private Interfaces.Callback<Long> makeReader(
AsynchronousFileChannel channel,
boolean autoClose,
long position,
Interfaces.Callback<ByteBuffer> cb) {
return (err, fileSize) -> {
if (fileSize > Integer.MAX_VALUE) {
String message =
"File size "
+ fileSize
+ " exceeds maximum allowed value. Use fs.createReadStream to read big files.";
eventLoop.runTicket(() -> cb.invoke(new IOException(message), null));
return;
}
if (err != null) {
eventLoop.runTicket(() -> cb.invoke(err, null));
return;
}
eventLoop.addBackgroundOperation();
ByteBuffer buffer = ByteBuffer.allocate(fileSize.intValue());
CompletionHandler<Integer, ByteBuffer> completion =
new ReadCompletionHandler(cb, channel, autoClose);
channel.read(buffer, position, buffer, completion);
};
}
public void readFile(String path, Interfaces.Callback<ByteBuffer> cb) {
Path file = Paths.get(path);
AsynchronousFileChannel channel = openFileChannel(cb, file);
if (channel == null) {
return;
}
eventLoop.runInBackground(() -> Files.size(file), makeReader(channel, true, 0, cb));
}
private <T> AsynchronousFileChannel openFileChannel(Interfaces.Callback<T> cb, Path file) {
AsynchronousFileChannel channel = null;
try {
channel = AsynchronousFileChannel.open(file);
} catch (IOException e) {
eventLoop.runTicket(() -> cb.invoke(new RuntimeException(e), null));
}
return channel;
}
public void readFile(String path, String encoding, Interfaces.Callback<String> cb) {
Path file = Paths.get(path);
AsynchronousFileChannel channel = openFileChannel(cb, file);
if (channel == null) {
return;
}
eventLoop.runInBackground(
() -> Files.size(file),
makeReader(
channel,
true,
0,
(err, buffer) -> {
Charset charset = Charset.forName(encoding);
cb.invoke(null, new String(buffer.array(), 0, buffer.position(), charset));
}));
}