@tldraw/sync-core/dist-esm/lib/chunk.mjs.map

tldraw infinite canvas SDK (multiplayer sync).

{
  "version": 3,
  "sources": ["../../src/lib/chunk.ts"],
  "sourcesContent": ["// quarter of a megabyte, max possible utf-8 string size\n\n// cloudflare workers only accept messages of max 1mb\nconst MAX_CLIENT_SENT_MESSAGE_SIZE_BYTES = 1024 * 1024\n// utf-8 is max 4 bytes per char\nconst MAX_BYTES_PER_CHAR = 4\n\n// in the (admittedly impossible) worst case, the max size is 1/4 of a megabyte\nconst MAX_SAFE_MESSAGE_SIZE = MAX_CLIENT_SENT_MESSAGE_SIZE_BYTES / MAX_BYTES_PER_CHAR\n\n/** @internal */\nexport function chunk(msg: string, maxSafeMessageSize = MAX_SAFE_MESSAGE_SIZE) {\n\tif (msg.length < maxSafeMessageSize) {\n\t\treturn [msg]\n\t} else {\n\t\tconst chunks = []\n\t\tlet chunkNumber = 0\n\t\tlet offset = msg.length\n\t\twhile (offset > 0) {\n\t\t\tconst prefix = `${chunkNumber}_`\n\t\t\tconst chunkSize = Math.max(Math.min(maxSafeMessageSize - prefix.length, offset), 1)\n\t\t\tchunks.unshift(prefix + msg.slice(offset - chunkSize, offset))\n\t\t\toffset -= chunkSize\n\t\t\tchunkNumber++\n\t\t}\n\t\treturn chunks\n\t}\n}\n\nconst chunkRe = /^(\\d+)_(.*)$/\n\nexport class JsonChunkAssembler {\n\tstate:\n\t\t| 'idle'\n\t\t| {\n\t\t\t\tchunksReceived: string[]\n\t\t\t\ttotalChunks: number\n\t\t  } = 'idle'\n\n\thandleMessage(msg: string): { error: Error } | { stringified: string; data: object } | null {\n\t\tif (msg.startsWith('{')) {\n\t\t\tconst error = this.state === 'idle' ? undefined : new Error('Unexpected non-chunk message')\n\t\t\tthis.state = 'idle'\n\t\t\treturn error ? { error } : { data: JSON.parse(msg), stringified: msg }\n\t\t} else {\n\t\t\tconst match = chunkRe.exec(msg)!\n\t\t\tif (!match) {\n\t\t\t\tthis.state = 'idle'\n\t\t\t\treturn { error: new Error('Invalid chunk: ' + JSON.stringify(msg.slice(0, 20) + '...')) }\n\t\t\t}\n\t\t\tconst numChunksRemaining = Number(match[1])\n\t\t\tconst data = match[2]\n\n\t\t\tif (this.state === 'idle') {\n\t\t\t\tthis.state = {\n\t\t\t\t\tchunksReceived: [data],\n\t\t\t\t\ttotalChunks: numChunksRemaining + 1,\n\t\t\t\t}\n\t\t\t} else {\n\t\t\t\tthis.state.chunksReceived.push(data)\n\t\t\t\tif (numChunksRemaining !== this.state.totalChunks - this.state.chunksReceived.length) {\n\t\t\t\t\tthis.state = 'idle'\n\t\t\t\t\treturn { error: new Error(`Chunks received in wrong order`) }\n\t\t\t\t}\n\t\t\t}\n\t\t\tif (this.state.chunksReceived.length === this.state.totalChunks) {\n\t\t\t\ttry {\n\t\t\t\t\tconst stringified = this.state.chunksReceived.join('')\n\t\t\t\t\tconst data = JSON.parse(stringified)\n\t\t\t\t\treturn { data, stringified }\n\t\t\t\t} catch (e) {\n\t\t\t\t\treturn { error: e as Error }\n\t\t\t\t} finally {\n\t\t\t\t\tthis.state = 'idle'\n\t\t\t\t}\n\t\t\t}\n\t\t\treturn null\n\t\t}\n\t}\n}\n"],
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