31 lines
939 B
TypeScript
31 lines
939 B
TypeScript
// Copyright 2017-2021 @polkadot/api-derive authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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import type { ApiInterfaceRx } from '@polkadot/api/types';
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import type { BlockNumber } from '@polkadot/types/interfaces';
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import type { Observable } from '@polkadot/x-rxjs';
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import { map } from '@polkadot/x-rxjs/operators';
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import { memo } from '../util';
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/**
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* @name bestNumberFinalized
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* @returns A BlockNumber
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* @description Get the latest finalized block number.
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* @example
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* <BR>
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*
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* ```javascript
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* api.derive.chain.bestNumberFinalized((blockNumber) => {
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* console.log(`the current finalized block is #${blockNumber}`);
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* });
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* ```
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*/
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export function bestNumberFinalized (instanceId: string, api: ApiInterfaceRx): () => Observable<BlockNumber> {
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return memo(instanceId, (): Observable<BlockNumber> =>
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api.rpc.chain.subscribeFinalizedHeads().pipe(
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map((header) => header.number.unwrap())
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));
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}
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