HcsCacheService API Reference

This document provides a detailed API reference for the HcsCacheService class — a service responsible for caching Hedera Consensus Service (HCS) topic information, messages, and files.

Constructor

constructor

constructor(configOrCache: CacheConfig | Cache)

Creates a new instance of HcsCacheService.

Parameters

  • configOrCache (required): Either a cache configuration object specifying cache size, or an existing cache instance implementing the Cache interface.

Methods

getTopicInfo

public getTopicInfo(client: Client, topicId: string): Promise<TopicInfo | null>

Retrieves cached topic information for a given client and topic ID.

Parameters

  • client (required): Hedera SDK client instance associated with the request.

  • topicId (required): The ID of the HCS topic.

Returns

  • A promise resolving to the cached TopicInfo if present, or null if not cached.

setTopicInfo

public setTopicInfo(client: Client, topicId: string, topicInfo: TopicInfo): Promise<void>

Stores topic information in the cache.

Parameters

  • client (required): Hedera SDK client instance associated with the cache entry.

  • topicId (required): The ID of the HCS topic.

  • topicInfo (required): The TopicInfo object to cache.

Returns

  • A promise that resolves when the data is cached.

removeTopicInfo

public async removeTopicInfo(client: Client, topicId: string): Promise<void>

Removes cached topic information and associated messages for a topic.

Parameters

  • client (required): Hedera SDK client instance.

  • topicId (required): The ID of the HCS topic to remove from cache.

Returns

  • A promise that resolves when the cache entries have been removed.

getTopicMessages

public getTopicMessages(client: Client, topicId: string): Promise<TopicMessageData[] | null>

Retrieves cached messages for a given topic.

Parameters

  • client (required): Hedera SDK client instance.

  • topicId (required): The ID of the HCS topic.

Returns

  • A promise resolving to an array of cached TopicMessageData, or null if no cached messages exist.

setTopicMessages

public async setTopicMessages(client: Client, topicId: string, messages: TopicMessageData[]): Promise<void>

Stores an array of topic messages in the cache and removes any cached file for the topic.

Parameters

  • client (required): Hedera SDK client instance.

  • topicId (required): The ID of the HCS topic.

  • messages (required): Array of TopicMessageData to cache.

Returns

  • A promise that resolves when the messages have been cached and related cached files are cleared.

removeTopicMessages

public async removeTopicMessages(client: Client, topicId: string): Promise<void>

Removes cached messages and cached file for a given topic.

Parameters

  • client (required): Hedera SDK client instance.

  • topicId (required): The ID of the HCS topic.

Returns

  • A promise that resolves when the cached messages and file for the topic have been removed.

getTopicFile

public getTopicFile(client: Client, topicId: string): Promise<Buffer | null>

Retrieves a cached file buffer for a topic, if available.

Parameters

  • client (required): Hedera SDK client instance.

  • topicId (required): The ID of the HCS topic.

Returns

  • A promise resolving to the cached file Buffer, or null if none exists.

setTopicFile

public setTopicFile(client: Client, topicId: string, file: Buffer): Promise<void>

Stores a file buffer in the cache for a given topic.

Parameters

  • client (required): Hedera SDK client instance.

  • topicId (required): The ID of the HCS topic.

  • file (required): The file contents as a Buffer.

Returns

  • A promise that resolves when the file has been cached.

removeTopicFile

public removeTopicFile(client: Client, topicId: string): Promise<void>

Removes a cached file for a given topic.

Parameters

  • client (required): Hedera SDK client instance.

  • topicId (required): The ID of the HCS topic.

Returns

  • A promise that resolves when the cached file has been removed.