Implement persistence layer

src/Persistence.js

@@ -0,0 +1,43 @@
+import { BinaryEncoder } from './Encoding.js'
+
+export default function extendPersistence (Y) {
+  class AbstractPersistence {
+    constructor (y, opts) {
+      this.y = y
+      this.opts = opts
+      this.saveOperationsBuffer = []
+      this.log = Y.debug('y:persistence')
+    }
+    saveToMessageQueue (binary) {
+      this.log('Room %s: Save message to message queue', this.y.options.connector.room)
+    }
+    saveOperations (ops) {
+      ops = ops.map(function (op) {
+        return Y.Struct[op.struct].encode(op)
+      })
+      const saveOperations = () => {
+        if (this.saveOperationsBuffer.length > 0) {
+          let encoder = new BinaryEncoder()
+          encoder.writeVarString(this.opts.room)
+          encoder.writeVarString('update')
+          let ops = this.saveOperationsBuffer
+          this.saveOperationsBuffer = []
+          let length = ops.length
+          encoder.writeUint32(length)
+          for (var i = 0; i < length; i++) {
+            let op = ops[i]
+            Y.Struct[op.struct].binaryEncode(encoder, op)
+          }
+          this.saveToMessageQueue(encoder.createBuffer())
+        }
+      }
+      if (this.saveOperationsBuffer.length === 0) {
+        this.saveOperationsBuffer = ops
+        this.y.db.whenTransactionsFinished().then(saveOperations)
+      } else {
+        this.saveOperationsBuffer = this.saveOperationsBuffer.concat(ops)
+      }
+    }
+  }
+  Y.AbstractPersistence = AbstractPersistence
+}