Create iterators in order (#75)

* Create iterators in order

* Add type property for reachdown

Because now that db._iterators is gone, reachdown can no longer
feature-detect deferred-leveldown.

deferred-leveldown.js

@@ -8,26 +8,28 @@ function DeferredLevelDOWN (db) {
   AbstractLevelDOWN.call(this, '')
   this._db = db
   this._operations = []
-  this._iterators = []
   closed(this)
 }
 
 inherits(DeferredLevelDOWN, AbstractLevelDOWN)
 
+DeferredLevelDOWN.prototype.type = 'deferred-leveldown'
+
 DeferredLevelDOWN.prototype._open = function (options, callback) {
   var self = this
 
   this._db.open(options, function (err) {
     if (err) return callback(err)
 
     self._operations.forEach(function (op) {
-      self._db[op.method].apply(self._db, op.args)
+      if (op.iterator) {
+        op.iterator.setDb(self._db)
+      } else {
+        self._db[op.method].apply(self._db, op.args)
+      }
     })
     self._operations = []
-    self._iterators.forEach(function (it) {
-      it.setDb(self._db)
-    })
-    self._iterators = []
+
     open(self)
     callback()
   })
@@ -73,7 +75,7 @@ function closed (self) {
   })
   self._iterator = function (options) {
     var it = new DeferredIterator(options)
-    this._iterators.push(it)
+    this._operations.push({ iterator: it })
     return it
   }
 }

package.json

@@ -21,6 +21,7 @@
     "hallmark": "^2.0.0",
     "level-community": "^3.0.0",
     "nyc": "^14.0.0",
+    "reachdown": "^1.0.0",
     "standard": "^14.0.0",
     "tape": "^4.10.0"
   },

test.js

@@ -1,5 +1,7 @@
 var test = require('tape')
+var reachdown = require('reachdown')
 var DeferredLevelDOWN = require('./')
+var noop = function () {}
 
 test('deferred open gets correct options', function (t) {
   var OPTIONS = { foo: 'BAR' }
@@ -482,3 +484,54 @@ test('iterator - non deferred operation', function (t) {
     })
   })
 })
+
+test('iterator - is created in order', function (t) {
+  t.plan(4)
+
+  function db () {
+    return {
+      order: [],
+      iterator: function (options) {
+        this.order.push('iterator created')
+        return {}
+      },
+      put: function (key, value, options, callback) {
+        this.order.push('put')
+      },
+      open: function (options, callback) {
+        process.nextTick(callback)
+      }
+    }
+  }
+
+  var ld1 = new DeferredLevelDOWN(db())
+  var ld2 = new DeferredLevelDOWN(db())
+
+  ld1.iterator()
+  ld1.put('key', 'value', noop)
+
+  ld2.put('key', 'value', noop)
+  ld2.iterator()
+
+  ld1.open(function (err) {
+    t.error(err, 'no error')
+    t.same(ld1._db.order, ['iterator created', 'put'])
+  })
+
+  ld2.open(function (err) {
+    t.error(err, 'no error')
+    t.same(ld2._db.order, ['put', 'iterator created'])
+  })
+})
+
+test('reachdown supports deferred-leveldown', function (t) {
+  // Define just enough methods for reachdown to see this as a real db
+  var db = { open: noop, _batch: noop, _iterator: noop }
+  var ld = new DeferredLevelDOWN(db)
+
+  t.is(ld.type, 'deferred-leveldown')
+  t.is(reachdown(ld, 'deferred-leveldown'), ld)
+  t.is(reachdown(ld), db)
+
+  t.end()
+})