[Android] read() and readFile() lead to "A resource failed to call close"

[raphaelheinz]

Hi @birdofpreyru,

thanks for taking over the maintenance of this library. We appreciate your time and effort.

Currently, I am facing a problem that is also reproducible with the original library. I would like to read a large file (>20MB) in Android and for performance reasons I read it in chunks within a for-loop.

import * as RNFS from '@dr.pogodin/react-native-fs';

const filepath="/storage/emulated/0/Android/data/com.testpackage.app/files/Download/largeFile.bin";

const size = (await RNFS.stat(filepath)).size;
const chunkSize = 32*1024;

for(let i = 0; i < size; i += chunkSize) {
  const data = await RNFS.read(filepath, chunkSize, i, 'base64');
  // do sth with data
}

Unfortunately a lot of Android system warnings are logged in the loop:
A resource failed to call close.

Are you aware of this problems? I do not feel comfortable releasing my app which contains tons of such warnings. Can I close the file manually to prevent this warning? Or do you recommend other techniques for my use case?

Thanks very much!

[birdofpreyru]

Hey @raphaelheinz , thanks for reporting.

a problem that is also reproducible with the original library

Yeah... there are lots of minor inconsistencies and bugs in the original library, also inherited into my fork.

Are you aware of this problems?

No, I haven't noticed it, but had no chance to carefully test everything either.

Can I close the file manually to prevent this warning? Or do you recommend other techniques for my use case?

I guess, it just requires a fix in this function implementation for Android (and perhaps other functions may have the same issue):

react-native-fs/android/src/main/java/com/drpogodin/reactnativefs/ReactNativeFsModule.java

Lines 535 to 555 in fc86f09

	@ReactMethod
	public void read(
	String filepath,
	double length,
	double position,
	Promise promise
	) {
	try {
	InputStream inputStream = getInputStream(filepath);
	byte[] buffer = new byte[(int)length];
	inputStream.skip((int)position);
	int bytesRead = inputStream.read(buffer, 0, (int)length);
	String base64Content = Base64.encodeToString(buffer, 0, bytesRead, Base64.NO_WRAP);
	promise.resolve(base64Content);
	} catch (Exception ex) {
	ex.printStackTrace();
	reject(promise, filepath, ex);
	}
	}

☝️ Looking at the code, and your warning, I guess it should close the file stream at function exit, but it never does.

[raphaelheinz]

Thanks for your input!

I can confirm that this was indeed the issue. After closing the file in the Android native module, the warning has disappeared.

If you like, I can submit a pull request after work :)

[birdofpreyru]

If you like, I can submit a pull request after work :)

It will be awesome if you do :)

[ISnowFoxI]

Hello, @birdofpreyru it also doesn't close on ios as well. When I read chunks in a loop, the memory consumption just keeps on getting higher and higher. Sadly, I couldn't figure out how to close the file on my own.

[birdofpreyru]

@ISnowFoxI this does not sound surprising to me. I created a new issue to track it (#12), though no idea when I'll have capacity to look into it.