Revert "Lock file during patching."

This reverts commit 90dcfe6.

Author: megoth

lib/handlers/patch.js

@@ -10,7 +10,6 @@ const $rdf = require('rdflib')
 const crypto = require('crypto')
 const overQuota = require('../utils').overQuota
 const getContentType = require('../utils').getContentType
-const { lock } = require('proper-lockfile')
 
 // Patch parsers by request body content type
 const PATCH_PARSERS = {
@@ -24,7 +23,6 @@ const DEFAULT_FOR_NEW_CONTENT_TYPE = 'text/turtle'
 async function patchHandler (req, res, next) {
   debug(`PATCH -- ${req.originalUrl}`)
   res.header('MS-Author-Via', 'SPARQL')
-  let releaseLock
   try {
     // Obtain details of the target resource
     const ldp = req.app.locals.ldp
@@ -52,24 +50,22 @@ async function patchHandler (req, res, next) {
       throw error(415, `Unsupported patch content type: ${patch.contentType}`)
     }
 
-    // Parse the patch document and verify permissions
-    const patchObject = await parsePatch(url, patch.uri, patch.text)
-    await checkPermission(req, patchObject)
+    // Parse the target graph and the patch document,
+    // and verify permission for performing this specific patch
+    const [graph, patchObject] = await Promise.all([
+      readGraph(resource),
+      parsePatch(url, patch.uri, patch.text)
+        .then(patchObject => checkPermission(req, patchObject))
+    ])
 
     // Patch the graph and write it back to the file
-    releaseLock = await lock(path, { retries: 10, realpath: false })
-    const graph = await readGraph(resource)
     await applyPatch(patchObject, graph, url)
     const result = await writeGraph(graph, resource, ldp.resourceMapper.rootPath, ldp.serverUri)
 
     // Send the result to the client
     res.send(result)
   } catch (err) {
     return next(err)
-  } finally {
-    if (releaseLock) {
-      await releaseLock()
-    }
   }
   return next()
 }