feat(FSYNC): Optional fsync when saving the database

Merge pull request #372 from drproktor/optional-fsync You can configure it in the settings.
Belphemur · Mar 11, 2022 · d1c67fd · d1c67fd
2 parents c33211e + c8fa0f7
commit d1c67fd
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Showing 3 changed files with 36 additions and 6 deletions.
diff --git a/src/JsonDB.ts b/src/JsonDB.ts
@@ -24,13 +24,14 @@ export class JsonDB {
    * @param saveOnPush save the database at each push command into the json file
    * @param humanReadable the JSON file will be readable easily by a human
    * @param separator what to use as separator
+   * @param syncOnSave force sync of the database (call fsync())
    */
-    constructor(filename: string | Config, saveOnPush: boolean = true, humanReadable: boolean = false, separator: string = '/') {
+    constructor(filename: string | Config, saveOnPush: boolean = true, humanReadable: boolean = false, separator: string = '/', syncOnSave: boolean = false) {
 
         if(filename instanceof Config) {
           this.config = filename
         } else {
-          this.config = new Config(filename, saveOnPush, humanReadable, separator)
+          this.config = new Config(filename, saveOnPush, humanReadable, separator, syncOnSave)
         }
 
         if (!FS.existsSync(this.config.filename)) {
@@ -363,7 +364,24 @@ export class JsonDB {
             else {
                 data = JSON.stringify(this.data)
             }
-            FS.writeFileSync(this.config.filename, data, 'utf8')
+            if(this.config.syncOnSave) {
+                const buffer = Buffer.from(String(data), 'utf8')
+                const fd_tmp = FS.openSync(this.config.filename, 'w')
+                let offset = 0
+                let length = buffer.byteLength
+                try {
+                    while (length > 0) {
+                    const written = FS.writeSync(fd_tmp, buffer, offset, length)
+                    offset += written
+                    length -= written
+                    }
+                } finally {
+                    FS.fsyncSync(fd_tmp)
+                    FS.closeSync(fd_tmp)
+                }
+            } else {
+                FS.writeFileSync(this.config.filename, data, 'utf8')
+            }
         } catch (err) {
             const error = new DatabaseError("Can't save the database", 2, err)
             throw error

diff --git a/src/lib/JsonDBConfig.ts b/src/lib/JsonDBConfig.ts
@@ -4,17 +4,18 @@ export interface JsonDBConfig {
   filename: string,
   saveOnPush: boolean,
   humanReadable: boolean,
-  separator: string
+  separator: string,
+  syncOnSave: boolean
 }
 
 export class Config implements JsonDBConfig {
   filename: string
   humanReadable: boolean
   saveOnPush: boolean
   separator: string
+  syncOnSave: boolean
 
-
-  constructor(filename: string, saveOnPush: boolean = true, humanReadable: boolean = false, separator: string = '/') {
+  constructor(filename: string, saveOnPush: boolean = true, humanReadable: boolean = false, separator: string = '/', syncOnSave: boolean = false) {
     this.filename = filename
 
     // Force json if no extension
@@ -25,5 +26,6 @@ export class Config implements JsonDBConfig {
     this.humanReadable = humanReadable
     this.saveOnPush = saveOnPush
     this.separator = separator
+    this.syncOnSave = syncOnSave
   }
 }
diff --git a/test/02-jsondb.test.ts b/test/02-jsondb.test.ts
@@ -10,6 +10,7 @@ const testFile3 = "test/test_file3"
 const testFile4 = "test/array_file"
 const testFile5 = "test/test_file_empty"
 const testFile6 = "test/test_delete"
+const testFile7 = "test/test_sync"
 
 
 interface Test {
@@ -56,6 +57,14 @@ describe('JsonDB', () => {
 
         })
 
+        test('should create JSON file with sync', done => {
+            const jsondb = new JsonDB(testFile7, true, false, '/', true)
+            fs.access(testFile7+ ".json", fs.constants.R_OK, function (err) {
+                expect(err).toBeNull()
+                done()
+            })
+        })
+
         test('should set en empty root', () => {
             expect(JSON.stringify(db.getData("/"))).toEqual("{}")
         })
@@ -652,6 +661,7 @@ describe('JsonDB', () => {
             fs.unlinkSync(testFile4 + ".json")
             fs.unlinkSync(testFile5 + ".json")
             fs.unlinkSync(testFile6 + ".json")
+            fs.unlinkSync(testFile7 + ".json")
             fs.rmdirSync("test/dirCreation")
         })
     })