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bksync.py
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bksync.py
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import sys, os, shutil, ConfigParser, errno, traceback, json, signal, datetime
from os.path import join as OPJ
# Assumptions:
# - The index numbers appear to monotonically increase, no matter what I do (input data, pruning, etc)
# - the block files only ever seem to be written to and replaced, never appended or modified
# Targets, Backends, Repos
# a Target contains Repos and is accessed using a Backend
# python bksync.py target1 target2
# Targets are sections in bk.ini, backend= specifies backend to use, config is passed to backend (path, creds, etc), E.g:
# [target1]
# backend=local
# path=d:\tmp\targ1
# For lifecycle considerations, a repo can be an empty dir / named bucket / etc, if necessary.
# It minimises creation-effort. Such an 'empty' repo can return an index number of 0, which will result in the algo here, copying everything into it.
# User actually has to create these empty 'repos' though. We dont do any lifecycle stuff here except Read/Update
# Typical usage: cron every 20 minutes. The backends should maintain locks on a per-repo basis, and fail to create if a lock is in use.
# --- Backends ---
def GetBackend(name): # only-if-needed imports
if name == 'local': # so e.g. people who just want local-drive copy and dont have
import localfiles # or care about zmq or boto3 deps, dont get screwed on startup
return localfiles.LocalFilesBackend
if name == 'zmq':
import remotezmq
return remotezmq.RemoteZMQBackend
if name == 's3':
import amazons3
return amazons3.AmazonS3Backend
raise NotImplementedError('Unknown backend name %r' % (name,))
# --- Helpers ---
def CheckMakeDirsFor(path):
wanted = os.path.dirname(path)
if not os.path.isdir(wanted):
try:
os.makedirs(wanted)
except OSError as e:
if e.errno != errno.EEXIST: # this will be an upper level perms error that the user will have to sort out.
raise
def LocalCheckAndCopy(src, dst, cn, hdr):
# --- OPTIMIZATION: if both are local files, use shutil to copy ---
sPath = src.LocalPathForChunk(cn) ; dPath = dst.LocalPathForChunk(cn)
if sPath and dPath:
print '%s copying #%s' % (hdr, cn)
CheckMakeDirsFor(dPath)
shutil.copyfile(sPath, dPath)
return True
return False
def ChunksToCopy(repo, srcCS, dstCS): # in: chunk names & sizes. If there is a size mismatch, we make sure that one gets copied again
# --- whichever is in src but not in dst ---
chunksToCopy = set(srcCS) - set(dstCS)
# --- if its in src and in dst BUT the sizes are different, copy it again ---
for cn in set(srcCS) & set(dstCS):
if srcCS[cn] != dstCS[cn]:
print '[%s] Warning: chunk size for #%s different - %s %s' % (repo, cn, srcCS[cn], dstCS[cn])
chunksToCopy.add(cn)
return chunksToCopy
# --- Algo ----
# get list of repos. propagate the ones we have in common.
# foreach repo:
# - figure out who is To and From using index filename numbers. Greater is newer, ie From.
# - copy needed data chunks
# - delete unnneded data chunks
# - copy new index files
# - delete old index files
def main():
signal.signal(signal.SIGINT, signal.SIG_DFL)
# --- Read Cfg ---
allCfg = ConfigParser.SafeConfigParser() #dict_type=AttrDict)
allCfg.read('bk.ini')
cfgTargets = allCfg.sections()
print '\n-------- %s --------' % (datetime.datetime.now().isoformat().replace('T',' '))
# --- Special case: 'server blahblah' ---
if sys.argv[1] == 'server':
serverBE = GetBackend('zmq')(sys.argv[2], dict(allCfg.items(sys.argv[2])), isServer=True)
print '\nServer running.'
serverBE.Serve() # runs 'forever'
return
# --- Commandline Targets ---
targ1 = sys.argv[1]
if targ1 not in cfgTargets:
print 'Error: Target "%s" not found in bk.ini' % targ1
return
targ2 = sys.argv[2]
if targ2 not in cfgTargets:
print 'Error: Target "%s" not found in bk.ini' % targ2
return
# --- Init Backends ---
cfg1 = dict(allCfg.items(targ1))
be1 = GetBackend(cfg1['backend'])(targ1, cfg1)
cfg2 = dict(allCfg.items(targ2))
be2 = GetBackend(cfg2['backend'])(targ2, cfg2)
# --- Get Common Repos ---
repos1 = be1.ListRepos()
print '%40s : %s' % ("Repos at '%s'" % (be1,), ', '.join(repos1))
repos2 = be2.ListRepos()
print '%40s : %s' % ("Repos at '%s'" % (be2,), ', '.join(repos2))
print
repos = set(repos1) & set(repos2)
if not repos:
print 'Error - no common Repos (bk* folders) to sync'
return
for repo in repos:
try:
be1.SetRepo(repo)
be2.SetRepo(repo)
# --- Figure out which way to sync ---
idx1 = be1.GetIndexNumber()
idx2 = be2.GetIndexNumber()
if idx1 == idx2:
print '[%s] up to date, skipping' % (repo)
continue
if idx1 > idx2:
src = be1 ; dst = be2 ; idxNew = str(idx1) ; idxOld = str(idx2)
else:
src = be2 ; dst = be1 ; idxNew = str(idx2) ; idxOld = str(idx1)
print '[%s] %s (%s) --> %s (%s)' % (repo, src, idxNew, dst, idxOld)
# --- Data Chunks ---
srcChunks = src.GetChunkNamesSizes()
dstChunks = dst.GetChunkNamesSizes()
# --- Copy new chunks src->dest ---
chunksToCopy = ChunksToCopy(repo, srcChunks, dstChunks)
numc = len(chunksToCopy) ; n = 0
for n,cn in enumerate(chunksToCopy):
hdr = '[%s] %5d/%-5d' % (repo, n+1, numc)
if LocalCheckAndCopy(src, dst, cn, hdr): continue # Local-drives optimization
# --- Otherwise copy the get/put way ---
print '%s getting #%s' % (hdr, cn)
data = src.GetChunkData(cn)
print '%s putting #%s' % (hdr, cn)
dst.PutChunkData(cn, data)
# --- Copy Core files ---
for fn in ['config','lock.roster','README']:
print '[%s] copying %s' % (repo, fn)
dst.PutCoreFile(fn, src.GetCoreFile(fn)) # Overwrite existing
for fn in ['hints.', 'index.']:
print '[%s] copying %s' % (repo, fn+idxNew)
dst.PutCoreFile(fn+idxNew, src.GetCoreFile(fn+idxNew)) # Copy new
# --- Delete stuff dst ---
chunksToDel = set(dstChunks) - set(srcChunks)
numc = len(chunksToDel) ; n = 0
for n,cn in enumerate(chunksToDel):
print '[%s] %5d/%-5d deleting #%s' % (repo, n+1,numc, cn)
dst.DelChunk(cn)
for fn in ['hints.', 'index.']:
print '[%s] deleting %s%s' % (repo, fn, idxOld)
dst.DelCoreFile(fn+idxOld) # Delete old
except Exception,e:
print '[%s] ERROR: %s' % (repo, str(e)) # yolo
# print traceback.format_exc()
finally:
be1.DoneRepo()
be2.DoneRepo()
if __name__ == '__main__':
main()