Add tasks table and API

progress will be tracked with this table instead of being in-process
like progress.js

src/tasks.js

@@ -0,0 +1,89 @@
+'use strict';
+
+exports = module.exports = {
+    setProgress: setProgress,
+    getProgress: getProgress,
+
+    stopTask: stopTask,
+
+    TaskError: TaskError,
+
+    TASK_BACKUP: 'backup'
+};
+
+let assert = require('assert'),
+    BackupsError = require('./backups.js').BackupsError,
+    backups = require('./backups.js'),
+    DatabaseError = require('./databaseerror.js'),
+    debug = require('debug')('box:tasks'),
+    taskdb = require('./taskdb.js'),
+    util = require('util');
+
+function TaskError(reason, errorOrMessage) {
+    assert.strictEqual(typeof reason, 'string');
+    assert(errorOrMessage instanceof Error || typeof errorOrMessage === 'string' || typeof errorOrMessage === 'undefined');
+
+    Error.call(this);
+    Error.captureStackTrace(this, this.constructor);
+
+    this.name = this.constructor.name;
+    this.reason = reason;
+    if (typeof errorOrMessage === 'undefined') {
+        this.message = reason;
+    } else if (typeof errorOrMessage === 'string') {
+        this.message = errorOrMessage;
+    } else {
+        this.message = 'Internal error';
+        this.nestedError = errorOrMessage;
+    }
+}
+util.inherits(TaskError, Error);
+TaskError.INTERNAL_ERROR = 'Internal Error';
+TaskError.BAD_STATE = 'Bad State';
+TaskError.NOT_FOUND = 'Not Found';
+
+function setProgress(id, progress, callback) {
+    assert.strictEqual(typeof id, 'string');
+    assert.strictEqual(typeof progress, 'object');
+    assert.strictEqual(typeof callback, 'function');
+
+    debug(`${id}: ${JSON.stringify(progress)}`);
+
+    taskdb.setProgress(id, progress, function (error) {
+        if (error) return callback(new TaskError(TaskError.INTERNAL_ERROR, error));
+
+        callback();
+    });
+}
+
+function getProgress(id, callback) {
+    assert.strictEqual(typeof id, 'string');
+    assert.strictEqual(typeof callback, 'function');
+
+    taskdb.getProgress(id, function (error, progress) {
+        if (error && error.reason == DatabaseError.NOT_FOUND) return callback(new TaskError(TaskError.NOT_FOUND));
+        if (error) return callback(new TaskError(TaskError.INTERNAL_ERROR, error));
+
+        callback(null, progress);
+    });
+}
+
+function stopTask(id, auditSource, callback) {
+    assert.strictEqual(typeof id, 'string');
+    assert.strictEqual(typeof auditSource, 'object');
+    assert.strictEqual(typeof callback, 'function');
+
+    switch (id) {
+    case exports.TASK_BACKUP:
+        backups.stopBackupTask(auditSource, function (error) {
+            if (error && error.reason === BackupsError.BAD_STATE) return callback(new TaskError(TaskError.NOT_FOUND));
+            if (error) return callback(new TaskError(TaskError.INTERNAL_ERROR, error));
+
+            callback(null);
+        });
+        break;
+
+    default:
+        return callback(new TaskError(TaskError.NOT_FOUND));
+    }
+}