Merge pull request #17047 from overleaf/mj-ranges-in-blobstore

[overleaf-editor-core] Store tracked changes and comments in blob-store

GitOrigin-RevId: 05cc69044bf26808b64b2687d81f2c40ef4cc972

libraries/overleaf-editor-core/lib/file.js

@@ -67,11 +67,12 @@ class File {
 
   /**
    * @param  {string} hash
+   * @param  {string} [rangesHash]
    * @param  {Object} [metadata]
    * @return {File}
    */
-  static fromHash(hash, metadata) {
-    return new File(new HashFileData(hash), metadata)
+  static fromHash(hash, rangesHash, metadata) {
+    return new File(new HashFileData(hash, rangesHash), metadata)
   }
 
   /**
@@ -95,11 +96,12 @@ class File {
 
   /**
    * @param {Blob} blob
+   * @param {Blob} [blob]
    * @param {Object} [metadata]
    * @return {File}
    */
-  static createLazyFromBlob(blob, metadata) {
-    return new File(FileData.createLazyFromBlob(blob), metadata)
+  static createLazyFromBlobs(blob, rangesBlob, metadata) {
+    return new File(FileData.createLazyFromBlobs(blob, rangesBlob), metadata)
   }
 
   toRaw() {
@@ -117,6 +119,16 @@ class File {
     return this.data.getHash()
   }
 
+  /**
+   * Hexadecimal SHA-1 hash of the ranges content (comments + tracked changes),
+   * if known.
+   *
+   * @return {string | null | undefined}
+   */
+  getRangesHash() {
+    return this.data.getRangesHash()
+  }
+
   /**
    * The content of the file, if it is known and if this file has UTF-8 encoded
    * content.

libraries/overleaf-editor-core/lib/file_data/hash_file_data.js

@@ -1,58 +1,120 @@
+// @ts-check
 'use strict'
 
 const assert = require('check-types').assert
 
 const Blob = require('../blob')
 const FileData = require('./')
+/**
+ * @typedef {import('./string_file_data')} StringFileData
+ * @typedef {import('./lazy_string_file_data')} LazyStringFileData
+ * @typedef {import('./hollow_string_file_data')} HollowStringFileData
+ * @typedef {import('../types').BlobStore} BlobStore
+ */
 
 class HashFileData extends FileData {
   /**
    * @constructor
    * @param {string} hash
+   * @param {string} [rangesHash]
    * @see FileData
    */
-  constructor(hash) {
+  constructor(hash, rangesHash) {
     super()
     assert.match(hash, Blob.HEX_HASH_RX, 'HashFileData: bad hash')
+    if (rangesHash) {
+      assert.match(
+        rangesHash,
+        Blob.HEX_HASH_RX,
+        'HashFileData: bad ranges hash'
+      )
+    }
     this.hash = hash
+    this.rangesHash = rangesHash
   }
 
+  /**
+   *
+   * @param {{hash: string, rangesHash?: string}} raw
+   * @returns
+   */
   static fromRaw(raw) {
-    return new HashFileData(raw.hash)
+    return new HashFileData(raw.hash, raw.rangesHash)
   }
 
-  /** @inheritdoc */
+  /**
+   * @inheritdoc
+   * @returns {{hash: string, rangesHash?: string}}
+   */
   toRaw() {
-    return { hash: this.hash }
+    const raw = { hash: this.hash }
+    if (this.rangesHash) {
+      raw.rangesHash = this.rangesHash
+    }
+    return raw
   }
 
-  /** @inheritdoc */
+  /**
+   * @inheritdoc
+   * @returns {string}
+   */
   getHash() {
     return this.hash
   }
 
-  /** @inheritdoc */
+  /**
+   * @inheritdoc
+   * @returns {string | undefined}
+   */
+  getRangesHash() {
+    return this.rangesHash
+  }
+
+  /**
+   * @inheritdoc
+   * @param {BlobStore} blobStore
+   * @returns {Promise<StringFileData>}
+   */
   async toEager(blobStore) {
     const lazyFileData = await this.toLazy(blobStore)
     return await lazyFileData.toEager(blobStore)
   }
 
-  /** @inheritdoc */
+  /**
+   * @inheritdoc
+   * @param {BlobStore} blobStore
+   * @returns {Promise<LazyStringFileData>}
+   */
   async toLazy(blobStore) {
     const blob = await blobStore.getBlob(this.hash)
+    let rangesBlob
+    if (this.rangesHash) {
+      rangesBlob = await blobStore.getBlob(this.rangesHash)
+    }
     if (!blob) throw new Error('blob not found: ' + this.hash)
-    return FileData.createLazyFromBlob(blob)
+    return FileData.createLazyFromBlobs(blob, rangesBlob)
   }
 
-  /** @inheritdoc */
+  /**
+   * @inheritdoc
+   * @param {BlobStore} blobStore
+   * @returns {Promise<HollowStringFileData>}
+   */
   async toHollow(blobStore) {
     const blob = await blobStore.getBlob(this.hash)
     return FileData.createHollow(blob.getByteLength(), blob.getStringLength())
   }
 
-  /** @inheritdoc */
+  /**
+   * @inheritdoc
+   * @returns {Promise<{hash: string, rangesHash?: string}>}
+   */
   async store() {
-    return { hash: this.hash }
+    const raw = { hash: this.hash }
+    if (this.rangesHash) {
+      raw.rangesHash = this.rangesHash
+    }
+    return raw
   }
 }
 

libraries/overleaf-editor-core/lib/file_data/index.js

@@ -50,13 +50,21 @@ class FileData {
     return new HollowStringFileData(stringLength)
   }
 
-  /** @see File.createLazyFromBlob */
-  static createLazyFromBlob(blob) {
+  /**
+   * @see File.createLazyFromBlob
+   * @param {Blob} blob
+   * @param {Blob} [rangesBlob]
+   */
+  static createLazyFromBlobs(blob, rangesBlob) {
     assert.instance(blob, Blob, 'FileData: bad blob')
     if (blob.getStringLength() == null) {
       return new BinaryFileData(blob.getHash(), blob.getByteLength())
     }
-    return new LazyStringFileData(blob.getHash(), blob.getStringLength())
+    return new LazyStringFileData(
+      blob.getHash(),
+      rangesBlob?.getHash(),
+      blob.getStringLength()
+    )
   }
 
   toRaw() {
@@ -72,6 +80,14 @@ class FileData {
     return null
   }
 
+  /**
+   * @see File#getHash
+   * @return {string | null | undefined}
+   */
+  getRangesHash() {
+    return null
+  }
+
   /**
    * @see File#getContent
    * @return {string | null | undefined}

libraries/overleaf-editor-core/lib/file_data/lazy_string_file_data.js

@@ -10,20 +10,30 @@ const EagerStringFileData = require('./string_file_data')
 const EditOperation = require('../operation/edit_operation')
 const EditOperationBuilder = require('../operation/edit_operation_builder')
 
+/**
+ *  @typedef {import('../types').BlobStore} BlobStore
+ *  @typedef {import('../types').RangesBlob} RangesBlob
+ */
+
 class LazyStringFileData extends FileData {
   /**
    * @param {string} hash
+   * @param {string | undefined} rangesHash
    * @param {number} stringLength
    * @param {Array.<EditOperation>} [operations]
    * @see FileData
    */
-  constructor(hash, stringLength, operations) {
+  constructor(hash, rangesHash, stringLength, operations) {
     super()
     assert.match(hash, Blob.HEX_HASH_RX)
+    if (rangesHash) {
+      assert.match(rangesHash, Blob.HEX_HASH_RX)
+    }
     assert.greaterOrEqual(stringLength, 0)
     assert.maybe.array.of.instance(operations, EditOperation)
 
     this.hash = hash
+    this.rangesHash = rangesHash
     this.stringLength = stringLength
     this.operations = operations || []
   }
@@ -31,6 +41,7 @@ class LazyStringFileData extends FileData {
   static fromRaw(raw) {
     return new LazyStringFileData(
       raw.hash,
+      raw.rangesHash,
       raw.stringLength,
       raw.operations && _.map(raw.operations, EditOperationBuilder.fromJSON)
     )
@@ -39,6 +50,9 @@ class LazyStringFileData extends FileData {
   /** @inheritdoc */
   toRaw() {
     const raw = { hash: this.hash, stringLength: this.stringLength }
+    if (this.rangesHash) {
+      raw.rangesHash = this.rangesHash
+    }
     if (this.operations.length) {
       raw.operations = _.map(this.operations, function (operation) {
         return operation.toJSON()
@@ -53,6 +67,12 @@ class LazyStringFileData extends FileData {
     return this.hash
   }
 
+  /** @inheritdoc */
+  getRangesHash() {
+    if (this.operations.length) return null
+    return this.rangesHash
+  }
+
   /** @inheritdoc */
   isEditable() {
     return true
@@ -86,11 +106,20 @@ class LazyStringFileData extends FileData {
 
   /**
    * @inheritdoc
+   * @param {BlobStore} blobStore
    * @returns {Promise<EagerStringFileData>}
    */
   async toEager(blobStore) {
     const content = await blobStore.getString(this.hash)
-    const file = new EagerStringFileData(content)
+    let comments
+    let trackedChanges
+    if (this.rangesHash) {
+      /** @type {RangesBlob} */
+      const ranges = await blobStore.getObject(this.rangesHash)
+      comments = ranges.comments
+      trackedChanges = ranges.trackedChanges
+    }
+    const file = new EagerStringFileData(content, comments, trackedChanges)
     applyOperations(this.operations, file)
     return file
   }
@@ -114,7 +143,11 @@ class LazyStringFileData extends FileData {
   /** @inheritdoc */
   async store(blobStore) {
     if (this.operations.length === 0) {
-      return { hash: this.hash }
+      const raw = { hash: this.hash }
+      if (this.rangesHash) {
+        raw.rangesHash = this.rangesHash
+      }
+      return raw
     }
     const eager = await this.toEager(blobStore)
     this.operations.length = 0

libraries/overleaf-editor-core/lib/file_data/string_file_data.js

@@ -13,6 +13,7 @@ const TrackedChangeList = require('./tracked_change_list')
  * @typedef {import("../types").BlobStore} BlobStore
  * @typedef {import("../types").CommentsListRawData} CommentsListRawData
  * @typedef {import("../types").TrackedChangeRawData} TrackedChangeRawData
+ * @typedef {import('../types').RangesBlob} RangesBlob
  */
 
 class StringFileData extends FileData {
@@ -111,6 +112,15 @@ class StringFileData extends FileData {
    */
   async store(blobStore) {
     const blob = await blobStore.putString(this.content)
+    if (this.comments.comments.size || this.trackedChanges.length) {
+      /** @type {RangesBlob} */
+      const ranges = {
+        comments: this.getComments(),
+        trackedChanges: this.trackedChanges.toRaw(),
+      }
+      const rangesBlob = await blobStore.putObject(ranges)
+      return { hash: blob.getHash(), rangesHash: rangesBlob.getHash() }
+    }
     return { hash: blob.getHash() }
   }
 }

libraries/overleaf-editor-core/lib/snapshot.js

@@ -186,7 +186,9 @@ class Snapshot {
     // eslint-disable-next-line array-callback-return
     this.fileMap.map(file => {
       const hash = file.getHash()
+      const rangeHash = file.getRangesHash()
       if (hash) blobHashes.add(hash)
+      if (rangeHash) blobHashes.add(rangeHash)
     })
   }
 

libraries/overleaf-editor-core/lib/types.ts

@@ -1,8 +1,16 @@
 import Blob from './blob'
 
 export type BlobStore = {
+  getBlob(hash: string): Promise<Blob>
   getString(hash: string): Promise<string>
   putString(content: string): Promise<Blob>
+  putObject(obj: object): Promise<Blob>
+  getObject<T = unknown>(hash: string): Promise<T>
+}
+
+export type RangesBlob = {
+  comments: CommentsListRawData
+  trackedChanges: TrackedChangeRawData[]
 }
 
 type Range = {

libraries/overleaf-editor-core/package.json

@@ -22,7 +22,8 @@
   "devDependencies": {
     "chai": "^3.3.0",
     "mocha": "^10.2.0",
-    "typescript": "^5.0.4"
+    "typescript": "^5.0.4",
+    "sinon": "^9.2.4"
   },
   "dependencies": {
     "@overleaf/o-error": "*",

libraries/overleaf-editor-core/test/file.test.js

@@ -23,7 +23,7 @@ describe('File', function () {
   describe('toRaw', function () {
     it('returns non-empty metadata', function () {
       const metadata = { main: true }
-      const file = File.fromHash(File.EMPTY_FILE_HASH, metadata)
+      const file = File.fromHash(File.EMPTY_FILE_HASH, undefined, metadata)
       expect(file.toRaw()).to.eql({
         hash: File.EMPTY_FILE_HASH,
         metadata,
@@ -35,7 +35,7 @@ describe('File', function () {
 
     it('returns a deep clone of metadata', function () {
       const metadata = { externalFile: { id: 123 } }
-      const file = File.fromHash(File.EMPTY_FILE_HASH, metadata)
+      const file = File.fromHash(File.EMPTY_FILE_HASH, undefined, metadata)
       const raw = file.toRaw()
       const fileMetadata = file.getMetadata()
       const rawMetadata = raw.metadata
@@ -54,7 +54,7 @@ describe('File', function () {
 
     it('returns non-empty metadata', async function () {
       const metadata = { main: true }
-      const file = File.fromHash(File.EMPTY_FILE_HASH, metadata)
+      const file = File.fromHash(File.EMPTY_FILE_HASH, undefined, metadata)
       const fakeBlobStore = new FakeBlobStore()
       const raw = await file.store(fakeBlobStore)
       expect(raw).to.eql({
@@ -65,7 +65,7 @@ describe('File', function () {
 
     it('returns a deep clone of metadata', async function () {
       const metadata = { externalFile: { id: 123 } }
-      const file = File.fromHash(File.EMPTY_FILE_HASH, metadata)
+      const file = File.fromHash(File.EMPTY_FILE_HASH, undefined, metadata)
       const fakeBlobStore = new FakeBlobStore()
       const raw = await file.store(fakeBlobStore)
       raw.metadata.externalFile.id = 456

libraries/overleaf-editor-core/test/lazy_string_file_data.test.js

@@ -1,20 +1,53 @@
+// @ts-check
 'use strict'
 
 const _ = require('lodash')
 const { expect } = require('chai')
+const sinon = require('sinon')
 
 const ot = require('..')
 const File = ot.File
 const TextOperation = ot.TextOperation
 const LazyStringFileData = require('../lib/file_data/lazy_string_file_data')
+const EagerStringFileData = require('../lib/file_data/string_file_data')
 
 describe('LazyStringFileData', function () {
+  beforeEach(function () {
+    this.rangesHash = '380de212d09bf8498065833dbf242aaf11184316'
+    this.fileHash = 'a5675307b61ec2517330622a6e649b4ca1ee5612'
+    this.blobStore = {
+      getString: sinon.stub(),
+      putString: sinon.stub().resolves(new ot.Blob(this.fileHash, 19, 19)),
+      getObject: sinon.stub(),
+      putObject: sinon.stub().resolves(new ot.Blob(this.rangesHash, 204, 204)),
+    }
+    this.blobStore.getString.withArgs(File.EMPTY_FILE_HASH).resolves('')
+    this.blobStore.getString
+      .withArgs(this.fileHash)
+      .resolves('the quick brown fox')
+    this.blobStore.getObject.withArgs(this.rangesHash).resolves({
+      comments: [
+        { id: 'foo', ranges: [{ pos: 0, length: 3 }], resolved: false },
+      ],
+      trackedChanges: [
+        {
+          range: { pos: 4, length: 5 },
+          tracking: {
+            type: 'delete',
+            userId: 'user1',
+            ts: '2024-01-01T00:00:00.000Z',
+          },
+        },
+      ],
+    })
+  })
+
   it('uses raw text operations for toRaw and fromRaw', function () {
     const testHash = File.EMPTY_FILE_HASH
-    const fileData = new LazyStringFileData(testHash, 0)
+    const fileData = new LazyStringFileData(testHash, undefined, 0)
     let roundTripFileData
 
-    expect(fileData.toRaw()).to.eql({
+    expect(fileData.toRaw()).to.deep.equal({
       hash: testHash,
       stringLength: 0,
     })
@@ -24,7 +57,7 @@ describe('LazyStringFileData', function () {
     expect(roundTripFileData.getOperations()).to.have.length(0)
 
     fileData.edit(new TextOperation().insert('a'))
-    expect(fileData.toRaw()).to.eql({
+    expect(fileData.toRaw()).to.deep.equal({
       hash: testHash,
       stringLength: 1,
       operations: [{ textOperation: ['a'] }],
@@ -33,10 +66,15 @@ describe('LazyStringFileData', function () {
     expect(roundTripFileData.getHash()).not.to.exist // file has changed
     expect(roundTripFileData.getStringLength()).to.equal(1)
     expect(roundTripFileData.getOperations()).to.have.length(1)
-    expect(roundTripFileData.getOperations()[0].ops).to.have.length(1)
+    expect(roundTripFileData.getOperations()[0]).to.be.instanceOf(TextOperation)
+    expect(
+      /** @type {InstanceType<TextOperation>} */ (
+        roundTripFileData.getOperations()[0]
+      ).ops
+    ).to.have.length(1)
 
     fileData.edit(new TextOperation().retain(1).insert('b'))
-    expect(fileData.toRaw()).to.eql({
+    expect(fileData.toRaw()).to.deep.equal({
       hash: testHash,
       stringLength: 2,
       operations: [{ textOperation: ['a'] }, { textOperation: [1, 'b'] }],
@@ -45,13 +83,75 @@ describe('LazyStringFileData', function () {
     expect(roundTripFileData.getHash()).not.to.exist // file has changed
     expect(roundTripFileData.getStringLength()).to.equal(2)
     expect(roundTripFileData.getOperations()).to.have.length(2)
-    expect(roundTripFileData.getOperations()[0].ops).to.have.length(1)
-    expect(roundTripFileData.getOperations()[1].ops).to.have.length(2)
+    expect(
+      /** @type {InstanceType<TextOperation>} */ (
+        roundTripFileData.getOperations()[0]
+      ).ops
+    ).to.have.length(1)
+    expect(
+      /** @type {InstanceType<TextOperation>} */ (
+        roundTripFileData.getOperations()[1]
+      ).ops
+    ).to.have.length(2)
+  })
+
+  it('should include rangesHash in toRaw and fromRaw when available', function () {
+    const testHash = File.EMPTY_FILE_HASH
+    const rangesHash = this.rangesHash
+    const fileData = new LazyStringFileData(testHash, rangesHash, 19)
+
+    expect(fileData.toRaw()).to.deep.equal({
+      hash: testHash,
+      rangesHash,
+      stringLength: 19,
+    })
+
+    const roundTripFileData = LazyStringFileData.fromRaw(fileData.toRaw())
+    expect(roundTripFileData.getHash()).to.equal(testHash)
+    expect(roundTripFileData.getRangesHash()).to.equal(rangesHash)
+    expect(roundTripFileData.getStringLength()).to.equal(19)
+    expect(roundTripFileData.getOperations()).to.have.length(0)
+  })
+
+  it('should fetch content from blob store when loading eager string', async function () {
+    const testHash = this.fileHash
+    const rangesHash = this.rangesHash
+    const fileData = new LazyStringFileData(testHash, rangesHash, 19)
+    const eagerString = await fileData.toEager(this.blobStore)
+    expect(eagerString).to.be.instanceOf(EagerStringFileData)
+    expect(eagerString.getContent()).to.equal('the quick brown fox')
+    expect(eagerString.getComments()).to.deep.equal([
+      { id: 'foo', ranges: [{ pos: 0, length: 3 }], resolved: false },
+    ])
+    expect(eagerString.trackedChanges.toRaw()).to.deep.equal([
+      {
+        range: { pos: 4, length: 5 },
+        tracking: {
+          type: 'delete',
+          userId: 'user1',
+          ts: '2024-01-01T00:00:00.000Z',
+        },
+      },
+    ])
+    expect(this.blobStore.getObject.calledWith(rangesHash)).to.be.true
+    expect(this.blobStore.getString.calledWith(testHash)).to.be.true
+  })
+
+  it('should not fetch ranges from blob store if not present', async function () {
+    const testHash = this.fileHash
+    const fileData = new LazyStringFileData(testHash, undefined, 19)
+    const eagerString = await fileData.toEager(this.blobStore)
+    expect(eagerString).to.be.instanceOf(EagerStringFileData)
+    expect(eagerString.getContent()).to.equal('the quick brown fox')
+    expect(eagerString.getComments()).to.be.empty
+    expect(eagerString.trackedChanges.length).to.equal(0)
+    expect(this.blobStore.getObject.called).to.be.false
+    expect(this.blobStore.getString.calledWith(testHash)).to.be.true
   })
 
   it('validates operations when edited', function () {
     const testHash = File.EMPTY_FILE_HASH
-    const fileData = new LazyStringFileData(testHash, 0)
+    const fileData = new LazyStringFileData(testHash, undefined, 0)
     expect(fileData.getHash()).equal(testHash)
     expect(fileData.getByteLength()).to.equal(0) // approximately
     expect(fileData.getStringLength()).to.equal(0)
@@ -74,7 +174,7 @@ describe('LazyStringFileData', function () {
 
   it('validates string length when edited', function () {
     const testHash = File.EMPTY_FILE_HASH
-    const fileData = new LazyStringFileData(testHash, 0)
+    const fileData = new LazyStringFileData(testHash, undefined, 0)
     expect(fileData.getHash()).equal(testHash)
     expect(fileData.getByteLength()).to.equal(0) // approximately
     expect(fileData.getStringLength()).to.equal(0)

package-lock.json

@@ -454,6 +454,7 @@
       "devDependencies": {
         "chai": "^3.3.0",
         "mocha": "^10.2.0",
+        "sinon": "^9.2.4",
         "typescript": "^5.0.4"
       }
     },
@@ -75729,6 +75730,7 @@
         "lodash": "^4.17.19",
         "mocha": "^10.2.0",
         "p-map": "^4.0.0",
+        "sinon": "^9.2.4",
         "typescript": "^5.0.4"
       },
       "dependencies": {

services/history-v1/storage/lib/blob_store/index.js

@@ -32,13 +32,14 @@ function makeProjectKey(projectId, hash) {
   return `${projectKey.format(projectId)}/${hash.slice(0, 2)}/${hash.slice(2)}`
 }
 
-async function uploadBlob(projectId, blob, stream) {
+async function uploadBlob(projectId, blob, stream, opts = {}) {
   const bucket = config.get('blobStore.projectBucket')
   const key = makeProjectKey(projectId, blob.getHash())
   logger.debug({ projectId, blob }, 'uploadBlob started')
   try {
     await persistor.sendStream(bucket, key, stream, {
       contentType: 'application/octet-stream',
+      ...opts,
     })
   } finally {
     logger.debug({ projectId, blob }, 'uploadBlob finished')
@@ -162,7 +163,7 @@ class BlobStore {
    * string content.
    *
    * @param {string} string
-   * @return {Promise.<Blob>}
+   * @return {Promise.<core.Blob>}
    */
   async putString(string) {
     assert.string(string, 'bad string')
@@ -185,7 +186,7 @@ class BlobStore {
    * temporary file).
    *
    * @param {string} pathname
-   * @return {Promise.<Blob>}
+   * @return {Promise.<core.Blob>}
    */
   async putFile(pathname) {
     assert.string(pathname, 'bad pathname')
@@ -205,6 +206,27 @@ class BlobStore {
   }
 
   /**
+   * Stores an object as a gzipped JSON string in a blob.
+   *
+   * @param {object} obj
+   * @returns {Promise.<core.Blob>}
+   */
+  async putObject(obj) {
+    assert.object(obj, 'bad object')
+    const string = JSON.stringify(obj)
+    const hash = blobHash.fromString(string)
+    const stream = await streams.gzipStringToStream(string)
+    const newBlob = new Blob(hash, Buffer.byteLength(string), string.length)
+    await uploadBlob(this.projectId, newBlob, stream, {
+      contentEncoding: 'gzip',
+      contentType: 'application/json',
+    })
+    await this.backend.insertBlob(this.projectId, newBlob)
+    return newBlob
+  }
+
+  /**
+   *
    * Fetch a blob's content by its hash as a UTF-8 encoded string.
    *
    * @param {string} hash hexadecimal SHA-1 hash
@@ -224,6 +246,27 @@ class BlobStore {
     }
   }
 
+  /**
+   * Fetch a JSON encoded gzipped blob by its hash, decompress and deserialize
+   * it.
+   *
+   * @template [T=unknown]
+   * @param {string} hash hexadecimal SHA-1 hash
+   * @return {Promise.<T>} promise for the content of the file
+   */
+  async getObject(hash) {
+    assert.blobHash(hash, 'bad hash')
+    const projectId = this.projectId
+    logger.debug({ projectId, hash }, 'getObject started')
+    try {
+      const stream = await this.getStream(hash)
+      const buffer = await streams.gunzipStreamToBuffer(stream)
+      return JSON.parse(buffer.toString())
+    } finally {
+      logger.debug({ projectId, hash }, 'getObject finished')
+    }
+  }
+
   /**
    * Fetch a blob by its hash as a stream.
    *
@@ -252,7 +295,7 @@ class BlobStore {
    * Read a blob metadata record by hexadecimal hash.
    *
    * @param {string} hash hexadecimal SHA-1 hash
-   * @return {Promise.<Blob?>}
+   * @return {Promise.<core.Blob?>}
    */
   async getBlob(hash) {
     assert.blobHash(hash, 'bad hash')

services/history-v1/storage/lib/streams.js

@@ -10,6 +10,15 @@ const zlib = require('zlib')
 const { WritableBuffer, ReadableString } = require('@overleaf/stream-utils')
 const { pipeline } = require('stream')
 
+/**
+ * Pipe a read stream to a write stream. The promise resolves when the write
+ * stream finishes.
+ *
+ * @function
+ * @param {stream.Readable} readStream
+ * @param {stream.Writable} writeStream
+ * @return {Promise}
+ */
 function promisePipe(readStream, writeStream) {
   return new BPromise(function (resolve, reject) {
     pipeline(readStream, writeStream, function (err) {
@@ -22,17 +31,15 @@ function promisePipe(readStream, writeStream) {
   })
 }
 
+exports.promisePipe = promisePipe
+
 /**
- * Pipe a read stream to a write stream. The promise resolves when the write
- * stream finishes.
+ * Create a promise for the result of reading a stream to a buffer.
  *
  * @function
  * @param {stream.Readable} readStream
- * @param {stream.Writable} writeStream
- * @return {Promise}
+ * @return {Promise.<Buffer>}
  */
-exports.promisePipe = promisePipe
-
 function readStreamToBuffer(readStream) {
   return new BPromise(function (resolve, reject) {
     const bufferStream = new WritableBuffer()
@@ -46,15 +53,15 @@ function readStreamToBuffer(readStream) {
   })
 }
 
+exports.readStreamToBuffer = readStreamToBuffer
+
 /**
- * Create a promise for the result of reading a stream to a buffer.
+ * Create a promise for the result of un-gzipping a stream to a buffer.
  *
  * @function
  * @param {stream.Readable} readStream
  * @return {Promise.<Buffer>}
  */
-exports.readStreamToBuffer = readStreamToBuffer
-
 function gunzipStreamToBuffer(readStream) {
   const gunzip = zlib.createGunzip()
   const bufferStream = new WritableBuffer()
@@ -69,15 +76,15 @@ function gunzipStreamToBuffer(readStream) {
   })
 }
 
+exports.gunzipStreamToBuffer = gunzipStreamToBuffer
+
 /**
- * Create a promise for the result of un-gzipping a stream to a buffer.
+ * Create a write stream that gzips the given string.
  *
  * @function
- * @param {stream.Readable} readStream
- * @return {Promise.<Buffer>}
+ * @param {string} string
+ * @return {Promise.<stream.Readable>}
  */
-exports.gunzipStreamToBuffer = gunzipStreamToBuffer
-
 function gzipStringToStream(string) {
   return new BPromise(function (resolve, reject) {
     zlib.gzip(Buffer.from(string), function (error, result) {
@@ -90,11 +97,4 @@ function gzipStringToStream(string) {
   })
 }
 
-/**
- * Create a write stream that gzips the given string.
- *
- * @function
- * @param {string} string
- * @return {Promise.<stream.Readable>}
- */
 exports.gzipStringToStream = gzipStringToStream