import * as sqlite3 from '@gristlabs/sqlite3'; import {mapGetOrSet} from 'app/common/AsyncCreate'; import {delay} from 'app/common/delay'; import {DocEntry} from 'app/common/DocListAPI'; import {DocSnapshots} from 'app/common/DocSnapshot'; import {buildUrlId, parseUrlId} from 'app/common/gristUrls'; import {KeyedOps} from 'app/common/KeyedOps'; import {DocReplacementOptions, NEW_DOCUMENT_CODE} from 'app/common/UserAPI'; import {HomeDBManager} from 'app/gen-server/lib/HomeDBManager'; import {checksumFile} from 'app/server/lib/checksumFile'; import {DocSnapshotInventory, DocSnapshotPruner} from 'app/server/lib/DocSnapshots'; import {IDocWorkerMap} from 'app/server/lib/DocWorkerMap'; import {ChecksummedExternalStorage, DELETED_TOKEN, ExternalStorage} from 'app/server/lib/ExternalStorage'; import {HostedMetadataManager} from 'app/server/lib/HostedMetadataManager'; import {ICreate} from 'app/server/lib/ICreate'; import {IDocStorageManager} from 'app/server/lib/IDocStorageManager'; import * as log from 'app/server/lib/log'; import {fromCallback} from 'app/server/lib/serverUtils'; import * as fse from 'fs-extra'; import * as path from 'path'; import * as uuidv4 from "uuid/v4"; import { OpenMode, SQLiteDB } from './SQLiteDB'; // Check for a valid document id. const docIdRegex = /^[-=_\w~%]+$/; // Wait this long after a change to the document before trying to make a backup of it. const GRIST_BACKUP_DELAY_SECS = parseInt(process.env.GRIST_BACKUP_DELAY_SECS || '15', 10); // This constant controls how many pages of the database we back up in a single step. // The larger it is, the faster the backup overall, but the slower each step is. // Slower steps result in longer periods when the database is locked, without any // opportunity for a waiting client to get in and make a write. // The size of a page, as far as sqlite is concerned, is 4096 bytes. const PAGES_TO_BACKUP_PER_STEP = 1024; // Backup is made in 4MB chunks. // Between steps of the backup, we pause in case a client is waiting to make a write. // The shorter the pause, the greater the odds that the client won't be able to make // its write, but the faster the backup will complete. const PAUSE_BETWEEN_BACKUP_STEPS_IN_MS = 10; function checkValidDocId(docId: string): void { if (!docIdRegex.test(docId)) { throw new Error(`Invalid docId ${docId}`); } } interface HostedStorageOptions { secondsBeforePush: number; secondsBeforeFirstRetry: number; pushDocUpdateTimes: boolean; testExternalStorageDoc?: ExternalStorage; testExternalStorageMeta?: ExternalStorage; } const defaultOptions: HostedStorageOptions = { secondsBeforePush: GRIST_BACKUP_DELAY_SECS, secondsBeforeFirstRetry: 3.0, pushDocUpdateTimes: true }; /** * HostedStorageManager manages Grist files in the hosted environment for a particular DocWorker. * These files are stored on S3 and synced to the local file system. It matches the interface of * DocStorageManager (used for standalone Grist), but is more limited, e.g. does not expose the * list of local files. * * In hosted environment, documents are uniquely identified by docId, which serves as the * canonical docName. This ID does not change on renaming. HostedStorageManager knows nothing of * friendlier doc names. * * TODO: Listen (to Redis?) to find out when a local document has been deleted or renamed. * (In case of rename, something on the DocWorker needs to inform the client about the rename) * TODO: Do something about the active flag in redis DocStatus. * TODO: Add an explicit createFlag in DocStatus for clarity and simplification. */ export class HostedStorageManager implements IDocStorageManager { // Handles pushing doc metadata changes when the doc is updated. private _metadataManager: HostedMetadataManager|null = null; // Maps docId to the promise for when the document is present on the local filesystem. private _localFiles = new Map>(); // Label to put in metadata for a document. Only one label supported per snapshot currently. // Holds the label that should be associated with a backup when a labeled backup is being made. private _labels = new Map(); // Time at which document was last changed. private _timestamps = new Map(); // Access external storage. private _ext: ChecksummedExternalStorage; private _extMeta: ChecksummedExternalStorage; // Prune external storage. private _pruner: DocSnapshotPruner; // Access to version information about documents. private _inventory: DocSnapshotInventory; // A set of filenames currently being created or downloaded. private _prepareFiles = new Set(); // Ongoing and scheduled uploads for documents. private _uploads: KeyedOps; // Set once the manager has been closed. private _closed: boolean = false; private _baseStore: ExternalStorage; // External store for documents, without checksumming. // Latest version ids of documents. private _latestVersions = new Map(); /** * Initialize with the given root directory, which should be a fully-resolved path. * If s3Bucket is blank, S3 storage will be disabled. */ constructor( private _docsRoot: string, private _docWorkerId: string, private _disableS3: boolean, extraS3Prefix: string, private _docWorkerMap: IDocWorkerMap, dbManager: HomeDBManager, create: ICreate, options: HostedStorageOptions = defaultOptions ) { // We store documents either in a test store, or in an s3 store // at s3:///.grist const externalStoreDoc = options.testExternalStorageDoc || (this._disableS3 ? undefined : create.ExternalStorage('doc', extraS3Prefix)); if (!externalStoreDoc) { this._disableS3 = true; } const secondsBeforePush = options.secondsBeforePush; if (options.pushDocUpdateTimes) { this._metadataManager = new HostedMetadataManager(dbManager); } this._uploads = new KeyedOps(key => this._pushToS3(key), { delayBeforeOperationMs: secondsBeforePush * 1000, retry: true, logError: (key, failureCount, err) => { log.error("HostedStorageManager: error pushing %s (%d): %s", key, failureCount, err); } }); if (!this._disableS3) { this._baseStore = externalStoreDoc!; // Whichever store we have, we use checksums to deal with // eventual consistency. this._ext = this._getChecksummedExternalStorage('doc', this._baseStore, this._latestVersions, options); const baseStoreMeta = options.testExternalStorageMeta || create.ExternalStorage('meta', extraS3Prefix); if (!baseStoreMeta) { throw new Error('bug: external storage should be created for "meta" if it is created for "doc"'); } this._extMeta = this._getChecksummedExternalStorage('meta', baseStoreMeta, new Map(), options); this._inventory = new DocSnapshotInventory(this._ext, this._extMeta, async docId => { const dir = this.getAssetPath(docId); await fse.mkdirp(dir); return path.join(dir, 'meta.json'); }); // The pruner could use an inconsistent store without any real loss overall, // but tests are easier if it is consistent. this._pruner = new DocSnapshotPruner(this._inventory, { delayBeforeOperationMs: 0, // prune as soon as we've made a first upload. minDelayBetweenOperationsMs: secondsBeforePush * 4000, // ... but wait awhile before // pruning again. }); } } /** * Send a document to S3, without doing anything fancy. Assumes this is the first time * the object is written in S3 - so no need to worry about consistency. */ public async addToStorage(docId: string) { if (this._disableS3) { return; } this._uploads.addOperation(docId); await this._uploads.expediteOperationAndWait(docId); } public getPath(docName: string): string { return this.getAssetPath(docName) + '.grist'; } // Where to store files related to a document locally. Document goes in .grist, // and other files go in / directory. public getAssetPath(docName: string): string { checkValidDocId(docName); return path.join(this._docsRoot, path.basename(docName, '.grist')); } // We don't deal with sample docs public getSampleDocPath(sampleDocName: string): string|null { return null; } /** * Translates a possibly non-canonical docName to a canonical one. Returns a bare docId, * stripping out any possible path components or .grist extension. (We don't expect these to * ever be used, but stripping seems better than asserting.) */ public async getCanonicalDocName(altDocName: string): Promise { return path.basename(altDocName, '.grist'); } /** * Prepares a document for use locally. Here we sync the doc from S3 to the local filesystem. * Returns whether the document is new (needs to be created). * Calling this method multiple times in parallel for the same document is treated as a sign * of a bug. * * The optional srcDocName parameter is set when preparing a fork. */ public async prepareLocalDoc(docName: string, srcDocName?: string): Promise { // We could be reopening a document that is still closing down. // Wait for that to happen. TODO: we could also try to interrupt the closing-down process. await this.closeDocument(docName); if (this._prepareFiles.has(docName)) { throw new Error(`Tried to call prepareLocalDoc('${docName}') twice in parallel`); } try { this._prepareFiles.add(docName); const isNew = !(await this._claimDocument(docName, srcDocName)); return isNew; } finally { this._prepareFiles.delete(docName); } } public async prepareToCreateDoc(docName: string): Promise { await this.prepareLocalDoc(docName, 'new'); if (this._inventory) { await this._inventory.create(docName); this._onInventoryChange(docName); } this.markAsChanged(docName); } /** * Initialize one document from another, associating the result with the current * worker. */ public async prepareFork(srcDocName: string, destDocName: string): Promise { await this.prepareLocalDoc(destDocName, srcDocName); } // Gets a copy of the document, eg. for downloading. Returns full file path. // Copy won't change if edits are made to the document. It is caller's responsibility // to delete the result. public async getCopy(docName: string): Promise { const present = await this._claimDocument(docName); if (!present) { throw new Error('cannot copy document that does not exist yet'); } return await this._prepareBackup(docName, uuidv4()); } public async replace(docId: string, options: DocReplacementOptions): Promise { // Make sure the current version of the document is flushed. await this.flushDoc(docId); // Figure out the source s3 key to copy from. For this purpose, we need to // remove any snapshotId embedded in the document id. const rawSourceDocId = options.sourceDocId || docId; const parts = parseUrlId(rawSourceDocId); const sourceDocId = buildUrlId({...parts, snapshotId: undefined}); const snapshotId = options.snapshotId || parts.snapshotId; if (sourceDocId === docId && !snapshotId) { return; } // Basic implementation for when S3 is not available. if (this._disableS3) { if (snapshotId) { throw new Error('snapshots not supported without S3'); } if (await fse.pathExists(this.getPath(sourceDocId))) { await fse.copy(this.getPath(sourceDocId), this.getPath(docId)); return; } else { throw new Error(`cannot find ${docId}`); } } // While replacing, move the current version of the document aside. If a problem // occurs, move it back. const docPath = this.getPath(docId); const tmpPath = `${docPath}-replacing`; // NOTE: fse.remove succeeds also when the file does not exist. await fse.remove(tmpPath); if (await fse.pathExists(docPath)) { await fse.move(docPath, tmpPath); } try { // Fetch new content from S3. if (!await this._fetchFromS3(docId, {sourceDocId, snapshotId})) { throw new Error('Cannot fetch document'); } // Make sure the new content is considered new. // NOTE: fse.remove succeeds also when the file does not exist. await fse.remove(this._getHashFile(this.getPath(docId))); this.markAsChanged(docId, 'edit'); } catch (err) { log.error("HostedStorageManager: problem replacing %s: %s", docId, err); await fse.move(tmpPath, docPath, {overwrite: true}); throw err; } finally { // NOTE: fse.remove succeeds also when the file does not exist. await fse.remove(tmpPath); } // Flush the document immediately if it has been changed. await this.flushDoc(docId); } // We don't deal with listing documents. public async listDocs(): Promise { return []; } public async deleteDoc(docName: string, deletePermanently?: boolean): Promise { if (!deletePermanently) { throw new Error("HostedStorageManager only implements permanent deletion in deleteDoc"); } await this.closeDocument(docName); if (!this._disableS3) { await this._ext.remove(docName); await this._extMeta.remove(docName); } // NOTE: fse.remove succeeds also when the file does not exist. await fse.remove(this.getPath(docName)); await fse.remove(this._getHashFile(this.getPath(docName), 'doc')); await fse.remove(this._getHashFile(this.getPath(docName), 'meta')); await fse.remove(this.getAssetPath(docName)); } // We don't implement document renames. public async renameDoc(oldName: string, newName: string): Promise { throw new Error("HostedStorageManager does not implement renameDoc"); } /** * We handle backups by syncing the current version of the file as a new object version in S3, * with the requested backupTag as metadata. */ public async makeBackup(docName: string, backupTag: string): Promise { if (this._labels.get(docName)) { await this.flushDoc(docName); } this._labels.set(docName, backupTag); this.markAsChanged(docName); await this.flushDoc(docName); // TODO: make an alternative way to store backups if operating without an external // store. return this._ext ? (this._ext.url(docName) + ' (' + this._latestVersions.get(docName) + ')') : 'no-external-storage-enabled'; } /** * Electron version only. Shows the given doc in the file explorer. */ public async showItemInFolder(docName: string): Promise { throw new Error("HostedStorageManager does not implement showItemInFolder"); } /** * Close the storage manager. Make sure any pending changes reach S3 first. */ public async closeStorage(): Promise { await this._uploads.wait(() => log.info('HostedStorageManager: waiting for closeStorage to finish')); // Close metadata manager. if (this._metadataManager) { await this._metadataManager.close(); } // Finish up everything incoming. This is most relevant for tests. // Wait for any downloads to wind up, since there's no easy way to cancel them. while (this._prepareFiles.size > 0) { await delay(100); } await Promise.all(this._localFiles.values()); this._closed = true; if (this._ext) { await this._ext.close(); } if (this._pruner) { await this._pruner.close(); } } /** * Allow storage manager to be used again - used in tests. */ public testReopenStorage() { this._closed = false; } public async testWaitForPrunes() { if (this._pruner) { await this._pruner.wait(); } } /** * Get direct access to the external store - used in tests. */ public testGetExternalStorage(): ExternalStorage { return this._baseStore; } // return true if document and inventory is backed up to external store (if attached). public isAllSaved(docName: string): boolean { return !this._uploads.hasPendingOperation(docName) && (this._inventory ? this._inventory.isSaved(docName) : true); } // pick up the pace of pushing to s3, from leisurely to urgent. public prepareToCloseStorage() { if (this._pruner) { this._pruner.close().catch(e => log.error("HostedStorageManager: pruning error %s", e)); } this._uploads.expediteOperations(); } /** * Finalize any operations involving the named document. */ public async closeDocument(docName: string): Promise { if (this._localFiles.has(docName)) { await this._localFiles.get(docName); } this._localFiles.delete(docName); return this.flushDoc(docName); } /** * Make sure document is backed up to s3. */ public async flushDoc(docName: string): Promise { while (!this.isAllSaved(docName)) { log.info('HostedStorageManager: waiting for document to finish: %s', docName); await this._uploads.expediteOperationAndWait(docName); await this._inventory?.flush(docName); if (!this.isAllSaved(docName)) { // Throttle slightly in case this operation ends up looping excessively. await delay(1000); } } } /** * This is called when a document may have been changed, via edits or migrations etc. */ public markAsChanged(docName: string, reason?: string): void { const timestamp = new Date().toISOString(); this._timestamps.set(docName, timestamp); try { if (parseUrlId(docName).snapshotId) { return; } if (this._localFiles.has(docName)) { // Make sure the file is marked as locally present (it may be newly created). this._localFiles.set(docName, Promise.resolve(true)); } if (this._disableS3) { return; } if (this._closed) { throw new Error("HostedStorageManager.markAsChanged called after closing"); } this._uploads.addOperation(docName); } finally { if (reason === 'edit') { this._markAsEdited(docName, timestamp); } } } /** * Check if there is a pending change to be pushed to S3. */ public needsUpdate(): boolean { return this._uploads.hasPendingOperations(); } public async removeSnapshots(docName: string, snapshotIds: string[]): Promise { if (this._disableS3) { return; } await this._pruner.prune(docName, snapshotIds); } public async getSnapshots(docName: string, skipMetadataCache?: boolean): Promise { if (this._disableS3) { return { snapshots: [{ snapshotId: 'current', lastModified: new Date().toISOString(), docId: docName, }] }; } const versions = skipMetadataCache ? await this._ext.versions(docName) : await this._inventory.versions(docName, this._latestVersions.get(docName) || null); const parts = parseUrlId(docName); return { snapshots: versions .map(v => { return { ...v, docId: buildUrlId({...parts, snapshotId: v.snapshotId}), }; }) }; } /** * This is called when a document was edited by the user. */ private _markAsEdited(docName: string, timestamp: string): void { if (parseUrlId(docName).snapshotId) { return; } // Schedule a metadata update for the modified doc. if (this._metadataManager) { this._metadataManager.scheduleUpdate(docName, timestamp); } } /** * Makes sure a document is assigned to this worker, adding an * assignment if it has none. If the document is present in * external storage, fetch it. Return true if the document was * fetched. * * The document can optionally be copied from an alternative * source (srcDocName). This is useful for forking. * * If srcDocName is 'new', checks for the document in external storage * are skipped. */ private async _claimDocument(docName: string, srcDocName?: string): Promise { // AsyncCreate.mapGetOrSet ensures we don't start multiple promises to talk to S3/Redis // and that we clean up the failed key in case of failure. return mapGetOrSet(this._localFiles, docName, async () => { if (this._closed) { throw new Error("HostedStorageManager._ensureDocumentIsPresent called after closing"); } checkValidDocId(docName); const {trunkId, forkId, snapshotId} = parseUrlId(docName); const canCreateFork = Boolean(srcDocName); const docStatus = await this._docWorkerMap.getDocWorkerOrAssign(docName, this._docWorkerId); if (!docStatus.isActive) { throw new Error(`Doc is not active on a DocWorker: ${docName}`); } if (docStatus.docWorker.id !== this._docWorkerId) { throw new Error(`Doc belongs to a different DocWorker (${docStatus.docWorker.id}): ${docName}`); } if (srcDocName === 'new') { return false; } if (this._disableS3) { // skip S3, just use file system let present: boolean = await fse.pathExists(this.getPath(docName)); if ((forkId || snapshotId) && !present) { if (!canCreateFork) { throw new Error(`Cannot create fork`); } if (snapshotId && snapshotId !== 'current') { throw new Error(`cannot find snapshot ${snapshotId} of ${docName}`); } if (await fse.pathExists(this.getPath(trunkId))) { await fse.copy(this.getPath(trunkId), this.getPath(docName)); present = true; } } return present; } const existsLocally = await fse.pathExists(this.getPath(docName)); if (existsLocally) { if (!docStatus.docMD5 || docStatus.docMD5 === DELETED_TOKEN) { // New doc appears to already exist, but not in S3 (according to redis). // Go ahead and use local version. return true; } else { // Doc exists locally and in S3 (according to redis). // Make sure the checksum matches. const checksum = await this._getHash(await this._prepareBackup(docName)); if (checksum === docStatus.docMD5) { // Fine, accept the doc as existing on our file system. return true; } else { log.info("Local hash does not match redis: %s vs %s", checksum, docStatus.docMD5); // The file that exists locally does not match S3. But S3 is the canonical version. // On the assumption that the local file is outdated, delete it. // TODO: may want to be more careful in case the local file has modifications that // simply never made it to S3 due to some kind of breakage. // NOTE: fse.remove succeeds also when the file does not exist. await fse.remove(this.getPath(docName)); } } } return this._fetchFromS3(docName, { sourceDocId: srcDocName, trunkId: forkId ? trunkId : undefined, snapshotId, canCreateFork }); }); } /** * Fetch a document from s3 and save it locally as destId.grist * * If the document is not present in s3: * + If it has a trunk: * - If we do not not have permission to create a fork, we throw an error * - Else we fetch the document from the trunk instead * + Otherwise return false * * Forks of fork will not spark joy at this time. An attempt to * fork a fork will result in a new fork of the original trunk. */ private async _fetchFromS3(destId: string, options: {sourceDocId?: string, trunkId?: string, snapshotId?: string, canCreateFork?: boolean}): Promise { const destIdWithoutSnapshot = buildUrlId({...parseUrlId(destId), snapshotId: undefined}); let sourceDocId = options.sourceDocId || destIdWithoutSnapshot; if (!await this._ext.exists(destIdWithoutSnapshot)) { if (!options.trunkId) { return false; } // Document not found in S3 // No such fork in s3 yet, try from trunk (if we are allowed to create the fork). if (!options.canCreateFork) { throw new Error('Cannot create fork'); } // The special NEW_DOCUMENT_CODE trunk means we should create an empty document. if (options.trunkId === NEW_DOCUMENT_CODE) { return false; } if (!await this._ext.exists(options.trunkId)) { throw new Error('Cannot find original'); } sourceDocId = options.trunkId; } await this._ext.downloadTo(sourceDocId, destId, this.getPath(destId), options.snapshotId); return true; } /** * Get a checksum for the given file (absolute path). */ private _getHash(srcPath: string): Promise { return checksumFile(srcPath, 'md5'); } /** * We'll save hashes in a file with the suffix -hash. */ private _getHashFile(docPath: string, family: string = 'doc'): string { return docPath + `-hash-${family}`; } /** * Makes a copy of a document to a file with the suffix -backup. The copy is * made using Sqlite's backup API. The backup is made incrementally so the db * is never locked for long by the backup. The backup process will survive * transient locks on the db. */ private async _prepareBackup(docId: string, postfix: string = 'backup'): Promise { const docPath = this.getPath(docId); const tmpPath = `${docPath}-${postfix}`; return backupSqliteDatabase(docPath, tmpPath, undefined, postfix); } /** * Send a document to S3. */ private async _pushToS3(docId: string): Promise { let tmpPath: string|null = null; try { if (this._prepareFiles.has(docId)) { throw new Error('too soon to consider pushing'); } tmpPath = await this._prepareBackup(docId); const docMetadata = await this._getDocMetadata(tmpPath); const label = this._labels.get(docId); const t = this._timestamps.get(docId) || new Date().toISOString(); this._labels.delete(docId); // Keep metadata keys simple, short, and lowercase. const metadata = { ...docMetadata, ...label && {label}, t, }; const prevSnapshotId = this._latestVersions.get(docId) || null; const newSnapshotId = await this._ext.upload(docId, tmpPath, metadata); if (!newSnapshotId) { // This is unexpected. throw new Error('No snapshotId allocated after upload'); } const snapshot = { lastModified: t, snapshotId: newSnapshotId, metadata } await this._inventory.add(docId, snapshot, prevSnapshotId); await this._onInventoryChange(docId); } finally { // Clean up backup. // NOTE: fse.remove succeeds also when the file does not exist. if (tmpPath) { await fse.remove(tmpPath); } } } // Make sure inventory change is followed up on. private async _onInventoryChange(docId: string) { const scheduled = this._pruner.requestPrune(docId); if (!scheduled) { await this._inventory.flush(docId); } } // Extract actionHash, actionNum, and timezone from a document backup. private async _getDocMetadata(fname: string): Promise<{[key: string]: string}> { const result: Record = {}; const db = await SQLiteDB.openDBRaw(fname, OpenMode.OPEN_READONLY); try { const actionQuery = await db.get('select actionHash, actionNum from _gristsys_ActionHistoryBranch as b ' + 'left join _gristsys_ActionHistory as h on h.id = b.actionRef ' + 'where b.name = ?', 'shared'); const h = actionQuery?.actionHash; if (h) { result.h = h; } const n = actionQuery?.actionNum; if (n) { result.n = String(n); } } catch (e) { // Tolerate files that don't have _gristsys_* yet (although we don't need to). } try { const tzQuery = await db.get('select timezone from _grist_DocInfo where id = 1'); const tz = tzQuery?.timezone; if (tz) { result.tz = tz; } } catch (e) { // Tolerate files that don't have _grist_DocInfo yet. } await db.close(); return result; } // Wrap external storage in a checksum-aware decorator this will retry until // consistency. private _getChecksummedExternalStorage(family: string, core: ExternalStorage, versions: Map, options: HostedStorageOptions) { return new ChecksummedExternalStorage(family, core, { maxRetries: 4, initialDelayMs: options.secondsBeforeFirstRetry * 1000, computeFileHash: this._getHash.bind(this), sharedHash: { save: async (key, checksum) => { await this._docWorkerMap.updateChecksum(family, key, checksum); }, load: async (key) => { return await this._docWorkerMap.getChecksum(family, key); } }, localHash: { save: async (key, checksum) => { const fname = this._getHashFile(this.getPath(key), family); await fse.writeFile(fname, checksum); }, load: async (key) => { const fname = this._getHashFile(this.getPath(key), family); if (!await fse.pathExists(fname)) { return null; } return await fse.readFile(fname, 'utf8'); } }, latestVersion: { save: async (key, ver) => { versions.set(key, ver); }, load: async (key) => versions.get(key) || null } }); } } /** * Make a copy of a sqlite database safely and without locking it for long periods, using the * sqlite backup api. * @param src: database to copy * @param dest: file to which we copy the database * @param testProgress: a callback used for test purposes to monitor detailed timing of backup. * @param label: a tag to add to log messages * @return dest */ export async function backupSqliteDatabase(src: string, dest: string, testProgress?: (e: BackupEvent) => void, label?: string): Promise { log.debug(`backupSqliteDatabase: starting copy of ${src} (${label})`); let db: sqlite3.DatabaseWithBackup|null = null; let success: boolean = false; try { // NOTE: fse.remove succeeds also when the file does not exist. await fse.remove(dest); // Just in case some previous process terminated very badly. // Sqlite will try to open any existing material at this // path prior to overwriting it. await fromCallback(cb => { db = new sqlite3.Database(dest, cb) as sqlite3.DatabaseWithBackup; }); // Turn off protections that can slow backup steps. If the app or OS // crashes, the backup may be corrupt. In Grist use case, if app or OS // crashes, no use will be made of backup, so we're OK. // This sets flags matching the --async option to .backup in the sqlite3 // shell program: https://www.sqlite.org/src/info/7b6a605b1883dfcb await fromCallback(cb => db!.exec("PRAGMA synchronous=OFF; PRAGMA journal_mode=OFF;", cb)); if (testProgress) { testProgress({action: 'open', phase: 'before'}); } const backup: sqlite3.Backup = db!.backup(src, 'main', 'main', false); if (testProgress) { testProgress({action: 'open', phase: 'after'}); } let remaining: number = -1; let prevError: Error|null = null; let errorMsgTime: number = 0; let restartMsgTime: number = 0; for (;;) { // For diagnostic purposes, issue a message if the backup appears to have been // restarted by sqlite. The symptom of a restart we use is that the number of // pages remaining in the backup increases rather than decreases. That number // is reported by backup.remaining (after an initial period of where sqlite // doesn't yet know how many pages there are and reports -1). // So as not to spam the log if the user is making a burst of changes, we report // this message at most once a second. // See https://www.sqlite.org/c3ref/backup_finish.html and // https://github.com/mapbox/node-sqlite3/pull/1116 for api details. if (remaining >= 0 && backup.remaining > remaining && Date.now() - restartMsgTime > 1000) { log.info(`backupSqliteDatabase: copy of ${src} (${label}) restarted`); restartMsgTime = Date.now(); } remaining = backup.remaining; if (testProgress) { testProgress({action: 'step', phase: 'before'}); } let isCompleted: boolean = false; try { isCompleted = Boolean(await fromCallback(cb => backup.step(PAGES_TO_BACKUP_PER_STEP, cb))); } catch (err) { if (String(err) !== String(prevError) || Date.now() - errorMsgTime > 1000) { log.info(`backupSqliteDatabase (${src} ${label}): ${err}`); errorMsgTime = Date.now(); } prevError = err; if (backup.failed) { throw new Error(`backupSqliteDatabase (${src} ${label}): internal copy failed`); } } if (testProgress) { testProgress({action: 'step', phase: 'after'}); } if (isCompleted) { log.info(`backupSqliteDatabase: copy of ${src} (${label}) completed successfully`); success = true; break; } await delay(PAUSE_BETWEEN_BACKUP_STEPS_IN_MS); } } finally { if (testProgress) { testProgress({action: 'close', phase: 'before'}); } try { if (db) { await fromCallback(cb => db!.close(cb)); } } catch (err) { log.debug(`backupSqliteDatabase: problem stopping copy of ${src} (${label}): ${err}`); } if (!success) { // Something went wrong, remove backup if it was started. try { // NOTE: fse.remove succeeds also when the file does not exist. await fse.remove(dest); } catch (err) { log.debug(`backupSqliteDatabase: problem removing copy of ${src} (${label}): ${err}`); } } if (testProgress) { testProgress({action: 'close', phase: 'after'}); } log.debug(`backupSqliteDatabase: stopped copy of ${src} (${label})`); } return dest; } /** * A summary of an event during a backup. Emitted for test purposes, to check timing. */ export interface BackupEvent { action: 'step' | 'close' | 'open'; phase: 'before' | 'after'; }