def Load(this, buffer):
this.Clear()
indicator = ord(buffer[0])
this.isLeaf = (indicator == LEAF)
if indicator not in NONFREE:
raise BplusTreeException, "can't parse buffer not marked non-free"
index = 1
this.ChildBufferNumbers[0] = BufferFile.RetrieveLong(buffer, index)
index += BufferFile.LONGSTORAGE
maxLength = this.owner.KeyLength
maxKeyPayload = maxLength - BufferFile.SHORTSTORAGE
lastkey = ""
keys = this.ChildKeys
numbers = this.ChildBufferNumbers
for KeyIndex in xrange(this.Size):
KeyLength = BufferFile.RetrieveShort(buffer, index)
index += BufferFile.SHORTSTORAGE
key = None
if (KeyLength == 0):
key = ""
elif (KeyLength > 0):
section = buffer[index:index + KeyLength]
(key, nchars) = DECODER(section)
keys[KeyIndex] = key
index += maxKeyPayload
seekPosition = BufferFile.RetrieveLong(buffer, index)
numbers[KeyIndex + 1] = seekPosition
index += BufferFile.LONGSTORAGE
def parseFreeBuffer(this, buffernumber):
freesize = 1 + BufferFile.LONGSTORAGE
buffer = this.buffers.getBuffer(buffernumber, freesize)
indicator = ord(buffer[0])
if indicator != FREE:
raise BplusTreeException, "free buffer not marked free " + repr(
buffernumber)
return BufferFile.RetrieveLong(buffer, 1)
def ParseBuffer(this, bufferNumber):
if bufferNumber < 0:
raise LinkedFileException, "buffer numbers cannot be negative " + repr(
bufferNumber)
thebuffer = this.buffers.getBuffer(bufferNumber)
typ = ord(thebuffer[0])
nextBufferNumber = BufferFile.RetrieveLong(thebuffer, 1)
realbuffer = thebuffer[BUFFEROVERHEAD:]
#print "<br>got", bufferNumber, typ, repr(realbuffer), nextBufferNumber
return (realbuffer, typ, nextBufferNumber)
def readHeader(this):
f = this.fromfile
f.seek(this.seekStart)
header = f.read(this.headersize)
index = len(HEADERPREFIX)
prefix = header[:index]
if prefix != HEADERPREFIX:
raise BplusTreeException, "bad prefix %s should be %s" % (repr(
header[:index]), repr(HEADERPREFIX))
index += 1 # skip version
this.NodeSize = BufferFile.RetrieveInt(header, index)
index += BufferFile.INTSTORAGE
this.KeyLength = BufferFile.RetrieveInt(header, index)
index += BufferFile.INTSTORAGE
CultureId = BufferFile.RetrieveInt(header, index)
index += BufferFile.INTSTORAGE
this.rootSeek = BufferFile.RetrieveLong(header, index)
index += BufferFile.LONGSTORAGE
this.freeHeadSeek = BufferFile.RetrieveLong(header, index)
this.SanityCheck()
def readHeader(this):
f = this.fromfile
f.seek(this.seekStart)
buffer = f.read(this.headersize)
index = len(HEADERPREFIX)
prefix = buffer[:index]
if prefix != HEADERPREFIX:
raise LinkedFileException, "bad header prefix"
remainder = buffer[index + 1:]
this.buffersize = BufferFile.RetrieveInt(remainder, 0)
this.FreeListHead = BufferFile.RetrieveLong(remainder,
BufferFile.INTSTORAGE)
#print "<br>linkedfile readheader buffersize=", this.buffersize, "freehead=", this.FreeListHead
this.headerDirty = False
this.sanityCheck()