Upload large files Spring Webflux - spring-webflux

Question

I want to upload files to a minio file container.
Smaller files work as expected with this code:
private Mono<Boolean> saveFileToMinio(FilePart filePart) {
log.info("About to save database to minio container...");
Mono<Boolean> result = Mono.from(
filePart.content().flatMap(dataBuffer -> {
var bytes = dataBuffer.asByteBuffer().array();
dataBuffer.read(bytes);
DataBufferUtils.release(dataBuffer);
return Flux.just(bytes);
})
.flatMap(databaseFileService::write)
.then(Mono.just(true))
.onErrorMap(throwable -> {
log.error(throwable.getMessage(), throwable);
return throwable;
}));
log.info("Successfully saved database to minio container...");
return result;
}
I need to provide a byte[] for my minio service to be uploaded.
Smaller files work as expected (will be stored to the container). But larger files (12 MB in my test) don´t work.
I get this exception:
java.lang.IndexOutOfBoundsException: readPosition 0 and length 1024 should be smaller than writePosition 808

Answer 1

I´ve tried a suggestion DataBufferUtils.join from another SO post. This is kind of odd but i think the following code does the job:
private Mono<Boolean> saveFileToMinio(FilePart filePart) {
var result = DataBufferUtils.join(filePart.content()).map(dataBuffer -> {
var bytes = dataBuffer.asByteBuffer().array();
dataBuffer.read(bytes);
DataBufferUtils.release(dataBuffer);
return bytes;
}).map(databaseFileService::write).then(Mono.just(true))
.onErrorMap(throwable -> {
log.error(throwable.getMessage(), throwable);
return throwable;
});
log.info("Successfully saved database to minio container...");
return result;
}
Especially this line seems to do the trick:
DataBufferUtils.join
I don´t know why but it seems to work.
EDIT:
Looking up the above static join sets a parameter maxByteCount to -1. Maybe the other (not working function for larger files) sets some limits. But i don´t know.