diff --git a/synapse/http/server.py b/synapse/http/server.py
index ffe6cfa09e..37fdf14405 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -22,12 +22,13 @@ import types
import urllib
from http import HTTPStatus
from io import BytesIO
-from typing import Any, Callable, Dict, Tuple, Union
+from typing import Any, Callable, Dict, Iterator, List, Tuple, Union
import jinja2
-from canonicaljson import encode_canonical_json, encode_pretty_printed_json
+from canonicaljson import iterencode_canonical_json, iterencode_pretty_printed_json
+from zope.interface import implementer
-from twisted.internet import defer
+from twisted.internet import defer, interfaces
from twisted.python import failure
from twisted.web import resource
from twisted.web.server import NOT_DONE_YET, Request
@@ -499,6 +500,78 @@ class RootOptionsRedirectResource(OptionsResource, RootRedirect):
pass
+@implementer(interfaces.IPullProducer)
+class _ByteProducer:
+ """
+ Iteratively write bytes to the request.
+ """
+
+ # The minimum number of bytes for each chunk. Note that the last chunk will
+ # usually be smaller than this.
+ min_chunk_size = 1024
+
+ def __init__(
+ self, request: Request, iterator: Iterator[bytes],
+ ):
+ self._request = request
+ self._iterator = iterator
+
+ def start(self) -> None:
+ self._request.registerProducer(self, False)
+
+ def _send_data(self, data: List[bytes]) -> None:
+ """
+ Send a list of strings as a response to the request.
+ """
+ if not data:
+ return
+ self._request.write(b"".join(data))
+
+ def resumeProducing(self) -> None:
+ # We've stopped producing in the meantime (note that this might be
+ # re-entrant after calling write).
+ if not self._request:
+ return
+
+ # Get the next chunk and write it to the request.
+ #
+ # The output of the JSON encoder is coalesced until min_chunk_size is
+ # reached. (This is because JSON encoders produce a very small output
+ # per iteration.)
+ #
+ # Note that buffer stores a list of bytes (instead of appending to
+ # bytes) to hopefully avoid many allocations.
+ buffer = []
+ buffered_bytes = 0
+ while buffered_bytes < self.min_chunk_size:
+ try:
+ data = next(self._iterator)
+ buffer.append(data)
+ buffered_bytes += len(data)
+ except StopIteration:
+ # The entire JSON object has been serialized, write any
+ # remaining data, finalize the producer and the request, and
+ # clean-up any references.
+ self._send_data(buffer)
+ self._request.unregisterProducer()
+ self._request.finish()
+ self.stopProducing()
+ return
+
+ self._send_data(buffer)
+
+ def stopProducing(self) -> None:
+ self._request = None
+
+
+def _encode_json_bytes(json_object: Any) -> Iterator[bytes]:
+ """
+ Encode an object into JSON. Returns an iterator of bytes.
+ """
+ for chunk in json_encoder.iterencode(json_object):
+ yield chunk.encode("utf-8")
+
+
def respond_with_json(
request: Request,
code: int,
@@ -533,15 +606,23 @@ def respond_with_json(
return None
if pretty_print:
- json_bytes = encode_pretty_printed_json(json_object) + b"\n"
+ encoder = iterencode_pretty_printed_json
else:
if canonical_json or synapse.events.USE_FROZEN_DICTS:
- # canonicaljson already encodes to bytes
- json_bytes = encode_canonical_json(json_object)
+ encoder = iterencode_canonical_json
else:
- json_bytes = json_encoder.encode(json_object).encode("utf-8")
+ encoder = _encode_json_bytes
+
+ request.setResponseCode(code)
+ request.setHeader(b"Content-Type", b"application/json")
+ request.setHeader(b"Cache-Control", b"no-cache, no-store, must-revalidate")
- return respond_with_json_bytes(request, code, json_bytes, send_cors=send_cors)
+ if send_cors:
+ set_cors_headers(request)
+
+ producer = _ByteProducer(request, encoder(json_object))
+ producer.start()
+ return NOT_DONE_YET
def respond_with_json_bytes(
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 3250d41dde..dd77a44b8d 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -43,7 +43,7 @@ REQUIREMENTS = [
"jsonschema>=2.5.1",
"frozendict>=1",
"unpaddedbase64>=1.1.0",
- "canonicaljson>=1.2.0",
+ "canonicaljson>=1.3.0",
# we use the type definitions added in signedjson 1.1.
"signedjson>=1.1.0",
"pynacl>=1.2.1",
diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
index 9b3f85b306..e266204f95 100644
--- a/synapse/rest/key/v2/remote_key_resource.py
+++ b/synapse/rest/key/v2/remote_key_resource.py
@@ -15,12 +15,12 @@
import logging
from typing import Dict, Set
-from canonicaljson import encode_canonical_json, json
+from canonicaljson import json
from signedjson.sign import sign_json
from synapse.api.errors import Codes, SynapseError
from synapse.crypto.keyring import ServerKeyFetcher
-from synapse.http.server import DirectServeJsonResource, respond_with_json_bytes
+from synapse.http.server import DirectServeJsonResource, respond_with_json
from synapse.http.servlet import parse_integer, parse_json_object_from_request
logger = logging.getLogger(__name__)
@@ -223,4 +223,4 @@ class RemoteKey(DirectServeJsonResource):
results = {"server_keys": signed_keys}
- respond_with_json_bytes(request, 200, encode_canonical_json(results))
+ respond_with_json(request, 200, results, canonical_json=True)
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