diff tests/test-wireproto-caching.t @ 40021:c537144fdbef

wireprotov2: support response caching One of the things I've learned from managing VCS servers over the years is that they are hard to scale. It is well known that some companies have very beefy (read: very expensive) servers to power their VCS needs. It is also known that specialized servers for various VCS exist in order to facilitate scaling servers. (Mercurial is in this boat.) One of the aspects that make a VCS server hard to scale is the high CPU load incurred by constant client clone/pull operations. To alleviate the scaling pain associated with data retrieval operations, I want to integrate caching into the Mercurial wire protocol server as robustly as possible such that servers can aggressively cache responses and defer as much server load as possible. This commit represents the initial implementation of a general caching layer in wire protocol version 2. We define a new interface and behavior for a wire protocol cacher in repository.py. (This is probably where a reviewer should look first to understand what is going on.) The bulk of the added code is in wireprotov2server.py, where we define how a command can opt in to being cached and integrate caching into command dispatching. From a very high-level: * A command can declare itself as cacheable by providing a callable that can be used to derive a cache key. * At dispatch time, if a command is cacheable, we attempt to construct a cacher and use it for serving the request and/or caching the request. * The dispatch layer handles the bulk of the business logic for caching, making cachers mostly "dumb content stores." * The mechanism for invalidating cached entries (one of the harder parts about caching in general) is by varying the cache key when state changes. As such, cachers don't need to be concerned with cache invalidation. Initially, we've hooked up support for caching "manifestdata" and "filedata" commands. These are the simplest to cache, as they should be immutable over time. Caching of commands related to changeset data is a bit harder (because cache validation is impacted by changes to bookmarks, phases, etc). This will be implemented later. (Strictly speaking, censoring a file should invalidate caches. I've added an inline TODO to track this edge case.) To prove it works, this commit implements a test-only extension providing in-memory caching backed by an lrucachedict. A new test showing this extension behaving properly is added. FWIW, the cacher is ~50 lines of code, demonstrating the relative ease with which a cache can be added to a server. While the test cacher is not suitable for production workloads, just for kicks I performed a clone of just the changeset and manifest data for the mozilla-unified repository. With a fully warmed cache (of just the manifest data since changeset data is not cached), server-side CPU usage dropped from ~73s to ~28s. That's pretty significant and demonstrates the potential that response caching has on server scalability! Differential Revision: https://phab.mercurial-scm.org/D4773
author Gregory Szorc <gregory.szorc@gmail.com>
date Wed, 26 Sep 2018 17:16:56 -0700
parents
children 393e44324037
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-wireproto-caching.t	Wed Sep 26 17:16:56 2018 -0700
@@ -0,0 +1,645 @@
+  $ . $TESTDIR/wireprotohelpers.sh
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > blackbox =
+  > [blackbox]
+  > track = simplecache
+  > EOF
+  $ hg init server
+  $ enablehttpv2 server
+  $ cd server
+  $ cat >> .hg/hgrc << EOF
+  > [extensions]
+  > simplecache = $TESTDIR/wireprotosimplecache.py
+  > EOF
+
+  $ echo a0 > a
+  $ echo b0 > b
+  $ hg -q commit -A -m 'commit 0'
+  $ echo a1 > a
+  $ hg commit -m 'commit 1'
+  $ echo b1 > b
+  $ hg commit -m 'commit 2'
+  $ echo a2 > a
+  $ echo b2 > b
+  $ hg commit -m 'commit 3'
+
+  $ hg log -G -T '{rev}:{node} {desc}'
+  @  3:50590a86f3ff5d1e9a1624a7a6957884565cc8e8 commit 3
+  |
+  o  2:4d01eda50c6ac5f7e89cbe1880143a32f559c302 commit 2
+  |
+  o  1:4432d83626e8a98655f062ec1f2a43b07f7fbbb0 commit 1
+  |
+  o  0:3390ef850073fbc2f0dfff2244342c8e9229013a commit 0
+  
+
+  $ hg --debug debugindex -m
+     rev linkrev nodeid                                   p1                                       p2
+       0       0 992f4779029a3df8d0666d00bb924f69634e2641 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000
+       1       1 a988fb43583e871d1ed5750ee074c6d840bbbfc8 992f4779029a3df8d0666d00bb924f69634e2641 0000000000000000000000000000000000000000
+       2       2 a8853dafacfca6fc807055a660d8b835141a3bb4 a988fb43583e871d1ed5750ee074c6d840bbbfc8 0000000000000000000000000000000000000000
+       3       3 3fe11dfbb13645782b0addafbe75a87c210ffddc a8853dafacfca6fc807055a660d8b835141a3bb4 0000000000000000000000000000000000000000
+
+  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
+  $ cat hg.pid > $DAEMON_PIDS
+
+Performing the same request should result in same result, with 2nd response
+coming from cache.
+
+  $ sendhttpv2peer << EOF
+  > command manifestdata
+  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
+  >     tree eval:b''
+  >     fields eval:[b'parents']
+  > EOF
+  creating http peer for wire protocol version 2
+  sending manifestdata command
+  s>     POST /api/exp-http-v2-0002/ro/manifestdata HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-exp-framing-0005\r\n
+  s>     content-type: application/mercurial-exp-framing-0005\r\n
+  s>     content-length: 83\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     user-agent: Mercurial debugwireproto\r\n
+  s>     \r\n
+  s>     K\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa3Ffields\x81GparentsEnodes\x81T\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&ADtree@DnameLmanifestdata
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
+  s>     Transfer-Encoding: chunked\r\n
+  s>     \r\n
+  s>     13\r\n
+  s>     \x0b\x00\x00\x01\x00\x02\x011
+  s>     \xa1FstatusBok
+  s>     \r\n
+  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
+  s>     63\r\n
+  s>     [\x00\x00\x01\x00\x02\x001
+  s>     \xa1Jtotalitems\x01\xa2DnodeT\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&AGparents\x82T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
+  s>     \r\n
+  received frame(size=91; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
+  s>     8\r\n
+  s>     \x00\x00\x00\x01\x00\x02\x002
+  s>     \r\n
+  s>     0\r\n
+  s>     \r\n
+  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
+  response: gen[
+    {
+      b'totalitems': 1
+    },
+    {
+      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
+      b'parents': [
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+      ]
+    }
+  ]
+
+  $ sendhttpv2peer << EOF
+  > command manifestdata
+  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
+  >     tree eval:b''
+  >     fields eval:[b'parents']
+  > EOF
+  creating http peer for wire protocol version 2
+  sending manifestdata command
+  s>     POST /api/exp-http-v2-0002/ro/manifestdata HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-exp-framing-0005\r\n
+  s>     content-type: application/mercurial-exp-framing-0005\r\n
+  s>     content-length: 83\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     user-agent: Mercurial debugwireproto\r\n
+  s>     \r\n
+  s>     K\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa3Ffields\x81GparentsEnodes\x81T\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&ADtree@DnameLmanifestdata
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
+  s>     Transfer-Encoding: chunked\r\n
+  s>     \r\n
+  s>     13\r\n
+  s>     \x0b\x00\x00\x01\x00\x02\x011
+  s>     \xa1FstatusBok
+  s>     \r\n
+  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
+  s>     63\r\n
+  s>     [\x00\x00\x01\x00\x02\x001
+  s>     \xa1Jtotalitems\x01\xa2DnodeT\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&AGparents\x82T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
+  s>     \r\n
+  received frame(size=91; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
+  s>     8\r\n
+  s>     \x00\x00\x00\x01\x00\x02\x002
+  s>     \r\n
+  s>     0\r\n
+  s>     \r\n
+  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
+  response: gen[
+    {
+      b'totalitems': 1
+    },
+    {
+      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
+      b'parents': [
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+      ]
+    }
+  ]
+
+Sending different request doesn't yield cache hit.
+
+  $ sendhttpv2peer << EOF
+  > command manifestdata
+  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41', b'\xa9\x88\xfb\x43\x58\x3e\x87\x1d\x1e\xd5\x75\x0e\xe0\x74\xc6\xd8\x40\xbb\xbf\xc8']
+  >     tree eval:b''
+  >     fields eval:[b'parents']
+  > EOF
+  creating http peer for wire protocol version 2
+  sending manifestdata command
+  s>     POST /api/exp-http-v2-0002/ro/manifestdata HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-exp-framing-0005\r\n
+  s>     content-type: application/mercurial-exp-framing-0005\r\n
+  s>     content-length: 104\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     user-agent: Mercurial debugwireproto\r\n
+  s>     \r\n
+  s>     `\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa3Ffields\x81GparentsEnodes\x82T\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&AT\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8Dtree@DnameLmanifestdata
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
+  s>     Transfer-Encoding: chunked\r\n
+  s>     \r\n
+  s>     13\r\n
+  s>     \x0b\x00\x00\x01\x00\x02\x011
+  s>     \xa1FstatusBok
+  s>     \r\n
+  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
+  s>     b1\r\n
+  s>     \xa9\x00\x00\x01\x00\x02\x001
+  s>     \xa1Jtotalitems\x02\xa2DnodeT\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&AGparents\x82T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xa2DnodeT\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8Gparents\x82T\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&AT\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
+  s>     \r\n
+  received frame(size=169; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
+  s>     8\r\n
+  s>     \x00\x00\x00\x01\x00\x02\x002
+  s>     \r\n
+  s>     0\r\n
+  s>     \r\n
+  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
+  response: gen[
+    {
+      b'totalitems': 2
+    },
+    {
+      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
+      b'parents': [
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+      ]
+    },
+    {
+      b'node': b'\xa9\x88\xfbCX>\x87\x1d\x1e\xd5u\x0e\xe0t\xc6\xd8@\xbb\xbf\xc8',
+      b'parents': [
+        b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+      ]
+    }
+  ]
+
+  $ cat .hg/blackbox.log
+  *> cacher constructed for manifestdata (glob)
+  *> cache miss for c045a581599d58608efd3d93d8129841f2af04a0 (glob)
+  *> storing cache entry for c045a581599d58608efd3d93d8129841f2af04a0 (glob)
+  *> cacher constructed for manifestdata (glob)
+  *> cache hit for c045a581599d58608efd3d93d8129841f2af04a0 (glob)
+  *> cacher constructed for manifestdata (glob)
+  *> cache miss for 6ed2f740a1cdd12c9e99c4f27695543143c26a11 (glob)
+  *> storing cache entry for 6ed2f740a1cdd12c9e99c4f27695543143c26a11 (glob)
+
+  $ cat error.log
+
+  $ killdaemons.py
+  $ rm .hg/blackbox.log
+
+Try with object caching mode
+
+  $ cat >> .hg/hgrc << EOF
+  > [simplecache]
+  > cacheobjects = true
+  > EOF
+
+  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
+  $ cat hg.pid > $DAEMON_PIDS
+
+  $ sendhttpv2peer << EOF
+  > command manifestdata
+  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
+  >     tree eval:b''
+  >     fields eval:[b'parents']
+  > EOF
+  creating http peer for wire protocol version 2
+  sending manifestdata command
+  s>     POST /api/exp-http-v2-0002/ro/manifestdata HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-exp-framing-0005\r\n
+  s>     content-type: application/mercurial-exp-framing-0005\r\n
+  s>     content-length: 83\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     user-agent: Mercurial debugwireproto\r\n
+  s>     \r\n
+  s>     K\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa3Ffields\x81GparentsEnodes\x81T\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&ADtree@DnameLmanifestdata
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
+  s>     Transfer-Encoding: chunked\r\n
+  s>     \r\n
+  s>     13\r\n
+  s>     \x0b\x00\x00\x01\x00\x02\x011
+  s>     \xa1FstatusBok
+  s>     \r\n
+  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
+  s>     63\r\n
+  s>     [\x00\x00\x01\x00\x02\x001
+  s>     \xa1Jtotalitems\x01\xa2DnodeT\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&AGparents\x82T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
+  s>     \r\n
+  received frame(size=91; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
+  s>     8\r\n
+  s>     \x00\x00\x00\x01\x00\x02\x002
+  s>     \r\n
+  s>     0\r\n
+  s>     \r\n
+  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
+  response: gen[
+    {
+      b'totalitems': 1
+    },
+    {
+      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
+      b'parents': [
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+      ]
+    }
+  ]
+
+  $ sendhttpv2peer << EOF
+  > command manifestdata
+  >     nodes eval:[b'\x99\x2f\x47\x79\x02\x9a\x3d\xf8\xd0\x66\x6d\x00\xbb\x92\x4f\x69\x63\x4e\x26\x41']
+  >     tree eval:b''
+  >     fields eval:[b'parents']
+  > EOF
+  creating http peer for wire protocol version 2
+  sending manifestdata command
+  s>     POST /api/exp-http-v2-0002/ro/manifestdata HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-exp-framing-0005\r\n
+  s>     content-type: application/mercurial-exp-framing-0005\r\n
+  s>     content-length: 83\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     user-agent: Mercurial debugwireproto\r\n
+  s>     \r\n
+  s>     K\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa3Ffields\x81GparentsEnodes\x81T\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&ADtree@DnameLmanifestdata
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
+  s>     Transfer-Encoding: chunked\r\n
+  s>     \r\n
+  s>     13\r\n
+  s>     \x0b\x00\x00\x01\x00\x02\x011
+  s>     \xa1FstatusBok
+  s>     \r\n
+  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
+  s>     63\r\n
+  s>     [\x00\x00\x01\x00\x02\x001
+  s>     \xa1Jtotalitems\x01\xa2DnodeT\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&AGparents\x82T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00T\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
+  s>     \r\n
+  received frame(size=91; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
+  s>     8\r\n
+  s>     \x00\x00\x00\x01\x00\x02\x002
+  s>     \r\n
+  s>     0\r\n
+  s>     \r\n
+  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
+  response: gen[
+    {
+      b'totalitems': 1
+    },
+    {
+      b'node': b'\x99/Gy\x02\x9a=\xf8\xd0fm\x00\xbb\x92OicN&A',
+      b'parents': [
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
+        b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
+      ]
+    }
+  ]
+
+  $ cat .hg/blackbox.log
+  *> cacher constructed for manifestdata (glob)
+  *> cache miss for c045a581599d58608efd3d93d8129841f2af04a0 (glob)
+  *> storing cache entry for c045a581599d58608efd3d93d8129841f2af04a0 (glob)
+  *> cacher constructed for manifestdata (glob)
+  *> cache hit for c045a581599d58608efd3d93d8129841f2af04a0 (glob)
+
+  $ cat error.log
+
+  $ killdaemons.py
+  $ rm .hg/blackbox.log
+
+A non-cacheable command does not instantiate cacher
+
+  $ hg serve -p $HGPORT -d --pid-file hg.pid -E error.log
+  $ cat hg.pid > $DAEMON_PIDS
+  $ sendhttpv2peer << EOF
+  > command capabilities
+  > EOF
+  creating http peer for wire protocol version 2
+  sending capabilities command
+  s>     POST /api/exp-http-v2-0002/ro/capabilities HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-exp-framing-0005\r\n
+  s>     content-type: application/mercurial-exp-framing-0005\r\n
+  s>     content-length: 27\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     user-agent: Mercurial debugwireproto\r\n
+  s>     \r\n
+  s>     \x13\x00\x00\x01\x00\x01\x01\x11\xa1DnameLcapabilities
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
+  s>     Transfer-Encoding: chunked\r\n
+  s>     \r\n
+  s>     13\r\n
+  s>     \x0b\x00\x00\x01\x00\x02\x011
+  s>     \xa1FstatusBok
+  s>     \r\n
+  received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
+  s>     52b\r\n
+  s>     #\x05\x00\x01\x00\x02\x001
+  s>     \xa5Hcommands\xaaIbranchmap\xa2Dargs\xa0Kpermissions\x81DpullLcapabilities\xa2Dargs\xa0Kpermissions\x81DpullMchangesetdata\xa2Dargs\xa4Ffields\xa4Gdefault\xd9\x01\x02\x80Hrequired\xf4DtypeCsetKvalidvalues\xd9\x01\x02\x84IbookmarksGparentsEphaseHrevisionInoderange\xa3Gdefault\xf6Hrequired\xf4DtypeDlistEnodes\xa3Gdefault\xf6Hrequired\xf4DtypeDlistJnodesdepth\xa3Gdefault\xf6Hrequired\xf4DtypeCintKpermissions\x81DpullHfiledata\xa2Dargs\xa4Ffields\xa4Gdefault\xd9\x01\x02\x80Hrequired\xf4DtypeCsetKvalidvalues\xd9\x01\x02\x82GparentsHrevisionKhaveparents\xa3Gdefault\xf4Hrequired\xf4DtypeDboolEnodes\xa2Hrequired\xf5DtypeDlistDpath\xa2Hrequired\xf5DtypeEbytesKpermissions\x81DpullEheads\xa2Dargs\xa1Jpubliconly\xa3Gdefault\xf4Hrequired\xf4DtypeDboolKpermissions\x81DpullEknown\xa2Dargs\xa1Enodes\xa3Gdefault\x80Hrequired\xf4DtypeDlistKpermissions\x81DpullHlistkeys\xa2Dargs\xa1Inamespace\xa2Hrequired\xf5DtypeEbytesKpermissions\x81DpullFlookup\xa2Dargs\xa1Ckey\xa2Hrequired\xf5DtypeEbytesKpermissions\x81DpullLmanifestdata\xa2Dargs\xa4Ffields\xa4Gdefault\xd9\x01\x02\x80Hrequired\xf4DtypeCsetKvalidvalues\xd9\x01\x02\x82GparentsHrevisionKhaveparents\xa3Gdefault\xf4Hrequired\xf4DtypeDboolEnodes\xa2Hrequired\xf5DtypeDlistDtree\xa2Hrequired\xf5DtypeEbytesKpermissions\x81DpullGpushkey\xa2Dargs\xa4Ckey\xa2Hrequired\xf5DtypeEbytesInamespace\xa2Hrequired\xf5DtypeEbytesCnew\xa2Hrequired\xf5DtypeEbytesCold\xa2Hrequired\xf5DtypeEbytesKpermissions\x81DpushKcompression\x82\xa1DnameDzstd\xa1DnameDzlibQframingmediatypes\x81X&application/mercurial-exp-framing-0005Rpathfilterprefixes\xd9\x01\x02\x82Epath:Lrootfilesin:Nrawrepoformats\x82LgeneraldeltaHrevlogv1
+  s>     \r\n
+  received frame(size=1315; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
+  s>     8\r\n
+  s>     \x00\x00\x00\x01\x00\x02\x002
+  s>     \r\n
+  s>     0\r\n
+  s>     \r\n
+  received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
+  response: gen[
+    {
+      b'commands': {
+        b'branchmap': {
+          b'args': {},
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'capabilities': {
+          b'args': {},
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'changesetdata': {
+          b'args': {
+            b'fields': {
+              b'default': set([]),
+              b'required': False,
+              b'type': b'set',
+              b'validvalues': set([
+                b'bookmarks',
+                b'parents',
+                b'phase',
+                b'revision'
+              ])
+            },
+            b'noderange': {
+              b'default': None,
+              b'required': False,
+              b'type': b'list'
+            },
+            b'nodes': {
+              b'default': None,
+              b'required': False,
+              b'type': b'list'
+            },
+            b'nodesdepth': {
+              b'default': None,
+              b'required': False,
+              b'type': b'int'
+            }
+          },
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'filedata': {
+          b'args': {
+            b'fields': {
+              b'default': set([]),
+              b'required': False,
+              b'type': b'set',
+              b'validvalues': set([
+                b'parents',
+                b'revision'
+              ])
+            },
+            b'haveparents': {
+              b'default': False,
+              b'required': False,
+              b'type': b'bool'
+            },
+            b'nodes': {
+              b'required': True,
+              b'type': b'list'
+            },
+            b'path': {
+              b'required': True,
+              b'type': b'bytes'
+            }
+          },
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'heads': {
+          b'args': {
+            b'publiconly': {
+              b'default': False,
+              b'required': False,
+              b'type': b'bool'
+            }
+          },
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'known': {
+          b'args': {
+            b'nodes': {
+              b'default': [],
+              b'required': False,
+              b'type': b'list'
+            }
+          },
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'listkeys': {
+          b'args': {
+            b'namespace': {
+              b'required': True,
+              b'type': b'bytes'
+            }
+          },
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'lookup': {
+          b'args': {
+            b'key': {
+              b'required': True,
+              b'type': b'bytes'
+            }
+          },
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'manifestdata': {
+          b'args': {
+            b'fields': {
+              b'default': set([]),
+              b'required': False,
+              b'type': b'set',
+              b'validvalues': set([
+                b'parents',
+                b'revision'
+              ])
+            },
+            b'haveparents': {
+              b'default': False,
+              b'required': False,
+              b'type': b'bool'
+            },
+            b'nodes': {
+              b'required': True,
+              b'type': b'list'
+            },
+            b'tree': {
+              b'required': True,
+              b'type': b'bytes'
+            }
+          },
+          b'permissions': [
+            b'pull'
+          ]
+        },
+        b'pushkey': {
+          b'args': {
+            b'key': {
+              b'required': True,
+              b'type': b'bytes'
+            },
+            b'namespace': {
+              b'required': True,
+              b'type': b'bytes'
+            },
+            b'new': {
+              b'required': True,
+              b'type': b'bytes'
+            },
+            b'old': {
+              b'required': True,
+              b'type': b'bytes'
+            }
+          },
+          b'permissions': [
+            b'push'
+          ]
+        }
+      },
+      b'compression': [
+        {
+          b'name': b'zstd'
+        },
+        {
+          b'name': b'zlib'
+        }
+      ],
+      b'framingmediatypes': [
+        b'application/mercurial-exp-framing-0005'
+      ],
+      b'pathfilterprefixes': set([
+        b'path:',
+        b'rootfilesin:'
+      ]),
+      b'rawrepoformats': [
+        b'generaldelta',
+        b'revlogv1'
+      ]
+    }
+  ]
+
+  $ test -f .hg/blackbox.log
+  [1]
+
+An error is not cached
+
+  $ sendhttpv2peer << EOF
+  > command manifestdata
+  >     nodes eval:[b'\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa']
+  >     tree eval:b''
+  >     fields eval:[b'parents']
+  > EOF
+  creating http peer for wire protocol version 2
+  sending manifestdata command
+  s>     POST /api/exp-http-v2-0002/ro/manifestdata HTTP/1.1\r\n
+  s>     Accept-Encoding: identity\r\n
+  s>     accept: application/mercurial-exp-framing-0005\r\n
+  s>     content-type: application/mercurial-exp-framing-0005\r\n
+  s>     content-length: 83\r\n
+  s>     host: $LOCALIP:$HGPORT\r\n (glob)
+  s>     user-agent: Mercurial debugwireproto\r\n
+  s>     \r\n
+  s>     K\x00\x00\x01\x00\x01\x01\x11\xa2Dargs\xa3Ffields\x81GparentsEnodes\x81T\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaaDtree@DnameLmanifestdata
+  s> makefile('rb', None)
+  s>     HTTP/1.1 200 OK\r\n
+  s>     Server: testing stub value\r\n
+  s>     Date: $HTTP_DATE$\r\n
+  s>     Content-Type: application/mercurial-exp-framing-0005\r\n
+  s>     Transfer-Encoding: chunked\r\n
+  s>     \r\n
+  s>     51\r\n
+  s>     I\x00\x00\x01\x00\x02\x012
+  s>     \xa2Eerror\xa2Dargs\x81T\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaaGmessagePunknown node: %sFstatusEerror
+  s>     \r\n
+  received frame(size=73; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=eos)
+  s>     0\r\n
+  s>     \r\n
+  abort: unknown node: \xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa! (esc)
+  [255]
+
+  $ cat .hg/blackbox.log
+  *> cacher constructed for manifestdata (glob)
+  *> cache miss for 9d1bb421d99e913d45f2d099aa49728514292dd2 (glob)
+  *> cacher exiting due to error (glob)
+
+  $ killdaemons.py
+  $ rm .hg/blackbox.log