class XidLruCache:
PAGES_PER_SEGMENT = 32
def __init__(self, datadir, pageclass, buffsz):
self.datadir = datadir
ctrlfile = ControlFile(datadir)
self.blcksz = ctrlfile.blcksz
self.buffer = LruCache(pageclass, self.blcksz, buffsz)
def getfilename(self, segno):
pass
def readfromdisk(self, pageno):
blocksz = self.blcksz
segno = pageno / self.PAGES_PER_SEGMENT
filename = self.getfilename(segno)
try:
with open(filename) as file:
file.seek(blocksz * pageno)
block = file.read(blocksz)
except:
raise UPgException('error in reading xid')
if len(block) != blocksz:
raise UPgException('error in reading xid')
return block
def getlrupage(self, pageno):
lrupage = self.buffer.get_and_visit(pageno)
if not lrupage:
block = self.readfromdisk(pageno)
lrupage = self.buffer.put(pageno, block)
return lrupage
class HeapBuffer:
def __init__(self, pgdatadir, catalog_class):
self.pgdatadir = pgdatadir
self.catalog_class = catalog_class
ctrlfile = ControlFile(pgdatadir)
self.blocksz = ctrlfile.blcksz
self.segfilesz = ctrlfile.relseg_size
self.catalog_version_no = ctrlfile.catalog_version_no
self.pg_majorversion = catalog_class.loadpgversion(pgdatadir)
self.heapbuffer = LruCache(HeapBufferPage, self.blocksz,
HEAP_BUFFER_COUNT)
'''
计算buffer tag。
'''
def __getbuftag(self, relfilenode, forknum, blocknum):
return struct.pack('5I', relfilenode.space_node, relfilenode.db_node,
relfilenode.rel_node, forknum, blocknum)
'''
根据relfilenode得到文件名。根据global tablespace，default table space，还有指定了table space，文件名
规则不一样。
'''
def getrelationpath(self, relfilenode, forknum):
assert forknum == MAIN_FORKNUM or forknum == FSM_FORKNUM \
or forknum == VISIBILITYMAP_FORKNUM or forknum == INIT_FORKNUM
pgdatadir = self.pgdatadir
forkNames = ('', 'fsm', 'vm', 'init')
if forknum == MAIN_FORKNUM:
filename = relfilenode.rel_node
else:
filename = '%u_%s' % (relfilenode.rel_node, forkNames[forknum])
if relfilenode.space_node == self.catalog_class.GLOBALTABLESPACE_OID:
return '%s/global/%s' % (pgdatadir, filename)
elif relfilenode.space_node == self.catalog_class.DEFAULTTABLESPACE_OID:
return '%s/base/%u/%s' % (pgdatadir, relfilenode.db_node, filename)
else:
tablespacedir = "PG_%s_%u" % (self.pg_majorversion,
self.catalog_version_no)
return '%s/pg_tblspc/%u/%s/%u/%s' % (
pgdatadir, relfilenode.space_node, tablespacedir,
relfilenode.db_node, filename)
def __loadbuffer(self, relfilenode, forknum, blocknum):
try:
blocksz = self.blocksz
segsz = self.segfilesz
filepath = self.getrelationpath(relfilenode, forknum)
segno = blocknum / segsz
if segno > 0:
filepath = '%s.%u' % (filepath, segno)
blockoff = blocksz * (blocknum % segsz)
with open(filepath) as file:
file.seek(blockoff)
block = file.read(blocksz)
if len(block) != blocksz:
logger.error('could not read block %u in file \"%s\": %m' %
(blocknum, filepath))
raise UPgException('could not read block in file')
return block
except IOError:
logger.error('could not read block %u in file \"%s\": %m' %
(blocknum, filepath))
raise UPgException('could not read block in file')
def readpage(self, relfilenode, forknum, blocknum):
tag = self.__getbuftag(relfilenode, forknum, blocknum)
buffpage = self.heapbuffer.get_and_visit(tag)
if not buffpage:
buffdata = self.__loadbuffer(relfilenode, forknum, blocknum)
buffpage = self.heapbuffer.put(tag, buffdata)
return buffpage
def getblocknums(self, relfilenode, forknum):
blocksz = self.blocksz
segsz = self.segfilesz
filepath = self.getrelationpath(relfilenode, forknum)
segno = 0
while True:
if segno > 0:
filepath = '%s.%u' % (filepath, segno)
if not os.path.exists(filepath):
return segno * segsz
filesize = os.path.getsize(filepath) / blocksz
if filesize > segsz:
raise UPgException('could not read block in file')
elif filesize < segsz:
return segno * segsz + filesize
else:
segno += 1
class HeapBuffer:
def __init__(self, pgdatadir, catalog_class):
self.pgdatadir = pgdatadir
self.catalog_class = catalog_class
ctrlfile = ControlFile(pgdatadir)
self.blocksz = ctrlfile.blcksz
self.segfilesz = ctrlfile.relseg_size
self.catalog_version_no = ctrlfile.catalog_version_no
self.pg_majorversion = catalog_class.loadpgversion(pgdatadir)
self.heapbuffer = LruCache(HeapBufferPage, self.blocksz, HEAP_BUFFER_COUNT)
'''
计算buffer tag。
'''
def __getbuftag(self, relfilenode, forknum, blocknum):
return struct.pack('5I', relfilenode.space_node, relfilenode.db_node, relfilenode.rel_node, forknum, blocknum)
'''
根据relfilenode得到文件名。根据global tablespace，default table space，还有指定了table space，文件名
规则不一样。
'''
def getrelationpath(self, relfilenode, forknum):
assert forknum == MAIN_FORKNUM or forknum == FSM_FORKNUM \
or forknum == VISIBILITYMAP_FORKNUM or forknum == INIT_FORKNUM
pgdatadir = self.pgdatadir
forkNames = ('', 'fsm', 'vm', 'init')
if forknum == MAIN_FORKNUM:
filename = relfilenode.rel_node
else:
filename = '%u_%s'%(relfilenode.rel_node, forkNames[forknum])
if relfilenode.space_node == self.catalog_class.GLOBALTABLESPACE_OID:
return '%s/global/%s'%(pgdatadir, filename)
elif relfilenode.space_node == self.catalog_class.DEFAULTTABLESPACE_OID:
return '%s/base/%u/%s'%(pgdatadir, relfilenode.db_node, filename)
else:
tablespacedir = "PG_%s_%u"%(self.pg_majorversion, self.catalog_version_no)
return '%s/pg_tblspc/%u/%s/%u/%s'%(pgdatadir, relfilenode.space_node, tablespacedir, relfilenode.db_node, filename)
def __loadbuffer(self, relfilenode, forknum, blocknum):
try:
blocksz = self.blocksz
segsz = self.segfilesz
filepath = self.getrelationpath(relfilenode, forknum)
segno = blocknum/segsz
if segno > 0:
filepath = '%s.%u'%(filepath, segno)
blockoff = blocksz * (blocknum%segsz)
with open(filepath) as file:
file.seek(blockoff)
block = file.read(blocksz)
if len(block) != blocksz:
logger.error('could not read block %u in file \"%s\": %m'%(blocknum, filepath))
raise UPgException('could not read block in file')
return block
except IOError:
logger.error('could not read block %u in file \"%s\": %m'%(blocknum, filepath))
raise UPgException('could not read block in file')
def readpage(self, relfilenode, forknum, blocknum):
tag = self.__getbuftag(relfilenode, forknum, blocknum)
buffpage = self.heapbuffer.get_and_visit(tag)
if not buffpage:
buffdata = self.__loadbuffer(relfilenode, forknum, blocknum)
buffpage = self.heapbuffer.put(tag, buffdata)
return buffpage
def getblocknums(self, relfilenode, forknum):
blocksz = self.blocksz
segsz = self.segfilesz
filepath = self.getrelationpath(relfilenode, forknum)
segno = 0
while True:
if segno > 0:
filepath = '%s.%u' % (filepath, segno)
if not os.path.exists(filepath):
return segno * segsz
filesize = os.path.getsize(filepath)/blocksz
if filesize > segsz:
raise UPgException('could not read block in file')
elif filesize < segsz:
return segno * segsz + filesize
else:
segno += 1
