pipelining

Python http.client has pipelining disabled in the most hard coded fashion possible with python, making implementing pipelining deliberately difficult. BUT I COULD GET ALL THE PREVIEW THUMBS AS A ONE BIG BLOB NOT LEETLE PIECES

update_from_db.py

@@ -1,9 +1,9 @@
 #!/usr/bin/python3
-from http.client import HTTPConnection,HTTPException
+from http.client import HTTPConnection,HTTPException,BadStatusLine
 import json
 import base64
 from contextlib import closing
-import sys,os,shutil
+import sys,os,shutil,time
 
 def die(message,code=23):
         print(message,file=sys.stderr)
@@ -12,7 +12,8 @@ def die(message,code=23):
 server = "minetest.fensta.bplaced.net"
 skinsdir = "u_skins/textures/"
 metadir = "u_skins/meta/"
-curskin = 0
+curskin = 580
+curpage = 59
 pages = None
 
 def replace(location,base,encoding=None,path=None):
@@ -34,6 +35,65 @@ def maybeReplace(location,base,encoding=None):
         return replace(location,base,encoding=encoding,path=path)(handle)
     return deco
 
+class Pipeline(list):
+    "Gawd why am I being so elaborate?"
+    def __init__(self, threshold=10):
+        "threshold is how many requests in parallel to pipeline"
+        self.threshold = threshold
+        self.sent = True
+    def __enter__(self,*a):
+        self.reopen()
+    def __exit__(self):
+        self.drain()
+    def reopen(self):
+        self.c = HTTPConnection(server)
+        self.send()
+    def append(self,url,recv,diemessage):
+        super().append((url,recv,diemessage))
+        if len(self) > self.threshold:			
+            self.send()
+            self.drain()
+    def trydrain(self):		
+        for url,recv,diemessage in self:
+            try:
+                recv(self.c)
+            except BadStatusLine as e:
+                return False			
+            except HTTPException as e:
+                die(diemessage+' (url='+url+')')
+            self.clear()
+            return True
+    def drain(self):
+        print('draining pipeline...')
+        assert self.sent, "Can't drain without sending the requests!"
+        self.sent = False
+        while trydrain() is not True:
+            self.c.close()
+            print('derped requesting',url)
+            print('drain failed, trying again')
+            time.sleep(1)
+            self.reopen()
+    def trysend(self):
+        for url,_,diemessage in pipeline:
+            try:
+                self.c.request("GET", url)
+            except BadStatusLine:
+                return False
+            except HTTPException as e:
+                die(diemessage)
+        return True
+    def send(self):
+        if self.sent: return
+        print('filling pipeline...')
+        while self.tryresend() is not True:
+            self.c.close()
+            print('derped resending')
+            time.sleep(1)
+            self.reopen()
+        self.sent = True
+        
+with Pipeline() as pipeline:
+    # two connections is okay, right? one for json, one for preview images
     c = HTTPConnection(server)
     def addpage(page):
         global curskin, pages
@@ -63,7 +123,7 @@ def addpage(page):
             if os.path.exists(preview):
                 print('skin',curskin,'already retrieved')
                 continue
-        print('updating skin',curskin)
+            print('updating skin',curskin,'id',s["id"])
             foundOne = True
             @maybeReplace(skinsdir, "character_" + str(curskin) + ".png")
             def go(f):
@@ -77,26 +137,25 @@ def addpage(page):
                 f.write(str(s["author"]) + '\n')
                 f.write(str(s["license"]))
             url = "/skins/1/" + str(s["id"]) + ".png"
-        try:
-            c.request("GET", url)
+            def tryget(c):			
                 with closing(c.getresponse()) as r:
                     if r.status != 200:
                         print("Error", r.status)
-                    continue
+                        return
                     @replace(skinsdir,previewbase,path=preview)
                     def go(f):
                         shutil.copyfileobj(r,f)
-        except HTTPException as e:
-            die("Couldn't get {} because of a {} (url={})".format(
+                
+            pipeline.append(url,tryget,
+                            "Couldn't get {} because of a {}".format(
                                 s["id"],
-                e,
-                url))
+                                e))
         if not foundOne:
             print("No skins updated on this page. Seems we're done?")
-        raise SystemExit
+            #raise SystemExit
     addpage(1)
-curpage = 1
     while pages > curpage:
         curpage = curpage + 1
         addpage(curpage)
     print("Skins have been updated!")
+