Fix multithreading issues in feeds2disk. This should make news fetching much more robust, though a little slower

src/calibre/web/fetch/simple.py

@@ -9,8 +9,8 @@ UTF-8 encoding with any charset declarations removed.
 '''
 import sys, socket, os, urlparse, logging, re, time, copy, urllib2, threading, traceback
 from urllib import url2pathname
+from threading import RLock
 from httplib import responses
-from contextlib import closing
 
 from calibre import setup_cli_handlers, browser, sanitize_file_name, \
                     relpath, LoggingInterface
@@ -21,6 +21,23 @@ from calibre.utils.config import OptionParser
 class FetchError(Exception):
     pass
 
+class closing(object):
+    'Context to automatically close something at the end of a block.'
+
+    def __init__(self, thing):
+        self.thing = thing
+    
+    def __enter__(self):
+        return self.thing
+    
+    def __exit__(self, *exc_info):
+        try:
+            self.thing.close()
+        except Exception:
+            pass
+
+_browser_lock = RLock()
+
 def basename(url):
     parts = urlparse.urlsplit(url)
     path = url2pathname(parts.path)
@@ -145,35 +162,25 @@ class RecursiveFetcher(object, LoggingInterface):
         delta = time.time() - self.last_fetch_at 
         if  delta < self.delay:
             time.sleep(delta)
-        try:
+        with _browser_lock:
             try:
                 with closing(self.browser.open(url)) as f:
-                    data = response(f.read())
+                    data = response(f.read()+f.read())
                     data.newurl = f.geturl()
-            except AttributeError:
-                time.sleep(2)
-                try:
+            except urllib2.URLError, err:
+                if hasattr(err, 'code') and responses.has_key(err.code):
+                    raise FetchError, responses[err.code]
+                if getattr(err, 'reason', [0])[0] == 104: # Connection reset by peer
+                    self.log_debug('Connection reset by peer retrying in 1 second.')
+                    time.sleep(1)
                     with closing(self.browser.open(url)) as f:
-                        data = response(f.read())
+                        data = response(f.read()+f.read())
                         data.newurl = f.geturl()
-                except AttributeError:
-                    data = response(urllib2.urlopen(url).read())
-                    data.newurl = f.geturl()
-        except urllib2.URLError, err:
-            if hasattr(err, 'code') and responses.has_key(err.code):
-                raise FetchError, responses[err.code]
-            if getattr(err, 'reason', [0])[0] == 104: # Connection reset by peer
-                self.log_debug('Connection reset by peer retrying in 1 second.')
-                time.sleep(1)
-                if hasattr(f, 'close'):
-                    f.close()
-                with closing(self.browser.open(url)) as f:
-                    data = f.read()
-            else: 
-                raise err
-        finally:
-            self.last_fetch_at = time.time()
-        return data
+                else: 
+                    raise err
+            finally:
+                self.last_fetch_at = time.time()
+            return data
 
         
     def start_fetch(self, url):