148 lines
4.1 KiB
JavaScript
148 lines
4.1 KiB
JavaScript
'use strict'
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// external modules
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const DiffMatchPatch = require('diff-match-patch')
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const dmp = new DiffMatchPatch()
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// core
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const logger = require('../logger')
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process.on('message', function (data) {
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if (!data || !data.msg || !data.cacheKey) {
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return logger.error('dmp worker error: not enough data')
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}
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switch (data.msg) {
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case 'create patch':
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if (
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!Object.prototype.hasOwnProperty.call(data, 'lastDoc') ||
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!Object.prototype.hasOwnProperty.call(data, 'currDoc')
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) {
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return logger.error(
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'dmp worker error: not enough data on create patch'
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)
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}
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try {
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const patch = createPatch(data.lastDoc, data.currDoc)
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process.send({
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msg: 'check',
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result: patch,
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cacheKey: data.cacheKey
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})
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} catch (err) {
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logger.error('dmp worker error', err)
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process.send({
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msg: 'error',
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error: err,
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cacheKey: data.cacheKey
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})
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}
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break
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case 'get revision':
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if (
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!Object.prototype.hasOwnProperty.call(data, 'revisions') ||
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!Object.prototype.hasOwnProperty.call(data, 'count')
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) {
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return logger.error(
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'dmp worker error: not enough data on get revision'
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)
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}
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try {
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const result = getRevision(data.revisions, data.count)
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process.send({
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msg: 'check',
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result: result,
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cacheKey: data.cacheKey
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})
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} catch (err) {
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logger.error('dmp worker error', err)
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process.send({
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msg: 'error',
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error: err,
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cacheKey: data.cacheKey
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})
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}
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break
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}
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})
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function createPatch (lastDoc, currDoc) {
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const msStart = new Date().getTime()
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const diff = dmp.diff_main(lastDoc, currDoc)
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let patch = dmp.patch_make(lastDoc, diff)
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patch = dmp.patch_toText(patch)
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const msEnd = new Date().getTime()
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logger.debug(patch)
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logger.debug(msEnd - msStart + 'ms')
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return patch
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}
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function getRevision (revisions, count) {
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const msStart = new Date().getTime()
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let startContent = null
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let lastPatch = []
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let applyPatches = []
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let authorship = []
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if (count <= Math.round(revisions.length / 2)) {
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// start from top to target
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for (let i = 0; i < count; i++) {
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const revision = revisions[i]
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if (i === 0) {
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startContent = revision.content || revision.lastContent
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}
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if (i !== count - 1) {
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const patch = dmp.patch_fromText(revision.patch)
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applyPatches = applyPatches.concat(patch)
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}
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lastPatch = revision.patch
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authorship = revision.authorship
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}
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// swap DIFF_INSERT and DIFF_DELETE to achieve unpatching
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for (let i = 0, l = applyPatches.length; i < l; i++) {
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for (let j = 0, m = applyPatches[i].diffs.length; j < m; j++) {
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const diff = applyPatches[i].diffs[j]
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if (diff[0] === DiffMatchPatch.DIFF_INSERT) {
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diff[0] = DiffMatchPatch.DIFF_DELETE
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} else if (diff[0] === DiffMatchPatch.DIFF_DELETE) {
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diff[0] = DiffMatchPatch.DIFF_INSERT
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}
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}
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}
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} else {
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// start from bottom to target
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const l = revisions.length - 1
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for (let i = l; i >= count - 1; i--) {
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const revision = revisions[i]
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if (i === l) {
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startContent = revision.lastContent
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authorship = revision.authorship
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}
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if (revision.patch) {
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const patch = dmp.patch_fromText(revision.patch)
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applyPatches = applyPatches.concat(patch)
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}
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lastPatch = revision.patch
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authorship = revision.authorship
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}
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}
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try {
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const finalContent = dmp.patch_apply(applyPatches, startContent)[0]
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const data = {
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content: finalContent,
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patch: dmp.patch_fromText(lastPatch),
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authorship: authorship
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}
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const msEnd = new Date().getTime()
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logger.debug(msEnd - msStart + 'ms')
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return data
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} catch (err) {
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throw new Error(err)
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}
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}
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// log uncaught exception
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process.on('uncaughtException', function (err) {
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logger.error('An uncaught exception has occured.')
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logger.error(err)
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logger.error('Process will exit now.')
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process.exit(1)
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})
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