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Fix circular dependency between transport streams
There is a circular dependency between the `TransportStream` (formerly in `index.js`) and `LegacyTransportStream` (in `legacy.js`). This causes some funky problems when you import the legacy module and later import the main module, as seen in winstonjs/winston#1886. I've resolved the circular issue here by definiting the main implementation of `TransportStream` in a separate module (which `LegacyTransportStream` now depends on) and then doing the work of decorating it with a `.LegacyTransportStream` property in `index.js` (and that's pretty much all the index module does).
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,215 +1,7 @@ | ||
| 'use strict'; | ||
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| const util = require('util'); | ||
| const Writable = require('readable-stream/lib/_stream_writable.js'); | ||
| const { LEVEL } = require('triple-beam'); | ||
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| /** | ||
| * 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, highWaterMark: options.highWaterMark }); | ||
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| this.format = options.format; | ||
| this.level = options.level; | ||
| this.handleExceptions = options.handleExceptions; | ||
| this.handleRejections = options.handleRejections; | ||
| this.silent = options.silent; | ||
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| if (options.log) this.log = options.log; | ||
| if (options.logv) this.logv = options.logv; | ||
| if (options.close) this.close = options.close; | ||
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| // 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.parent = logger; | ||
| }); | ||
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| // 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(); | ||
| } | ||
| } | ||
| }); | ||
| }; | ||
|
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| /* | ||
| * Inherit from Writeable using Node.js built-ins | ||
| */ | ||
| util.inherits(TransportStream, Writable); | ||
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| /** | ||
| * 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); | ||
| } | ||
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| // Remark: This has to be handled in the base transport now because we | ||
| // cannot conditionally write to our pipe targets as stream. We always | ||
| // prefer any explicit level set on the Transport itself falling back to | ||
| // any level set on the parent. | ||
| const level = this.level || (this.parent && this.parent.level); | ||
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| if (!level || this.levels[level] >= this.levels[info[LEVEL]]) { | ||
| if (info && !this.format) { | ||
| return this.log(info, callback); | ||
| } | ||
|
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| let errState; | ||
| let transformed; | ||
|
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| // We trap(and re-throw) any errors generated by the user-provided format, but also | ||
| // guarantee that the streams callback is invoked so that we can continue flowing. | ||
| try { | ||
| transformed = this.format.transform(Object.assign({}, info), this.format.options); | ||
| } catch (err) { | ||
| errState = err; | ||
| } | ||
|
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| if (errState || !transformed) { | ||
| // eslint-disable-next-line callback-return | ||
| callback(); | ||
| if (errState) throw errState; | ||
| return; | ||
| } | ||
|
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| return this.log(transformed, callback); | ||
| } | ||
| this._writableState.sync = false; | ||
| return callback(null); | ||
| }; | ||
|
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| /** | ||
| * 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); | ||
| } | ||
|
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| // 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); | ||
| } | ||
|
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| for (let i = 0; i < chunks.length; i++) { | ||
| if (!this._accept(chunks[i])) continue; | ||
|
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| if (chunks[i].chunk && !this.format) { | ||
| this.log(chunks[i].chunk, chunks[i].callback); | ||
| continue; | ||
| } | ||
|
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| let errState; | ||
| let transformed; | ||
|
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| // We trap(and re-throw) any errors generated by the user-provided format, but also | ||
| // guarantee that the streams callback is invoked so that we can continue flowing. | ||
| try { | ||
| transformed = this.format.transform( | ||
| Object.assign({}, chunks[i].chunk), | ||
| this.format.options | ||
| ); | ||
| } catch (err) { | ||
| errState = err; | ||
| } | ||
|
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| if (errState || !transformed) { | ||
| // eslint-disable-next-line callback-return | ||
| chunks[i].callback(); | ||
| if (errState) { | ||
| // eslint-disable-next-line callback-return | ||
| callback(null); | ||
| throw errState; | ||
| } | ||
| } else { | ||
| this.log(transformed, chunks[i].callback); | ||
| } | ||
| } | ||
|
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| return callback(null); | ||
| }; | ||
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| /** | ||
| * 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; | ||
| } | ||
|
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| // We always prefer any explicit level set on the Transport itself | ||
| // falling back to any level set on the parent. | ||
| const level = this.level || (this.parent && this.parent.level); | ||
|
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| // Immediately check the average case: log level filtering. | ||
| if ( | ||
| info.exception === true || | ||
| !level || | ||
| this.levels[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; | ||
| } | ||
| } | ||
|
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| return false; | ||
| }; | ||
|
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| /** | ||
| * _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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| // Expose modern transport directly as the export | ||
| module.exports = require('./modern'); | ||
|
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| // Expose legacy stream | ||
| module.exports.LegacyTransportStream = require('./legacy'); |
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