gecko-dev/toolkit/modules/Sqlite.jsm

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/* 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/commonjs/sdk/core/promise.js");
Cu.import("resource://gre/modules/osfile.jsm");
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://services-common/log4moz.js");
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");
// Counts the number of created connections per database basename(). This is
// used for logging to distinguish connection instances.
let connectionCounters = {};
/**
* 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 = Log4Moz.repository.getLogger("Sqlite.ConnectionOpener");
if (!options.path) {
throw new Error("path not specified in connection options.");
}
// 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 openDatabaseFn = sharedMemoryCache ?
Services.storage.openDatabase :
Services.storage.openUnsharedDatabase;
let basename = OS.Path.basename(path);
if (!connectionCounters[basename]) {
connectionCounters[basename] = 1;
}
let number = connectionCounters[basename]++;
let identifier = basename + "#" + number;
log.info("Opening database: " + path + " (" + identifier + ")");
try {
let connection = openDatabaseFn(file);
if (!connection.connectionReady) {
log.warn("Connection is not ready.");
return Promise.reject(new Error("Connection is not ready."));
}
return Promise.resolve(new OpenedConnection(connection, basename, number,
openedOptions));
} catch (ex) {
log.warn("Could not open database: " + CommonUtils.exceptionStr(ex));
return Promise.reject(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 basename
* (string) The basename of this database name. Used for logging.
* @param number
* (Number) The connection number to this database.
* @param options
* (object) Options to control behavior of connection. See
* `openConnection`.
*/
function OpenedConnection(connection, basename, number, options) {
let log = Log4Moz.repository.getLogger("Sqlite.Connection." + basename);
// getLogger() returns a shared object. We can't modify the functions on this
// object since they would have effect on all instances and last write would
// win. So, we create a "proxy" object with our custom functions. Everything
// else is proxied back to the shared logger instance via prototype
// inheritance.
let logProxy = {__proto__: log};
// Automatically prefix all log messages with the identifier.
for (let level in Log4Moz.Level) {
if (level == "Desc") {
continue;
}
let lc = level.toLowerCase();
logProxy[lc] = function (msg) {
return log[lc].call(log, "Conn #" + number + ": " + msg);
};
}
this._log = logProxy;
this._log.info("Opened");
this._connection = connection;
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.
}
}
OpenedConnection.prototype = Object.freeze({
TRANSACTION_DEFERRED: "DEFERRED",
TRANSACTION_IMMEDIATE: "IMMEDIATE",
TRANSACTION_EXCLUSIVE: "EXCLUSIVE",
TRANSACTION_TYPES: ["DEFERRED", "IMMEDIATE", "EXCLUSIVE"],
get connectionReady() {
return this._open && this._connection.connectionReady;
},
/**
* The row ID from the last INSERT operation.
*
* Because all statements are executed asynchronously, this could
* return unexpected results if multiple statements are performed in
* parallel. It is the caller's responsibility to schedule
* appropriately.
*
* It is recommended to only use this within transactions (which are
* handled as sequential statements via Tasks).
*/
get lastInsertRowID() {
this._ensureOpen();
return this._connection.lastInsertRowID;
},
/**
* The number of rows that were changed, inserted, or deleted by the
* last operation.
*
* The same caveats regarding asynchronous execution for
* `lastInsertRowID` also apply here.
*/
get affectedRows() {
this._ensureOpen();
return this._connection.affectedRows;
},
/**
* The integer schema version of the database.
*
* This is 0 if not schema version has been set.
*/
get schemaVersion() {
this._ensureOpen();
return this._connection.schemaVersion;
},
set schemaVersion(value) {
this._ensureOpen();
this._connection.schemaVersion = 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.
*
* IMPROVEMENT: Resolve the promise to a closed connection which can be
* reopened.
*
* @return Promise<>
*/
close: function () {
if (!this._connection) {
return Promise.resolve();
}
this._log.debug("Request to close connection.");
this._clearIdleShrinkTimer();
let deferred = Promise.defer();
// 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(deferred);
return deferred.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, deferred);
this.execute("ROLLBACK TRANSACTION").then(onRollback, onRollback);
this._inProgressTransaction.reject(new Error("Connection being closed."));
this._inProgressTransaction = null;
return deferred.promise;
},
_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;
this._log.debug("Calling asyncClose().");
this._connection.asyncClose({
complete: function () {
this._log.info("Closed");
this._connection = null;
deferred.resolve();
}.bind(this),
});
},
/**
* 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) {
this._ensureOpen();
if (!sql) {
throw new Error("sql argument is empty.");
}
let statement = this._cachedStatements.get(sql);
if (!statement) {
statement = this._connection.createAsyncStatement(sql);
this._cachedStatements.set(sql, statement);
}
this._clearIdleShrinkTimer();
let deferred = Promise.defer();
try {
this._executeStatement(sql, statement, params, onRow).then(
function onResult(result) {
this._startIdleShrinkTimer();
deferred.resolve(result);
}.bind(this),
function onError(error) {
this._startIdleShrinkTimer();
deferred.reject(error);
}.bind(this)
);
} catch (ex) {
this._startIdleShrinkTimer();
throw ex;
}
return deferred.promise;
},
/**
* 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) {
if (typeof(sql) != "string") {
throw new Error("Must define SQL to execute as a string: " + sql);
}
this._ensureOpen();
let statement = this._connection.createAsyncStatement(sql);
let index = this._anonymousCounter++;
this._anonymousStatements.set(index, statement);
this._clearIdleShrinkTimer();
let onFinished = function () {
this._anonymousStatements.delete(index);
statement.finalize();
this._startIdleShrinkTimer();
}.bind(this);
let deferred = Promise.defer();
try {
this._executeStatement(sql, statement, params, onRow).then(
function onResult(rows) {
onFinished();
deferred.resolve(rows);
}.bind(this),
function onError(error) {
onFinished();
deferred.reject(error);
}.bind(this)
);
} catch (ex) {
onFinished();
throw ex;
}
return deferred.promise;
},
/**
* Whether a transaction is currently in progress.
*/
get transactionInProgress() {
return this._open && !!this._inProgressTransaction;
},
/**
* 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);
}
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(this));
} 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;
},
/**
* Whether a table exists in the database.
*
* IMPROVEMENT: Look for temporary tables.
*
* @param name
* (string) Name of the table.
*
* @return Promise<bool>
*/
tableExists: function (name) {
return this.execute(
"SELECT name FROM sqlite_master WHERE type='table' AND name=?",
[name])
.then(function onResult(rows) {
return Promise.resolve(rows.length > 0);
}
);
},
/**
* Whether a named index exists.
*
* IMPROVEMENT: Look for indexes in temporary tables.
*
* @param name
* (string) Name of the index.
*
* @return Promise<bool>
*/
indexExists: function (name) {
return this.execute(
"SELECT name FROM sqlite_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 () {
this._log.info("Shrinking memory usage.");
let onShrunk = this._clearIdleShrinkTimer.bind(this);
return this.execute("PRAGMA shrink_memory").then(onShrunk, onShrunk);
},
/**
* 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 () {
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;
},
_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);
}
if (Array.isArray(params)) {
for (let i = 0; i < params.length; i++) {
statement.bindByIndex(i, params[i]);
}
} else if (params && typeof(params) == "object") {
for (let k in params) {
statement.bindByName(k, params[k]);
}
} else if (params) {
throw new Error("Invalid type for bound parameters. Expected Array or " +
"object. Got: " + params);
}
let index = this._statementCounter++;
let deferred = Promise.defer();
let userCancelled = false;
let errors = [];
let rows = [];
// Don't incur overhead for serializing params unless the messages go
// somewhere.
if (this._log.level <= Log4Moz.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;
}
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 resolve to null.
let result = onRow ? null : rows;
deferred.resolve(result);
break;
case Ci.mozIStorageStatementCallback.REASON_CANCELLED:
// It is not an error if the user explicitly requested cancel via
// the onRow handler.
if (userCancelled) {
let result = onRow ? null : 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);
},
});
this.Sqlite = {
openConnection: openConnection,
};