feat(resolve): Fallback to expired Cache if remote resolve fails

AraBlocks · Dec 6, 2019 · e8fb764 · e8fb764
1 parent 1a97695
commit e8fb764
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Showing 3 changed files with 19 additions and 6 deletions.
diff --git a/fs.js b/fs.js
@@ -1,5 +1,5 @@
+const { dirname, resolve, join } = require('path')
 const { toHex, writeCache } = require('./util')
-const { dirname, resolve } = require('path')
 const { createSwarm } = require('ara-network/discovery')
 const { createCFS } = require('cfsnet/create')
 const { normalize } = require('./did')
@@ -199,7 +199,7 @@ async function readFile(identifier, filename, opts) {
  try {
  const buffer = await cfs.readFile(filename)
  if (false === isBrowser) {
- await writeCache(did.identifier, buffer)
+ await writeCache(did.identifier, filename, buffer)
  }
  done(null, buffer)
  } catch (err) {

diff --git a/resolve.js b/resolve.js
@@ -270,6 +270,19 @@ async function findResolution(did, opts, state) {
  }
 
  if (0 === pending && !didResolve && 0 === resolvers.length && !state.aborted) {
+
+ // Revert to expired cache copy if present
+ if (!isBrowser) {
+ try {
+ const cachePath = path.join(os.tmpdir(), 'aid', did.identifier, 'ddo.json')
+ const json = await pify(readFile)(cachePath, 'utf8')
+ done(null, (opts.parse || JSON.parse)(String(json)))
+ } catch (err) {
+ console.log(err)
+ debug(err)
+ }
+ }
+
  cleanup()
  done(null, result)
  } else if (resolvers.length && !state.aborted && !didResolve) {
@@ -296,7 +309,7 @@ async function findResolution(did, opts, state) {
 
  // Write DDO to temp cache folder
  if (false === isBrowser) {
- await writeCache(did.identifier, JSON.stringify(result))
+ await writeCache(did.identifier, 'ddo.json', JSON.stringify(result))
  }
  didResolve = true
  cleanup()

diff --git a/util.js b/util.js
@@ -1,5 +1,5 @@
-const { createIdentityKeyPath } = require('./key-path')
 const { dirname, resolve, join } = require('path')
+const { createIdentityKeyPath } = require('./key-path')
 const isBuffer = require('is-buffer')
 const mkdirp = require('mkdirp')
 const debug = require('debug')('ara:identity:util')
@@ -106,9 +106,9 @@ async function resolveDNS(uri) {
  return null
 }
 
-async function writeCache(identifier, buffer) {
+async function writeCache(identifier, filename, buffer) {
  try {
- const cachePath = join(os.tmpdir(), 'aid', identifier, 'ddo.json')
+ const cachePath = join(os.tmpdir(), 'aid', identifier, filename)
  await pify(mkdirp)(dirname(cachePath))
  await pify(fs.writeFile)(cachePath, buffer)
  } catch (err) {