overleaf/services/clsi/app/coffee/OutputCacheManager.coffee

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async = require "async"
fs = require "fs"
fse = require "fs-extra"
Path = require "path"
logger = require "logger-sharelatex"
_ = require "underscore"
OutputFileOptimiser = require "./OutputFileOptimiser"
module.exports = OutputCacheManager =
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CACHE_SUBDIR: '.cache/clsi'
BUILD_REGEX: /^[0-9a-f]+$/ # build id is Date.now() converted to hex
CACHE_LIMIT: 32 # maximum of 32 cache directories
CACHE_AGE: 60*60*1000 # up to one hour old
path: (buildId, file) ->
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# used by static server, given build id return '.cache/clsi/buildId'
if buildId.match OutputCacheManager.BUILD_REGEX
return Path.join(OutputCacheManager.CACHE_SUBDIR, buildId, file)
else
# for invalid build id, return top level
return file
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saveOutputFiles: (outputFiles, compileDir, callback = (error) ->) ->
# make a compileDir/CACHE_SUBDIR/build_id directory and
# copy all the output files into it
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cacheRoot = Path.join(compileDir, OutputCacheManager.CACHE_SUBDIR)
# Put the files into a new cache subdirectory
buildId = Date.now().toString(16)
cacheDir = Path.join(compileDir, OutputCacheManager.CACHE_SUBDIR, buildId)
# let file expiry run in the background
OutputCacheManager.expireOutputFiles cacheRoot, {keep: buildId}
checkFile = (src, callback) ->
# check if we have a valid file to copy into the cache
fs.stat src, (err, stats) ->
if err?
# some problem reading the file
logger.error err: err, file: src, "stat error for file in cache"
callback(err)
else if not stats.isFile()
# other filetype - reject it
logger.error err: err, src: src, dst: dst, stat: stats, "nonfile output - refusing to copy to cache"
callback(new Error("output file is not a file"), file)
else
# it's a plain file, ok to copy
callback(null)
copyFile = (src, dst, callback) ->
# copy output file into the cache
fse.copy src, dst, (err) ->
if err?
logger.error err: err, src: src, dst: dst, "copy error for file in cache"
callback(err)
else
# call the optimiser for the file too
OutputFileOptimiser.optimiseFile src, dst, callback
# make the new cache directory
fse.ensureDir cacheDir, (err) ->
if err?
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logger.error err: err, directory: cacheDir, "error creating cache directory"
callback(err, outputFiles)
else
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# copy all the output files into the new cache directory
async.mapSeries outputFiles, (file, cb) ->
newFile = _.clone(file)
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[src, dst] = [Path.join(compileDir, file.path), Path.join(cacheDir, file.path)]
checkFile src, (err) ->
copyFile src, dst, (err) ->
if not err?
newFile.build = buildId # attach a build id if we cached the file
cb(err, newFile)
, (err, results) ->
if err?
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# pass back the original files if we encountered *any* error
callback(err, outputFiles)
else
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# pass back the list of new files in the cache
callback(err, results)
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expireOutputFiles: (cacheRoot, options, callback = (error) ->) ->
# look in compileDir for build dirs and delete if > N or age of mod time > T
fs.readdir cacheRoot, (err, results) ->
if err?
logger.error err: err, project_id: cacheRoot, "error clearing cache"
return callback(err)
dirs = results.sort().reverse()
currentTime = Date.now()
isExpired = (dir, index) ->
return false if options?.keep == dir
# remove any directories over the hard limit
return true if index > OutputCacheManager.CACHE_LIMIT
# we can get the build time from the directory name
dirTime = parseInt(dir, 16)
age = currentTime - dirTime
return age > OutputCacheManager.CACHE_AGE
toRemove = _.filter(dirs, isExpired)
removeDir = (dir, cb) ->
fse.remove Path.join(cacheRoot, dir), (err, result) ->
logger.log cache: cacheRoot, dir: dir, "removed expired cache dir"
if err?
logger.error err: err, dir: dir, "cache remove error"
cb(err, result)
async.eachSeries toRemove, (dir, cb) ->
removeDir dir, cb
, callback