diff options
Diffstat (limited to 'lib/pure/memfiles.nim')
| -rw-r--r-- | lib/pure/memfiles.nim | 38 |
1 files changed, 34 insertions, 4 deletions
diff --git a/lib/pure/memfiles.nim b/lib/pure/memfiles.nim index e5345e645..810223d72 100644 --- a/lib/pure/memfiles.nim +++ b/lib/pure/memfiles.nim @@ -36,11 +36,12 @@ type size*: int ## size of the memory mapped file when defined(windows): - fHandle: Handle - mapHandle: Handle - wasOpened: bool ## only close if wasOpened + fHandle*: Handle ## **Caution**: Windows specific public field to allow + ## even more low level trickery. + mapHandle*: Handle ## **Caution**: Windows specific public field. + wasOpened*: bool ## **Caution**: Windows specific public field. else: - handle: cint + handle*: cint ## **Caution**: Posix specific public field. proc mapMem*(m: var MemFile, mode: FileMode = fmRead, mappedSize = -1, offset = 0): pointer = @@ -281,6 +282,35 @@ proc flush*(f: var MemFile; attempts: Natural = 3) = if lastErr != EBUSY.OSErrorCode: raiseOSError(lastErr, "error flushing mapping") +when defined(posix) or defined(nimdoc): + proc resize*(f: var MemFile, newFileSize: int) {.raises: [IOError, OSError].} = + ## resize and re-map the file underlying an ``allowRemap MemFile``. + ## **Note**: this assumes the entire file is mapped read-write at offset zero. + ## Also, the value of ``.mem`` will probably change. + ## **Note**: This is not (yet) avaiable on Windows. + when defined(posix): + if f.handle == -1: + raise newException(IOError, + "Cannot resize MemFile opened with allowRemap=false") + if ftruncate(f.handle, newFileSize) == -1: + raiseOSError(osLastError()) + when defined(linux): #Maybe NetBSD, too? + #On Linux this can be over 100 times faster than a munmap,mmap cycle. + proc mremap(old: pointer; oldSize,newSize: csize; flags: cint): pointer {. + importc: "mremap", header: "<sys/mman.h>" .} + let newAddr = mremap(f.mem, csize(f.size), csize(newFileSize), cint(1)) + if newAddr == cast[pointer](MAP_FAILED): + raiseOSError(osLastError()) + else: + if munmap(f.mem, f.size) != 0: + raiseOSError(osLastError()) + let newAddr = mmap(nil, newFileSize, PROT_READ or PROT_WRITE, + MAP_SHARED or MAP_POPULATE, f.handle, 0) + if newAddr == cast[pointer](MAP_FAILED): + raiseOSError(osLastError()) + f.mem = newAddr + f.size = newFileSize + proc close*(f: var MemFile) = ## closes the memory mapped file `f`. All changes are written back to the ## file system, if `f` was opened with write access. |