adding tooling around working with permissions

.gitignore

@@ -3,3 +3,4 @@ node_modules
 dist
 .vscode
 .test_dbs
+test.html

src/db.js

@@ -2,6 +2,9 @@ import * as dbtypes from './dbtypes.js'
 import * as isodb from 'isodb'
 import * as utils from './utils.js'
 import * as number from 'lib0/number'
+import * as promise from 'lib0/promise'
+import * as array from 'lib0/array'
+import * as math from 'lib0/math'
 
 /**
  * @typedef {import('./ydb.js').Ydb} Ydb
@@ -32,12 +35,39 @@ export const def = {
       }
     },
     clocks: {
-      key: isodb.Uint32Key, // is a clientid
+      key: dbtypes.ClocksKey,
       value: dbtypes.ClientClockValue
     }
   }
 }
 
+/**
+ * # Algorithm to sync documents that a user just got permission to:
+ *
+ * The information that a document has been created (the first update) is always sent to all users.
+ * However, users that don't have permission won't receive the content and simply store a "no
+ * permission" information in the `oplog`.
+ *
+ * When we receive new permission, we store an "todo item in the `reqs`" table: "check table
+ * starting at clock X". The name should be unique. Two separate permission changes should update
+ * the same item. Simpler implementation: `reqs` table uses AutoKey or `collection/autokey` (by
+ * index) and we have to work through the list until completion.
+ *
+ * We iterate through the table and sync each document individually until we completed the whole
+ * collection table. Every time we synced a document, we update the todo item. Once completed,
+ * we delete the todo item in reqs.
+ *
+ * # Todo
+ * - ( ) implement request "sync document starting from clock X"
+ * - ( ) implement requests table and figure out key-system.
+ */
+
+/**
+ * @param {string} dbname
+ */
+export const createDb = dbname =>
+  isodb.openDB(dbname, def)
+
 /**
  * @param {Ydb} ydb
  * @param {Array<{ value: dbtypes.OpValue, fkey: isodb.AutoKey }>} updates
@@ -49,12 +79,6 @@ const updateOpClocks = (ydb, updates) => updates.map(update => {
   return update.value
 })
 
-/**
- * @param {string} dbname
- */
-export const createDb = dbname =>
-  isodb.openDB(dbname, def)
-
 /**
  * @param {Ydb} ydb
  * @param {number} clock
@@ -111,3 +135,47 @@ export const getDocOps = async (ydb, collection, doc, clock) => {
   })
   return updateOpClocks(ydb, entries)
 }
+
+/**
+ * @param {Ydb} ydb
+ * @param {number} clientid
+ * @param {string?} collection
+ * @param {string?} doc
+ */
+export const getClock = async (ydb, clientid, collection, doc) =>
+  ydb.db.transact(async tr => {
+    if (ydb.clientid === clientid) {
+      const latestEntry = await tr.tables.oplog.getKeys({
+        end: number.HIGHEST_INT32, // @todo change to uint
+        reverse: true,
+        limit: 1
+      })
+      return latestEntry.length > 0 ? latestEntry[0].v : 0
+    }
+    const clocksTable = tr.tables.clocks
+    const queries = [
+      clocksTable.get(new dbtypes.ClocksKey(clientid, null, null))
+    ]
+    collection && queries.push(clocksTable.get(new dbtypes.ClocksKey(clientid, collection, null)))
+    doc && queries.push(clocksTable.get(new dbtypes.ClocksKey(clientid, collection, doc)))
+    const clocks = await promise.all(queries)
+    return array.fold(clocks.map(c => c ? c.clock : 0), 0, math.max)
+  })
+
+/**
+ * Confirm that a all updates of a doc/collection/* from a client have been received.
+ *
+ * @param {Ydb} ydb
+ * @param {number} clientid
+ * @param {string?} collection
+ * @param {string?} doc
+ * @param {number} newClock
+ */
+export const confirmClientClock = async (ydb, clientid, collection, doc, newClock) => {
+  ydb.db.transact(async tr => {
+    const currClock = await getClock(ydb, clientid, collection, doc)
+    if (currClock < newClock) {
+      tr.tables.clocks.set(new dbtypes.ClocksKey(clientid, collection, doc), newClock)
+    }
+  })
+}

src/dbtypes.js

@@ -143,6 +143,45 @@ export class CollectionKey {
   }
 }
 
+/**
+ * @implements isodb.IEncodable
+ */
+export class ClocksKey {
+  /**
+   * @param {number} clientid
+   * @param {string?} collection
+   * @param {string?} doc
+   */
+  constructor (clientid, collection, doc) {
+    this.clientid = clientid
+    this.collection = collection
+    this.doc = doc
+  }
+
+  /**
+   * @param {encoding.Encoder} encoder
+   */
+  encode (encoder) {
+    const info = (this.collection ? 1 : 0) + (this.doc ? 2 : 0)
+    encoding.writeUint8(encoder, info)
+    encoding.writeUint32(encoder, this.clientid)
+    this.collection && encoding.writeVarString(encoder, this.collection)
+    this.doc && encoding.writeVarString(encoder, this.doc)
+  }
+
+  /**
+   * @param {decoding.Decoder} decoder
+   * @return {isodb.IEncodable}
+   */
+  static decode (decoder) {
+    const info = decoding.readUint8(decoder)
+    const clientid = decoding.readUint32(decoder)
+    const collection = (info & 1) > 0 ? decoding.readVarString(decoder) : null
+    const doc = (info & 2) > 0 ? decoding.readVarString(decoder) : null
+    return new ClocksKey(clientid, collection, doc)
+  }
+}
+
 /**
  * @implements isodb.IEncodable
  */