def choose(self):
"""
Start from the current position and find the next available commit
log. If none are available, create and fill a new one.
"""
# Loop from the current position, wrapping around the end until an
# available commit log is found or we're back where we started.
i = ii = self.file.index
while 1:
i = (i + 1) % self.files
try:
self.file = File(i, self.flags, False)
break
except OSError:
pass
# We're back where we started. If we want write access, make
# a new file to get it. Otherwise, hunt for new files.
if i == ii:
while 1:
try:
self.file = File(self.files, self.flags,
File.WRITE == self.flags)
self.files += 1
break
except OSError as e:
if errno.ENOENT == e[0]:
return False
self.files += 1
break
sys.stderr.write("[commitlog] chose commit log {0:010}\n".format(
self.file.index
))
return True
def __init__(self, flags):
"""
Create the data directory, write all of the commit logs full and
choose the initial commit log.
"""
self.files = settings.FILES
self.flags = flags
# Create the data directory
try:
os.mkdir(settings.DIRNAME)
except OSError:
pass
# Check that the first FILES files are in good shape.
for i in range(self.files):
try:
File(i, File.WRITE, True)
except OSError:
pass
# Check that any extra files are in good shape, too.
while 1:
i += 1
try:
File(i, File.WRITE, False)
self.files += 1
except OSError as e:
if errno.ENOENT == e[0]:
break
# Act like the current file is the last one so the first rotation
# comes back to the first available file.
class DummyFile(object):
pass
self.file = DummyFile()
self.file.index = self.files - 1
if File.WRITE == self.flags:
self.choose()
class CommitLog(object):
"""
The entire commit log group which takes care of rotating through logs or
creating new ones when necessary.
"""
# Flags for the CommitLog constructor. READ will only allow access to
# dirty commit logs. WRITE will only allow access to clean commit logs.
READ = File.READ
WRITE = File.WRITE
def __init__(self, flags):
"""
Create the data directory, write all of the commit logs full and
choose the initial commit log.
"""
self.files = settings.FILES
self.flags = flags
# Create the data directory
try:
os.mkdir(settings.DIRNAME)
except OSError:
pass
# Check that the first FILES files are in good shape.
for i in range(self.files):
try:
File(i, File.WRITE, True)
except OSError:
pass
# Check that any extra files are in good shape, too.
while 1:
i += 1
try:
File(i, File.WRITE, False)
self.files += 1
except OSError as e:
if errno.ENOENT == e[0]:
break
# Act like the current file is the last one so the first rotation
# comes back to the first available file.
class DummyFile(object):
pass
self.file = DummyFile()
self.file.index = self.files - 1
if File.WRITE == self.flags:
self.choose()
def choose(self):
"""
Start from the current position and find the next available commit
log. If none are available, create and fill a new one.
"""
# Loop from the current position, wrapping around the end until an
# available commit log is found or we're back where we started.
i = ii = self.file.index
while 1:
i = (i + 1) % self.files
try:
self.file = File(i, self.flags, False)
break
except OSError:
pass
# We're back where we started. If we want write access, make
# a new file to get it. Otherwise, hunt for new files.
if i == ii:
while 1:
try:
self.file = File(self.files, self.flags,
File.WRITE == self.flags)
self.files += 1
break
except OSError as e:
if errno.ENOENT == e[0]:
return False
self.files += 1
break
sys.stderr.write("[commitlog] chose commit log {0:010}\n".format(
self.file.index
))
return True
def write(self, message):
"""
Write the contents of the given message.Write object into the
current file.
"""
if self.file.full():
self.choose()
self.file.write(message)