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Revert to prototypal-based syntax for backwards compatibility #23

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merged 3 commits into from
May 31, 2018
Merged

Revert to prototypal-based syntax for backwards compatibility #23

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8ba8fca
[dist] Bump package versions.
indexzero May 30, 2018
8928bf7
[api] Allow for prototypal inheritance from Transport and LegacyTrans…
indexzero May 30, 2018
a49671f
[test] Add tests for different inheritance patterns.
indexzero May 30, 2018
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286 changes: 144 additions & 142 deletions index.js
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Original file line number Diff line number Diff line change
@@ -1,171 +1,173 @@
'use strict';

const util = require('util');
const { Writable } = require('stream');
const { LEVEL } = require('triple-beam');

module.exports = class TransportStream extends Writable {
/**
* Constructor function for the TransportStream. This is the base prototype
* that all `winston >= 3` transports should inherit from.
* @param {Object} options - Options for this TransportStream instance
* @param {String} options.level - Highest level according to RFC5424.
* @param {Boolean} options.handleExceptions - If true, info with
* { exception: true } will be written.
* @param {Function} options.log - Custom log function for simple Transport
* creation
* @param {Function} options.close - Called on "unpipe" from parent.
*/
constructor(options = {}) {
super({
objectMode: true
});

this.format = options.format;
this.level = options.level;
this.handleExceptions = options.handleExceptions;
this.silent = options.silent;

if (options.log) {
this.log = options.log;
}
if (options.logv) {
this.logv = options.logv;
}
if (options.close) {
this.close = options.close;
}

// Get the levels from the source we are piped from.
this.once('pipe', logger => {
// Remark (indexzero): this bookkeeping can only support multiple
// Logger parents with the same `levels`. This comes into play in
// the `winston.Container` code in which `container.add` takes
// a fully realized set of options with pre-constructed TransportStreams.
this.levels = logger.levels;
this.level = this.level || logger.level;
this.parent = logger;
});

// If and/or when the transport is removed from this instance
this.once('unpipe', src => {
// Remark (indexzero): this bookkeeping can only support multiple
// Logger parents with the same `levels`. This comes into play in
// the `winston.Container` code in which `container.add` takes
// a fully realized set of options with pre-constructed TransportStreams.
if (src === this.parent) {
this.parent = null;
if (this.close) {
this.close();
}
}
});
/**
* Constructor function for the TransportStream. This is the base prototype
* that all `winston >= 3` transports should inherit from.
* @param {Object} options - Options for this TransportStream instance
* @param {String} options.level - Highest level according to RFC5424.
* @param {Boolean} options.handleExceptions - If true, info with
* { exception: true } will be written.
* @param {Function} options.log - Custom log function for simple Transport
* creation
* @param {Function} options.close - Called on "unpipe" from parent.
*/
const TransportStream = module.exports = function TransportStream(options = {}) {
Writable.call(this, { objectMode: true });

this.format = options.format;
this.level = options.level;
this.handleExceptions = options.handleExceptions;
this.silent = options.silent;

if (options.log) {
this.log = options.log;
}
if (options.logv) {
this.logv = options.logv;
}
if (options.close) {
this.close = options.close;
}

/**
* Writes the info object to our transport instance.
* @param {mixed} info - TODO: add param description.
* @param {mixed} enc - TODO: add param description.
* @param {function} callback - TODO: add param description.
* @returns {undefined}
* @private
*/
_write(info, enc, callback) {
if (this.silent || (info.exception === true && !this.handleExceptions)) {
return callback(null);
}

// Remark: This has to be handled in the base transport now because we
// cannot conditionally write to our pipe targets as stream.
if (!this.level || this.levels[this.level] >= this.levels[info[LEVEL]]) {
info = this.format
? this.format.transform(Object.assign({}, info), this.format.options)
: info;

if (info) {
return this.log(info, callback);
// Get the levels from the source we are piped from.
this.once('pipe', logger => {
// Remark (indexzero): this bookkeeping can only support multiple
// Logger parents with the same `levels`. This comes into play in
// the `winston.Container` code in which `container.add` takes
// a fully realized set of options with pre-constructed TransportStreams.
this.levels = logger.levels;
this.level = this.level || logger.level;
this.parent = logger;
});

// If and/or when the transport is removed from this instance
this.once('unpipe', src => {
// Remark (indexzero): this bookkeeping can only support multiple
// Logger parents with the same `levels`. This comes into play in
// the `winston.Container` code in which `container.add` takes
// a fully realized set of options with pre-constructed TransportStreams.
if (src === this.parent) {
this.parent = null;
if (this.close) {
this.close();
}
}
});
};

/*
* Inherit from Writeable using Node.js built-ins
*/
util.inherits(TransportStream, Writable);

/**
* Writes the info object to our transport instance.
* @param {mixed} info - TODO: add param description.
* @param {mixed} enc - TODO: add param description.
* @param {function} callback - TODO: add param description.
* @returns {undefined}
* @private
*/
TransportStream.prototype._write = function _write(info, enc, callback) {
if (this.silent || (info.exception === true && !this.handleExceptions)) {
return callback(null);
}

/**
* Writes the batch of info objects (i.e. "object chunks") to our transport
* instance after performing any necessary filtering.
* @param {mixed} chunks - TODO: add params description.
* @param {function} callback - TODO: add params description.
* @returns {mixed} - TODO: add returns description.
* @private
*/
_writev(chunks, callback) {
if (this.logv) {
const infos = chunks.filter(this._accept, this);
if (!infos.length) {
return callback(null);
}
// Remark: This has to be handled in the base transport now because we
// cannot conditionally write to our pipe targets as stream.
if (!this.level || this.levels[this.level] >= this.levels[info[LEVEL]]) {
info = this.format
? this.format.transform(Object.assign({}, info), this.format.options)
: info;

// Remark (indexzero): from a performance perspective if Transport
// implementers do choose to implement logv should we make it their
// responsibility to invoke their format?
return this.logv(infos, callback);
if (info) {
return this.log(info, callback);
}
}

for (let i = 0; i < chunks.length; i++) {
if (this._accept(chunks[i])) {
const info = this.format
? this.format.transform(
Object.assign({}, chunks[i].chunk),
this.format.options
)
: chunks[i].chunk;

if (info) {
this.log(info, chunks[i].callback);
}
}
return callback(null);
};

/**
* Writes the batch of info objects (i.e. "object chunks") to our transport
* instance after performing any necessary filtering.
* @param {mixed} chunks - TODO: add params description.
* @param {function} callback - TODO: add params description.
* @returns {mixed} - TODO: add returns description.
* @private
*/
TransportStream.prototype._writev = function _writev(chunks, callback) {
if (this.logv) {
const infos = chunks.filter(this._accept, this);
if (!infos.length) {
return callback(null);
}

return callback(null);
// Remark (indexzero): from a performance perspective if Transport
// implementers do choose to implement logv should we make it their
// responsibility to invoke their format?
return this.logv(infos, callback);
}

/**
* Predicate function that returns true if the specfied `info` on the
* WriteReq, `write`, should be passed down into the derived
* TransportStream's I/O via `.log(info, callback)`.
* @param {WriteReq} write - winston@3 Node.js WriteReq for the `info` object
* representing the log message.
* @returns {Boolean} - Value indicating if the `write` should be accepted &
* logged.
*/
_accept(write) {
const info = write.chunk;
if (this.silent) {
return false;
}
for (let i = 0; i < chunks.length; i++) {
if (this._accept(chunks[i])) {
const info = this.format
? this.format.transform(
Object.assign({}, chunks[i].chunk),
this.format.options
)
: chunks[i].chunk;

// Immediately check the average case: log level filtering.
if (
info.exception === true ||
!this.level ||
this.levels[this.level] >= this.levels[info[LEVEL]]
) {
// Ensure the info object is valid based on `{ exception }`:
// 1. { handleExceptions: true }: all `info` objects are valid
// 2. { exception: false }: accepted by all transports.
if (this.handleExceptions || info.exception !== true) {
return true;
if (info) {
this.log(info, chunks[i].callback);
}
}
}

return callback(null);
};

/**
* Predicate function that returns true if the specfied `info` on the
* WriteReq, `write`, should be passed down into the derived
* TransportStream's I/O via `.log(info, callback)`.
* @param {WriteReq} write - winston@3 Node.js WriteReq for the `info` object
* representing the log message.
* @returns {Boolean} - Value indicating if the `write` should be accepted &
* logged.
*/
TransportStream.prototype._accept = function _accept(write) {
const info = write.chunk;
if (this.silent) {
return false;
}

/**
* _nop is short for "No operation"
* @returns {Boolean} Intentionally false.
*/
_nop() {
// eslint-disable-next-line no-undefined
return void undefined;
// Immediately check the average case: log level filtering.
if (
info.exception === true ||
!this.level ||
this.levels[this.level] >= this.levels[info[LEVEL]]
) {
// Ensure the info object is valid based on `{ exception }`:
// 1. { handleExceptions: true }: all `info` objects are valid
// 2. { exception: false }: accepted by all transports.
if (this.handleExceptions || info.exception !== true) {
return true;
}
}

return false;
};

/**
* _nop is short for "No operation"
* @returns {Boolean} Intentionally false.
*/
TransportStream.prototype._nop = function _nop() {
// eslint-disable-next-line no-undefined
return void undefined;
};
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