I think this code is useful for Remus or live migration hackers too (we don't
have python parsers for the save format elsewhere that I know of), and would
prefer to keep it as is.
On 2011-06-22, at 6:37 AM, Shriram Rajagopalan wrote:
> # HG changeset patch
> # User Shriram Rajagopalan <rshriram@xxxxxxxxx>
> # Date 1308683504 25200
> # Node ID 794ead1a2be0578d70c38f006e7ab61c7abe9203
> # Parent ca4a8d0d504344a84f64bc7e939f8910baac236e
> remus: move makeheader from image.py to vm.py
>
> makeheader is the only function used from image.py. Move it
> to vm.py and remove image.py file.
>
> Signed-off-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
>
> diff -r ca4a8d0d5043 -r 794ead1a2be0 tools/python/xen/remus/image.py
> --- a/tools/python/xen/remus/image.py Tue Jun 21 12:11:41 2011 -0700
> +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
> @@ -1,227 +0,0 @@
> -# VM image file manipulation
> -
> -import logging, struct
> -
> -import vm
> -
> -SIGNATURE = 'LinuxGuestRecord'
> -LONGLEN = struct.calcsize('L')
> -INTLEN = struct.calcsize('i')
> -PAGE_SIZE = 4096
> -# ~0L
> -P2M_EXT_SIG = 4294967295L
> -# frames per page
> -FPP = 1024
> -LTAB_MASK = 0xf << 28
> -BATCH_SIZE = 1024
> -IDXLEN = INTLEN + BATCH_SIZE * LONGLEN
> -
> -logging.basicConfig(level=logging.DEBUG)
> -log = logging.getLogger()
> -
> -class VMParseException(Exception): pass
> -
> -class VMImage(object):
> - def __init__(self, img=None):
> - """img may be a path or a file object.
> - If compact is True, apply checkpoints to base image instead
> - of simply concatenating them.
> - """
> - self.img = img
> -
> - self.dom = None
> - self.fd = None
> - self.header = None
> - self.nr_pfns = 0
> - # p2m extension header (unparsed)
> - self.p2mext = None
> -
> - if self.img:
> - self.open(self.img)
> -
> - def open(self, img):
> - if isinstance(img, str):
> - self.fd = file(img, 'rb')
> - else:
> - self.fd = img
> -
> - self.readheader()
> -
> - def readheader(self):
> - sig = self.fd.read(len(SIGNATURE))
> - if sig != SIGNATURE:
> - raise VMParseException("Bad signature in image")
> -
> - hlen = self.fd.read(INTLEN)
> - hlen, = struct.unpack('!i', hlen)
> -
> - self.header = self.fd.read(hlen)
> - self.dom = parseheader(self.header)
> -
> - def readp2mfl(self):
> - "read the P2M frame list"
> - pfnlen = self.fd.read(LONGLEN)
> - self.nr_pfns, = struct.unpack('L', pfnlen)
> - p2m0 = self.fd.read(LONGLEN)
> -
> - p2mhdr = p2m0
> - p2m0, = struct.unpack('L', p2m0)
> - if p2m0 == P2M_EXT_SIG:
> - elen = self.fd.read(INTLEN)
> - elen, = struct.unpack('I', elen)
> -
> - self.p2mext = self.fd.read(elen)
> -
> - p2m0 = self.fd.read(LONGLEN)
> - p2m0, = struct.unpack('L', p2m0)
> - p2mfl = [p2m0]
> -
> - p2mfle = (self.nr_pfns + FPP - 1)/FPP - 1
> - p2ms = self.fd.read(LONGLEN * p2mfle)
> - p2mfl.extend(struct.unpack('%dL' % p2mfle, p2ms))
> -
> - self.p2mfl = p2mfl
> -
> - def flush(self):
> - self.ofd.write(self.tail)
> -
> -class Writer(object):
> - """compress a stream of checkpoints into a single image of the
> - last checkpoint"""
> - def __init__(self, fd, compact=False):
> - self.fd = fd
> - self.compact = compact
> -
> - self.vm = None
> - self.tail = None
> - # offset to first batch of pages
> - self.imgstart = 0
> - # PFN mappings
> - self.pfns = []
> -
> - def __del__(self):
> - self.close()
> -
> - def writeheader(self):
> - hlen = struct.pack('!i', len(self.vm.header))
> - header = ''.join([SIGNATURE, hlen, self.vm.header])
> - self.fd.write(header)
> -
> - def writep2mfl(self):
> - p2m = [struct.pack('L', self.vm.nr_pfns)]
> - if self.vm.p2mext:
> - p2m.extend([struct.pack('L', P2M_EXT_SIG), self.vm.p2mext])
> - p2m.append(struct.pack('%dL' % len(self.vm.p2mfl), *self.vm.p2mfl))
> - self.fd.write(''.join(p2m))
> -
> - def writebatch(self, batch):
> - def offset(pfn):
> - isz = (pfn / BATCH_SIZE + 1) * IDXLEN
> - return self.imgstart + isz + pfn * PAGE_SIZE
> -
> - if not self.compact:
> - return self.fd.write(batch)
> -
> - batch = parsebatch(batch)
> - # sort pages for better disk seek behaviour
> - batch.sort(lambda x, y: cmp(x[0] & ~LTAB_MASK, y[0] & ~LTAB_MASK))
> -
> - for pfndesc, page in batch:
> - pfn = pfndesc & ~LTAB_MASK
> - if pfn > self.vm.nr_pfns:
> - log.error('INVALID PFN: %d' % pfn)
> - if len(self.pfns) <= pfn:
> - self.pfns.extend([0] * (pfn - len(self.pfns) + 1))
> - self.pfns[pfn] = pfndesc
> - self.fd.seek(offset(pfn))
> - self.fd.write(page)
> -
> - #print "max offset: %d, %d" % (len(self.pfns), offset(self.pfns[-1]))
> -
> - def writeindex(self):
> - "Write batch header in front of each page"
> - hdrlen = INTLEN + BATCH_SIZE * LONGLEN
> - batches = (len(self.pfns) + BATCH_SIZE - 1) / BATCH_SIZE
> -
> - for i in xrange(batches):
> - offset = self.imgstart + i * (hdrlen + (PAGE_SIZE * BATCH_SIZE))
> - pfnoff = i * BATCH_SIZE
> - # python auto-clamps overreads
> - pfns = self.pfns[pfnoff:pfnoff + BATCH_SIZE]
> -
> - self.fd.seek(offset)
> - self.fd.write(struct.pack('i', len(pfns)))
> - self.fd.write(struct.pack('%dL' % len(pfns), *pfns))
> -
> - def slurp(self, ifd):
> - """Apply an incremental checkpoint to a loaded image.
> - accepts a path or a file object."""
> - if isinstance(ifd, str):
> - ifd = file(ifd, 'rb')
> -
> - if not self.vm:
> - self.vm = VMImage(ifd)
> - self.writeheader()
> -
> - self.vm.readp2mfl()
> - self.writep2mfl()
> - self.imgstart = self.fd.tell()
> -
> - while True:
> - l, batch = readbatch(ifd)
> - if l <= 0:
> - break
> - self.writebatch(batch)
> - self.tail = batch + ifd.read()
> -
> - def flush(self):
> - if self.tail:
> - self.fd.seek(0, 2)
> - self.fd.write(self.tail)
> - if self.compact:
> - self.writeindex()
> - self.tail = None
> -
> - def close(self):
> - self.flush()
> -
> -def parseheader(header):
> - "parses a header sexpression"
> - return vm.parsedominfo(vm.strtosxpr(header))
> -
> -def makeheader(dominfo):
> - "create an image header from a VM dominfo sxpr"
> - items = [SIGNATURE]
> - sxpr = vm.sxprtostr(dominfo)
> - items.append(struct.pack('!i', len(sxpr)))
> - items.append(sxpr)
> - return ''.join(items)
> -
> -def readbatch(fd):
> - batch = []
> - batchlen = fd.read(INTLEN)
> - batch.append(batchlen)
> - batchlen, = struct.unpack('i', batchlen)
> - log.info("batch length: %d" % batchlen)
> - if batchlen <= 0:
> - return (batchlen, batch[0])
> -
> - batchfns = fd.read(LONGLEN * batchlen)
> - batch.append(batchfns)
> - pages = fd.read(PAGE_SIZE * batchlen)
> - if len(pages) != PAGE_SIZE * batchlen:
> - log.error('SHORT READ: %d' % len(pages))
> - batch.append(pages)
> -
> - return (batchlen, ''.join(batch))
> -
> -def parsebatch(batch):
> - "parse a batch string into pages"
> - batchlen, batch = batch[:INTLEN], batch[INTLEN:]
> - batchlen, = struct.unpack('i', batchlen)
> - #print 'batch length: %d' % batchlen
> - pfnlen = batchlen * LONGLEN
> - pfns = struct.unpack('%dL' % batchlen, batch[:pfnlen])
> - pagebuf = batch[pfnlen:]
> - pages = [pagebuf[i*PAGE_SIZE:(i+1)*PAGE_SIZE] for i in xrange(batchlen)]
> - return zip(pfns, pages)
> diff -r ca4a8d0d5043 -r 794ead1a2be0 tools/python/xen/remus/save.py
> --- a/tools/python/xen/remus/save.py Tue Jun 21 12:11:41 2011 -0700
> +++ b/tools/python/xen/remus/save.py Tue Jun 21 12:11:44 2011 -0700
> @@ -10,7 +10,7 @@
>
> import xen.lowlevel.checkpoint
>
> -import vm, image
> +import vm
>
> class _proxy(object):
> "proxy simulates an object without inheritance"
> @@ -70,7 +70,7 @@
> def start(self):
> vm.getshadowmem(self.vm)
>
> - hdr = image.makeheader(self.vm.dominfo)
> + hdr = vm.makeheader(self.vm.dominfo)
> self.fd.write(hdr)
> self.fd.flush()
>
> diff -r ca4a8d0d5043 -r 794ead1a2be0 tools/python/xen/remus/vm.py
> --- a/tools/python/xen/remus/vm.py Tue Jun 21 12:11:41 2011 -0700
> +++ b/tools/python/xen/remus/vm.py Tue Jun 21 12:11:44 2011 -0700
> @@ -1,6 +1,6 @@
> #!/usr/bin/env python
>
> -import xmlrpclib
> +import xmlrpclib, struct
>
> from xen.xend.XendClient import server
> from xen.xend import sxp, osdep
> @@ -11,6 +11,7 @@
> # need a nicer way to load disk drivers
> import vbd
>
> +SIGNATURE = 'LinuxGuestRecord'
> class VMException(Exception): pass
>
> class VM(object):
> @@ -162,3 +163,11 @@
> # target is in MB, not KB
> target = (dom0cur - needed) / 1024
> server.xend.domain.setMemoryTarget(0, target)
> +
> +def makeheader(dominfo):
> + "create an image header from a VM dominfo sxpr"
> + items = [SIGNATURE]
> + sxpr = sxprtostr(dominfo)
> + items.append(struct.pack('!i', len(sxpr)))
> + items.append(sxpr)
> + return ''.join(items)
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>
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