Hi,
I don't know this is bug or my fault. Here's the case:
I use environ's file_wrapper to send file to client. It's not file
from disk, but PCAP file generated dynamicaly from DB and it can be
really big. But generated file is generated whole into memory and then
sent.
I'm stuck on this for last two days and I don't know, what else try.
Thoughts I had and tried:
1) Content-Length and BINARY data
- tried to send fake Content-Length, didn't help
2) Tried sending different packeges (package -> one filelike.read()
call) with STRING as returned value
- this is interesting:
- when i tried to send same string (and same length) for each
read() call, file was streamed and not buffered
- when i tried to send random generated string (and random
length), file was buffered first and then sent
But... everytime i send generated PCAP file it is buffered. Is this
because of sending binary data?
I would really appreciate some some help or where to start.
========= MY CODE
=== Returning PCAP - do not work
import cStringIO
from module.netstat.pcap import pcapHeader, pktHeader
class PcapGenerator(object):
def __init__(self, pool, conn, cursor, size=8192):
self.size = size
self.packets = 200
self.pool = pool
self.conn = conn
self.cursor = cursor
self.buffer = cStringIO.StringIO()
self.queue = []
pcapHeader(self.buffer)
def read(self, size=None):
size = self.size
packets = self.packets
buffer = self.buffer
queue = self.queue
# load new packets if needed
if len(queue) <= 1:
if len(queue) == 1:
last = queue.pop()
buffer.write(last)
# load from db, build each packet and write to buffer
rows = self.cursor.fetchmany(packets)
for row in rows:
pktHeader(buffer, row[0], row[1], len(row[3]), row[2])
buffer.write(str(row[3]))
# read buffer by specified size (tried because returning
fixed length strings worked) and prepare values to return
buffer.seek(0)
while True:
data = buffer.read(size)
if not data:
break
queue.insert(0, data)
buffer.truncate(0)
if len(queue) > 0:
print "RETURN SIZE: ", len(queue[-1])
return queue.pop()
else:
return ''
def close(self):
pass
============
=== Returning fixed length string worked
class StringGenerator(object):
def __init__(self):
self.loops = 1000000
def read(self, size=None):
self.loops -= 1
if self.loops > 0:
return 'ABCDEFGHIJKLMNOPGRSTUVWXYZ'
return ''
def close(self):
pass
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