lib6/result.js
/**
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [https://neo4j.com]
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
var _a;
/* eslint-disable @typescript-eslint/promise-function-async */
import ResultSummary from './result-summary';
import { util, connectionHolder } from './internal';
import { newError, PROTOCOL_ERROR } from './error';
const { EMPTY_CONNECTION_HOLDER } = connectionHolder;
/**
* @private
* @param {Error} error The error
* @returns {void}
*/
const DEFAULT_ON_ERROR = (error) => {
// eslint-disable-next-line @typescript-eslint/restrict-plus-operands, @typescript-eslint/no-base-to-string
console.log('Uncaught error when processing result: ' + error);
};
/**
* @private
* @param {ResultSummary} summary
* @returns {void}
*/
const DEFAULT_ON_COMPLETED = (summary) => { };
/**
* @private
* @param {string[]} keys List of keys of the record in the result
* @return {void}
*/
const DEFAULT_ON_KEYS = (keys) => { };
/**
* A stream of {@link Record} representing the result of a query.
* Can be consumed eagerly as {@link Promise} resolved with array of records and {@link ResultSummary}
* summary, or rejected with error that contains {@link string} code and {@link string} message.
* Alternatively can be consumed lazily using {@link Result#subscribe} function.
* @access public
*/
class Result {
/**
* Inject the observer to be used.
* @constructor
* @access private
* @param {Promise<observer.ResultStreamObserver>} streamObserverPromise
* @param {mixed} query - Cypher query to execute
* @param {Object} parameters - Map with parameters to use in query
* @param {ConnectionHolder} connectionHolder - to be notified when result is either fully consumed or error happened.
*/
constructor(streamObserverPromise, query, parameters, connectionHolder, watermarks = { high: Number.MAX_VALUE, low: Number.MAX_VALUE }) {
/**
* Called when finally the result is done
*
* *Should not be combined with {@link Result#subscribe} function.*
* @param {function()|null} onfinally - function when the promise finished
* @return {Promise} promise.
*/
this[_a] = 'Result';
this._stack = captureStacktrace();
this._streamObserverPromise = streamObserverPromise;
this._p = null;
this._query = query;
this._parameters = parameters !== null && parameters !== void 0 ? parameters : {};
this._connectionHolder = connectionHolder !== null && connectionHolder !== void 0 ? connectionHolder : EMPTY_CONNECTION_HOLDER;
this._keys = null;
this._summary = null;
this._error = null;
this._watermarks = watermarks;
}
/**
* Returns a promise for the field keys.
*
* *Should not be combined with {@link Result#subscribe} function.*
*
* @public
* @returns {Promise<string[]>} - Field keys, in the order they will appear in records.
}
*/
keys() {
if (this._keys !== null) {
return Promise.resolve(this._keys);
}
else if (this._error !== null) {
return Promise.reject(this._error);
}
return new Promise((resolve, reject) => {
this._streamObserverPromise
.then(observer => observer.subscribe(this._decorateObserver({
onKeys: keys => resolve(keys),
onError: err => reject(err)
})))
.catch(reject);
});
}
/**
* Returns a promise for the result summary.
*
* *Should not be combined with {@link Result#subscribe} function.*
*
* @public
* @returns {Promise<ResultSummary<T>>} - Result summary.
*
*/
summary() {
if (this._summary !== null) {
// This type casting is needed since we are defining the number type of
// summary in Result template
return Promise.resolve(this._summary);
}
else if (this._error !== null) {
return Promise.reject(this._error);
}
return new Promise((resolve, reject) => {
this._streamObserverPromise
.then(o => {
o.cancel();
o.subscribe(this._decorateObserver({
// This type casting is needed since we are defining the number type of
// summary in Result template
onCompleted: summary => resolve(summary),
onError: err => reject(err)
}));
})
.catch(reject);
});
}
/**
* Create and return new Promise
*
* @private
* @return {Promise} new Promise.
*/
_getOrCreatePromise() {
if (this._p == null) {
this._p = new Promise((resolve, reject) => {
const records = [];
const observer = {
onNext: (record) => {
records.push(record);
},
onCompleted: (summary) => {
resolve({ records, summary });
},
onError: (error) => {
reject(error);
}
};
this.subscribe(observer);
});
}
return this._p;
}
/**
* Provides a async iterator over the records in the result.
*
* *Should not be combined with {@link Result#subscribe} or ${@link Result#then} functions.*
*
* @public
* @returns {PeekableAsyncIterator<Record<R>, ResultSummary>} The async iterator for the Results
*/
[Symbol.asyncIterator]() {
if (!this.isOpen()) {
const error = newError('Result is already consumed');
return {
next: () => Promise.reject(error),
peek: () => Promise.reject(error)
};
}
const state = { paused: true, firstRun: true, finished: false };
const controlFlow = () => {
var _b, _c;
if (state.streaming == null) {
return;
}
const size = (_c = (_b = state.queuedObserver) === null || _b === void 0 ? void 0 : _b.size) !== null && _c !== void 0 ? _c : 0;
const queueSizeIsOverHighOrEqualWatermark = size >= this._watermarks.high;
const queueSizeIsBellowOrEqualLowWatermark = size <= this._watermarks.low;
if (queueSizeIsOverHighOrEqualWatermark && !state.paused) {
state.paused = true;
state.streaming.pause();
}
else if ((queueSizeIsBellowOrEqualLowWatermark && state.paused) || (state.firstRun && !queueSizeIsOverHighOrEqualWatermark)) {
state.firstRun = false;
state.paused = false;
state.streaming.resume();
}
};
const initializeObserver = () => __awaiter(this, void 0, void 0, function* () {
if (state.queuedObserver === undefined) {
state.queuedObserver = this._createQueuedResultObserver(controlFlow);
state.streaming = yield this._subscribe(state.queuedObserver, true).catch(() => undefined);
controlFlow();
}
return state.queuedObserver;
});
const assertSummary = (summary) => {
if (summary === undefined) {
throw newError('InvalidState: Result stream finished without Summary', PROTOCOL_ERROR);
}
return true;
};
return {
next: () => __awaiter(this, void 0, void 0, function* () {
if (state.finished) {
if (assertSummary(state.summary)) {
return { done: true, value: state.summary };
}
}
const queuedObserver = yield initializeObserver();
const next = yield queuedObserver.dequeue();
if (next.done === true) {
state.finished = next.done;
state.summary = next.value;
}
return next;
}),
return: (value) => __awaiter(this, void 0, void 0, function* () {
var _b;
if (state.finished) {
if (assertSummary(state.summary)) {
return { done: true, value: value !== null && value !== void 0 ? value : state.summary };
}
}
(_b = state.streaming) === null || _b === void 0 ? void 0 : _b.cancel();
const queuedObserver = yield initializeObserver();
const last = yield queuedObserver.dequeueUntilDone();
state.finished = true;
last.value = value !== null && value !== void 0 ? value : last.value;
state.summary = last.value;
return last;
}),
peek: () => __awaiter(this, void 0, void 0, function* () {
if (state.finished) {
if (assertSummary(state.summary)) {
return { done: true, value: state.summary };
}
}
const queuedObserver = yield initializeObserver();
return yield queuedObserver.head();
})
};
}
/**
* Waits for all results and calls the passed in function with the results.
*
* *Should not be combined with {@link Result#subscribe} function.*
*
* @param {function(result: {records:Array<Record>, summary: ResultSummary})} onFulfilled - function to be called
* when finished.
* @param {function(error: {message:string, code:string})} onRejected - function to be called upon errors.
* @return {Promise} promise.
*/
then(onFulfilled, onRejected) {
return this._getOrCreatePromise().then(onFulfilled, onRejected);
}
/**
* Catch errors when using promises.
*
* *Should not be combined with {@link Result#subscribe} function.*
*
* @param {function(error: Neo4jError)} onRejected - Function to be called upon errors.
* @return {Promise} promise.
*/
catch(onRejected) {
return this._getOrCreatePromise().catch(onRejected);
}
finally(onfinally) {
return this._getOrCreatePromise().finally(onfinally);
}
/**
* Stream records to observer as they come in, this is a more efficient method
* of handling the results, and allows you to handle arbitrarily large results.
*
* @param {Object} observer - Observer object
* @param {function(keys: string[])} observer.onKeys - handle stream head, the field keys.
* @param {function(record: Record)} observer.onNext - handle records, one by one.
* @param {function(summary: ResultSummary)} observer.onCompleted - handle stream tail, the result summary.
* @param {function(error: {message:string, code:string})} observer.onError - handle errors.
* @return {void}
*/
subscribe(observer) {
this._subscribe(observer)
.catch(() => { });
}
/**
* Check if this result is active, i.e., neither a summary nor an error has been received by the result.
* @return {boolean} `true` when neither a summary or nor an error has been received by the result.
*/
isOpen() {
return this._summary === null && this._error === null;
}
/**
* Stream records to observer as they come in, this is a more efficient method
* of handling the results, and allows you to handle arbitrarily large results.
*
* @access private
* @param {ResultObserver} observer The observer to send records to.
* @param {boolean} paused The flag to indicate if the stream should be started paused
* @returns {Promise<observer.ResultStreamObserver>} The result stream observer.
*/
_subscribe(observer, paused = false) {
const _observer = this._decorateObserver(observer);
return this._streamObserverPromise
.then(o => {
if (paused) {
o.pause();
}
o.subscribe(_observer);
return o;
})
.catch(error => {
if (_observer.onError != null) {
_observer.onError(error);
}
return Promise.reject(error);
});
}
/**
* Decorates the ResultObserver with the necessary methods.
*
* @access private
* @param {ResultObserver} observer The ResultObserver to decorate.
* @returns The decorated result observer
*/
_decorateObserver(observer) {
var _b, _c, _d;
const onCompletedOriginal = (_b = observer.onCompleted) !== null && _b !== void 0 ? _b : DEFAULT_ON_COMPLETED;
const onErrorOriginal = (_c = observer.onError) !== null && _c !== void 0 ? _c : DEFAULT_ON_ERROR;
const onKeysOriginal = (_d = observer.onKeys) !== null && _d !== void 0 ? _d : DEFAULT_ON_KEYS;
const onCompletedWrapper = (metadata) => {
this._releaseConnectionAndGetSummary(metadata).then(summary => {
if (this._summary !== null) {
return onCompletedOriginal.call(observer, this._summary);
}
this._summary = summary;
return onCompletedOriginal.call(observer, summary);
}).catch(onErrorOriginal);
};
const onErrorWrapper = (error) => {
// notify connection holder that the used connection is not needed any more because error happened
// and result can't bee consumed any further; call the original onError callback after that
this._connectionHolder.releaseConnection().then(() => {
replaceStacktrace(error, this._stack);
this._error = error;
onErrorOriginal.call(observer, error);
}).catch(onErrorOriginal);
};
const onKeysWrapper = (keys) => {
this._keys = keys;
return onKeysOriginal.call(observer, keys);
};
return {
onNext: (observer.onNext != null) ? observer.onNext.bind(observer) : undefined,
onKeys: onKeysWrapper,
onCompleted: onCompletedWrapper,
onError: onErrorWrapper
};
}
/**
* Signals the stream observer that the future records should be discarded on the server.
*
* @protected
* @since 4.0.0
* @returns {void}
*/
_cancel() {
if (this._summary === null && this._error === null) {
this._streamObserverPromise.then(o => o.cancel())
.catch(() => { });
}
}
/**
* @access private
* @param metadata
* @returns
*/
_releaseConnectionAndGetSummary(metadata) {
const { validatedQuery: query, params: parameters } = util.validateQueryAndParameters(this._query, this._parameters, {
skipAsserts: true
});
const connectionHolder = this._connectionHolder;
return connectionHolder
.getConnection()
.then(
// onFulfilled:
connection => connectionHolder
.releaseConnection()
.then(() => connection === null || connection === void 0 ? void 0 : connection.getProtocolVersion()),
// onRejected:
_ => undefined)
.then(protocolVersion => new ResultSummary(query, parameters, metadata, protocolVersion));
}
/**
* @access private
*/
_createQueuedResultObserver(onQueueSizeChanged) {
function createResolvablePromise() {
const resolvablePromise = {};
resolvablePromise.promise = new Promise((resolve, reject) => {
resolvablePromise.resolve = resolve;
resolvablePromise.reject = reject;
});
return resolvablePromise;
}
function isError(elementOrError) {
return elementOrError instanceof Error;
}
function dequeue() {
var _b;
return __awaiter(this, void 0, void 0, function* () {
if (buffer.length > 0) {
const element = (_b = buffer.shift()) !== null && _b !== void 0 ? _b : newError('Unexpected empty buffer', PROTOCOL_ERROR);
onQueueSizeChanged();
if (isError(element)) {
throw element;
}
return element;
}
promiseHolder.resolvable = createResolvablePromise();
return yield promiseHolder.resolvable.promise;
});
}
const buffer = [];
const promiseHolder = { resolvable: null };
const observer = {
onNext: (record) => {
observer._push({ done: false, value: record });
},
onCompleted: (summary) => {
observer._push({ done: true, value: summary });
},
onError: (error) => {
observer._push(error);
},
_push(element) {
if (promiseHolder.resolvable !== null) {
const resolvable = promiseHolder.resolvable;
promiseHolder.resolvable = null;
if (isError(element)) {
resolvable.reject(element);
}
else {
resolvable.resolve(element);
}
}
else {
buffer.push(element);
onQueueSizeChanged();
}
},
dequeue,
dequeueUntilDone: () => __awaiter(this, void 0, void 0, function* () {
while (true) {
const element = yield dequeue();
if (element.done === true) {
return element;
}
}
}),
head: () => __awaiter(this, void 0, void 0, function* () {
if (buffer.length > 0) {
const element = buffer[0];
if (isError(element)) {
throw element;
}
return element;
}
promiseHolder.resolvable = createResolvablePromise();
try {
const element = yield promiseHolder.resolvable.promise;
buffer.unshift(element);
return element;
}
catch (error) {
buffer.unshift(error);
throw error;
}
finally {
onQueueSizeChanged();
}
}),
get size() {
return buffer.length;
}
};
return observer;
}
}
_a = Symbol.toStringTag;
function captureStacktrace() {
const error = new Error('');
if (error.stack != null) {
return error.stack.replace(/^Error(\n\r)*/, ''); // we don't need the 'Error\n' part, if only it exists
}
return null;
}
/**
* @private
* @param {Error} error The error
* @param {string| null} newStack The newStack
* @returns {void}
*/
function replaceStacktrace(error, newStack) {
if (newStack != null) {
// Error.prototype.toString() concatenates error.name and error.message nicely
// then we add the rest of the stack trace
// eslint-disable-next-line @typescript-eslint/no-base-to-string
error.stack = error.toString() + '\n' + newStack;
}
}
export default Result;
