[GitHub] [cordova-plugin-file] grizio opened a new issue #311: Application crash with big data (JSON)

[GitBox <gi...@apache.org>]

grizio opened a new issue #311: Application crash with big data (JSON)
URL: https://github.com/apache/cordova-plugin-file/issues/311
 
 
   # Bug Report
   
   ## Problem
   
   ### What is expected to happen?
   
   The (big) data is correctly written in the file.
   
   ### What does actually happen?
   
   The application crashes.
   
   ### 💡
   
   I found a workaround but I think it remains an issue in the codebase (and could impact other developers). The below for the workaround.
   
   ## Information
   
   I use:
   
   * cordova-plugin-file
   * react-native
   * redux-persist
   
   For the persistance (with redux-persist), I have a custom storage handler to write into a file.
   The write part is very simple :
   
   ```typescript
   function writeFile(fileEntry: FileEntry, data: any): Promise<void> {
     return new Promise((resolve, reject) => {
       fileEntry.createWriter(writer => {
         writer.onerror = reject
         writer.onwriteend = resolve
         writer.write(new Blob([JSON.stringify(data)], { type: 'text/plain' }))
       }, reject)
     })
   }
   ```
   
   However, with an evolution, our `data` passed from ~2Mo to ~20Mo. At this moment, the application crashes when saving the file.
   It is the call to `writer.write` which seemed to cause the application to crash, if I build the Blob without saving it, I do not have any issue.
   
   The size of the data differs from IOS and ipad version.
   
   ### Workaround
   
   I corrected (quick-win) the issue by doing so:
   
   ```typescript
   function writeFile(fileEntry: FileEntry, data: any): Promise<void> {
     return new Promise((resolve, reject) => {
       fileEntry.createWriter(writer => {
         splitByChunks(JSON.stringify(data), 1000 * 1000) // 1Mo
           // Ensure order of execution, could be improved
           .reduce((acc, chunk) => acc.then(() => writeChunk(writer, chunk)), Promise.resolve())
           .then(resolve)
           .catch(reject)
       }, reject)
     })
   }
   
   function writeChunk(writer: FileWriter, chunk: string): Promise<void> {
     // tslint:disable:no-object-mutation
     return new Promise((resolve, reject) => {
       writer.onerror = reject
       writer.onwriteend = () => {
         resolve()
       }
       writer.write(new Blob([chunk], { type: 'text/plain' }))
     })
     // tslint:enable:no-object-mutation
   }
   
   function splitByChunks(value: string, chunkLength: number): ReadonlyArray<string> {
     return Array(Math.ceil(value.length / chunkLength))
       .fill(0)
       .map((_, index) => value.slice(index * chunkLength, (index + 1) * chunkLength))
   }
   ```
   
   Although this correction works in my project there is an issue when the file is not totally written (application closed during write). I resolved it by ignoring incomplete file (= `JSON.parse` fails) because my project permits it.
   
   ### Environment, Platform, Device
   
   * ipad4 / ios10
   * ipad5 / ios12
   * ipad6 / ios12
   
   ### Version information
   
   * cordova: 8.1.2
   * "cordova-browser": "5.0.1", // also tested on v6.0.1 - same issue
   * "cordova-ios": "4.5.4",
   * "cordova-plugin-file": "5.0.0",
   
   ## Checklist
   
   - [x] I searched for existing GitHub issues
     * Maybe related: #291, #297
   - [x] I updated all Cordova tooling to most recent version
     * But rolled back because of some incompatibilities in other parts of the application, issue still happening in last versions
   - [x] I included all the necessary information above
   
   Thanks for the plugin! 👍 

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