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factored the metadatafile code out into a separate class
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,156 @@ | ||
| import debug from "debug"; | ||
| import { stat, readFile } from "fs/promises"; | ||
| import { decode } from "lz4"; | ||
| import binarySearch from "binarysearch"; | ||
| import { symbolicToMode } from "./util"; | ||
| import { join } from "path"; | ||
|
|
||
| const log = debug("websocketfs:metadata-file"); | ||
|
|
||
| const METADATA_FILE_INTERVAL_MS = 3000; | ||
|
|
||
| export class MetadataFile { | ||
| private attrCache; | ||
| private dirCache; | ||
| private metadataFile: string; | ||
| private metadataFileContents: string[]; | ||
| private metadataFileInterval?: ReturnType<typeof setInterval>; | ||
| private cacheTimeoutMs: number; | ||
| private lastSuccess: number = 0; | ||
| private lastMtimeMs: number = 0; | ||
| private state: "init" | "ready" | "expired" | "closed" = "init"; | ||
|
|
||
| constructor({ metadataFile, cacheTimeout, attrCache, dirCache }) { | ||
| this.metadataFile = metadataFile; | ||
| this.attrCache = attrCache; | ||
| this.dirCache = dirCache; | ||
| this.cacheTimeoutMs = cacheTimeout * 1000; | ||
| this.init(); | ||
| } | ||
|
|
||
| isReady = () => { | ||
| return this.state == "ready"; | ||
| }; | ||
|
|
||
| private init = () => { | ||
| if (this.metadataFileInterval) { | ||
| throw Error("bug -- do not call init more than once"); | ||
| } | ||
| this.metadataFileInterval = setInterval( | ||
| this.update, | ||
| METADATA_FILE_INTERVAL_MS, | ||
| ); | ||
| this.state = "expired"; | ||
| this.update(); | ||
| }; | ||
|
|
||
| private update = async () => { | ||
| // try to read the file. It's fine it doesn't exist. | ||
| try { | ||
| const { mtimeMs } = await stat(this.metadataFile); | ||
| if (Date.now() - mtimeMs >= this.cacheTimeoutMs) { | ||
| log( | ||
| `metadataFile: '${this.metadataFile}' is older than cache timeout -- not loading`, | ||
| ); | ||
| this.state = "expired"; | ||
| this.metadataFileContents = []; | ||
| return; | ||
| } | ||
| if (mtimeMs <= this.lastMtimeMs) { | ||
| // it hasn't changed so nothing to do | ||
| return; | ||
| } | ||
| const start = Date.now(); | ||
| this.lastMtimeMs = mtimeMs; | ||
| let content = await readFile(this.metadataFile); | ||
| if (this.metadataFile.endsWith(".lz4")) { | ||
| content = decode(content); | ||
| } | ||
| this.metadataFileContents = content.toString().split("\0\0"); | ||
| this.metadataFileContents.sort(); | ||
| this.lastSuccess = Date.now(); | ||
| this.state = "ready"; | ||
| log( | ||
| `metadataFile: "${this.metadataFile}" is NEW -- parsed in `, | ||
| Date.now() - start, | ||
| "ms", | ||
| ); | ||
| } catch (err) { | ||
| log( | ||
| "metadataFile: not reading -- ", | ||
| err.code == "ENOENT" ? `no file '${this.metadataFile}'` : err, | ||
| ); | ||
| if (Date.now() - this.lastSuccess >= this.cacheTimeoutMs) { | ||
| // expire the metadataFile cache contents. | ||
| // NOTE: this could take slightly longer than cacheTimeoutMs, depending | ||
| // on METADATA_FILE_INTERVAL_MS, but for my application I don't care. | ||
| this.state = "expired"; | ||
| this.metadataFileContents = []; | ||
| } | ||
| } | ||
| }; | ||
|
|
||
| close = () => { | ||
| this.state = "closed"; | ||
| this.metadataFileContents = []; | ||
| if (this.metadataFileInterval) { | ||
| clearInterval(this.metadataFileInterval); | ||
| delete this.metadataFileInterval; | ||
| } | ||
| }; | ||
|
|
||
| readdir = (path: string) => { | ||
| if (!this.isReady()) { | ||
| throw Error("MetadataFile is not ready"); | ||
| } | ||
| log("readdir", path); | ||
| let i = binarySearch(this.metadataFileContents, path, (value, find) => { | ||
| const path = "/" + value.split("\0")[0]; | ||
| if (path < find) { | ||
| return -1; | ||
| } | ||
| if (path > find) { | ||
| return 1; | ||
| } | ||
| return 0; | ||
| }); | ||
| if (i == -1) { | ||
| log("readdir", path, " -- does not exist"); | ||
| return []; | ||
| } | ||
| const filenames: string[] = []; | ||
| const pathDir = path == "/" ? path : path + "/"; | ||
| i += 1; | ||
| while (i < this.metadataFileContents.length) { | ||
| const v = this.metadataFileContents[i].split("\0"); | ||
| const name = "/" + v[0]; | ||
| if (!name.startsWith(path)) { | ||
| // definitely done. | ||
| break; | ||
| } | ||
| if (name.startsWith(pathDir)) { | ||
| const filename = name.slice(pathDir.length); | ||
| if (!filename.includes("/")) { | ||
| filenames.push(filename); | ||
| const data = v[1].split(" "); | ||
| const mtime = new Date(parseFloat(data[0]) * 1000); | ||
| const attr = { | ||
| mtime, | ||
| atime: new Date(parseFloat(data[1]) * 1000), | ||
| ctime: mtime, | ||
| blocks: parseInt(data[2]), | ||
| size: parseInt(data[3]), | ||
| mode: symbolicToMode(data[4]), | ||
| flags: 0, | ||
| uid: 0, | ||
| gid: 0, | ||
| }; | ||
| this.attrCache.set(join(path, filename), { attr }); | ||
| } | ||
| } | ||
| i += 1; | ||
| } | ||
| this.dirCache.set(path, filenames); | ||
| return filenames; | ||
| }; | ||
| } |
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