[LUCY-83] FSFileHandle

• Type: Sub-task
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Component/s: Core
• Assignee: Marvin Humphrey
• Reporter: Marvin Humphrey
• Created: 06/Dec/09 00:06
• Updated: 06/Dec/09 20:23
• Resolved: 06/Dec/09 20:23

Description

FSFileHandle abstracts out low level interaction with the OS and file system.

Some form of memory map support is required: mmap() on unixen, and
CreateFileMapping()/MapViewOfFile() on Windows.

Only atomic, positional reads are supported, using 64-bit pread() on unixen,
and ReadFile() with an OVERLAPPED structure on Windows.

Multiple InStreams may share a single read-only FSFileHandle, because
FSFH_Read() does not change file position or other state in the underlying
OS-specific file object. Theoretically, operating multiple InStreams in
different threads against a single shared FileHandle will also work – which
is crucial for threadsafe compound files. Thread safety is as yet untested,
though, since Lucy's Perl bindings are single-threaded.