Adding forEach Helper (#1150)

Author: schmidt-sebastian

packages/firestore/src/core/sync_engine.ts

@@ -679,20 +679,16 @@ export class SyncEngine implements RemoteSyncer, SharedClientStateSyncer {
         queryView.targetId
       );
       this.limboDocumentRefs.removeReferencesForId(queryView.targetId);
-      let p = PersistencePromise.resolve();
-      limboKeys.forEach(limboKey => {
-        p = p.next(() => {
-          return this.limboDocumentRefs
-            .containsKey(null, limboKey)
-            .next(isReferenced => {
-              if (!isReferenced) {
-                // We removed the last reference for this key
-                this.removeLimboTarget(limboKey);
-              }
-            });
-        });
-      });
-      await p.toPromise();
+      await PersistencePromise.forEach(limboKeys.toArray(), limboKey => {
+        return this.limboDocumentRefs
+          .containsKey(null, limboKey)
+          .next(isReferenced => {
+            if (!isReferenced) {
+              // We removed the last reference for this key
+              this.removeLimboTarget(limboKey);
+            }
+          });
+      }).toPromise();
     }
   }
 

packages/firestore/src/local/indexeddb_persistence.ts

@@ -369,14 +369,12 @@ export class IndexedDbPersistence implements Persistence {
               client => activeClients.indexOf(client) === -1
             );
           })
-          .next(() => {
+          .next(() =>
             // Delete metadata for clients that are no longer considered active.
-            let p = PersistencePromise.resolve();
-            inactiveClients.forEach(inactiveClient => {
-              p = p.next(() => metadataStore.delete(inactiveClient.clientId));
-            });
-            return p;
-          })
+            PersistencePromise.forEach(inactiveClients, inactiveClient =>
+              metadataStore.delete(inactiveClient.clientId)
+            )
+          )
           .next(() => {
             // Retrieve the minimum change ID from the set of active clients.
 

packages/firestore/src/local/local_store.ts

@@ -301,13 +301,11 @@ export class LocalStore {
           return PersistencePromise.resolve([]);
         }
       })
-      .next(ackedBatches => {
-        let p = PersistencePromise.resolve();
-        ackedBatches.forEach(batch => {
-          p = p.next(() => this.mutationQueue.removeMutationBatch(txn, batch));
-        });
-        return p;
-      });
+      .next(ackedBatches =>
+        PersistencePromise.forEach(ackedBatches, batch =>
+          this.mutationQueue.removeMutationBatch(txn, batch)
+        )
+      );
   }
 
   /* Accept locally generated Mutations and commit them to storage. */
@@ -979,17 +977,15 @@ export class LocalStore {
     batches: MutationBatch[]
   ): PersistencePromise<DocumentKeySet> {
     let affectedDocs = documentKeySet();
-
-    let p = PersistencePromise.resolve();
     for (const batch of batches) {
       for (const mutation of batch.mutations) {
         const key = mutation.key;
         affectedDocs = affectedDocs.add(key);
       }
-      p = p.next(() => this.mutationQueue.removeMutationBatch(txn, batch));
     }
-
-    return p.next(() => affectedDocs);
+    return PersistencePromise.forEach(batches, batch =>
+      this.mutationQueue.removeMutationBatch(txn, batch)
+    ).next(() => affectedDocs);
   }
 
   private applyWriteToRemoteDocuments(

packages/firestore/src/local/persistence_promise.ts

@@ -205,4 +205,15 @@ export class PersistencePromise<T> {
       return results;
     });
   }
+
+  static forEach<T>(
+    elements: T[],
+    callback: (T) => PersistencePromise<void>
+  ): PersistencePromise<void> {
+    let p = PersistencePromise.resolve();
+    for (const element of elements) {
+      p = p.next(() => callback(element));
+    }
+    return p;
+  }
 }

packages/firestore/test/unit/local/indexeddb_persistence.test.ts

@@ -284,11 +284,9 @@ describe('IndexedDbSchema: createOrUpgradeDb', () => {
       const sdb = new SimpleDb(db);
       return sdb.runTransaction('readwrite', [DbMutationBatch.store], txn => {
         const store = txn.store(DbMutationBatch.store);
-        let p = PersistencePromise.resolve();
-        for (const testMutation of testMutations) {
-          p = p.next(() => store.put(testMutation));
-        }
-        return p;
+        return PersistencePromise.forEach(testMutations, testMutation =>
+          store.put(testMutation)
+        );
       });
     }).then(() =>
       withDb(4, db => {
@@ -300,14 +298,11 @@ describe('IndexedDbSchema: createOrUpgradeDb', () => {
           const store = txn.store<DbMutationBatchKey, DbMutationBatch>(
             DbMutationBatch.store
           );
-          let p = PersistencePromise.resolve();
-          for (const testMutation of testMutations) {
-            p = p.next(() =>
-              store.get(testMutation.batchId).next(mutationBatch => {
-                expect(mutationBatch).to.deep.equal(testMutation);
-              })
-            );
-          }
+          let p = PersistencePromise.forEach(testMutations, testMutation =>
+            store.get(testMutation.batchId).next(mutationBatch => {
+              expect(mutationBatch).to.deep.equal(testMutation);
+            })
+          );
           p = p.next(() => {
             store
               .add({} as any) // tslint:disable-line:no-any

packages/firestore/test/unit/local/persistence_promise.test.ts

@@ -213,4 +213,13 @@ describe('PersistencePromise', () => {
       })
       .toPromise();
   });
+
+  it('executes forEach in order', async () => {
+    let result = '';
+    await PersistencePromise.forEach(['a', 'b', 'c'], el => {
+      result += el;
+      return PersistencePromise.resolve();
+    }).toPromise;
+    expect(result).to.equal('abc');
+  });
 });