Valentin Fernandez
ed62d164ea
* document derives from accounts to democracy * Derive Documentation progress * Derive Documentation progress * tx and staking docs * Staking docs progress * more staking docs * Staking module complete * imonline, elections and progress in democracy * Document missing derives * lint
63 lines
2.2 KiB
TypeScript
63 lines
2.2 KiB
TypeScript
// Copyright 2017-2025 @polkadot/api-derive authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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import type { Observable } from 'rxjs';
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import type { Hash, Header } from '@polkadot/types/interfaces';
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import type { DeriveApi } from '../types.js';
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import { from, of, switchMap } from 'rxjs';
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import { memo } from '../util/index.js';
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/**
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* Returns a header range from startHash to to (not including) endHash, i.e. lastBlock.parentHash === endHash
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*/
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export function _getHeaderRange (instanceId: string, api: DeriveApi): (startHash: Hash, endHash: Hash, prev?: Header[]) => Observable<Header[]> {
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return memo(instanceId, (startHash: Hash, endHash: Hash, prev: Header[] = []): Observable<Header[]> =>
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api.rpc.chain.getHeader(startHash).pipe(
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switchMap((header) =>
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header.parentHash.eq(endHash)
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? of([header, ...prev])
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: api.derive.chain._getHeaderRange(header.parentHash, endHash, [header, ...prev])
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)
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)
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);
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}
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/**
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* @name subscribeFinalizedHeads
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* @description An observable of the finalized block headers. Unlike the base
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* chain.subscribeFinalizedHeads this does not skip any headers. Since finalization
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* may skip specific blocks (finalization happens in terms of chains), this version
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* of the derive tracks missing headers (since last retrieved) and provides them
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* to the caller.
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* @example
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* ```javascript
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* const unsub = await api.derive.chain.subscribeFinalizedHeads((finalizedHead) => {
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* console.log(`${finalizedHead.hash}`);
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* });
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* ```
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*/
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export function subscribeFinalizedHeads (instanceId: string, api: DeriveApi): () => Observable<Header> {
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return memo(instanceId, (): Observable<Header> => {
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let prevHash: Hash | null = null;
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return api.rpc.chain.subscribeFinalizedHeads().pipe(
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switchMap((header) => {
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const endHash = prevHash;
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const startHash = header.parentHash;
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prevHash = header.createdAtHash = header.hash;
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return endHash === null || startHash.eq(endHash)
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? of(header)
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: api.derive.chain._getHeaderRange(startHash, endHash, [header]).pipe(
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switchMap((headers) =>
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from(headers)
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)
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);
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})
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);
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});
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}
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