mirror of
https://github.com/advplyr/audiobookshelf.git
synced 2025-11-04 03:17:00 -05:00
343 lines
11 KiB
JavaScript
343 lines
11 KiB
JavaScript
'use strict';
|
|
|
|
const path = require('path');
|
|
const fs = require('graceful-fs');
|
|
const retry = require('../../retry');
|
|
const onExit = require('../../signalExit');
|
|
const mtimePrecision = require('./mtime-precision');
|
|
|
|
const locks = {};
|
|
|
|
function getLockFile(file, options) {
|
|
return options.lockfilePath || `${file}.lock`;
|
|
}
|
|
|
|
function resolveCanonicalPath(file, options, callback) {
|
|
if (!options.realpath) {
|
|
return callback(null, path.resolve(file));
|
|
}
|
|
|
|
// Use realpath to resolve symlinks
|
|
// It also resolves relative paths
|
|
options.fs.realpath(file, callback);
|
|
}
|
|
|
|
function acquireLock(file, options, callback) {
|
|
const lockfilePath = getLockFile(file, options);
|
|
|
|
// Use mkdir to create the lockfile (atomic operation)
|
|
options.fs.mkdir(lockfilePath, (err) => {
|
|
if (!err) {
|
|
// At this point, we acquired the lock!
|
|
// Probe the mtime precision
|
|
return mtimePrecision.probe(lockfilePath, options.fs, (err, mtime, mtimePrecision) => {
|
|
// If it failed, try to remove the lock..
|
|
/* istanbul ignore if */
|
|
if (err) {
|
|
options.fs.rmdir(lockfilePath, () => { });
|
|
|
|
return callback(err);
|
|
}
|
|
|
|
callback(null, mtime, mtimePrecision);
|
|
});
|
|
}
|
|
|
|
// If error is not EEXIST then some other error occurred while locking
|
|
if (err.code !== 'EEXIST') {
|
|
return callback(err);
|
|
}
|
|
|
|
// Otherwise, check if lock is stale by analyzing the file mtime
|
|
if (options.stale <= 0) {
|
|
return callback(Object.assign(new Error('Lock file is already being held'), { code: 'ELOCKED', file }));
|
|
}
|
|
|
|
options.fs.stat(lockfilePath, (err, stat) => {
|
|
if (err) {
|
|
// Retry if the lockfile has been removed (meanwhile)
|
|
// Skip stale check to avoid recursiveness
|
|
if (err.code === 'ENOENT') {
|
|
return acquireLock(file, { ...options, stale: 0 }, callback);
|
|
}
|
|
|
|
return callback(err);
|
|
}
|
|
|
|
if (!isLockStale(stat, options)) {
|
|
return callback(Object.assign(new Error('Lock file is already being held'), { code: 'ELOCKED', file }));
|
|
}
|
|
|
|
// If it's stale, remove it and try again!
|
|
// Skip stale check to avoid recursiveness
|
|
removeLock(file, options, (err) => {
|
|
if (err) {
|
|
return callback(err);
|
|
}
|
|
|
|
acquireLock(file, { ...options, stale: 0 }, callback);
|
|
});
|
|
});
|
|
});
|
|
}
|
|
|
|
function isLockStale(stat, options) {
|
|
return stat.mtime.getTime() < Date.now() - options.stale;
|
|
}
|
|
|
|
function removeLock(file, options, callback) {
|
|
// Remove lockfile, ignoring ENOENT errors
|
|
options.fs.rmdir(getLockFile(file, options), (err) => {
|
|
if (err && err.code !== 'ENOENT') {
|
|
return callback(err);
|
|
}
|
|
|
|
callback();
|
|
});
|
|
}
|
|
|
|
function updateLock(file, options) {
|
|
const lock = locks[file];
|
|
|
|
// Just for safety, should never happen
|
|
/* istanbul ignore if */
|
|
if (lock.updateTimeout) {
|
|
return;
|
|
}
|
|
|
|
lock.updateDelay = lock.updateDelay || options.update;
|
|
lock.updateTimeout = setTimeout(() => {
|
|
lock.updateTimeout = null;
|
|
|
|
// Stat the file to check if mtime is still ours
|
|
// If it is, we can still recover from a system sleep or a busy event loop
|
|
options.fs.stat(lock.lockfilePath, (err, stat) => {
|
|
const isOverThreshold = lock.lastUpdate + options.stale < Date.now();
|
|
|
|
// If it failed to update the lockfile, keep trying unless
|
|
// the lockfile was deleted or we are over the threshold
|
|
if (err) {
|
|
if (err.code === 'ENOENT' || isOverThreshold) {
|
|
return setLockAsCompromised(file, lock, Object.assign(err, { code: 'ECOMPROMISED' }));
|
|
}
|
|
|
|
lock.updateDelay = 1000;
|
|
|
|
return updateLock(file, options);
|
|
}
|
|
|
|
const isMtimeOurs = lock.mtime.getTime() === stat.mtime.getTime();
|
|
|
|
if (!isMtimeOurs) {
|
|
return setLockAsCompromised(
|
|
file,
|
|
lock,
|
|
Object.assign(
|
|
new Error('Unable to update lock within the stale threshold'),
|
|
{ code: 'ECOMPROMISED' }
|
|
));
|
|
}
|
|
|
|
const mtime = mtimePrecision.getMtime(lock.mtimePrecision);
|
|
|
|
options.fs.utimes(lock.lockfilePath, mtime, mtime, (err) => {
|
|
const isOverThreshold = lock.lastUpdate + options.stale < Date.now();
|
|
|
|
// Ignore if the lock was released
|
|
if (lock.released) {
|
|
return;
|
|
}
|
|
|
|
// If it failed to update the lockfile, keep trying unless
|
|
// the lockfile was deleted or we are over the threshold
|
|
if (err) {
|
|
if (err.code === 'ENOENT' || isOverThreshold) {
|
|
return setLockAsCompromised(file, lock, Object.assign(err, { code: 'ECOMPROMISED' }));
|
|
}
|
|
|
|
lock.updateDelay = 1000;
|
|
|
|
return updateLock(file, options);
|
|
}
|
|
|
|
// All ok, keep updating..
|
|
lock.mtime = mtime;
|
|
lock.lastUpdate = Date.now();
|
|
lock.updateDelay = null;
|
|
updateLock(file, options);
|
|
});
|
|
});
|
|
}, lock.updateDelay);
|
|
|
|
// Unref the timer so that the nodejs process can exit freely
|
|
// This is safe because all acquired locks will be automatically released
|
|
// on process exit
|
|
|
|
// We first check that `lock.updateTimeout.unref` exists because some users
|
|
// may be using this module outside of NodeJS (e.g., in an electron app),
|
|
// and in those cases `setTimeout` return an integer.
|
|
/* istanbul ignore else */
|
|
if (lock.updateTimeout.unref) {
|
|
lock.updateTimeout.unref();
|
|
}
|
|
}
|
|
|
|
function setLockAsCompromised(file, lock, err) {
|
|
// Signal the lock has been released
|
|
lock.released = true;
|
|
|
|
// Cancel lock mtime update
|
|
// Just for safety, at this point updateTimeout should be null
|
|
/* istanbul ignore if */
|
|
if (lock.updateTimeout) {
|
|
clearTimeout(lock.updateTimeout);
|
|
}
|
|
|
|
if (locks[file] === lock) {
|
|
delete locks[file];
|
|
}
|
|
|
|
lock.options.onCompromised(err);
|
|
}
|
|
|
|
// ----------------------------------------------------------
|
|
|
|
function lock(file, options, callback) {
|
|
/* istanbul ignore next */
|
|
options = {
|
|
stale: 10000,
|
|
update: null,
|
|
realpath: true,
|
|
retries: 0,
|
|
fs,
|
|
onCompromised: (err) => { throw err; },
|
|
...options,
|
|
};
|
|
|
|
options.retries = options.retries || 0;
|
|
options.retries = typeof options.retries === 'number' ? { retries: options.retries } : options.retries;
|
|
options.stale = Math.max(options.stale || 0, 2000);
|
|
options.update = options.update == null ? options.stale / 2 : options.update || 0;
|
|
options.update = Math.max(Math.min(options.update, options.stale / 2), 1000);
|
|
|
|
// Resolve to a canonical file path
|
|
resolveCanonicalPath(file, options, (err, file) => {
|
|
if (err) {
|
|
return callback(err);
|
|
}
|
|
|
|
// Attempt to acquire the lock
|
|
const operation = retry.operation(options.retries);
|
|
|
|
operation.attempt(() => {
|
|
acquireLock(file, options, (err, mtime, mtimePrecision) => {
|
|
if (operation.retry(err)) {
|
|
return;
|
|
}
|
|
|
|
if (err) {
|
|
return callback(operation.mainError());
|
|
}
|
|
|
|
// We now own the lock
|
|
const lock = locks[file] = {
|
|
lockfilePath: getLockFile(file, options),
|
|
mtime,
|
|
mtimePrecision,
|
|
options,
|
|
lastUpdate: Date.now(),
|
|
};
|
|
|
|
// We must keep the lock fresh to avoid staleness
|
|
updateLock(file, options);
|
|
|
|
callback(null, (releasedCallback) => {
|
|
if (lock.released) {
|
|
return releasedCallback &&
|
|
releasedCallback(Object.assign(new Error('Lock is already released'), { code: 'ERELEASED' }));
|
|
}
|
|
|
|
// Not necessary to use realpath twice when unlocking
|
|
unlock(file, { ...options, realpath: false }, releasedCallback);
|
|
});
|
|
});
|
|
});
|
|
});
|
|
}
|
|
|
|
function unlock(file, options, callback) {
|
|
options = {
|
|
fs,
|
|
realpath: true,
|
|
...options,
|
|
};
|
|
|
|
// Resolve to a canonical file path
|
|
resolveCanonicalPath(file, options, (err, file) => {
|
|
if (err) {
|
|
return callback(err);
|
|
}
|
|
|
|
// Skip if the lock is not acquired
|
|
const lock = locks[file];
|
|
|
|
if (!lock) {
|
|
return callback(Object.assign(new Error('Lock is not acquired/owned by you'), { code: 'ENOTACQUIRED' }));
|
|
}
|
|
|
|
lock.updateTimeout && clearTimeout(lock.updateTimeout); // Cancel lock mtime update
|
|
lock.released = true; // Signal the lock has been released
|
|
delete locks[file]; // Delete from locks
|
|
|
|
removeLock(file, options, callback);
|
|
});
|
|
}
|
|
|
|
function check(file, options, callback) {
|
|
options = {
|
|
stale: 10000,
|
|
realpath: true,
|
|
fs,
|
|
...options,
|
|
};
|
|
|
|
options.stale = Math.max(options.stale || 0, 2000);
|
|
|
|
// Resolve to a canonical file path
|
|
resolveCanonicalPath(file, options, (err, file) => {
|
|
if (err) {
|
|
return callback(err);
|
|
}
|
|
|
|
// Check if lockfile exists
|
|
options.fs.stat(getLockFile(file, options), (err, stat) => {
|
|
if (err) {
|
|
// If does not exist, file is not locked. Otherwise, callback with error
|
|
return err.code === 'ENOENT' ? callback(null, false) : callback(err);
|
|
}
|
|
|
|
// Otherwise, check if lock is stale by analyzing the file mtime
|
|
return callback(null, !isLockStale(stat, options));
|
|
});
|
|
});
|
|
}
|
|
|
|
function getLocks() {
|
|
return locks;
|
|
}
|
|
|
|
// Remove acquired locks on exit
|
|
/* istanbul ignore next */
|
|
onExit(() => {
|
|
for (const file in locks) {
|
|
const options = locks[file].options;
|
|
|
|
try { options.fs.rmdirSync(getLockFile(file, options)); } catch (e) { /* Empty */ }
|
|
}
|
|
});
|
|
|
|
module.exports.lock = lock;
|
|
module.exports.unlock = unlock;
|
|
module.exports.check = check;
|
|
module.exports.getLocks = getLocks;
|