noop on duplicates

README.md

@@ -56,6 +56,7 @@ List all `archives` in the `multidrive`.
 
 ### drive.create(data, callback(err, drive))
 Create a new Hyperdrive archive. `data` is passed into `createArchive`.
+If an archive with the same key already exists, returns that instead.
 
 ### drive.close(key, callback(err))
 Remove an archive by its public key. Calls `closeArchive()`

index.js

@@ -39,6 +39,12 @@ function multidrive (store, createArchive, closeArchive, cb) {
     createArchive(data, function (err, archive) {
       if (err) return cb(err)
       var key = archive.key
+
+      var duplicates = archives.filter(function (_archive) {
+        return _archive.key === key
+      })
+      if (duplicates.length) return cb(null, duplicates[0])
+
       var _data
       if (data) _data = JSON.stringify(data)
       store.write(key, _data, function (err) {

test.js

@@ -73,6 +73,31 @@ test('drive.create', function (t) {
       done(null, archive)
     }
   })
+
+  t.test('should noop on duplicates', function (t) {
+    t.plan(4)
+    flushToilet()
+    var store = toilet('state.json')
+    var db = memdb()
+    var drive = hyperdrive(db)
+    multidrive(store, createArchive, noop, function (err, drive) {
+      t.ifError(err, 'no err')
+
+      drive.create({ hello: 'world' }, function (err, archive) {
+        t.ifError(err, 'no err')
+
+        drive.create({ key: archive.key }, function (err, _archive) {
+          t.ifError(err, 'no err')
+          t.equal(_archive, archive)
+        })
+      })
+    })
+
+    function createArchive (data, done) {
+      var archive = drive.createArchive({ key: data.key })
+      done(null, archive)
+    }
+  })
 })
 
 test('drive.list', function (t) {