david_bai
83 lines
2.7 KiB
TypeScript
83 lines
2.7 KiB
TypeScript
/**
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* 🚀 Chunk range calculation utilities
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* Provides unified chunk calculation logic to ensure consistency between sender and receiver
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*/
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export class ChunkRangeCalculator {
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/**
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* Calculate chunk range for a file with given parameters
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* This method ensures both sender and receiver use identical calculation logic
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*/
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static getChunkRange(fileSize: number, startOffset: number, chunkSize: number) {
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// Calculate starting chunk index
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const startChunk = Math.floor(startOffset / chunkSize);
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// Calculate ending chunk index based on the last byte of the file
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const lastByteIndex = fileSize - 1;
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const endChunk = Math.floor(lastByteIndex / chunkSize);
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// Calculate total chunks to be sent/received (from startChunk to endChunk inclusive)
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const totalChunks = endChunk - startChunk + 1;
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// Calculate absolute total chunks in the entire file
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const absoluteTotalChunks = Math.ceil(fileSize / chunkSize);
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return {
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startChunk, // First chunk index to process
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endChunk, // Last chunk index to process
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totalChunks, // Number of chunks to process (for resume transfers)
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absoluteTotalChunks // Total chunks in the entire file
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};
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}
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/**
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* Calculate expected chunks count for resume transfer
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* Identical to ReceptionConfig.calculateExpectedChunks()
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*/
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static calculateExpectedChunks(fileSize: number, startOffset: number, chunkSize: number): number {
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return Math.ceil((fileSize - startOffset) / chunkSize);
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}
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/**
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* Get chunk index from file offset
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* Identical to ReceptionConfig.getChunkIndexFromOffset()
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*/
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static getChunkIndexFromOffset(offset: number, chunkSize: number): number {
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return Math.floor(offset / chunkSize);
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}
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/**
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* Get file offset from chunk index
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* Identical to ReceptionConfig.getOffsetFromChunkIndex()
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*/
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static getOffsetFromChunkIndex(chunkIndex: number, chunkSize: number): number {
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return chunkIndex * chunkSize;
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}
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/**
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* Validate chunk index within expected range
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*/
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static isChunkIndexValid(
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chunkIndex: number,
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startOffset: number,
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fileSize: number,
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chunkSize: number
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): boolean {
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const range = this.getChunkRange(fileSize, startOffset, chunkSize);
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return chunkIndex >= range.startChunk && chunkIndex <= range.endChunk;
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}
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/**
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* Calculate relative chunk index from absolute chunk index
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* Used by receiver to map sender's absolute index to local array index
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*/
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static getRelativeChunkIndex(
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absoluteChunkIndex: number,
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startOffset: number,
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chunkSize: number
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): number {
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const startChunkIndex = this.getChunkIndexFromOffset(startOffset, chunkSize);
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return absoluteChunkIndex - startChunkIndex;
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}
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}
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