load() is safe in race conditions

lib/index.js

@@ -94,7 +94,7 @@ function initSet(peer, config) {
   if (ghostSpan < 1) throw new Error('config.set.ghostSpan must be >= 0')
 
   //#region state
-  let accountID = /** @type {string | null} */ (null)
+  let loadedAccountID = /** @type {string | null} */ (null)
   let loadPromise = /** @type {Promise<void> | null} */ (null)
   let cancelOnRecordAdded = /** @type {CallableFunction | null} */ (null)
   const watch = /**@type {ObzType}*/ (Obz())
@@ -178,10 +178,10 @@ function initSet(peer, config) {
    */
   function isValidSetMoot(msg) {
     if (!msg) return false
-    if (msg.metadata.account !== accountID) return false
+    if (msg.metadata.account !== loadedAccountID) return false
     const domain = msg.metadata.domain
     if (!domain.startsWith(PREFIX)) return false
-    return MsgV4.isMoot(msg, accountID, domain)
+    return MsgV4.isMoot(msg, loadedAccountID, domain)
   }
 
   /**
@@ -192,7 +192,7 @@ function initSet(peer, config) {
   function isValidSetMsg(msg) {
     if (!msg) return false
     if (!msg.data) return false
-    if (msg.metadata.account !== accountID) return false
+    if (msg.metadata.account !== loadedAccountID) return false
     if (!msg.metadata.domain.startsWith(PREFIX)) return false
     if (!Array.isArray(msg.data.add)) return false
     if (!Array.isArray(msg.data.del)) return false
@@ -269,7 +269,7 @@ function initSet(peer, config) {
    * @param {Msg} msg
    */
   function maybeLearnAboutSet(msgID, msg) {
-    if (msg.metadata.account !== accountID) return
+    if (msg.metadata.account !== loadedAccountID) return
     if (isValidSetMoot(msg)) {
       learnSetMoot(msgID, msg)
       return
@@ -294,10 +294,11 @@ function initSet(peer, config) {
    */
   function _squeezePotential(subdomain) {
     assertDBPlugin(peer)
-    if (!accountID) throw new Error('Cannot squeeze potential before loading')
+    // prettier-ignore
+    if (!loadedAccountID) throw new Error('Cannot squeeze potential before loading')
     // TODO: improve this so that the squeezePotential is the size of the
     // tangle suffix built as a slice from the fieldRoots
-    const mootID = MsgV4.getMootID(accountID, fromSubdomain(subdomain))
+    const mootID = MsgV4.getMootID(loadedAccountID, fromSubdomain(subdomain))
     const tangle = peer.db.getTangle(mootID)
     const maxDepth = tangle.maxDepth
     const currentItemRoots = itemRoots.getAll(subdomain)
@@ -314,37 +315,42 @@ function initSet(peer, config) {
 
   //#region public methods
   /**
-   * @param {string} id
+   * @param {string} accountID
    * @param {CB<void>} cb
    */
-  function load(id, cb) {
+  function load(accountID, cb) {
     assertDBPlugin(peer)
-    if (accountID === id) {
+    if (accountID === loadedAccountID) {
       loaded(cb)
       return
     }
-    if (accountID !== null) {
+    if (loadedAccountID !== null) {
       // prettier-ignore
-      cb(new Error(`Cannot load Set for account "${id}" because Set for account "${accountID}" is already loaded`))
+      cb(new Error(`Cannot load Set for account "${accountID}" because Set for account "${loadedAccountID}" is already loaded`))
       return
     }
-    accountID = id
+    loadedAccountID = accountID
     loadPromise = new Promise((resolve, reject) => {
-      for (const rec of peer.db.records()) {
+      // microtask is needed to ensure that loadPromise is assigned BEFORE this
-        if (!rec.msg) continue
+      // body is executed (which in turn does inversion of control when `cb` or
-        maybeLearnAboutSet(rec.id, rec.msg)
+      // `resolve` is called)
-      }
+      queueMicrotask(() => {
-      cancelOnRecordAdded = peer.db.onRecordAdded(
+        for (const rec of peer.db.records()) {
-        (/** @type {RecPresent} */ rec) => {
+          if (!rec.msg) continue
-          try {
+          maybeLearnAboutSet(rec.id, rec.msg)
-            maybeLearnAboutSet(rec.id, rec.msg)
-          } catch (err) {
-            console.error(err)
-          }
         }
-      )
+        cancelOnRecordAdded = peer.db.onRecordAdded(
-      resolve()
+          (/** @type {RecPresent} */ rec) => {
-      cb()
+            try {
+              maybeLearnAboutSet(rec.id, rec.msg)
+            } catch (err) {
+              console.error(err)
+            }
+          }
+        )
+        resolve()
+        cb()
+      })
     })
   }
 
@@ -355,13 +361,15 @@ function initSet(peer, config) {
    */
   function add(subdomain, value, cb) {
     assertDBPlugin(peer)
-    assert(!!accountID, 'Cannot add to Set before loading')
+    // TODO this error needs to be put into the `cb`, not thrown
+    assert(!!loadedAccountID, 'Cannot add to Set before loading')
     // prettier-ignore
     assert(typeof cb === 'function', 'add() does not accept an accountID in the 3rd argument, must be callback instead')
 
     loaded(() => {
-      assert(!!accountID, 'Cannot add to Set before loading')
+      // TODO this error needs to be put into the `cb`, not thrown
-      const currentSet = readSet(accountID, subdomain)
+      assert(!!loadedAccountID, 'Cannot add to Set before loading')
+      const currentSet = readSet(loadedAccountID, subdomain)
       if (currentSet.has(value)) return cb(null, false)
       const domain = fromSubdomain(subdomain)
 
@@ -381,16 +389,19 @@ function initSet(peer, config) {
       }
 
       const data = { add: [value], del: [], supersedes }
-      peer.db.feed.publish({ account: accountID, domain, data }, (err, rec) => {
+      peer.db.feed.publish(
-        // prettier-ignore
+        { account: loadedAccountID, domain, data },
-        if (err) return cb(new Error(`Failed to create msg when adding to Set "${subdomain}"`, { cause: err }))
+        (err, rec) => {
-        for (const [msgID, item] of toDeleteFromItemRoots) {
+          // prettier-ignore
-          itemRoots.del(subdomain, item, msgID)
+          if (err) return cb(new Error(`Failed to create msg when adding to Set "${subdomain}"`, { cause: err }))
+          for (const [msgID, item] of toDeleteFromItemRoots) {
+            itemRoots.del(subdomain, item, msgID)
+          }
+          // @ts-ignore
+          cb(null, true)
+          watch.set({ event: 'add', subdomain, value })
         }
-        // @ts-ignore
+      )
-        cb(null, true)
-        watch.set({ event: 'add', subdomain, value })
-      })
     })
   }
 
@@ -401,13 +412,15 @@ function initSet(peer, config) {
    */
   function del(subdomain, value, cb) {
     assertDBPlugin(peer)
-    assert(!!accountID, 'Cannot add to Set before loading')
+    // TODO this error needs to be put into the `cb`, not thrown
+    assert(!!loadedAccountID, 'Cannot add to Set before loading')
     // prettier-ignore
     assert(typeof cb === 'function', 'del() does not accept an accountID in the 3rd argument, must be callback instead')
 
     loaded(() => {
-      assert(!!accountID, 'Cannot add to Set before loading')
+      // TODO this error needs to be put into the `cb`, not thrown
-      const currentSet = readSet(accountID, subdomain)
+      assert(!!loadedAccountID, 'Cannot add to Set before loading')
+      const currentSet = readSet(loadedAccountID, subdomain)
       if (!currentSet.has(value)) return cb(null, false)
       const domain = fromSubdomain(subdomain)
 
@@ -421,13 +434,16 @@ function initSet(peer, config) {
       }
 
       const data = { add: [], del: [value], supersedes }
-      peer.db.feed.publish({ account: accountID, domain, data }, (err, rec) => {
+      peer.db.feed.publish(
-        // prettier-ignore
+        { account: loadedAccountID, domain, data },
-        if (err) return cb(new Error(`Failed to create msg when deleting from Set "${subdomain}"`, { cause: err }))
+        (err, rec) => {
-        // @ts-ignore
+          // prettier-ignore
-        cb(null, true)
+          if (err) return cb(new Error(`Failed to create msg when deleting from Set "${subdomain}"`, { cause: err }))
-        watch.set({ event: 'del', subdomain, value })
+          // @ts-ignore
-      })
+          cb(null, true)
+          watch.set({ event: 'del', subdomain, value })
+        }
+      )
     })
   }
 
@@ -437,8 +453,8 @@ function initSet(peer, config) {
    * @param {string=} id
    */
   function has(subdomain, value, id) {
-    assert(!!accountID, 'Cannot call has() before loading')
+    assert(!!loadedAccountID, 'Cannot call has() before loading')
-    const set = readSet(id ?? accountID, subdomain)
+    const set = readSet(id ?? loadedAccountID, subdomain)
     return set.has(value)
   }
 
@@ -447,8 +463,8 @@ function initSet(peer, config) {
    * @param {string=} id
    */
   function values(subdomain, id) {
-    assert(!!accountID, 'Cannot call values() before loading')
+    assert(!!loadedAccountID, 'Cannot call values() before loading')
-    const set = readSet(id ?? accountID, subdomain)
+    const set = readSet(id ?? loadedAccountID, subdomain)
     return [...set]
   }
 
@@ -506,10 +522,10 @@ function initSet(peer, config) {
    * @returns {string}
    */
   function getFeedID(subdomain) {
-    assert(!!accountID, 'Cannot getFeedID() before loading')
+    assert(!!loadedAccountID, 'Cannot getFeedID() before loading')
     assertDBPlugin(peer)
     const domain = fromSubdomain(subdomain)
-    return MsgV4.getMootID(accountID, domain)
+    return MsgV4.getMootID(loadedAccountID, domain)
   }
 
   /**
@@ -553,7 +569,7 @@ function initSet(peer, config) {
    * @param {any} subdomain
    */
   function _getItemRoots(subdomain) {
-    if (!accountID) throw new Error(`Cannot getItemRoots before loading`)
+    if (!loadedAccountID) throw new Error(`Cannot getItemRoots before loading`)
     return itemRoots.getAll(subdomain)
   }
 
@@ -563,15 +579,17 @@ function initSet(peer, config) {
    */
   function squeeze(subdomain, cb) {
     assertDBPlugin(peer)
-    assert(!!accountID, 'Cannot squeeze Set before loading')
+    // TODO this error needs to be put into the `cb`, not thrown
+    assert(!!loadedAccountID, 'Cannot squeeze Set before loading')
 
     const potential = _squeezePotential(subdomain)
     if (potential < 1) return cb(null, false)
 
     loaded(() => {
-      assert(!!accountID, 'Cannot squeeze Set before loading')
+      // TODO this error needs to be put into the `cb`, not thrown
+      assert(!!loadedAccountID, 'Cannot squeeze Set before loading')
       const domain = fromSubdomain(subdomain)
-      const currentSet = readSet(accountID, subdomain)
+      const currentSet = readSet(loadedAccountID, subdomain)
 
       const supersedes = []
       const currentItemRoots = itemRoots.getAll(subdomain)
@@ -580,12 +598,15 @@ function initSet(peer, config) {
       }
 
       const data = { add: [...currentSet], del: [], supersedes }
-      peer.db.feed.publish({ account: accountID, domain, data }, (err, rec) => {
+      peer.db.feed.publish(
-        // prettier-ignore
+        { account: loadedAccountID, domain, data },
-        if (err) return cb(new Error(`Failed to create msg when squeezing Set "${subdomain}"`, { cause: err }))
+        (err, rec) => {
-        // @ts-ignore
+          // prettier-ignore
-        cb(null, true)
+          if (err) return cb(new Error(`Failed to create msg when squeezing Set "${subdomain}"`, { cause: err }))
-      })
+          // @ts-ignore
+          cb(null, true)
+        }
+      )
     })
   }
   //#endregion