140 lines
4.6 KiB
JavaScript
140 lines
4.6 KiB
JavaScript
// external modules
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var DiffMatchPatch = require('diff-match-patch');
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var dmp = new DiffMatchPatch();
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// core
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var config = require("../config.js");
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var logger = require("../logger.js");
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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 (!data.hasOwnProperty('lastDoc') || !data.hasOwnProperty('currDoc')) {
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return logger.error('dmp worker error: not enough data on create patch');
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}
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try {
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var 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 (!data.hasOwnProperty('revisions') || !data.hasOwnProperty('count')) {
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return logger.error('dmp worker error: not enough data on get revision');
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}
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try {
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var 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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var ms_start = (new Date()).getTime();
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var diff = dmp.diff_main(lastDoc, currDoc);
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var patch = dmp.patch_make(lastDoc, diff);
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patch = dmp.patch_toText(patch);
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var ms_end = (new Date()).getTime();
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if (config.debug) {
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logger.info(patch);
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logger.info((ms_end - ms_start) + 'ms');
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}
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return patch;
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}
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function getRevision(revisions, count) {
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var ms_start = (new Date()).getTime();
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var startContent = null;
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var lastPatch = [];
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var applyPatches = [];
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var 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 (var i = 0; i < count; i++) {
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var 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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var 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 (var i = 0, l = applyPatches.length; i < l; i++) {
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for (var j = 0, m = applyPatches[i].diffs.length; j < m; j++) {
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var 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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} else {
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// start from bottom to target
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var l = revisions.length - 1;
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for (var i = l; i >= count - 1; i--) {
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var 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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var 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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var finalContent = dmp.patch_apply(applyPatches, startContent)[0];
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} catch (err) {
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throw new Error(err);
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}
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var 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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var ms_end = (new Date()).getTime();
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if (config.debug) {
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logger.info((ms_end - ms_start) + 'ms');
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}
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return data;
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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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}); |