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keksAccountGUI/node_modulesOLD/loader-fs-cache/index.js

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2019-08-11 18:48:02 +00:00
/**
* Filesystem cache
*
* Given a file and a transform function, cache the result into files
* or retrieve the previously cached files if the given file is already known.
*
* @see https://github.com/babel/babel-loader/issues/34
* @see https://github.com/babel/babel-loader/pull/41
* @see https://github.com/babel/babel-loader/blob/master/src/fs-cache.js
*/
var crypto = require("crypto");
var mkdirp = require("mkdirp");
var findCacheDir = require("find-cache-dir");
var fs = require("fs");
var os = require("os");
var path = require("path");
var zlib = require("zlib");
var defaultCacheDirectory = null; // Lazily instantiated when needed
/**
* Read the contents from the compressed file.
*
* @async
* @params {String} filename
* @params {Function} callback
*/
var read = function(filename, callback) {
return fs.readFile(filename, function(err, data) {
if (err) {
return callback(err);
}
return zlib.gunzip(data, function(err, content) {
var result = {};
if (err) {
return callback(err);
}
try {
result = JSON.parse(content);
} catch (e) {
return callback(e);
}
return callback(null, result);
});
});
};
/**
* Write contents into a compressed file.
*
* @async
* @params {String} filename
* @params {String} result
* @params {Function} callback
*/
var write = function(filename, result, callback) {
var content = JSON.stringify(result);
return zlib.gzip(content, function(err, data) {
if (err) {
return callback(err);
}
return fs.writeFile(filename, data, callback);
});
};
/**
* Build the filename for the cached file
*
* @params {String} source File source code
* @params {Object} options Options used
*
* @return {String}
*/
var filename = function(source, identifier, options) {
var hash = crypto.createHash("SHA1");
var contents = JSON.stringify({
source: source,
options: options,
identifier: identifier
});
hash.end(contents);
return hash.read().toString("hex") + ".json.gz";
};
/**
* Handle the cache
*
* @params {String} directory
* @params {Object} params
* @params {Function} callback
*/
var handleCache = function(directory, params, callback) {
var source = params.source;
var options = params.options || {};
var transform = params.transform;
var identifier = params.identifier;
var shouldFallback = typeof params.directory !== "string" &&
directory !== os.tmpdir();
// Make sure the directory exists.
mkdirp(directory, function(err) {
// Fallback to tmpdir if node_modules folder not writable
if (err)
return shouldFallback
? handleCache(os.tmpdir(), params, callback)
: callback(err);
var file = path.join(directory, filename(source, identifier, options));
return read(file, function(err, content) {
var result = {};
// No errors mean that the file was previously cached
// we just need to return it
if (!err) return callback(null, content);
// Otherwise just transform the file
// return it to the user asap and write it in cache
try {
result = transform(source, options);
} catch (error) {
return callback(error);
}
return write(file, result, function(err) {
// Fallback to tmpdir if node_modules folder not writable
if (err)
return shouldFallback
? handleCache(os.tmpdir(), params, callback)
: callback(err);
callback(null, result);
});
});
});
};
/**
* Retrieve file from cache, or create a new one for future reads
*
* @async
* @param {Object} params
* @param {String} params.directory Directory to store cached files
* @param {String} params.identifier Unique identifier to bust cache
* @param {String} params.source Original contents of the file to be cached
* @param {Object} params.options Options to be given to the transform fn
* @param {Function} params.transform Function that will transform the
* original file and whose result will be
* cached
*
* @param {Function<err, result>} callback
*
* @example
*
* cache({
* directory: '.tmp/cache',
* identifier: 'babel-loader-cachefile',
* source: *source code from file*,
* options: {
* experimental: true,
* runtime: true
* },
* transform: function(source, options) {
* var content = *do what you need with the source*
* return content
* }
* }, function(err, result) {
*
* })
*/
module.exports = function createFsCache(name) {
return function(params, callback) {
var directory;
if (typeof params.directory === "string") {
directory = params.directory;
} else {
if (defaultCacheDirectory === null) {
defaultCacheDirectory = findCacheDir({
name: name
}) ||
os.tmpdir();
}
directory = defaultCacheDirectory;
}
handleCache(directory, params, callback);
};
};