being finalized.
*/
let finalizationObserver = function (subject, topic, identifier) {
let connectionData = ConnectionData.byId.get(identifier);
if (connectionData === undefined) {
logScriptError("Error: Attempt to finalize unknown Sqlite connection: " +
identifier + "\n");
return;
}
ConnectionData.byId.delete(identifier);
logScriptError("Warning: Sqlite connection '" + identifier +
"' was not properly closed. Auto-close triggered by garbage collection.\n");
connectionData.close();
};
Services.obs.addObserver(finalizationObserver, "sqlite-finalization-witness", false);
/**
* Ensure that Sqlite.jsm:
* - informs its clients before shutting down;
* - lets clients open connections during shutdown, if necessary;
* - waits for all connections to be closed before shutdown.
*/
AsyncShutdown.profileBeforeChange.addBlocker("Sqlite.jsm shutdown blocker",
Task.async(function* () {
yield Barriers.shutdown.wait();
// At this stage, all clients have had a chance to open (and close)
// their databases. Some previous close operations may still be pending,
// so we need to wait until they are complete before proceeding.
// Prevent any new opening.
isClosed = true;
// Now, wait until all databases are closed
yield Barriers.connections.wait();
// Everything closed, no finalization events to catch
Services.obs.removeObserver(finalizationObserver, "sqlite-finalization-witness");
}),
function status() {
if (isClosed) {
// We are waiting for the connections to close. The interesting
// status is therefore the list of connections still pending.
return { description: "Waiting for connections to close",
state: Barriers.connections.state };
}
// We are still in the first stage: waiting for the barrier
// to be lifted. The interesting status is therefore that of
// the barrier.
return { description: "Waiting for the barrier to be lifted",
state: Barriers.shutdown.state };
});
return Barriers;
});
/**
* Connection data with methods necessary for closing the connection.
*
* To support auto-closing in the event of garbage collection, this
* data structure contains all the connection data of an opened
* connection and all of the methods needed for sucessfully closing
* it.
*
* By putting this information in its own separate object, it is
* possible to store an additional reference to it without preventing
* a garbage collection of a finalization witness in
* OpenedConnection. When the witness detects a garbage collection,
* this object can be used to close the connection.
*
* This object contains more methods than just `close`. When
* OpenedConnection needs to use the methods in this object, it will
* dispatch its method calls here.
*/
function ConnectionData(connection, identifier, options={}) {
this._log = Log.repository.getLoggerWithMessagePrefix("Sqlite.Connection." +
identifier + ": ");
this._log.info("Opened");
this._dbConn = connection;
// This is a unique identifier for the connection, generated through
// getIdentifierByPath. It may be used for logging or as a key in Maps.
this._identifier = identifier;
this._open = true;
this._cachedStatements = new Map();
this._anonymousStatements = new Map();
this._anonymousCounter = 0;
// A map from statement index to mozIStoragePendingStatement, to allow for
// canceling prior to finalizing the mozIStorageStatements.
this._pendingStatements = new Map();
// Increments for each executed statement for the life of the connection.
this._statementCounter = 0;
this._inProgressTransaction = null;
this._idleShrinkMS = options.shrinkMemoryOnConnectionIdleMS;
if (this._idleShrinkMS) {
this._idleShrinkTimer = Cc["@mozilla.org/timer;1"]
.createInstance(Ci.nsITimer);
// We wait for the first statement execute to start the timer because
// shrinking now would not do anything.
}
this._deferredClose = Promise.defer();
this._closeRequested = false;
Barriers.connections.client.addBlocker(
this._identifier + ": waiting for shutdown",
this._deferredClose.promise,
() => ({
identifier: this._identifier,
isCloseRequested: this._closeRequested,
hasDbConn: !!this._dbConn,
hasInProgressTransaction: !!this._inProgressTransaction,
pendingStatements: this._pendingStatements.size,
statementCounter: this._statementCounter,
})
);
}
/**
* Map of connection identifiers to ConnectionData objects
*
* The connection identifier is a human-readable name of the
* database. Used by finalization witnesses to be able to close opened
* connections on garbage collection.
*
* Key: _identifier of ConnectionData
* Value: ConnectionData object
*/
ConnectionData.byId = new Map();
ConnectionData.prototype = Object.freeze({
close: function () {
this._closeRequested = true;
if (!this._dbConn) {
return this._deferredClose.promise;
}
this._log.debug("Request to close connection.");
this._clearIdleShrinkTimer();
// We need to take extra care with transactions during shutdown.
//
// If we don't have a transaction in progress, we can proceed with shutdown
// immediately.
if (!this._inProgressTransaction) {
this._finalize(this._deferredClose);
return this._deferredClose.promise;
}
// Else if we do have a transaction in progress, we forcefully roll it
// back. This is an async task, so we wait on it to finish before
// performing finalization.
this._log.warn("Transaction in progress at time of close. Rolling back.");
let onRollback = this._finalize.bind(this, this._deferredClose);
this.execute("ROLLBACK TRANSACTION").then(onRollback, onRollback);
this._inProgressTransaction.reject(new Error("Connection being closed."));
this._inProgressTransaction = null;
return this._deferredClose.promise;
},
clone: function (readOnly=false) {
this.ensureOpen();
this._log.debug("Request to clone connection.");
let options = {
connection: this._dbConn,
readOnly: readOnly,
};
if (this._idleShrinkMS)
options.shrinkMemoryOnConnectionIdleMS = this._idleShrinkMS;
return cloneStorageConnection(options);
},
_finalize: function (deferred) {
this._log.debug("Finalizing connection.");
// Cancel any pending statements.
for (let [k, statement] of this._pendingStatements) {
statement.cancel();
}
this._pendingStatements.clear();
// We no longer need to track these.
this._statementCounter = 0;
// Next we finalize all active statements.
for (let [k, statement] of this._anonymousStatements) {
statement.finalize();
}
this._anonymousStatements.clear();
for (let [k, statement] of this._cachedStatements) {
statement.finalize();
}
this._cachedStatements.clear();
// This guards against operations performed between the call to this
// function and asyncClose() finishing. See also bug 726990.
this._open = false;
// We must always close the connection at the Sqlite.jsm-level, not
// necessarily at the mozStorage-level.
let markAsClosed = () => {
this._log.info("Closed");
this._dbConn = null;
// Now that the connection is closed, no need to keep
// a blocker for Barriers.connections.
Barriers.connections.client.removeBlocker(deferred.promise);
deferred.resolve();
}
if (wrappedConnections.has(this._identifier)) {
wrappedConnections.delete(this._identifier);
markAsClosed();
} else {
this._log.debug("Calling asyncClose().");
this._dbConn.asyncClose(markAsClosed);
}
},
executeCached: function (sql, params=null, onRow=null) {
this.ensureOpen();
if (!sql) {
throw new Error("sql argument is empty.");
}
let statement = this._cachedStatements.get(sql);
if (!statement) {
statement = this._dbConn.createAsyncStatement(sql);
this._cachedStatements.set(sql, statement);
}
this._clearIdleShrinkTimer();
let deferred = Promise.defer();
try {
this._executeStatement(sql, statement, params, onRow).then(
result => {
this._startIdleShrinkTimer();
deferred.resolve(result);
},
error => {
this._startIdleShrinkTimer();
deferred.reject(error);
}
);
} catch (ex) {
this._startIdleShrinkTimer();
throw ex;
}
return deferred.promise;
},
execute: function (sql, params=null, onRow=null) {
if (typeof(sql) != "string") {
throw new Error("Must define SQL to execute as a string: " + sql);
}
this.ensureOpen();
let statement = this._dbConn.createAsyncStatement(sql);
let index = this._anonymousCounter++;
this._anonymousStatements.set(index, statement);
this._clearIdleShrinkTimer();
let onFinished = () => {
this._anonymousStatements.delete(index);
statement.finalize();
this._startIdleShrinkTimer();
};
let deferred = Promise.defer();
try {
this._executeStatement(sql, statement, params, onRow).then(
rows => {
onFinished();
deferred.resolve(rows);
},
error => {
onFinished();
deferred.reject(error);
}
);
} catch (ex) {
onFinished();
throw ex;
}
return deferred.promise;
},
get transactionInProgress() {
return this._open && !!this._inProgressTransaction;
},
executeTransaction: function (func, type) {
this.ensureOpen();
if (this._inProgressTransaction) {
throw new Error("A transaction is already active. Only one transaction " +
"can be active at a time.");
}
this._log.debug("Beginning transaction");
let deferred = Promise.defer();
this._inProgressTransaction = deferred;
Task.spawn(function doTransaction() {
// It's tempting to not yield here and rely on the implicit serial
// execution of issued statements. However, the yield serves an important
// purpose: catching errors in statement execution.
yield this.execute("BEGIN " + type + " TRANSACTION");
let result;
try {
result = yield Task.spawn(func);
} catch (ex) {
// It's possible that a request to close the connection caused the
// error.
// Assertion: close() will unset
// this._inProgressTransaction when called.
if (!this._inProgressTransaction) {
this._log.warn("Connection was closed while performing transaction. " +
"Received error should be due to closed connection: " +
CommonUtils.exceptionStr(ex));
throw ex;
}
this._log.warn("Error during transaction. Rolling back: " +
CommonUtils.exceptionStr(ex));
try {
yield this.execute("ROLLBACK TRANSACTION");
} catch (inner) {
this._log.warn("Could not roll back transaction. This is weird: " +
CommonUtils.exceptionStr(inner));
}
throw ex;
}
// See comment above about connection being closed during transaction.
if (!this._inProgressTransaction) {
this._log.warn("Connection was closed while performing transaction. " +
"Unable to commit.");
throw new Error("Connection closed before transaction committed.");
}
try {
yield this.execute("COMMIT TRANSACTION");
} catch (ex) {
this._log.warn("Error committing transaction: " +
CommonUtils.exceptionStr(ex));
throw ex;
}
throw new Task.Result(result);
}.bind(this)).then(
function onSuccess(result) {
this._inProgressTransaction = null;
deferred.resolve(result);
}.bind(this),
function onError(error) {
this._inProgressTransaction = null;
deferred.reject(error);
}.bind(this)
);
return deferred.promise;
},
shrinkMemory: function () {
this._log.info("Shrinking memory usage.");
let onShrunk = this._clearIdleShrinkTimer.bind(this);
return this.execute("PRAGMA shrink_memory").then(onShrunk, onShrunk);
},
discardCachedStatements: function () {
let count = 0;
for (let [k, statement] of this._cachedStatements) {
++count;
statement.finalize();
}
this._cachedStatements.clear();
this._log.debug("Discarded " + count + " cached statements.");
return count;
},
/**
* Helper method to bind parameters of various kinds through
* reflection.
*/
_bindParameters: function (statement, params) {
if (!params) {
return;
}
if (Array.isArray(params)) {
// It's an array of separate params.
if (params.length && (typeof(params[0]) == "object")) {
let paramsArray = statement.newBindingParamsArray();
for (let p of params) {
let bindings = paramsArray.newBindingParams();
for (let [key, value] of Iterator(p)) {
bindings.bindByName(key, value);
}
paramsArray.addParams(bindings);
}
statement.bindParameters(paramsArray);
return;
}
// Indexed params.
for (let i = 0; i < params.length; i++) {
statement.bindByIndex(i, params[i]);
}
return;
}
// Named params.
if (params && typeof(params) == "object") {
for (let k in params) {
statement.bindByName(k, params[k]);
}
return;
}
throw new Error("Invalid type for bound parameters. Expected Array or " +
"object. Got: " + params);
},
_executeStatement: function (sql, statement, params, onRow) {
if (statement.state != statement.MOZ_STORAGE_STATEMENT_READY) {
throw new Error("Statement is not ready for execution.");
}
if (onRow && typeof(onRow) != "function") {
throw new Error("onRow must be a function. Got: " + onRow);
}
this._bindParameters(statement, params);
let index = this._statementCounter++;
let deferred = Promise.defer();
let userCancelled = false;
let errors = [];
let rows = [];
let handledRow = false;
// Don't incur overhead for serializing params unless the messages go
// somewhere.
if (this._log.level <= Log.Level.Trace) {
let msg = "Stmt #" + index + " " + sql;
if (params) {
msg += " - " + JSON.stringify(params);
}
this._log.trace(msg);
} else {
this._log.debug("Stmt #" + index + " starting");
}
let self = this;
let pending = statement.executeAsync({
handleResult: function (resultSet) {
// .cancel() may not be immediate and handleResult() could be called
// after a .cancel().
for (let row = resultSet.getNextRow(); row && !userCancelled; row = resultSet.getNextRow()) {
if (!onRow) {
rows.push(row);
continue;
}
handledRow = true;
try {
onRow(row);
} catch (e if e instanceof StopIteration) {
userCancelled = true;
pending.cancel();
break;
} catch (ex) {
self._log.warn("Exception when calling onRow callback: " +
CommonUtils.exceptionStr(ex));
}
}
},
handleError: function (error) {
self._log.info("Error when executing SQL (" +
error.result + "): " + error.message);
errors.push(error);
},
handleCompletion: function (reason) {
self._log.debug("Stmt #" + index + " finished.");
self._pendingStatements.delete(index);
switch (reason) {
case Ci.mozIStorageStatementCallback.REASON_FINISHED:
// If there is an onRow handler, we always instead resolve to a
// boolean indicating whether the onRow handler was called or not.
let result = onRow ? handledRow : rows;
deferred.resolve(result);
break;
case Ci.mozIStorageStatementCallback.REASON_CANCELED:
// It is not an error if the user explicitly requested cancel via
// the onRow handler.
if (userCancelled) {
let result = onRow ? handledRow : rows;
deferred.resolve(result);
} else {
deferred.reject(new Error("Statement was cancelled."));
}
break;
case Ci.mozIStorageStatementCallback.REASON_ERROR:
let error = new Error("Error(s) encountered during statement execution.");
error.errors = errors;
deferred.reject(error);
break;
default:
deferred.reject(new Error("Unknown completion reason code: " +
reason));
break;
}
},
});
this._pendingStatements.set(index, pending);
return deferred.promise;
},
ensureOpen: function () {
if (!this._open) {
throw new Error("Connection is not open.");
}
},
_clearIdleShrinkTimer: function () {
if (!this._idleShrinkTimer) {
return;
}
this._idleShrinkTimer.cancel();
},
_startIdleShrinkTimer: function () {
if (!this._idleShrinkTimer) {
return;
}
this._idleShrinkTimer.initWithCallback(this.shrinkMemory.bind(this),
this._idleShrinkMS,
this._idleShrinkTimer.TYPE_ONE_SHOT);
}
});
/**
* Opens a connection to a SQLite database.
*
* The following parameters can control the connection:
*
* path -- (string) The filesystem path of the database file to open. If the
* file does not exist, a new database will be created.
*
* sharedMemoryCache -- (bool) Whether multiple connections to the database
* share the same memory cache. Sharing the memory cache likely results
* in less memory utilization. However, sharing also requires connections
* to obtain a lock, possibly making database access slower. Defaults to
* true.
*
* shrinkMemoryOnConnectionIdleMS -- (integer) If defined, the connection
* will attempt to minimize its memory usage after this many
* milliseconds of connection idle. The connection is idle when no
* statements are executing. There is no default value which means no
* automatic memory minimization will occur. Please note that this is
* *not* a timer on the idle service and this could fire while the
* application is active.
*
* FUTURE options to control:
*
* special named databases
* pragma TEMP STORE = MEMORY
* TRUNCATE JOURNAL
* SYNCHRONOUS = full
*
* @param options
* (Object) Parameters to control connection and open options.
*
* @return Promise<OpenedConnection>
*/
function openConnection(options) {
let log = Log.repository.getLogger("Sqlite.ConnectionOpener");
if (!options.path) {
throw new Error("path not specified in connection options.");
}
if (isClosed) {
throw new Error("Sqlite.jsm has been shutdown. Cannot open connection to: " + options.path);
}
// Retains absolute paths and normalizes relative as relative to profile.
let path = OS.Path.join(OS.Constants.Path.profileDir, options.path);
let sharedMemoryCache = "sharedMemoryCache" in options ?
options.sharedMemoryCache : true;
let openedOptions = {};
if ("shrinkMemoryOnConnectionIdleMS" in options) {
if (!Number.isInteger(options.shrinkMemoryOnConnectionIdleMS)) {
throw new Error("shrinkMemoryOnConnectionIdleMS must be an integer. " +
"Got: " + options.shrinkMemoryOnConnectionIdleMS);
}
openedOptions.shrinkMemoryOnConnectionIdleMS =
options.shrinkMemoryOnConnectionIdleMS;
}
let file = FileUtils.File(path);
let identifier = getIdentifierByPath(path);
log.info("Opening database: " + path + " (" + identifier + ")");
let deferred = Promise.defer();
let dbOptions = null;
if (!sharedMemoryCache) {
dbOptions = Cc["@mozilla.org/hash-property-bag;1"].
createInstance(Ci.nsIWritablePropertyBag);
dbOptions.setProperty("shared", false);
}
Services.storage.openAsyncDatabase(file, dbOptions, function(status, connection) {
if (!connection) {
log.warn("Could not open connection: " + status);
deferred.reject(new Error("Could not open connection: " + status));
return;
}
log.info("Connection opened");
try {
deferred.resolve(
new OpenedConnection(connection.QueryInterface(Ci.mozIStorageAsyncConnection),
identifier, openedOptions));
} catch (ex) {
log.warn("Could not open database: " + CommonUtils.exceptionStr(ex));
deferred.reject(ex);
}
});
return deferred.promise;
}
/**
* Creates a clone of an existing and open Storage connection. The clone has
* the same underlying characteristics of the original connection and is
* returned in form of an OpenedConnection handle.
*
* The following parameters can control the cloned connection:
*
* connection -- (mozIStorageAsyncConnection) The original Storage connection
* to clone. It's not possible to clone connections to memory databases.
*
* readOnly -- (boolean) - If true the clone will be read-only. If the
* original connection is already read-only, the clone will be, regardless
* of this option. If the original connection is using the shared cache,
* this parameter will be ignored and the clone will be as privileged as
* the original connection.
* shrinkMemoryOnConnectionIdleMS -- (integer) If defined, the connection
* will attempt to minimize its memory usage after this many
* milliseconds of connection idle. The connection is idle when no
* statements are executing. There is no default value which means no
* automatic memory minimization will occur. Please note that this is
* *not* a timer on the idle service and this could fire while the
* application is active.
*
*
* @param options
* (Object) Parameters to control connection and clone options.
*
* @return Promise<OpenedConnection>
*/
function cloneStorageConnection(options) {
let log = Log.repository.getLogger("Sqlite.ConnectionCloner");
let source = options && options.connection;
if (!source) {
throw new TypeError("connection not specified in clone options.");
}
if (!source instanceof Ci.mozIStorageAsyncConnection) {
throw new TypeError("Connection must be a valid Storage connection.");
}
if (isClosed) {
throw new Error("Sqlite.jsm has been shutdown. Cannot clone connection to: " + source.database.path);
}
let openedOptions = {};
if ("shrinkMemoryOnConnectionIdleMS" in options) {
if (!Number.isInteger(options.shrinkMemoryOnConnectionIdleMS)) {
throw new TypeError("shrinkMemoryOnConnectionIdleMS must be an integer. " +
"Got: " + options.shrinkMemoryOnConnectionIdleMS);
}
openedOptions.shrinkMemoryOnConnectionIdleMS =
options.shrinkMemoryOnConnectionIdleMS;
}
let path = source.databaseFile.path;
let identifier = getIdentifierByPath(path);
log.info("Cloning database: " + path + " (" + identifier + ")");
let deferred = Promise.defer();
source.asyncClone(!!options.readOnly, (status, connection) => {
if (!connection) {
log.warn("Could not clone connection: " + status);
deferred.reject(new Error("Could not clone connection: " + status));
}
log.info("Connection cloned");
try {
let conn = connection.QueryInterface(Ci.mozIStorageAsyncConnection);
deferred.resolve(new OpenedConnection(conn, identifier, openedOptions));
} catch (ex) {
log.warn("Could not clone database: " + CommonUtils.exceptionStr(ex));
deferred.reject(ex);
}
});
return deferred.promise;
}
/**
* Wraps an existing and open Storage connection with Sqlite.jsm API. The
* wrapped connection clone has the same underlying characteristics of the
* original connection and is returned in form of an OpenedConnection handle.
*
* Clients are responsible for closing both the Sqlite.jsm wrapper and the
* underlying mozStorage connection.
*
* The following parameters can control the wrapped connection:
*
* connection -- (mozIStorageAsyncConnection) The original Storage connection
* to wrap.
*
* @param options
* (Object) Parameters to control connection and wrap options.
*
* @return Promise<OpenedConnection>
*/
function wrapStorageConnection(options) {
let log = Log.repository.getLogger("Sqlite.ConnectionWrapper");
let connection = options && options.connection;
if (!connection || !(connection instanceof Ci.mozIStorageAsyncConnection)) {
throw new TypeError("connection not specified or invalid.");
}
if (isClosed) {
throw new Error("Sqlite.jsm has been shutdown. Cannot wrap connection to: " + connection.database.path);
}
let path = connection.databaseFile.path;
let identifier = getIdentifierByPath(path);
log.info("Wrapping database: " + path + " (" + identifier + ")");
return new Promise(resolve => {
try {
let conn = connection.QueryInterface(Ci.mozIStorageAsyncConnection);
let wrapper = new OpenedConnection(conn, identifier);
// We must not handle shutdown of a wrapped connection, since that is
// already handled by the opener.
wrappedConnections.add(identifier);
resolve(wrapper);
} catch (ex) {
log.warn("Could not wrap database: " + CommonUtils.exceptionStr(ex));
throw ex;
}
});
}
/**
* Handle on an opened SQLite database.
*
* This is essentially a glorified wrapper around mozIStorageConnection.
* However, it offers some compelling advantages.
*
* The main functions on this type are `execute` and `executeCached`. These are
* ultimately how all SQL statements are executed. It's worth explaining their
* differences.
*
* `execute` is used to execute one-shot SQL statements. These are SQL
* statements that are executed one time and then thrown away. They are useful
* for dynamically generated SQL statements and clients who don't care about
* performance (either their own or wasting resources in the overall
* application). Because of the performance considerations, it is recommended
* to avoid `execute` unless the statement you are executing will only be
* executed once or seldomly.
*
* `executeCached` is used to execute a statement that will presumably be
* executed multiple times. The statement is parsed once and stuffed away
* inside the connection instance. Subsequent calls to `executeCached` will not
* incur the overhead of creating a new statement object. This should be used
* in preference to `execute` when a specific SQL statement will be executed
* multiple times.
*
* Instances of this type are not meant to be created outside of this file.
* Instead, first open an instance of `UnopenedSqliteConnection` and obtain
* an instance of this type by calling `open`.
*
* FUTURE IMPROVEMENTS
*
* Ability to enqueue operations. Currently there can be race conditions,
* especially as far as transactions are concerned. It would be nice to have
* an enqueueOperation(func) API that serially executes passed functions.
*
* Support for SAVEPOINT (named/nested transactions) might be useful.
*
* @param connection
* (mozIStorageConnection) Underlying SQLite connection.
* @param identifier
* (string) The unique identifier of this database. It may be used for
* logging or as a key in Maps.
* @param options [optional]
* (object) Options to control behavior of connection. See
* `openConnection`.
*/
function OpenedConnection(connection, identifier, options={}) {
// Store all connection data in a field distinct from the
// witness. This enables us to store an additional reference to this
// field without preventing garbage collection of
// OpenedConnection. On garbage collection, we will still be able to
// close the database using this extra reference.
this._connectionData = new ConnectionData(connection, identifier, options);
// Store the extra reference in a map with connection identifier as
// key.
ConnectionData.byId.set(this._connectionData._identifier,
this._connectionData);
// Make a finalization witness. If this object is garbage collected
// before its `forget` method has been called, an event with topic
// "sqlite-finalization-witness" is broadcasted along with the
// connection identifier string of the database.
this._witness = FinalizationWitnessService.make(
"sqlite-finalization-witness",
this._connectionData._identifier);
}
OpenedConnection.prototype = Object.freeze({
TRANSACTION_DEFERRED: "DEFERRED",
TRANSACTION_IMMEDIATE: "IMMEDIATE",
TRANSACTION_EXCLUSIVE: "EXCLUSIVE",
TRANSACTION_TYPES: ["DEFERRED", "IMMEDIATE", "EXCLUSIVE"],
/**
* The integer schema version of the database.
*
* This is 0 if not schema version has been set.
*
* @return Promise<int>
*/
getSchemaVersion: function() {
let self = this;
return this.execute("PRAGMA user_version").then(
function onSuccess(result) {
if (result == null) {
return 0;
}
return JSON.stringify(result[0].getInt32(0));
}
);
},
setSchemaVersion: function(value) {
if (!Number.isInteger(value)) {
// Guarding against accidental SQLi
throw new TypeError("Schema version must be an integer. Got " + value);
}
this._connectionData.ensureOpen();
return this.execute("PRAGMA user_version = " + value);
},
/**
* Close the database connection.
*
* This must be performed when you are finished with the database.
*
* Closing the database connection has the side effect of forcefully
* cancelling all active statements. Therefore, callers should ensure that
* all active statements have completed before closing the connection, if
* possible.
*
* The returned promise will be resolved once the connection is closed.
* Successive calls to close() return the same promise.
*
* IMPROVEMENT: Resolve the promise to a closed connection which can be
* reopened.
*
* @return Promise<>
*/
close: function () {
// Unless cleanup has already been done by a previous call to
// `close`, delete the database entry from map and tell the
// finalization witness to forget.
if (ConnectionData.byId.has(this._connectionData._identifier)) {
ConnectionData.byId.delete(this._connectionData._identifier);
this._witness.forget();
}
return this._connectionData.close();
},
/**
* Clones this connection to a new Sqlite one.
*
* The following parameters can control the cloned connection:
*
* @param readOnly
* (boolean) - If true the clone will be read-only. If the original
* connection is already read-only, the clone will be, regardless of
* this option. If the original connection is using the shared cache,
* this parameter will be ignored and the clone will be as privileged as
* the original connection.
*
* @return Promise<OpenedConnection>
*/
clone: function (readOnly=false) {
return this._connectionData.clone(readOnly);
},
/**
* Execute a SQL statement and cache the underlying statement object.
*
* This function executes a SQL statement and also caches the underlying
* derived statement object so subsequent executions are faster and use
* less resources.
*
* This function optionally binds parameters to the statement as well as
* optionally invokes a callback for every row retrieved.
*
* By default, no parameters are bound and no callback will be invoked for
* every row.
*
* Bound parameters can be defined as an Array of positional arguments or
* an object mapping named parameters to their values. If there are no bound
* parameters, the caller can pass nothing or null for this argument.
*
* Callers are encouraged to pass objects rather than Arrays for bound
* parameters because they prevent foot guns. With positional arguments, it
* is simple to modify the parameter count or positions without fixing all
* users of the statement. Objects/named parameters are a little safer
* because changes in order alone won't result in bad things happening.
*
* When `onRow` is not specified, all returned rows are buffered before the
* returned promise is resolved. For INSERT or UPDATE statements, this has
* no effect because no rows are returned from these. However, it has
* implications for SELECT statements.
*
* If your SELECT statement could return many rows or rows with large amounts
* of data, for performance reasons it is recommended to pass an `onRow`
* handler. Otherwise, the buffering may consume unacceptable amounts of
* resources.
*
* If a `StopIteration` is thrown during execution of an `onRow` handler,
* the execution of the statement is immediately cancelled. Subsequent
* rows will not be processed and no more `onRow` invocations will be made.
* The promise is resolved immediately.
*
* If a non-`StopIteration` exception is thrown by the `onRow` handler, the
* exception is logged and processing of subsequent rows occurs as if nothing
* happened. The promise is still resolved (not rejected).
*
* The return value is a promise that will be resolved when the statement
* has completed fully.
*
* The promise will be rejected with an `Error` instance if the statement
* did not finish execution fully. The `Error` may have an `errors` property.
* If defined, it will be an Array of objects describing individual errors.
* Each object has the properties `result` and `message`. `result` is a
* numeric error code and `message` is a string description of the problem.
*
* @param name
* (string) The name of the registered statement to execute.
* @param params optional
* (Array or object) Parameters to bind.
* @param onRow optional
* (function) Callback to receive each row from result.
*/
executeCached: function (sql, params=null, onRow=null) {
return this._connectionData.executeCached(sql, params, onRow);
},
/**
* Execute a one-shot SQL statement.
*
* If you find yourself feeding the same SQL string in this function, you
* should *not* use this function and instead use `executeCached`.
*
* See `executeCached` for the meaning of the arguments and extended usage info.
*
* @param sql
* (string) SQL to execute.
* @param params optional
* (Array or Object) Parameters to bind to the statement.
* @param onRow optional
* (function) Callback to receive result of a single row.
*/
execute: function (sql, params=null, onRow=null) {
return this._connectionData.execute(sql, params, onRow);
},
/**
* Whether a transaction is currently in progress.
*/
get transactionInProgress() {
return this._connectionData.transactionInProgress;
},
/**
* Perform a transaction.
*
* A transaction is specified by a user-supplied function that is a
* generator function which can be used by Task.jsm's Task.spawn(). The
* function receives this connection instance as its argument.
*
* The supplied function is expected to yield promises. These are often
* promises created by calling `execute` and `executeCached`. If the
* generator is exhausted without any errors being thrown, the
* transaction is committed. If an error occurs, the transaction is
* rolled back.
*
* The returned value from this function is a promise that will be resolved
* once the transaction has been committed or rolled back. The promise will
* be resolved to whatever value the supplied function resolves to. If
* the transaction is rolled back, the promise is rejected.
*
* @param func
* (function) What to perform as part of the transaction.
* @param type optional
* One of the TRANSACTION_* constants attached to this type.
*/
executeTransaction: function (func, type=this.TRANSACTION_DEFERRED) {
if (this.TRANSACTION_TYPES.indexOf(type) == -1) {
throw new Error("Unknown transaction type: " + type);
}
return this._connectionData.executeTransaction(() => func(this), type);
},
/**
* Whether a table exists in the database (both persistent and temporary tables).
*
* @param name
* (string) Name of the table.
*
* @return Promise<bool>
*/
tableExists: function (name) {
return this.execute(
"SELECT name FROM (SELECT * FROM sqlite_master UNION ALL " +
"SELECT * FROM sqlite_temp_master) " +
"WHERE type = 'table' AND name=?",
[name])
.then(function onResult(rows) {
return Promise.resolve(rows.length > 0);
}
);
},
/**
* Whether a named index exists (both persistent and temporary tables).
*
* @param name
* (string) Name of the index.
*
* @return Promise<bool>
*/
indexExists: function (name) {
return this.execute(
"SELECT name FROM (SELECT * FROM sqlite_master UNION ALL " +
"SELECT * FROM sqlite_temp_master) " +
"WHERE type = 'index' AND name=?",
[name])
.then(function onResult(rows) {
return Promise.resolve(rows.length > 0);
}
);
},
/**
* Free up as much memory from the underlying database connection as possible.
*
* @return Promise<>
*/
shrinkMemory: function () {
return this._connectionData.shrinkMemory();
},
/**
* Discard all cached statements.
*
* Note that this relies on us being non-interruptible between
* the insertion or retrieval of a statement in the cache and its
* execution: we finalize all statements, which is only safe if
* they will not be executed again.
*
* @return (integer) the number of statements discarded.
*/
discardCachedStatements: function () {
return this._connectionData.discardCachedStatements();
},
});
this.Sqlite = {
openConnection: openConnection,
cloneStorageConnection: cloneStorageConnection,
wrapStorageConnection: wrapStorageConnection,
/**
* Shutdown barrier client. May be used by clients to perform last-minute
* cleanup prior to the shutdown of this module.
*
* See the documentation of AsyncShutdown.Barrier.prototype.client.
*/
get shutdown() {
return Barriers.shutdown.client;
}
};