Implement experimental new encoder 🚀

2020-07-12 18:25:45 +02:00
parent e31e968f0d
commit 6c2cf0f769
36 changed files with 1224 additions and 336 deletions
--- a/src/utils/DeleteSet.js
+++ b/src/utils/DeleteSet.js
@@ -3,9 +3,8 @@ import {
  findIndexSS,
  getState,
  splitItem,
-  createID,
  iterateStructs,
-  Item, AbstractStruct, GC, StructStore, Transaction, ID // eslint-disable-line
+  AbstractUpdateDecoder, AbstractDSDecoder, AbstractDSEncoder, DSDecoderV2, DSEncoderV2, Item, GC, StructStore, Transaction, ID // eslint-disable-line
 } from '../internals.js'

 import * as array from 'lib0/array.js'
@@ -163,14 +162,15 @@ export const mergeDeleteSets = dss => {

 /**
 * @param {DeleteSet} ds
- * @param {ID} id
+ * @param {number} client
+ * @param {number} clock
 * @param {number} length
 *
 * @private
 * @function
 */
-export const addToDeleteSet = (ds, id, length) => {
-  map.setIfUndefined(ds.clients, id.client, () => []).push(new DeleteItem(id.clock, length))
+export const addToDeleteSet = (ds, client, clock, length) => {
+  map.setIfUndefined(ds.clients, client, () => []).push(new DeleteItem(clock, length))
 }

 export const createDeleteSet = () => new DeleteSet()
@@ -210,28 +210,29 @@ export const createDeleteSetFromStructStore = ss => {
 }

 /**
- * @param {encoding.Encoder} encoder
+ * @param {AbstractDSEncoder} encoder
 * @param {DeleteSet} ds
 *
 * @private
 * @function
 */
 export const writeDeleteSet = (encoder, ds) => {
-  encoding.writeVarUint(encoder, ds.clients.size)
+  encoding.writeVarUint(encoder.restEncoder, ds.clients.size)
  ds.clients.forEach((dsitems, client) => {
-    encoding.writeVarUint(encoder, client)
+    encoder.resetDsCurVal()
+    encoding.writeVarUint(encoder.restEncoder, client)
    const len = dsitems.length
-    encoding.writeVarUint(encoder, len)
+    encoding.writeVarUint(encoder.restEncoder, len)
    for (let i = 0; i < len; i++) {
      const item = dsitems[i]
-      encoding.writeVarUint(encoder, item.clock)
-      encoding.writeVarUint(encoder, item.len)
+      encoder.writeDsClock(item.clock)
+      encoder.writeDsLen(item.len)
    }
  })
 }

 /**
- * @param {decoding.Decoder} decoder
+ * @param {AbstractDSDecoder} decoder
 * @return {DeleteSet}
 *
 * @private
@@ -239,19 +240,27 @@ export const writeDeleteSet = (encoder, ds) => {
 */
 export const readDeleteSet = decoder => {
  const ds = new DeleteSet()
-  const numClients = decoding.readVarUint(decoder)
+  const numClients = decoding.readVarUint(decoder.restDecoder)
  for (let i = 0; i < numClients; i++) {
-    const client = decoding.readVarUint(decoder)
-    const numberOfDeletes = decoding.readVarUint(decoder)
-    for (let i = 0; i < numberOfDeletes; i++) {
-      addToDeleteSet(ds, createID(client, decoding.readVarUint(decoder)), decoding.readVarUint(decoder))
+    decoder.resetDsCurVal()
+    const client = decoding.readVarUint(decoder.restDecoder)
+    const numberOfDeletes = decoding.readVarUint(decoder.restDecoder)
+    if (numberOfDeletes > 0) {
+      const dsField = map.setIfUndefined(ds.clients, client, () => [])
+      for (let i = 0; i < numberOfDeletes; i++) {
+        dsField.push(new DeleteItem(decoder.readDsClock(), decoder.readDsLen()))
+      }
    }
  }
  return ds
 }

 /**
- * @param {decoding.Decoder} decoder
+ * @todo YDecoder also contains references to String and other Decoders. Would make sense to exchange YDecoder.toUint8Array for YDecoder.DsToUint8Array()..
+ */
+
+/**
+ * @param {AbstractDSDecoder} decoder
 * @param {Transaction} transaction
 * @param {StructStore} store
 *
@@ -260,18 +269,19 @@ export const readDeleteSet = decoder => {
 */
 export const readAndApplyDeleteSet = (decoder, transaction, store) => {
  const unappliedDS = new DeleteSet()
-  const numClients = decoding.readVarUint(decoder)
+  const numClients = decoding.readVarUint(decoder.restDecoder)
  for (let i = 0; i < numClients; i++) {
-    const client = decoding.readVarUint(decoder)
-    const numberOfDeletes = decoding.readVarUint(decoder)
+    decoder.resetDsCurVal()
+    const client = decoding.readVarUint(decoder.restDecoder)
+    const numberOfDeletes = decoding.readVarUint(decoder.restDecoder)
    const structs = store.clients.get(client) || []
    const state = getState(store, client)
    for (let i = 0; i < numberOfDeletes; i++) {
-      const clock = decoding.readVarUint(decoder)
-      const len = decoding.readVarUint(decoder)
+      const clock = decoder.readDsClock()
+      const clockEnd = clock + decoder.readDsLen()
      if (clock < state) {
-        if (state < clock + len) {
-          addToDeleteSet(unappliedDS, createID(client, state), clock + len - state)
+        if (state < clockEnd) {
+          addToDeleteSet(unappliedDS, client, state, clockEnd - state)
        }
        let index = findIndexSS(structs, clock)
        /**
@@ -288,10 +298,10 @@ export const readAndApplyDeleteSet = (decoder, transaction, store) => {
        while (index < structs.length) {
          // @ts-ignore
          struct = structs[index++]
-          if (struct.id.clock < clock + len) {
+          if (struct.id.clock < clockEnd) {
            if (!struct.deleted) {
-              if (clock + len < struct.id.clock + struct.length) {
-                structs.splice(index, 0, splitItem(transaction, struct, clock + len - struct.id.clock))
+              if (clockEnd < struct.id.clock + struct.length) {
+                structs.splice(index, 0, splitItem(transaction, struct, clockEnd - struct.id.clock))
              }
              struct.delete(transaction)
            }
@@ -300,14 +310,14 @@ export const readAndApplyDeleteSet = (decoder, transaction, store) => {
          }
        }
      } else {
-        addToDeleteSet(unappliedDS, createID(client, clock), len)
+        addToDeleteSet(unappliedDS, client, clock, clockEnd - clock)
      }
    }
  }
  if (unappliedDS.clients.size > 0) {
    // TODO: no need for encoding+decoding ds anymore
-    const unappliedDSEncoder = encoding.createEncoder()
+    const unappliedDSEncoder = new DSEncoderV2()
    writeDeleteSet(unappliedDSEncoder, unappliedDS)
-    store.pendingDeleteReaders.push(decoding.createDecoder(encoding.toUint8Array(unappliedDSEncoder)))
+    store.pendingDeleteReaders.push(new DSDecoderV2(decoding.createDecoder((unappliedDSEncoder.toUint8Array()))))
  }
 }
--- a/src/utils/PermanentUserData.js
+++ b/src/utils/PermanentUserData.js
@@ -5,11 +5,11 @@ import {
  readDeleteSet,
  writeDeleteSet,
  createDeleteSet,
-  ID, DeleteSet, YArrayEvent, Transaction, Doc // eslint-disable-line
+  DSEncoderV1, DSDecoderV1, ID, DeleteSet, YArrayEvent, Transaction, Doc // eslint-disable-line
 } from '../internals.js'

 import * as decoding from 'lib0/decoding.js'
-import * as encoding from 'lib0/encoding.js'
+
 import { mergeDeleteSets, isDeleted } from './DeleteSet.js'

 export class PermanentUserData {
@@ -46,12 +46,12 @@ export class PermanentUserData {
        event.changes.added.forEach(item => {
          item.content.getContent().forEach(encodedDs => {
            if (encodedDs instanceof Uint8Array) {
-              this.dss.set(userDescription, mergeDeleteSets([this.dss.get(userDescription) || createDeleteSet(), readDeleteSet(decoding.createDecoder(encodedDs))]))
+              this.dss.set(userDescription, mergeDeleteSets([this.dss.get(userDescription) || createDeleteSet(), readDeleteSet(new DSDecoderV1(decoding.createDecoder(encodedDs)))]))
            }
          })
        })
      })
-      this.dss.set(userDescription, mergeDeleteSets(ds.map(encodedDs => readDeleteSet(decoding.createDecoder(encodedDs)))))
+      this.dss.set(userDescription, mergeDeleteSets(ds.map(encodedDs => readDeleteSet(new DSDecoderV1(encodedDs)))))
      ids.observe(/** @param {YArrayEvent<any>} event */ event =>
        event.changes.added.forEach(item => item.content.getContent().forEach(addClientId))
      )
@@ -97,11 +97,11 @@ export class PermanentUserData {
              user.get('ids').push([clientid])
            }
          })
-          const encoder = encoding.createEncoder()
+          const encoder = new DSEncoderV1()
          const ds = this.dss.get(userDescription)
          if (ds) {
            writeDeleteSet(encoder, ds)
-            user.get('ds').push([encoding.toUint8Array(encoder)])
+            user.get('ds').push([encoder.toUint8Array()])
          }
        }
      }, 0)
@@ -111,9 +111,9 @@ export class PermanentUserData {
        const yds = user.get('ds')
        const ds = transaction.deleteSet
        if (transaction.local && ds.clients.size > 0 && filter(transaction, ds)) {
-          const encoder = encoding.createEncoder()
+          const encoder = new DSEncoderV1()
          writeDeleteSet(encoder, ds)
-          yds.push([encoding.toUint8Array(encoder)])
+          yds.push([encoder.toUint8Array()])
        }
      })
    })
--- a/src/utils/Snapshot.js
+++ b/src/utils/Snapshot.js
@@ -12,13 +12,13 @@ import {
  createDeleteSet,
  createID,
  getState,
-  Transaction, Doc, DeleteSet, Item // eslint-disable-line
+  AbstractDSDecoder, AbstractDSEncoder, DSEncoderV1, DSEncoderV2, DSDecoderV1, DSDecoderV2, Transaction, Doc, DeleteSet, Item // eslint-disable-line
 } from '../internals.js'

 import * as map from 'lib0/map.js'
 import * as set from 'lib0/set.js'
-import * as encoding from 'lib0/encoding.js'
 import * as decoding from 'lib0/decoding.js'
+import { DefaultDSEncoder } from './encoding.js'

 export class Snapshot {
  /**
@@ -74,23 +74,35 @@ export const equalSnapshots = (snap1, snap2) => {

 /**
 * @param {Snapshot} snapshot
+ * @param {AbstractDSEncoder} [encoder]
 * @return {Uint8Array}
 */
-export const encodeSnapshot = snapshot => {
-  const encoder = encoding.createEncoder()
+export const encodeSnapshotV2 = (snapshot, encoder = new DSEncoderV2()) => {
  writeDeleteSet(encoder, snapshot.ds)
  writeStateVector(encoder, snapshot.sv)
-  return encoding.toUint8Array(encoder)
+  return encoder.toUint8Array()
+}
+
+/**
+ * @param {Snapshot} snapshot
+ * @return {Uint8Array}
+ */
+export const encodeSnapshot = snapshot => encodeSnapshotV2(snapshot, new DefaultDSEncoder())
+
+/**
+ * @param {Uint8Array} buf
+ * @param {AbstractDSDecoder} [decoder]
+ * @return {Snapshot}
+ */
+export const decodeSnapshotV2 = (buf, decoder = new DSDecoderV2(decoding.createDecoder(buf))) => {
+  return new Snapshot(readDeleteSet(decoder), readStateVector(decoder))
 }

 /**
 * @param {Uint8Array} buf
 * @return {Snapshot}
 */
-export const decodeSnapshot = buf => {
-  const decoder = decoding.createDecoder(buf)
-  return new Snapshot(readDeleteSet(decoder), readStateVector(decoder))
-}
+export const decodeSnapshot = buf => decodeSnapshotV2(buf, new DSDecoderV1(decoding.createDecoder(buf)))

 /**
 * @param {DeleteSet} ds
--- a/src/utils/StructStore.js
+++ b/src/utils/StructStore.js
@@ -2,12 +2,11 @@
 import {
  GC,
  splitItem,
-  AbstractStruct, Transaction, ID, Item // eslint-disable-line
+  Transaction, ID, Item, DSDecoderV2 // eslint-disable-line
 } from '../internals.js'

 import * as math from 'lib0/math.js'
 import * as error from 'lib0/error.js'
-import * as decoding from 'lib0/decoding.js' // eslint-disable-line

 export class StructStore {
  constructor () {
@@ -31,7 +30,7 @@ export class StructStore {
     */
    this.pendingStack = []
    /**
-     * @type {Array<decoding.Decoder>}
+     * @type {Array<DSDecoderV2>}
     */
    this.pendingDeleteReaders = []
  }
--- a/src/utils/Transaction.js
+++ b/src/utils/Transaction.js
@@ -11,15 +11,16 @@ import {
  Item,
  generateNewClientId,
  createID,
-  GC, StructStore, ID, AbstractType, AbstractStruct, YEvent, Doc // eslint-disable-line
+  AbstractUpdateEncoder, GC, StructStore, UpdateEncoderV1, AbstractType, AbstractStruct, YEvent, Doc // eslint-disable-line
 } from '../internals.js'

-import * as encoding from 'lib0/encoding.js'
 import * as map from 'lib0/map.js'
 import * as math from 'lib0/math.js'
 import * as set from 'lib0/set.js'
 import * as logging from 'lib0/logging.js'
 import { callAll } from 'lib0/function.js'
+import { DefaultUpdateEncoder } from './encoding.js'
+import { UpdateEncoderV2 } from './UpdateEncoder.js'

 /**
 * A transaction is created for every change on the Yjs model. It is possible
@@ -107,17 +108,18 @@ export class Transaction {
 }

 /**
+ * @param {AbstractUpdateEncoder} encoder
 * @param {Transaction} transaction
+ * @return {boolean} Whether data was written.
 */
-export const computeUpdateMessageFromTransaction = transaction => {
+export const writeUpdateMessageFromTransaction = (encoder, transaction) => {
  if (transaction.deleteSet.clients.size === 0 && !map.any(transaction.afterState, (clock, client) => transaction.beforeState.get(client) !== clock)) {
-    return null
+    return false
  }
-  const encoder = encoding.createEncoder()
  sortAndMergeDeleteSet(transaction.deleteSet)
  writeStructsFromTransaction(encoder, transaction)
  writeDeleteSet(encoder, transaction.deleteSet)
-  return encoder
+  return true
 }

 /**
@@ -322,9 +324,17 @@ const cleanupTransactions = (transactionCleanups, i) => {
      // @todo Merge all the transactions into one and provide send the data as a single update message
      doc.emit('afterTransactionCleanup', [transaction, doc])
      if (doc._observers.has('update')) {
-        const updateMessage = computeUpdateMessageFromTransaction(transaction)
-        if (updateMessage !== null) {
-          doc.emit('update', [encoding.toUint8Array(updateMessage), transaction.origin, doc])
+        const encoder = new DefaultUpdateEncoder()
+        const hasContent = writeUpdateMessageFromTransaction(encoder, transaction)
+        if (hasContent) {
+          doc.emit('update', [encoder.toUint8Array(), transaction.origin, doc])
+        }
+      }
+      if (doc._observers.has('updateV2')) {
+        const encoder = new UpdateEncoderV2()
+        const hasContent = writeUpdateMessageFromTransaction(encoder, transaction)
+        if (hasContent) {
+          doc.emit('updateV2', [encoder.toUint8Array(), transaction.origin, doc])
        }
      }
      if (transactionCleanups.length <= i + 1) {
--- a/src/utils/UpdateDecoder.js
+++ b/src/utils/UpdateDecoder.js
@@ -0,0 +1,392 @@
+import * as buffer from 'lib0/buffer.js'
+import * as error from 'lib0/error.js'
+import * as decoding from 'lib0/decoding.js'
+import {
+  ID, createID
+} from '../internals.js'
+
+export class AbstractDSDecoder {
+  /**
+   * @param {decoding.Decoder} decoder
+   */
+  constructor (decoder) {
+    this.restDecoder = decoder
+    error.methodUnimplemented()
+  }
+
+  resetDsCurVal () { }
+
+  /**
+   * @return {number}
+   */
+  readDsClock () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {number}
+   */
+  readDsLen () {
+    error.methodUnimplemented()
+  }
+}
+
+export class AbstractUpdateDecoder extends AbstractDSDecoder {
+  /**
+   * @return {ID}
+   */
+  readLeftID () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {ID}
+   */
+  readRightID () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * Read the next client id.
+   * Use this in favor of readID whenever possible to reduce the number of objects created.
+   *
+   * @return {number}
+   */
+  readClient () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readInfo () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {string}
+   */
+  readString () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {boolean} isKey
+   */
+  readParentInfo () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readTypeRef () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @return {number} len
+   */
+  readLen () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {any}
+   */
+  readAny () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {Uint8Array}
+   */
+  readBuf () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * Legacy implementation uses JSON parse. We use any-decoding in v2.
+   *
+   * @return {any}
+   */
+  readJSON () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @return {string}
+   */
+  readKey () {
+    error.methodUnimplemented()
+  }
+}
+
+export class DSDecoderV1 {
+  /**
+   * @param {decoding.Decoder} decoder
+   */
+  constructor (decoder) {
+    this.restDecoder = decoder
+  }
+
+  resetDsCurVal () {
+    // nop
+  }
+
+  /**
+   * @return {number}
+   */
+  readDsClock () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * @return {number}
+   */
+  readDsLen () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+}
+
+export class UpdateDecoderV1 extends DSDecoderV1 {
+  /**
+   * @return {ID}
+   */
+  readLeftID () {
+    return createID(decoding.readVarUint(this.restDecoder), decoding.readVarUint(this.restDecoder))
+  }
+
+  /**
+   * @return {ID}
+   */
+  readRightID () {
+    return createID(decoding.readVarUint(this.restDecoder), decoding.readVarUint(this.restDecoder))
+  }
+
+  /**
+   * Read the next client id.
+   * Use this in favor of readID whenever possible to reduce the number of objects created.
+   */
+  readClient () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readInfo () {
+    return decoding.readUint8(this.restDecoder)
+  }
+
+  /**
+   * @return {string}
+   */
+  readString () {
+    return decoding.readVarString(this.restDecoder)
+  }
+
+  /**
+   * @return {boolean} isKey
+   */
+  readParentInfo () {
+    return decoding.readVarUint(this.restDecoder) === 1
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readTypeRef () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @return {number} len
+   */
+  readLen () {
+    return decoding.readVarUint(this.restDecoder)
+  }
+
+  /**
+   * @return {any}
+   */
+  readAny () {
+    return decoding.readAny(this.restDecoder)
+  }
+
+  /**
+   * @return {Uint8Array}
+   */
+  readBuf () {
+    return buffer.copyUint8Array(decoding.readVarUint8Array(this.restDecoder))
+  }
+
+  /**
+   * Legacy implementation uses JSON parse. We use any-decoding in v2.
+   *
+   * @return {any}
+   */
+  readJSON () {
+    return JSON.parse(decoding.readVarString(this.restDecoder))
+  }
+
+  /**
+   * @return {string}
+   */
+  readKey () {
+    return decoding.readVarString(this.restDecoder)
+  }
+}
+
+export class DSDecoderV2 {
+  /**
+   * @param {decoding.Decoder} decoder
+   */
+  constructor (decoder) {
+    this.dsCurrVal = 0
+    this.restDecoder = decoder
+  }
+
+  resetDsCurVal () {
+    this.dsCurrVal = 0
+  }
+
+  readDsClock () {
+    this.dsCurrVal += decoding.readVarUint(this.restDecoder)
+    return this.dsCurrVal
+  }
+
+  readDsLen () {
+    const diff = decoding.readVarUint(this.restDecoder) + 1
+    this.dsCurrVal += diff
+    return diff
+  }
+}
+
+export class UpdateDecoderV2 extends DSDecoderV2 {
+  /**
+   * @param {decoding.Decoder} decoder
+   */
+  constructor (decoder) {
+    super(decoder)
+    /**
+     * List of cached keys. If the keys[id] does not exist, we read a new key
+     * from stringEncoder and push it to keys.
+     *
+     * @type {Array<string>}
+     */
+    this.keys = []
+    decoding.readUint8(decoder) // read feature flag - currently unused
+    this.keyClockDecoder = new decoding.IntDiffOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.clientDecoder = new decoding.UintOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.leftClockDecoder = new decoding.IntDiffOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.rightClockDecoder = new decoding.IntDiffOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.infoDecoder = new decoding.RleDecoder(decoding.readVarUint8Array(decoder), decoding.readUint8)
+    this.stringDecoder = new decoding.StringDecoder(decoding.readVarUint8Array(decoder))
+    this.parentInfoDecoder = new decoding.RleDecoder(decoding.readVarUint8Array(decoder), decoding.readUint8)
+    this.typeRefDecoder = new decoding.UintOptRleDecoder(decoding.readVarUint8Array(decoder))
+    this.lenDecoder = new decoding.UintOptRleDecoder(decoding.readVarUint8Array(decoder))
+  }
+
+  /**
+   * @return {ID}
+   */
+  readLeftID () {
+    return new ID(this.clientDecoder.read(), this.leftClockDecoder.read())
+  }
+
+  /**
+   * @return {ID}
+   */
+  readRightID () {
+    return new ID(this.clientDecoder.read(), this.rightClockDecoder.read())
+  }
+
+  /**
+   * Read the next client id.
+   * Use this in favor of readID whenever possible to reduce the number of objects created.
+   */
+  readClient () {
+    return this.clientDecoder.read()
+  }
+
+  /**
+   * @return {number} info An unsigned 8-bit integer
+   */
+  readInfo () {
+    return /** @type {number} */ (this.infoDecoder.read())
+  }
+
+  /**
+   * @return {string}
+   */
+  readString () {
+    return this.stringDecoder.read()
+  }
+
+  /**
+   * @return {boolean}
+   */
+  readParentInfo () {
+    return this.parentInfoDecoder.read() === 1
+  }
+
+  /**
+   * @return {number} An unsigned 8-bit integer
+   */
+  readTypeRef () {
+    return this.typeRefDecoder.read()
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @return {number}
+   */
+  readLen () {
+    return this.lenDecoder.read()
+  }
+
+  /**
+   * @return {any}
+   */
+  readAny () {
+    return decoding.readAny(this.restDecoder)
+  }
+
+  /**
+   * @return {Uint8Array}
+   */
+  readBuf () {
+    return decoding.readVarUint8Array(this.restDecoder)
+  }
+
+  /**
+   * This is mainly here for legacy purposes.
+   *
+   * Initial we incoded objects using JSON. Now we use the much faster lib0/any-encoder. This method mainly exists for legacy purposes for the v1 encoder.
+   *
+   * @return {any}
+   */
+  readJSON () {
+    return decoding.readAny(this.restDecoder)
+  }
+
+  /**
+   * @return {string}
+   */
+  readKey () {
+    const keyClock = this.keyClockDecoder.read()
+    if (keyClock < this.keys.length) {
+      return this.keys[keyClock]
+    } else {
+      const key = this.stringDecoder.read()
+      this.keys.push(key)
+      return key
+    }
+  }
+}
--- a/src/utils/UpdateEncoder.js
+++ b/src/utils/UpdateEncoder.js
@@ -0,0 +1,408 @@
+
+import * as error from 'lib0/error.js'
+import * as encoding from 'lib0/encoding.js'
+
+import {
+  ID // eslint-disable-line
+} from '../internals.js'
+
+export class AbstractDSEncoder {
+  constructor () {
+    this.restEncoder = encoding.createEncoder()
+  }
+
+  /**
+   * @return {Uint8Array}
+   */
+  toUint8Array () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * Resets the ds value to 0.
+   * The v2 encoder uses this information to reset the initial diff value.
+   */
+  resetDsCurVal () { }
+
+  /**
+   * @param {number} clock
+   */
+  writeDsClock (clock) { }
+
+  /**
+   * @param {number} len
+   */
+  writeDsLen (len) { }
+}
+
+export class AbstractUpdateEncoder extends AbstractDSEncoder {
+  /**
+   * @return {Uint8Array}
+   */
+  toUint8Array () {
+    error.methodUnimplemented()
+  }
+
+  /**
+   * @param {ID} id
+   */
+  writeLeftID (id) { }
+
+  /**
+   * @param {ID} id
+   */
+  writeRightID (id) { }
+
+  /**
+   * Use writeClient and writeClock instead of writeID if possible.
+   * @param {number} client
+   */
+  writeClient (client) { }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeInfo (info) { }
+
+  /**
+   * @param {string} s
+   */
+  writeString (s) { }
+
+  /**
+   * @param {boolean} isYKey
+   */
+  writeParentInfo (isYKey) { }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeTypeRef (info) { }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @param {number} len
+   */
+  writeLen (len) { }
+
+  /**
+   * @param {any} any
+   */
+  writeAny (any) { }
+
+  /**
+   * @param {Uint8Array} buf
+   */
+  writeBuf (buf) { }
+
+  /**
+   * @param {any} embed
+   */
+  writeJSON (embed) { }
+
+  /**
+   * @param {string} key
+   */
+  writeKey (key) { }
+}
+
+export class DSEncoderV1 {
+  constructor () {
+    this.restEncoder = new encoding.Encoder()
+  }
+
+  toUint8Array () {
+    return encoding.toUint8Array(this.restEncoder)
+  }
+
+  resetDsCurVal () {
+    // nop
+  }
+
+  /**
+   * @param {number} clock
+   */
+  writeDsClock (clock) {
+    encoding.writeVarUint(this.restEncoder, clock)
+  }
+
+  /**
+   * @param {number} len
+   */
+  writeDsLen (len) {
+    encoding.writeVarUint(this.restEncoder, len)
+  }
+}
+
+export class UpdateEncoderV1 extends DSEncoderV1 {
+  /**
+   * @param {ID} id
+   */
+  writeLeftID (id) {
+    encoding.writeVarUint(this.restEncoder, id.client)
+    encoding.writeVarUint(this.restEncoder, id.clock)
+  }
+
+  /**
+   * @param {ID} id
+   */
+  writeRightID (id) {
+    encoding.writeVarUint(this.restEncoder, id.client)
+    encoding.writeVarUint(this.restEncoder, id.clock)
+  }
+
+  /**
+   * Use writeClient and writeClock instead of writeID if possible.
+   * @param {number} client
+   */
+  writeClient (client) {
+    encoding.writeVarUint(this.restEncoder, client)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeInfo (info) {
+    encoding.writeUint8(this.restEncoder, info)
+  }
+
+  /**
+   * @param {string} s
+   */
+  writeString (s) {
+    encoding.writeVarString(this.restEncoder, s)
+  }
+
+  /**
+   * @param {boolean} isYKey
+   */
+  writeParentInfo (isYKey) {
+    encoding.writeVarUint(this.restEncoder, isYKey ? 1 : 0)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeTypeRef (info) {
+    encoding.writeVarUint(this.restEncoder, info)
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @param {number} len
+   */
+  writeLen (len) {
+    encoding.writeVarUint(this.restEncoder, len)
+  }
+
+  /**
+   * @param {any} any
+   */
+  writeAny (any) {
+    encoding.writeAny(this.restEncoder, any)
+  }
+
+  /**
+   * @param {Uint8Array} buf
+   */
+  writeBuf (buf) {
+    encoding.writeVarUint8Array(this.restEncoder, buf)
+  }
+
+  /**
+   * @param {any} embed
+   */
+  writeJSON (embed) {
+    encoding.writeVarString(this.restEncoder, JSON.stringify(embed))
+  }
+
+  /**
+   * @param {string} key
+   */
+  writeKey (key) {
+    encoding.writeVarString(this.restEncoder, key)
+  }
+}
+
+export class DSEncoderV2 {
+  constructor () {
+    this.restEncoder = new encoding.Encoder() // encodes all the rest / non-optimized
+    this.dsCurrVal = 0
+  }
+
+  toUint8Array () {
+    return encoding.toUint8Array(this.restEncoder)
+  }
+
+  resetDsCurVal () {
+    this.dsCurrVal = 0
+  }
+
+  /**
+   * @param {number} clock
+   */
+  writeDsClock (clock) {
+    const diff = clock - this.dsCurrVal
+    this.dsCurrVal = clock
+    encoding.writeVarUint(this.restEncoder, diff)
+  }
+
+  /**
+   * @param {number} len
+   */
+  writeDsLen (len) {
+    if (len === 0) {
+      error.unexpectedCase()
+    }
+    encoding.writeVarUint(this.restEncoder, len - 1)
+    this.dsCurrVal += len
+  }
+}
+
+export class UpdateEncoderV2 extends DSEncoderV2 {
+  constructor () {
+    super()
+    /**
+     * @type {Map<string,number>}
+     */
+    this.keyMap = new Map()
+    /**
+     * Refers to the next uniqe key-identifier to me used.
+     * See writeKey method for more information.
+     *
+     * @type {number}
+     */
+    this.keyClock = 0
+    this.keyClockEncoder = new encoding.IntDiffOptRleEncoder()
+    this.clientEncoder = new encoding.UintOptRleEncoder()
+    this.leftClockEncoder = new encoding.IntDiffOptRleEncoder()
+    this.rightClockEncoder = new encoding.IntDiffOptRleEncoder()
+    this.infoEncoder = new encoding.RleEncoder(encoding.writeUint8)
+    this.stringEncoder = new encoding.StringEncoder()
+    this.parentInfoEncoder = new encoding.RleEncoder(encoding.writeUint8)
+    this.typeRefEncoder = new encoding.UintOptRleEncoder()
+    this.lenEncoder = new encoding.UintOptRleEncoder()
+  }
+
+  toUint8Array () {
+    const encoder = encoding.createEncoder()
+    encoding.writeUint8(encoder, 0) // this is a feature flag that we might use in the future
+    encoding.writeVarUint8Array(encoder, this.keyClockEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.clientEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.leftClockEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.rightClockEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, encoding.toUint8Array(this.infoEncoder))
+    encoding.writeVarUint8Array(encoder, this.stringEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, encoding.toUint8Array(this.parentInfoEncoder))
+    encoding.writeVarUint8Array(encoder, this.typeRefEncoder.toUint8Array())
+    encoding.writeVarUint8Array(encoder, this.lenEncoder.toUint8Array())
+    // @note The rest encoder is appended! (note the missing var)
+    encoding.writeUint8Array(encoder, encoding.toUint8Array(this.restEncoder))
+    return encoding.toUint8Array(encoder)
+  }
+
+  /**
+   * @param {ID} id
+   */
+  writeLeftID (id) {
+    this.clientEncoder.write(id.client)
+    this.leftClockEncoder.write(id.clock)
+  }
+
+  /**
+   * @param {ID} id
+   */
+  writeRightID (id) {
+    this.clientEncoder.write(id.client)
+    this.rightClockEncoder.write(id.clock)
+  }
+
+  /**
+   * @param {number} client
+   */
+  writeClient (client) {
+    this.clientEncoder.write(client)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeInfo (info) {
+    this.infoEncoder.write(info)
+  }
+
+  /**
+   * @param {string} s
+   */
+  writeString (s) {
+    this.stringEncoder.write(s)
+  }
+
+  /**
+   * @param {boolean} isYKey
+   */
+  writeParentInfo (isYKey) {
+    this.parentInfoEncoder.write(isYKey ? 1 : 0)
+  }
+
+  /**
+   * @param {number} info An unsigned 8-bit integer
+   */
+  writeTypeRef (info) {
+    this.typeRefEncoder.write(info)
+  }
+
+  /**
+   * Write len of a struct - well suited for Opt RLE encoder.
+   *
+   * @param {number} len
+   */
+  writeLen (len) {
+    this.lenEncoder.write(len)
+  }
+
+  /**
+   * @param {any} any
+   */
+  writeAny (any) {
+    encoding.writeAny(this.restEncoder, any)
+  }
+
+  /**
+   * @param {Uint8Array} buf
+   */
+  writeBuf (buf) {
+    encoding.writeVarUint8Array(this.restEncoder, buf)
+  }
+
+  /**
+   * This is mainly here for legacy purposes.
+   *
+   * Initial we incoded objects using JSON. Now we use the much faster lib0/any-encoder. This method mainly exists for legacy purposes for the v1 encoder.
+   *
+   * @param {any} embed
+   */
+  writeJSON (embed) {
+    encoding.writeAny(this.restEncoder, embed)
+  }
+
+  /**
+   * Property keys are often reused. For example, in y-prosemirror the key `bold` might
+   * occur very often. For a 3d application, the key `position` might occur very often.
+   *
+   * We cache these keys in a Map and refer to them via a unique number.
+   *
+   * @param {string} key
+   */
+  writeKey (key) {
+    const clock = this.keyMap.get(key)
+    if (clock === undefined) {
+      this.keyClockEncoder.write(this.keyClock++)
+      this.stringEncoder.write(key)
+    } else {
+      this.keyClockEncoder.write(this.keyClock++)
+    }
+  }
+}
--- a/src/utils/encoding.js
+++ b/src/utils/encoding.js
@@ -1,7 +1,8 @@

 /**
 * @module encoding
- *
+ */
+/*
 * We use the first five bits in the info flag for determining the type of the struct.
 *
 * 0: GC
@@ -16,8 +17,6 @@

 import {
  findIndexSS,
-  writeID,
-  readID,
  getState,
  createID,
  getStateVector,
@@ -25,16 +24,36 @@ import {
  writeDeleteSet,
  createDeleteSetFromStructStore,
  transact,
-  readItem,
-  Doc, Transaction, GC, Item, StructStore, ID // eslint-disable-line
+  readItemContent,
+  UpdateDecoderV1,
+  UpdateDecoderV2,
+  UpdateEncoderV1,
+  UpdateEncoderV2,
+  DSDecoderV2,
+  DSEncoderV2,
+  DSDecoderV1,
+  DSEncoderV1,
+  AbstractDSEncoder, AbstractDSDecoder, AbstractUpdateEncoder, AbstractUpdateDecoder, AbstractContent, Doc, Transaction, GC, Item, StructStore, ID // eslint-disable-line
 } from '../internals.js'

 import * as encoding from 'lib0/encoding.js'
 import * as decoding from 'lib0/decoding.js'
 import * as binary from 'lib0/binary.js'

+export let DefaultDSEncoder = DSEncoderV1
+export let DefaultDSDecoder = DSDecoderV1
+export let DefaultUpdateEncoder = UpdateEncoderV1
+export let DefaultUpdateDecoder = UpdateDecoderV1
+
+export const useV2Encoding = () => {
+  DefaultDSEncoder = DSEncoderV2
+  DefaultDSDecoder = DSDecoderV2
+  DefaultUpdateEncoder = UpdateEncoderV2
+  DefaultUpdateDecoder = UpdateDecoderV2
+}
+
 /**
- * @param {encoding.Encoder} encoder
+ * @param {AbstractUpdateEncoder} encoder
 * @param {Array<GC|Item>} structs All structs by `client`
 * @param {number} client
 * @param {number} clock write structs starting with `ID(client,clock)`
@@ -45,8 +64,9 @@ const writeStructs = (encoder, structs, client, clock) => {
  // write first id
  const startNewStructs = findIndexSS(structs, clock)
  // write # encoded structs
-  encoding.writeVarUint(encoder, structs.length - startNewStructs)
-  writeID(encoder, createID(client, clock))
+  encoding.writeVarUint(encoder.restEncoder, structs.length - startNewStructs)
+  encoder.writeClient(client)
+  encoding.writeVarUint(encoder.restEncoder, clock)
  const firstStruct = structs[startNewStructs]
  // write first struct with an offset
  firstStruct.write(encoder, clock - firstStruct.id.clock)
@@ -56,7 +76,7 @@ const writeStructs = (encoder, structs, client, clock) => {
 }

 /**
- * @param {encoding.Encoder} encoder
+ * @param {AbstractUpdateEncoder} encoder
 * @param {StructStore} store
 * @param {Map<number,number>} _sm
 *
@@ -78,7 +98,7 @@ export const writeClientsStructs = (encoder, store, _sm) => {
    }
  })
  // write # states that were updated
-  encoding.writeVarUint(encoder, sm.size)
+  encoding.writeVarUint(encoder.restEncoder, sm.size)
  // Write items with higher client ids first
  // This heavily improves the conflict algorithm.
  Array.from(sm.entries()).sort((a, b) => b[0] - a[0]).forEach(([client, clock]) => {
@@ -88,7 +108,7 @@ export const writeClientsStructs = (encoder, store, _sm) => {
 }

 /**
- * @param {decoding.Decoder} decoder The decoder object to read data from.
+ * @param {AbstractUpdateDecoder} decoder The decoder object to read data from.
 * @param {Map<number,Array<GC|Item>>} clientRefs
 * @param {Doc} doc
 * @return {Map<number,Array<GC|Item>>}
@@ -97,21 +117,52 @@ export const writeClientsStructs = (encoder, store, _sm) => {
 * @function
 */
 export const readClientsStructRefs = (decoder, clientRefs, doc) => {
-  const numOfStateUpdates = decoding.readVarUint(decoder)
+  const numOfStateUpdates = decoding.readVarUint(decoder.restDecoder)
  for (let i = 0; i < numOfStateUpdates; i++) {
-    const numberOfStructs = decoding.readVarUint(decoder)
+    const numberOfStructs = decoding.readVarUint(decoder.restDecoder)
    /**
     * @type {Array<GC|Item>}
     */
    const refs = []
-    let { client, clock } = readID(decoder)
-    let info, struct
+    const client = decoder.readClient()
+    let clock = decoding.readVarUint(decoder.restDecoder)
    clientRefs.set(client, refs)
    for (let i = 0; i < numberOfStructs; i++) {
-      info = decoding.readUint8(decoder)
-      struct = (binary.BITS5 & info) === 0 ? new GC(createID(client, clock), decoding.readVarUint(decoder)) : readItem(decoder, createID(client, clock), info, doc)
-      refs.push(struct)
-      clock += struct.length
+      const info = decoder.readInfo()
+      if ((binary.BITS5 & info) !== 0) {
+        /**
+         * The item that was originally to the left of this item.
+         * @type {ID | null}
+         */
+        const origin = (info & binary.BIT8) === binary.BIT8 ? decoder.readLeftID() : null
+        /**
+         * The item that was originally to the right of this item.
+         * @type {ID | null}
+         */
+        const rightOrigin = (info & binary.BIT7) === binary.BIT7 ? decoder.readRightID() : null
+        const canCopyParentInfo = (info & (binary.BIT7 | binary.BIT8)) === 0
+        const hasParentYKey = canCopyParentInfo ? decoder.readParentInfo() : false
+        /**
+         * If parent = null and neither left nor right are defined, then we know that `parent` is child of `y`
+         * and we read the next string as parentYKey.
+         * It indicates how we store/retrieve parent from `y.share`
+         * @type {string|null}
+         */
+        const parentYKey = canCopyParentInfo && hasParentYKey ? decoder.readString() : null
+
+        const struct = new Item(
+          createID(client, clock), null, origin, null, rightOrigin,
+          canCopyParentInfo && !hasParentYKey ? decoder.readLeftID() : (parentYKey ? doc.get(parentYKey) : null), // parent
+          canCopyParentInfo && (info & binary.BIT6) === binary.BIT6 ? decoder.readString() : null, // parentSub
+          /** @type {AbstractContent} */ (readItemContent(decoder, info)) // item content
+        )
+        refs.push(struct)
+        clock += struct.length
+      } else {
+        const len = decoder.readLen()
+        refs.push(new GC(createID(client, clock), len))
+        clock += len
+      }
    }
  }
  return clientRefs
@@ -222,7 +273,7 @@ export const tryResumePendingDeleteReaders = (transaction, store) => {
 }

 /**
- * @param {encoding.Encoder} encoder
+ * @param {AbstractUpdateEncoder} encoder
 * @param {Transaction} transaction
 *
 * @private
@@ -275,7 +326,7 @@ const cleanupPendingStructs = pendingClientsStructRefs => {
 *
 * This is called when data is received from a remote peer.
 *
- * @param {decoding.Decoder} decoder The decoder object to read data from.
+ * @param {AbstractUpdateDecoder} decoder The decoder object to read data from.
 * @param {Transaction} transaction
 * @param {StructStore} store
 *
@@ -299,15 +350,46 @@ export const readStructs = (decoder, transaction, store) => {
 * @param {decoding.Decoder} decoder
 * @param {Doc} ydoc
 * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ * @param {AbstractUpdateDecoder} [structDecoder]
 *
 * @function
 */
-export const readUpdate = (decoder, ydoc, transactionOrigin) =>
+export const readUpdateV2 = (decoder, ydoc, transactionOrigin, structDecoder = new UpdateDecoderV2(decoder)) =>
  transact(ydoc, transaction => {
-    readStructs(decoder, transaction, ydoc.store)
-    readAndApplyDeleteSet(decoder, transaction, ydoc.store)
+    readStructs(structDecoder, transaction, ydoc.store)
+    readAndApplyDeleteSet(structDecoder, transaction, ydoc.store)
  }, transactionOrigin, false)

+/**
+ * Read and apply a document update.
+ *
+ * This function has the same effect as `applyUpdate` but accepts an decoder.
+ *
+ * @param {decoding.Decoder} decoder
+ * @param {Doc} ydoc
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ *
+ * @function
+ */
+export const readUpdate = (decoder, ydoc, transactionOrigin) => readUpdateV2(decoder, ydoc, transactionOrigin, new DefaultUpdateDecoder(decoder))
+
+/**
+ * Apply a document update created by, for example, `y.on('update', update => ..)` or `update = encodeStateAsUpdate()`.
+ *
+ * This function has the same effect as `readUpdate` but accepts an Uint8Array instead of a Decoder.
+ *
+ * @param {Doc} ydoc
+ * @param {Uint8Array} update
+ * @param {any} [transactionOrigin] This will be stored on `transaction.origin` and `.on('update', (update, origin))`
+ * @param {typeof UpdateDecoderV1 | typeof UpdateDecoderV2} [YDecoder]
+ *
+ * @function
+ */
+export const applyUpdateV2 = (ydoc, update, transactionOrigin, YDecoder = UpdateDecoderV2) => {
+  const decoder = decoding.createDecoder(update)
+  readUpdateV2(decoder, ydoc, transactionOrigin, new YDecoder(decoder))
+}
+
 /**
 * Apply a document update created by, for example, `y.on('update', update => ..)` or `update = encodeStateAsUpdate()`.
 *
@@ -319,14 +401,13 @@ export const readUpdate = (decoder, ydoc, transactionOrigin) =>
 *
 * @function
 */
-export const applyUpdate = (ydoc, update, transactionOrigin) =>
-  readUpdate(decoding.createDecoder(update), ydoc, transactionOrigin)
+export const applyUpdate = (ydoc, update, transactionOrigin) => applyUpdateV2(ydoc, update, transactionOrigin, DefaultUpdateDecoder)

 /**
 * Write all the document as a single update message. If you specify the state of the remote client (`targetStateVector`) it will
 * only write the operations that are missing.
 *
- * @param {encoding.Encoder} encoder
+ * @param {AbstractUpdateEncoder} encoder
 * @param {Doc} doc
 * @param {Map<number,number>} [targetStateVector] The state of the target that receives the update. Leave empty to write all known structs
 *
@@ -345,31 +426,45 @@ export const writeStateAsUpdate = (encoder, doc, targetStateVector = new Map())
 *
 * @param {Doc} doc
 * @param {Uint8Array} [encodedTargetStateVector] The state of the target that receives the update. Leave empty to write all known structs
+ * @param {AbstractUpdateEncoder} [encoder]
 * @return {Uint8Array}
 *
 * @function
 */
-export const encodeStateAsUpdate = (doc, encodedTargetStateVector) => {
-  const encoder = encoding.createEncoder()
+export const encodeStateAsUpdateV2 = (doc, encodedTargetStateVector, encoder = new UpdateEncoderV2()) => {
  const targetStateVector = encodedTargetStateVector == null ? new Map() : decodeStateVector(encodedTargetStateVector)
  writeStateAsUpdate(encoder, doc, targetStateVector)
-  return encoding.toUint8Array(encoder)
+  return encoder.toUint8Array()
 }

+/**
+ * Write all the document as a single update message that can be applied on the remote document. If you specify the state of the remote client (`targetState`) it will
+ * only write the operations that are missing.
+ *
+ * Use `writeStateAsUpdate` instead if you are working with lib0/encoding.js#Encoder
+ *
+ * @param {Doc} doc
+ * @param {Uint8Array} [encodedTargetStateVector] The state of the target that receives the update. Leave empty to write all known structs
+ * @return {Uint8Array}
+ *
+ * @function
+ */
+export const encodeStateAsUpdate = (doc, encodedTargetStateVector) => encodeStateAsUpdateV2(doc, encodedTargetStateVector, new DefaultUpdateEncoder())
+
 /**
 * Read state vector from Decoder and return as Map
 *
- * @param {decoding.Decoder} decoder
+ * @param {AbstractDSDecoder} decoder
 * @return {Map<number,number>} Maps `client` to the number next expected `clock` from that client.
 *
 * @function
 */
 export const readStateVector = decoder => {
  const ss = new Map()
-  const ssLength = decoding.readVarUint(decoder)
+  const ssLength = decoding.readVarUint(decoder.restDecoder)
  for (let i = 0; i < ssLength; i++) {
-    const client = decoding.readVarUint(decoder)
-    const clock = decoding.readVarUint(decoder)
+    const client = decoding.readVarUint(decoder.restDecoder)
+    const clock = decoding.readVarUint(decoder.restDecoder)
    ss.set(client, clock)
  }
  return ss
@@ -383,28 +478,34 @@ export const readStateVector = decoder => {
 *
 * @function
 */
-export const decodeStateVector = decodedState => readStateVector(decoding.createDecoder(decodedState))
+export const decodeStateVectorV2 = decodedState => readStateVector(new DSDecoderV2(decoding.createDecoder(decodedState)))

 /**
- * Write State Vector to `lib0/encoding.js#Encoder`.
+ * Read decodedState and return State as Map.
 *
- * @param {encoding.Encoder} encoder
+ * @param {Uint8Array} decodedState
+ * @return {Map<number,number>} Maps `client` to the number next expected `clock` from that client.
+ *
+ * @function
+ */
+export const decodeStateVector = decodedState => readStateVector(new DefaultDSDecoder(decoding.createDecoder(decodedState)))
+
+/**
+ * @param {AbstractDSEncoder} encoder
 * @param {Map<number,number>} sv
 * @function
 */
 export const writeStateVector = (encoder, sv) => {
-  encoding.writeVarUint(encoder, sv.size)
+  encoding.writeVarUint(encoder.restEncoder, sv.size)
  sv.forEach((clock, client) => {
-    encoding.writeVarUint(encoder, client)
-    encoding.writeVarUint(encoder, clock)
+    encoding.writeVarUint(encoder.restEncoder, client) // @todo use a special client decoder that is based on mapping
+    encoding.writeVarUint(encoder.restEncoder, clock)
  })
  return encoder
 }

 /**
- * Write State Vector to `lib0/encoding.js#Encoder`.
- *
- * @param {encoding.Encoder} encoder
+ * @param {AbstractDSEncoder} encoder
 * @param {Doc} doc
 *
 * @function
@@ -415,12 +516,22 @@ export const writeDocumentStateVector = (encoder, doc) => writeStateVector(encod
 * Encode State as Uint8Array.
 *
 * @param {Doc} doc
+ * @param {AbstractDSEncoder} [encoder]
 * @return {Uint8Array}
 *
 * @function
 */
-export const encodeStateVector = doc => {
-  const encoder = encoding.createEncoder()
+export const encodeStateVectorV2 = (doc, encoder = new DSEncoderV2()) => {
  writeDocumentStateVector(encoder, doc)
-  return encoding.toUint8Array(encoder)
+  return encoder.toUint8Array()
 }
+
+/**
+ * Encode State as Uint8Array.
+ *
+ * @param {Doc} doc
+ * @return {Uint8Array}
+ *
+ * @function
+ */
+export const encodeStateVector = doc => encodeStateVectorV2(doc, new DefaultDSEncoder())