Cache dynamic bucket lookups.

Author: rkistner

modules/module-mongodb-storage/src/storage/implementation/MongoSyncBucketStorage.ts

@@ -38,6 +38,7 @@ import { MongoBucketBatch } from './MongoBucketBatch.js';
 import { MongoCompactor } from './MongoCompactor.js';
 import { MongoWriteCheckpointAPI } from './MongoWriteCheckpointAPI.js';
 import { idPrefixFilter, mapOpEntry, readSingleBatch } from './util.js';
+import { LRUCache } from 'lru-cache';
 
 export class MongoSyncBucketStorage
   extends BaseObserver<storage.SyncRulesBucketStorageListener>
@@ -868,25 +869,40 @@ export class MongoSyncBucketStorage
     return pipeline;
   }
 
-  async getCheckpointChanges(options: GetCheckpointChangesOptions): Promise<CheckpointChanges> {
-    const dataBuckets = await this.db.bucket_data
-      .find(
-        {
-          '_id.g': this.group_id,
-          '_id.o': { $gt: BigInt(options.lastCheckpoint), $lte: BigInt(options.nextCheckpoint) }
-        },
-        {
-          projection: {
-            '_id.b': 1
-          },
-          limit: 1001,
-          batchSize: 1001,
-          singleBatch: true
-        }
-      )
-      .toArray();
-    const invalidateDataBuckets = dataBuckets.length > 1000;
+  private async getDataBucketChanges(
+    options: GetCheckpointChangesOptions
+  ): Promise<Pick<CheckpointChanges, 'updatedDataBuckets' | 'invalidateDataBuckets'>> {
+    // The query below can be slow, since we don't have an index on _id.o.
+    // We could try to query the oplog for these, but that is risky.
+    // Or we could store updated buckets in a separate collection, and query those.
+    // For now, we ignore this optimization
+
+    // const dataBuckets = await this.db.bucket_data
+    //   .find(
+    //     {
+    //       '_id.g': this.group_id,
+    //       '_id.o': { $gt: BigInt(options.lastCheckpoint), $lte: BigInt(options.nextCheckpoint) }
+    //     },
+    //     {
+    //       projection: {
+    //         '_id.b': 1
+    //       },
+    //       limit: 1001,
+    //       batchSize: 1001,
+    //       singleBatch: true
+    //     }
+    //   )
+    //   .toArray();
+
+    return {
+      invalidateDataBuckets: true,
+      updatedDataBuckets: []
+    };
+  }
 
+  private async getParameterBucketChanges(
+    options: GetCheckpointChangesOptions
+  ): Promise<Pick<CheckpointChanges, 'updatedParameterBucketDefinitions' | 'invalidateParameterBuckets'>> {
     const parameterUpdates = await this.db.bucket_parameters
       .find(
         {
@@ -906,13 +922,37 @@ export class MongoSyncBucketStorage
     const invalidateParameterUpdates = parameterUpdates.length > 1000;
 
     return {
-      invalidateDataBuckets,
-      updatedDataBuckets: invalidateDataBuckets ? [] : dataBuckets.map((b) => b._id.b),
-
       invalidateParameterBuckets: invalidateParameterUpdates,
       updatedParameterBucketDefinitions: invalidateParameterUpdates
         ? []
         : [...new Set<string>(parameterUpdates.map((p) => getLookupBucketDefinitionName(p.lookup)))]
     };
   }
+
+  private checkpointChangesCache = new LRUCache<string, CheckpointChanges, { options: GetCheckpointChangesOptions }>({
+    max: 50,
+    maxSize: 10 * 1024 * 1024,
+    sizeCalculation: (value: CheckpointChanges) => {
+      return value.updatedParameterBucketDefinitions.reduce<number>((a, b) => a + b.length, 0);
+    },
+    fetchMethod: async (_key, _staleValue, options) => {
+      return this.getCheckpointChangesInternal(options.context.options);
+    }
+  });
+
+  async getCheckpointChanges(options: GetCheckpointChangesOptions): Promise<CheckpointChanges> {
+    const key = `${options.lastCheckpoint}_${options.nextCheckpoint}`;
+    const result = await this.checkpointChangesCache.fetch(key, { context: { options } });
+    return result!;
+  }
+
+  private async getCheckpointChangesInternal(options: GetCheckpointChangesOptions): Promise<CheckpointChanges> {
+    const dataUpdates = await this.getDataBucketChanges(options);
+    const parameterUpdates = await this.getParameterBucketChanges(options);
+
+    return {
+      ...dataUpdates,
+      ...parameterUpdates
+    };
+  }
 }

packages/service-core/src/sync/BucketChecksumState.ts

@@ -268,6 +268,7 @@ export class BucketParameterState {
   public readonly syncParams: RequestParameters;
   private readonly querier: BucketParameterQuerier;
   private readonly staticBuckets: Map<string, BucketDescription>;
+  private cachedDynamicBuckets: BucketDescription[] | null = null;
 
   constructor(
     context: SyncContext,
@@ -361,29 +362,39 @@ export class BucketParameterState {
     const staticBuckets = querier.staticBuckets;
     const update = checkpoint.update;
 
-    let hasChange = false;
+    let hasDataChange = false;
+    let hasParameterChange = false;
     if (update.invalidateDataBuckets || update.updatedDataBuckets?.length > 0) {
-      hasChange = true;
-    } else if (update.invalidateParameterBuckets) {
-      hasChange = true;
+      hasDataChange = true;
+    }
+
+    if (update.invalidateParameterBuckets) {
+      hasParameterChange = true;
     } else {
-      for (let bucket of update.updatedParameterBucketDefinitions ?? []) {
+      for (let bucket of update.updatedParameterBucketDefinitions) {
+        // This is a very coarse check, but helps
         if (querier.dynamicBucketDefinitions.has(bucket)) {
-          hasChange = true;
+          hasParameterChange = true;
           break;
         }
       }
     }
 
-    if (!hasChange) {
+    if (!hasDataChange && !hasParameterChange) {
       return null;
     }
 
-    const dynamicBuckets = await querier.queryDynamicBucketDescriptions({
-      getParameterSets(lookups) {
-        return storage.getParameterSets(checkpoint.base.checkpoint, lookups);
-      }
-    });
+    let dynamicBuckets: BucketDescription[];
+    if (hasParameterChange || this.cachedDynamicBuckets == null) {
+      dynamicBuckets = await querier.queryDynamicBucketDescriptions({
+        getParameterSets(lookups) {
+          return storage.getParameterSets(checkpoint.base.checkpoint, lookups);
+        }
+      });
+      this.cachedDynamicBuckets = dynamicBuckets;
+    } else {
+      dynamicBuckets = this.cachedDynamicBuckets;
+    }
     const allBuckets = [...staticBuckets, ...dynamicBuckets];
 
     return {