Skip conflict when content is identical

packages/syncing-server/src/Domain/Item/SaveRule/TimeDifferenceFilter.spec.ts

@@ -221,6 +221,51 @@ describe('TimeDifferenceFilter', () => {
     })
   })
 
+  it('should pass items with different timestamp but identical content (microsecond precision)', async () => {
+    itemHash = ItemHash.create({
+      ...itemHash.props,
+      content: 'foobar',
+      enc_item_key: undefined,
+      updated_at_timestamp: existingItem.props.timestamps.updatedAt + 1,
+    }).getValue()
+
+    const result = await createFilter().check({
+      userUuid: '1-2-3',
+      apiVersion: ApiVersion.v20200115,
+      snjsVersion: '2.200.0',
+      itemHash,
+      existingItem,
+    })
+
+    expect(result).toEqual({
+      passed: true,
+    })
+  })
+
+  it('should still conflict items with different timestamp AND different content', async () => {
+    itemHash = ItemHash.create({
+      ...itemHash.props,
+      content: 'totally different stuff',
+      updated_at_timestamp: existingItem.props.timestamps.updatedAt + 1,
+    }).getValue()
+
+    const result = await createFilter().check({
+      userUuid: '1-2-3',
+      apiVersion: ApiVersion.v20200115,
+      snjsVersion: '2.200.0',
+      itemHash,
+      existingItem,
+    })
+
+    expect(result).toEqual({
+      passed: false,
+      conflict: {
+        serverItem: existingItem,
+        type: 'sync_conflict',
+      },
+    })
+  })
+
   it('should leave items having update at timestamp different by less than a millisecond', async () => {
     itemHash = ItemHash.create({
       ...itemHash.props,

packages/syncing-server/src/Domain/Item/SaveRule/TimeDifferenceFilter.ts

@@ -37,6 +37,10 @@ export class TimeDifferenceFilter implements ItemSaveRuleInterface {
     if (this.itemHashHasMicrosecondsPrecision(dto.itemHash)) {
       const passed = difference === 0
 
+      if (!passed && this.contentIsIdentical(dto)) {
+        return { passed: true }
+      }
+
       return {
         passed,
         conflict: passed
@@ -50,6 +54,10 @@ export class TimeDifferenceFilter implements ItemSaveRuleInterface {
 
     const passed = Math.abs(difference) < this.getMinimalConflictIntervalMicroseconds(dto.apiVersion)
 
+    if (!passed && this.contentIsIdentical(dto)) {
+      return { passed: true }
+    }
+
     return {
       passed,
       conflict: passed
@@ -69,6 +77,18 @@ export class TimeDifferenceFilter implements ItemSaveRuleInterface {
     return itemHash.props.updated_at_timestamp !== undefined
   }
 
+  private contentIsIdentical(dto: ItemSaveValidationDTO): boolean {
+    if (!dto.existingItem) {
+      return false
+    }
+    const incomingContent = dto.itemHash.props.content ?? null
+    const existingContent = dto.existingItem.props.content
+    const incomingEncKey = dto.itemHash.props.enc_item_key ?? null
+    const existingEncKey = dto.existingItem.props.encItemKey
+
+    return incomingContent !== null && incomingContent === existingContent && incomingEncKey === existingEncKey
+  }
+
   private getMinimalConflictIntervalMicroseconds(apiVersion?: string): number {
     switch (apiVersion) {
       case ApiVersion.v20161215: