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instance method

IO::Buffer::Storage#shared?

shared? → true or false

static VALUE
rb_io_buffer_shared_p(VALUE self)
{
    struct rb_io_buffer_view *buffer = get_io_buffer_view(self);

    return RBOOL(buffer->flags & RB_IO_BUFFER_SHARED);
}

If the buffer is shared, meaning it references memory that can be shared with other processes (and thus might change without being modified locally).

Example

# Create a test file:
File.write('test.txt', 'test')

# Create a shared mapping from the given file, the file must be opened in
# read-write mode unless we also specify IO::Buffer::READONLY:
buffer = IO::Buffer.map(File.open('test.txt', 'r+'), nil, 0)
# => #<IO::Buffer 0x00007f1bffd5e000+4 EXTERNAL MAPPED SHARED>

# Write to the buffer, which will modify the mapped file:
buffer.set_string('b', 0)
# => 1

# The file itself is modified:
File.read('test.txt')
# => "best"