Disabling gzip responses.

[lovelydinosaur]

Prompted by this comment from @bratao...

Debugging httpx on a high speed crawler, the decode (httpx/_decoders.py:76) is a bottleneck. I would like the option to not decode it automatically to speedup my code.

The line that's being referenced there is part of the Gzip decoding...

httpx/httpx/_decoders.py

Lines 64 to 84 in c5eb4b8

	class GZipDecoder(ContentDecoder):
	"""
	Handle 'gzip' decoding.
	See: https://stackoverflow.com/questions/1838699
	"""
	def __init__(self) -> None:
	self.decompressor = zlib.decompressobj(zlib.MAX_WBITS | 16)
	def decode(self, data: bytes) -> bytes:
	try:
	return self.decompressor.decompress(data)
	except zlib.error as exc:
	raise DecodingError(str(exc)) from exc
	def flush(self) -> bytes:
	try:
	return self.decompressor.flush()
	except zlib.error as exc: # pragma: nocover
	raise DecodingError(str(exc)) from exc

It's not particularly surprising that gzip decoding is compute heavy.

If users would like to disable gzip, brotli, and deflate compression, so that responses are not compressed, they can do so be either of these two styles...

# Remove the `accept-encoding` header from all requests.
# Servers will no longer send compressed responses.
>>> import httpx
>>> c = httpx.Client()
>>> c.headers
Headers({'accept': '*/*', 'accept-encoding': 'gzip, deflate, br', 'connection': 'keep-alive', 'user-agent': 'python-httpx/0.23.0'})
>>> del c.headers['accept-encoding']
>>> c.headers
Headers({'accept': '*/*', 'connection': 'keep-alive', 'user-agent': 'python-httpx/0.23.0'})

Or...

# Use the 'identity' marker to indicate that compressed responses should not be used.
# Has the same effect as omitting the header.
>>> import httpx
>>> c = httpx.Client(headers={'accept-encoding': 'identity'})
>>> c.headers
Headers({'accept': '*/*', 'connection': 'keep-alive', 'user-agent': 'python-httpx/0.23.0', 'accept-encoding': 'identity'})

Both of those will disable compressed responses. This will increase the bandwidth of the responses that are sent, but decrease the compute, as they no longer need to be decoded.