Skip to content

Remove work-around for uart_get_buffered_data_len #890

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jul 28, 2022
Merged

Remove work-around for uart_get_buffered_data_len #890

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
13 changes: 3 additions & 10 deletions src/resources/uart_esp32.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -290,17 +290,12 @@ PRIMITIVE(read) {
return Primitive::os_error(err, process);
}

// The uart_get_buffered_data_len is not thread safe, so it's not guaranteed that
// we get an updated value. As false negatives can lead to deadlock, we don't trust
// when it returns 0. To work around this, we instead try to read 8 bytes, whenever
// we are suggested 0; it is always safe to try to read too much, so this is only a
// performance issue.
size_t capacity = Utils::max(available, (size_t)8);

Error* error = null;
ByteArray* data = process->allocate_byte_array(capacity, &error, /*force_external*/ true);
ByteArray* data = process->allocate_byte_array(available, &error, /*force_external*/ available != 0);
if (data == null) return error;

if (available == 0) return data;

ByteArray::Bytes rx(data);
int read = uart_read_bytes(uart->port(), rx.address(), rx.length(), 0);
if (read == -1) {
Expand All @@ -311,8 +306,6 @@ PRIMITIVE(read) {
return process->allocate_string_or_error("broken UART read");
}

data->resize_external(process, read);

return data;
}

Expand Down