脚本的前几行解释了结构和机制。
我面临的问题是执行卡在第 53 行。一旦下载器对第一个请求起作用，它就会正确生成 api，但是在到达http_object.request(audioscrobbler_api)它时会卡住。
该脚本在另一个系统上进行了编码和测试，并产生了正确的结果。
我可以确认 httplib2 包没有损坏，因为它在request从其他脚本调用该库的方法（包括 ）时正常运行。
是什么导致脚本卡住？
脚本：
#
# Album artwork downloading module for Encore Music Player application.
# Loosely based on the producer-consumer model devised by E W Djikstra.
#
# The Downloader class (implemented as a daemon thread) acts as the consumer
# in the system where it reads requests from the buffer and tries to fetch the
# artwork from ws.audioscrobbler.com (LastFM's web service portal).
#
# Requester class, the producer, is a standard thread class that places the request
# in the buffer when started.
#
# DBusRequester class provides an interface to the script and is made available on
# the session bus of the DBus daemon under the name of 'com.encore.AlbumArtDownloader'
# which enables the core music player to request downloads.
#
import threading, urllib, httplib2, md5, libxml2, os, dbus, dbus.service, signal
from collections import deque
from gi.repository import GObject
from dbus.mainloop.glib import DBusGMainLoop
requests = deque()
mutex = threading.Lock()
count = threading.Semaphore(0)
DBusGMainLoop(set_as_default = True)
class Downloader(threading.Thread):
def __init__(self):
threading.Thread.__init__(self)
def run(self):
while True:
print "=> Downloader waiting for requests"
count.acquire() # wait for new request if buffer is empty
mutex.acquire() # enter critical section
request = requests.popleft()
mutex.release() # leave critical section
(p, q) = request
try:
print "=> Generating api for %s by %s" % (p,q)
params = urllib.urlencode({'method': 'album.getinfo', 'api_key': 'XXX', 'artist': p, 'album': q})
audioscrobbler_api = "http://ws.audioscrobbler.com/2.0/?%s" % params
print "=> Generated URL %s" % (audioscrobbler_api)
http_object = httplib2.Http()
print "=> Requesting response"
resp, content = http_object.request(audioscrobbler_api)
print "=> Received response"
if not resp.status == 200:
print "Unable to fetch artwork for %s by %s" % (q, p)
continue # proceed to the next item in queue if request fails
doc = libxml2.parseDoc(content)
ctxt = doc.xpathNewContext()
res = ctxt.xpathEval("//image[@size='medium']") # grab the element containing the link to a medium sized artwork
if len(res) < 1:
continue # proceed to the next item in queue if the required image node is not found
image_uri = res[0].content # extract uri from node
wget_status = os.system("wget %s -q --tries 3 -O temp" % (image_uri))
if not wget_status == 0:
continue # proceed to the next item in queue if download fails
artwork_name = "%s.png" % (md5.md5("%s + %s" % (p, q)).hexdigest())
os.system("convert temp -resize 64x64 %s" % artwork_name)
except:
pass # handle http request error
class Requester(threading.Thread):
def __init__(self, request):
self.request = request
threading.Thread.__init__(self)
def run(self):
mutex.acquire() # enter critical section
if not self.request in requests:
requests.append(self.request)
count.release() # signal downloader
mutex.release() # leave critical section
class DBusRequester(dbus.service.Object):
def __init__(self):
bus_name = dbus.service.BusName('com.encore.AlbumArtDownloader', bus=dbus.SessionBus())
dbus.service.Object.__init__(self, bus_name, '/com/encore/AlbumArtDownloader')
@dbus.service.method('com.encore.AlbumArtDownloader')
def queue_request(self, artist_name, album_name):
request = (artist_name, album_name)
requester = Requester(request)
requester.start()
def sigint_handler(signum, frame):
"""Exit gracefully on receiving SIGINT."""
loop.quit()
signal.signal(signal.SIGINT, sigint_handler)
downloader_daemon = Downloader()
downloader_daemon.daemon = True
downloader_daemon.start()
requester_service = DBusRequester()
loop = GObject.MainLoop()
loop.run()
在做一个 Ctrl-C
=> Downloader waiting for requests
=> Generating api for paul van dyk by evolution
=> Generated URL http://ws.audioscrobbler.com/2.0/?album=evolution&api_key=XXXXXXXXXXXXXXXXXXXX&method=album.getinfo&artist=paul+van+dyk
=> Requesting response
^C
谢谢 ！！