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from rngcache import RandomFileCache
cache = RandomFileCache(rootdir, cache_size=200) # 200MB cache
cache.start()
# ...
with cache.get_random_file() as file_path:
# load file ... cPickle.load(open(file_path,"rb")) ...
# ...
cache.terminate()
"""
import signal
import ctypes
import shutil
import random
import os
from time import time, sleep
import multiprocessing as mp
from glob import glob
class RandomFileCache(object):
def __init__(self,
root_dir,
cache_size, #in MB
cache_dir="/dev/shm/",
max_files=10000
):
if not root_dir.endswith("/"): root_dir += "/"
self.cache_dir = cache_dir
self.root_dir = root_dir
self.max_MB = cache_size
self.max_files = max_files
self.init = False
def start(self):
self.is_terminated = mp.Value(ctypes.c_bool, False)
self.cache_ready = mp.Event()
self.files = glob(self.root_dir+"*")
manager = mp.Manager()
self.cache = manager.list()
self.cache_dir += "rngcache"+str(time())+"/"
os.mkdir(self.cache_dir)
# locks can't be made on the fly (not pickable), so allocate a bunch of them
self.locks = [mp.Lock() for _ in range(self.max_files)]
self.lock_idxs = range(self.max_files) # lock references
self.job = mp.Process(target=self._cache_process)
self.job.daemon = True
self.job.start()
signal.signal(signal.SIGINT, self.terminate)
signal.signal(signal.SIGTERM, self.terminate)
self.init = True
def get_random_file(self):
self.cache_ready.wait()
tries = 0
while tries < 100:
try: entry = random.choice(self.cache)
except:
if self.is_terminated.value: return None
tries += 1
sleep(0.01)
continue
lock = self.locks[entry["lock"]]
if not lock.acquire(False): continue # is locked, go to next
cached_file = CachedFile(self.cache_dir + entry["key"])
cached_file.set_lock(lock)
return cached_file # extension of string
raise Exception("Failed to get random file")
def _cache_process(self):
try: self.cache_process()
except Exception as e: print e
finally: self.terminate()
def cache_process(self):
self.size = 0
while not self.is_terminated.value:
file = random.choice(self.files)
file_size = os.path.getsize(file) >> 20
# if not enough space, remove a random entry
if self.size + file_size > self.max_MB:
self.cache_ready.set()
self.remove_entry()
continue
key = os.path.basename(file)
# don't allow duplicates
if self.contains(key): continue
shutil.copyfile(file, self.cache_dir+key)
self.size += file_size
self.cache.append( {"key":key, "lock":self.lock_idxs.pop(0)} )
def remove_entry(self):
if len(self.cache) == 0: return
while True:
for i, entry in enumerate(self.cache):
# lock entry
lock_idx = entry["lock"]
lock = self.locks[lock_idx]
if not lock.acquire(False): continue
file = self.cache_dir+entry["key"]
self.size -= os.path.getsize(file) >> 20
# remove file
os.remove(file)
del self.cache[i]
self.lock_idxs.append(lock_idx)
lock.release()
return
sleep(0.01)
def contains(self, key):
for entry in self.cache:
if entry["key"] == key: return True
return False
def terminate(self, sig=None, frame=None):
try:
if not self.init or self.is_terminated.value: return
self.is_terminated.value = True
for lock in self.locks:
try: lock.release()
except ValueError: pass
self.job.join(timeout=5)
try:self.job.terminate()
except: pass
finally:
if os.path.exists(self.cache_dir):
shutil.rmtree(self.cache_dir)
class CachedFile(str):
def set_lock(self, lock): self.lock = lock
def __enter__(self): return self
def __exit__(self, type, value, traceback):
try: self.lock.release()
except ValueError: pass
if __name__ == '__main__':
import yaml
from moviepy.editor import VideoFileClip
os.chdir("..")
with open("paths.yaml", "r") as f: PATH = yaml.load(f)
cache = RandomFileCache(PATH["preproc"] + "25fps_crf28", cache_size=200)
cache.start()
print len(cache.files)
for i in range(10):
with cache.get_random_file() as file:
print file
print cache.cache
clip = VideoFileClip(file)
clip.preview()
# for l in cache.locks:
# if not l.acquire(False):
# count += 1
# continue
# l.release()
# print count, "locked"
cache.terminate()
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