Implementation of 'connecting' sync status from Dart SDK (#434)

Author: LucDeCaf

.changeset/swift-seahorses-help.md

@@ -0,0 +1,5 @@
+---
+'@powersync/common': minor
+---
+
+add 'connecting' flag to SyncStatus

packages/common/src/client/AbstractPowerSyncDatabase.ts

@@ -232,6 +232,10 @@ export abstract class AbstractPowerSyncDatabase extends BaseObserver<PowerSyncDB
     return this.currentStatus?.connected || false;
   }
 
+  get connecting() {
+    return this.currentStatus?.connecting || false;
+  }
+
   /**
    * Opens the DBAdapter given open options using a default open factory
    */

packages/common/src/client/sync/stream/AbstractStreamingSyncImplementation.ts

@@ -156,6 +156,7 @@ export abstract class AbstractStreamingSyncImplementation
 
     this.syncStatus = new SyncStatus({
       connected: false,
+      connecting: false,
       lastSyncedAt: undefined,
       dataFlow: {
         uploading: false,
@@ -347,7 +348,7 @@ The next upload iteration will be delayed.`);
     this.streamingSyncPromise = undefined;
 
     this.abortController = null;
-    this.updateSyncStatus({ connected: false });
+    this.updateSyncStatus({ connected: false, connecting: false });
   }
 
   /**
@@ -382,6 +383,7 @@ The next upload iteration will be delayed.`);
       this.crudUpdateListener = undefined;
       this.updateSyncStatus({
         connected: false,
+        connecting: false,
         dataFlow: {
           downloading: false
         }
@@ -395,6 +397,7 @@ The next upload iteration will be delayed.`);
      *  - Close any sync stream ReadableStreams (which will also close any established network requests)
      */
     while (true) {
+      this.updateSyncStatus({ connecting: true });
       try {
         if (signal?.aborted) {
           break;
@@ -423,6 +426,8 @@ The next upload iteration will be delayed.`);
         } else {
           this.logger.error(ex);
         }
+
+        // On error, wait a little before retrying
         await this.delayRetry();
       } finally {
         if (!signal.aborted) {
@@ -431,15 +436,14 @@ The next upload iteration will be delayed.`);
         }
 
         this.updateSyncStatus({
-          connected: false
+          connected: false,
+          connecting: true // May be unnecessary
         });
-
-        // On error, wait a little before retrying
       }
     }
 
     // Mark as disconnected if here
-    this.updateSyncStatus({ connected: false });
+    this.updateSyncStatus({ connected: false, connecting: false });
   }
 
   protected async streamingSyncIteration(
@@ -647,6 +651,7 @@ The next upload iteration will be delayed.`);
   protected updateSyncStatus(options: SyncStatusOptions) {
     const updatedStatus = new SyncStatus({
       connected: options.connected ?? this.syncStatus.connected,
+      connecting: !options.connected && (options.connecting ?? this.syncStatus.connecting),
       lastSyncedAt: options.lastSyncedAt ?? this.syncStatus.lastSyncedAt,
       dataFlow: {
         ...this.syncStatus.dataFlowStatus,

packages/common/src/db/crud/SyncStatus.ts

@@ -5,6 +5,7 @@ export type SyncDataFlowStatus = Partial<{
 
 export type SyncStatusOptions = {
   connected?: boolean;
+  connecting?: boolean;
   dataFlow?: SyncDataFlowStatus;
   lastSyncedAt?: Date;
   hasSynced?: boolean;
@@ -20,6 +21,10 @@ export class SyncStatus {
     return this.options.connected ?? false;
   }
 
+  get connecting() {
+    return this.options.connecting ?? false;
+  }
+
   /**
    *  Time that a last sync has fully completed, if any.
    *  Currently this is reset to null after a restart.
@@ -61,12 +66,13 @@ export class SyncStatus {
 
   getMessage() {
     const dataFlow = this.dataFlowStatus;
-    return `SyncStatus<connected: ${this.connected} lastSyncedAt: ${this.lastSyncedAt} hasSynced: ${this.hasSynced}. Downloading: ${dataFlow.downloading}. Uploading: ${dataFlow.uploading}`;
+    return `SyncStatus<connected: ${this.connected} connecting: ${this.connecting} lastSyncedAt: ${this.lastSyncedAt} hasSynced: ${this.hasSynced}. Downloading: ${dataFlow.downloading}. Uploading: ${dataFlow.uploading}`;
   }
 
   toJSON(): SyncStatusOptions {
     return {
       connected: this.connected,
+      connecting: this.connecting,
       dataFlow: this.dataFlowStatus,
       lastSyncedAt: this.lastSyncedAt,
       hasSynced: this.hasSynced