Append/read lock compatibility in a distributed file system

摘要

Extensions are provided to a lock for supporting concurrency of read and write operations of a shared resource in a computer system. Both reader and writer modes are maintained. In addition, an append mode and a prefix mode are provided. The append mode supports non-exclusive access to the shared resource while enabling modification of the shared resource after a marker. The prefix mode supports non-exclusive access to read the shared resource prior to the marker. Lock mode requests to the shared resources are mediated to ensure compatibility of granted lock modes with lock mode requests.