/*
* Copyright (c) 2015-present, Vitaly Tomilov
*
* See the LICENSE file at the top-level directory of this distribution
* for licensing information.
*
* Removal or modification of this copyright notice is prohibited.
*/
const {Events} = require('./events');
const npm = {
spex: require('spex'),
utils: require('./utils'),
mode: require('./tx-mode'),
query: require('./query'),
text: require('./text')
};
/**
* @interface Task
* @description
* Extends {@link Database} for an automatic connection session, with methods for executing multiple database queries.
*
* The type isn't available directly, it can only be created via methods {@link Database#task Database.task}, {@link Database#tx Database.tx},
* or their derivations.
*
* When executing more than one request at a time, one should allocate and release the connection only once,
* while executing all the required queries within the same connection session. More importantly, a transaction
* can only work within a single connection.
*
* This is an interface for tasks/transactions to implement a connection session, during which you can
* execute multiple queries against the same connection that's released automatically when the task/transaction is finished.
*
* Each task/transaction manages the connection automatically. When executed on the root {@link Database} object, the connection
* is allocated from the pool, and once the method's callback has finished, the connection is released back to the pool.
* However, when invoked inside another task or transaction, the method reuses the parent connection.
*
* @see
* {@link Task#ctx ctx},
* {@link Task#batch batch},
* {@link Task#sequence sequence},
* {@link Task#page page}
*
* @example
* db.task(t => {
* // t = task protocol context;
* // t.ctx = Task Context;
* return t.one('select * from users where id=$1', 123)
* .then(user => {
* return t.any('select * from events where login=$1', user.name);
* });
* })
* .then(events => {
* // success;
* })
* .catch(error => {
* // error;
* });
*
*/
function Task(ctx, tag, isTX, config) {
const $p = config.promise;
/**
* @member {TaskContext} Task#ctx
* @readonly
* @description
* Task/Transaction Context object - contains individual properties for each task/transaction.
*
* @see event {@link event:query query}
*
* @example
*
* db.task(t => {
* return t.ctx; // task context object
* })
* .then(ctx => {
* console.log('Task Duration:', ctx.duration);
* });
*
* @example
*
* db.tx(t => {
* return t.ctx; // transaction context object
* })
* .then(ctx => {
* console.log('Transaction Duration:', ctx.duration);
* });
*/
this.ctx = ctx.ctx = {}; // task context object;
npm.utils.addReadProp(this.ctx, 'isTX', isTX);
if ('context' in ctx) {
npm.utils.addReadProp(this.ctx, 'context', ctx.context);
}
npm.utils.addReadProp(this.ctx, 'connected', !ctx.db);
npm.utils.addReadProp(this.ctx, 'tag', tag);
npm.utils.addReadProp(this.ctx, 'dc', ctx.dc);
npm.utils.addReadProp(this.ctx, 'level', ctx.level);
npm.utils.addReadProp(this.ctx, 'inTransaction', ctx.inTransaction);
if (isTX) {
npm.utils.addReadProp(this.ctx, 'txLevel', ctx.txLevel);
}
npm.utils.addReadProp(this.ctx, 'parent', ctx.parentCtx);
// generic query method;
this.query = function (query, values, qrm) {
if (!ctx.db) {
return $p.reject(new Error(npm.text.looseQuery));
}
return config.$npm.query.call(this, ctx, query, values, qrm);
};
/**
* @deprecated
* Consider using <b>async/await</b> syntax instead, or if you must have
* pre-generated promises, then $[Promise.allSettled].
*
* @method Task#batch
* @description
* Settles a predefined array of mixed values by redirecting to method $[spex.batch].
*
* For complete method documentation see $[spex.batch].
*
* @param {array} values
* @param {Object} [options]
* Optional Parameters.
* @param {function} [options.cb]
*
* @returns {external:Promise}
*/
this.batch = function (values, options) {
return config.$npm.spex.batch.call(this, values, options);
};
/**
* @method Task#page
* @description
* Resolves a dynamic sequence of arrays/pages with mixed values, by redirecting to method $[spex.page].
*
* For complete method documentation see $[spex.page].
*
* @param {function} source
* @param {Object} [options]
* Optional Parameters.
* @param {function} [options.dest]
* @param {number} [options.limit=0]
*
* @returns {external:Promise}
*/
this.page = function (source, options) {
return config.$npm.spex.page.call(this, source, options);
};
/**
* @method Task#sequence
* @description
* Resolves a dynamic sequence of mixed values by redirecting to method $[spex.sequence].
*
* For complete method documentation see $[spex.sequence].
*
* @param {function} source
* @param {Object} [options]
* Optional Parameters.
* @param {function} [options.dest]
* @param {number} [options.limit=0]
* @param {boolean} [options.track=false]
*
* @returns {external:Promise}
*/
this.sequence = function (source, options) {
return config.$npm.spex.sequence.call(this, source, options);
};
}
/**
* @private
* @method Task.callback
* Callback invocation helper.
*
* @param ctx
* @param obj
* @param cb
* @param config
* @returns {Promise.<TResult>}
*/
const callback = (ctx, obj, cb, config) => {
const $p = config.promise;
let result;
try {
if (cb.constructor.name === 'GeneratorFunction') {
// v9.0 dropped all support for ES6 generator functions;
// Clients should use the new ES7 async/await syntax.
throw new TypeError('ES6 generator functions are no longer supported!');
}
result = cb.call(obj, obj); // invoking the callback function;
} catch (err) {
Events.error(ctx.options, err, {
client: ctx.db && ctx.db.client, // the error can be due to loss of connectivity
dc: ctx.dc,
ctx: ctx.ctx
});
return $p.reject(err); // reject with the error;
}
if (result && typeof result.then === 'function') {
return result; // result is a valid promise object;
}
return $p.resolve(result);
};
/**
* @private
* @method Task.execute
* Executes a task.
*
* @param ctx
* @param obj
* @param isTX
* @param config
* @returns {Promise.<TResult>}
*/
const execute = (ctx, obj, isTX, config) => {
const $p = config.promise;
// updates the task context and notifies the client;
function update(start, success, result) {
const c = ctx.ctx;
if (start) {
npm.utils.addReadProp(c, 'start', new Date());
} else {
c.finish = new Date();
c.success = success;
c.result = result;
c.duration = c.finish - c.start;
}
(isTX ? Events.transact : Events.task)(ctx.options, {
client: ctx.db && ctx.db.client, // loss of connectivity is possible at this point
dc: ctx.dc,
ctx: c
});
}
let cbData, cbReason, success,
spName; // Save-Point Name;
const capSQL = ctx.options.capSQL; // capitalize sql;
update(true);
if (isTX) {
// executing a transaction;
spName = `sp_${ctx.txLevel}_${ctx.nextTxCount}`;
return begin()
.then(() => callback(ctx, obj, ctx.cb, config)
.then(data => {
cbData = data; // save callback data;
success = true;
return commit();
}, err => {
cbReason = err; // save callback failure reason;
return rollback();
})
.then(() => {
if (success) {
update(false, true, cbData);
return cbData;
}
update(false, false, cbReason);
return $p.reject(cbReason);
},
err => {
// either COMMIT or ROLLBACK has failed, which is impossible
// to replicate in a test environment, so skipping from the test;
// istanbul ignore next:
update(false, false, err);
// istanbul ignore next:
return $p.reject(err);
}),
err => {
// BEGIN has failed, which is impossible to replicate in a test
// environment, so skipping the whole block from the test;
// istanbul ignore next:
update(false, false, err);
// istanbul ignore next:
return $p.reject(err);
});
}
function begin() {
if (!ctx.txLevel && ctx.mode instanceof npm.mode.TransactionMode) {
return exec(ctx.mode.begin(capSQL), 'savepoint');
}
return exec('begin', 'savepoint');
}
function commit() {
return exec('commit', 'release savepoint');
}
function rollback() {
return exec('rollback', 'rollback to savepoint');
}
function exec(top, nested) {
if (ctx.txLevel) {
return obj.none((capSQL ? nested.toUpperCase() : nested) + ' ' + spName);
}
return obj.none(capSQL ? top.toUpperCase() : top);
}
// executing a task;
return callback(ctx, obj, ctx.cb, config)
.then(data => {
update(false, true, data);
return data;
})
.catch(error => {
update(false, false, error);
return $p.reject(error);
});
};
module.exports = config => {
const npmLocal = config.$npm;
// istanbul ignore next:
// we keep 'npm.query' initialization here, even though it is always
// pre-initialized by the 'database' module, for integrity purpose.
npmLocal.query = npmLocal.query || npm.query(config);
npmLocal.spex = npmLocal.spex || npm.spex(config.promiseLib);
return {
Task, execute, callback
};
};
/**
* @typedef TaskContext
* @description
* Task/Transaction Context used via property {@link Task#ctx ctx} inside tasks (methods {@link Database#task Database.task} and {@link Database#taskIf Database.taskIf})
* and transactions (methods {@link Database#tx Database.tx} and {@link Database#txIf Database.txIf}).
*
* Properties `context`, `connected`, `parent`, `level`, `dc`, `isTX`, `tag`, `start`, `useCount` and `serverVersion` are set just before the operation has started,
* while properties `finish`, `duration`, `success` and `result` are set immediately after the operation has finished.
*
* @property {*} context
* If the operation was invoked with a calling context - `task.call(context,...)` or `tx.call(context,...)`,
* this property is set with the context that was passed in. Otherwise, the property doesn't exist.
*
* @property {*} dc
* _Database Context_ that was passed into the {@link Database} object during construction.
*
* @property {boolean} isTX
* Indicates whether this operation is a transaction (as opposed to a regular task).
*
* @property {number} duration
* Number of milliseconds consumed by the operation.
*
* Set after the operation has finished, it is simply a shortcut for `finish - start`.
*
* @property {number} level
* Task nesting level, starting from 0, counting both regular tasks and transactions.
*
* @property {number} txLevel
* Transaction nesting level, starting from 0. Transactions on level 0 use `BEGIN/COMMIT/ROLLBACK`,
* while transactions on nested levels use the corresponding `SAVEPOINT` commands.
*
* This property exists only within the context of a transaction (`isTX = true`).
*
* @property {boolean} inTransaction
* Available in both tasks and transactions, it simplifies checking when there is a transaction
* going on either on this level or above.
*
* For example, when you want to check for a containing transaction while inside a task, and
* only start a transaction when there is none yet.
*
* @property {TaskContext} parent
* Parent task/transaction context, or `null` when it is top-level.
*
* @property {boolean} connected
* Indicates when the task/transaction acquired the connection on its own (`connected = true`), and will release it once
* the operation has finished. When the value is `false`, the operation is reusing an existing connection.
*
* @property {*} tag
* Tag value as it was passed into the task. See methods {@link Database#task task} and {@link Database#tx tx}.
*
* @property {Date} start
* Date/Time of when this operation started the execution.
*
* @property {number} useCount
* Number of times the connection has been previously used, starting with 0 for a freshly
* allocated physical connection.
*
* @property {string} serverVersion
* Version of the PostgreSQL server to which we are connected.
* Not available with $[Native Bindings].
*
* @property {Date} finish
* Once the operation has finished, this property is set to the Data/Time of when it happened.
*
* @property {boolean} success
* Once the operation has finished, this property indicates whether it was successful.
*
* @property {*} result
* Once the operation has finished, this property contains the result, depending on property `success`:
* - data resolved by the operation, if `success = true`
* - error / rejection reason, if `success = false`
*
*/