Use `AckExplicitPolicy` instead of `AckAllPolicy` (#3288)

Fixes https://github.com/matrix-org/dendrite/issues/3240 and potentially
a root cause for state resets.

While testing, I've had added some more debug logging:
```
time="2023-12-16T18:13:11.319458084Z" level=warning msg="already processed event" event_id="$qFYMl_F2vb1N0yxmvlFAMhqhGhLKq4kA-o_YCQKH7tQ" kind=KindNew times=2
time="2023-12-16T18:13:14.537389126Z" level=warning msg="already processed event" event_id="$EU-LTsKErT6Mt1k12-p_3xOHfiLaK6gtwVDlZ35lSuo" kind=KindNew times=5
time="2023-12-16T18:13:16.789551206Z" level=warning msg="already processed event" event_id="$dIPuAfTL5x0VyG873LKPslQeljCSxFT1WKxUtjIMUGE" kind=KindNew times=5
time="2023-12-16T18:13:17.383838767Z" level=warning msg="already processed event" event_id="$7noSZiCkzerpkz_UBO3iatpRnaOiPx-3IXc0GPDQVGE" kind=KindNew times=2
time="2023-12-16T18:13:22.091946597Z" level=warning msg="already processed event" event_id="$3Lvo3Wbi2ol9-nNbQ93N-E2MuGQCJZo5397KkFH-W6E" kind=KindNew times=1
time="2023-12-16T18:13:23.026417446Z" level=warning msg="already processed event" event_id="$lj1xS46zsLBCChhKOLJEG-bu7z-_pq9i_Y2DUIjzGy4" kind=KindNew times=4
```

So we did receive the same event over and over again. Given they are
`KindNew`, we don't short circuit if we already processed them, which
potentially caused the state to be calculated with a now wrong state
snapshot.

Also fixes the back pressure metric. We now correctly increment the
counter once we sent the message to NATS and decrement it once we
actually processed an event.

1 files changed, 18 insertions, 18 deletions

diff --git a/go.sum b/go.sum
index fba25076..543b8b4a 100644
--- a/go.sum
+++ b/go.sum
@@ -190,8 +190,8 @@ github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:C
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/klauspost/compress v1.10.3/go.mod h1:aoV0uJVorq1K+umq18yTdKaF57EivdYsUV+/s2qKfXs=
-github.com/klauspost/compress v1.16.7 h1:2mk3MPGNzKyxErAw8YaohYh69+pa4sIQSC0fPGCFR9I=
-github.com/klauspost/compress v1.16.7/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
+github.com/klauspost/compress v1.17.4 h1:Ej5ixsIri7BrIjBkRZLTo6ghwrEtHFk7ijlczPW4fZ4=
+github.com/klauspost/compress v1.17.4/go.mod h1:/dCuZOvVtNoHsyb+cuJD3itjs3NbnF6KH9zAO4BDxPM=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -242,12 +242,12 @@ github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7P
 github.com/mschoch/smat v0.0.0-20160514031455-90eadee771ae/go.mod h1:qAyveg+e4CE+eKJXWVjKXM4ck2QobLqTDytGJbLLhJg=
 github.com/mschoch/smat v0.2.0 h1:8imxQsjDm8yFEAVBe7azKmKSgzSkZXDuKkSq9374khM=
 github.com/mschoch/smat v0.2.0/go.mod h1:kc9mz7DoBKqDyiRL7VZN8KvXQMWeTaVnttLRXOlotKw=
-github.com/nats-io/jwt/v2 v2.5.0 h1:WQQ40AAlqqfx+f6ku+i0pOVm+ASirD4fUh+oQsiE9Ak=
-github.com/nats-io/jwt/v2 v2.5.0/go.mod h1:24BeQtRwxRV8ruvC4CojXlx/WQ/VjuwlYiH+vu/+ibI=
-github.com/nats-io/nats-server/v2 v2.9.23 h1:6Wj6H6QpP9FMlpCyWUaNu2yeZ/qGj+mdRkZ1wbikExU=
-github.com/nats-io/nats-server/v2 v2.9.23/go.mod h1:wEjrEy9vnqIGE4Pqz4/c75v9Pmaq7My2IgFmnykc4C0=
-github.com/nats-io/nats.go v1.28.0 h1:Th4G6zdsz2d0OqXdfzKLClo6bOfoI/b1kInhRtFIy5c=
-github.com/nats-io/nats.go v1.28.0/go.mod h1:XpbWUlOElGwTYbMR7imivs7jJj9GtK7ypv321Wp6pjc=
+github.com/nats-io/jwt/v2 v2.5.3 h1:/9SWvzc6hTfamcgXJ3uYRpgj+QuY2aLNqRiqrKcrpEo=
+github.com/nats-io/jwt/v2 v2.5.3/go.mod h1:iysuPemFcc7p4IoYots3IuELSI4EDe9Y0bQMe+I3Bf4=
+github.com/nats-io/nats-server/v2 v2.10.7 h1:f5VDy+GMu7JyuFA0Fef+6TfulfCs5nBTgq7MMkFJx5Y=
+github.com/nats-io/nats-server/v2 v2.10.7/go.mod h1:V2JHOvPiPdtfDXTuEUsthUnCvSDeFrK4Xn9hRo6du7c=
+github.com/nats-io/nats.go v1.31.0 h1:/WFBHEc/dOKBF6qf1TZhrdEfTmOZ5JzdJ+Y3m6Y/p7E=
+github.com/nats-io/nats.go v1.31.0/go.mod h1:di3Bm5MLsoB4Bx61CBTsxuarI36WbhAwOm8QrW39+i8=
 github.com/nats-io/nkeys v0.4.6 h1:IzVe95ru2CT6ta874rt9saQRkWfe2nFj1NtvYSLqMzY=
 github.com/nats-io/nkeys v0.4.6/go.mod h1:4DxZNzenSVd1cYQoAa8948QY3QDjrHfcfVADymtkpts=
 github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
@@ -354,8 +354,8 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20210421170649-83a5a9bb288b/go.mod h1:T9bdIzuCu7OtxOm1hfPfRQxPLYneinmdGuTeoZ9dtd4=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
-golang.org/x/crypto v0.14.0 h1:wBqGXzWJW6m1XrIKlAH0Hs1JJ7+9KBwnIO8v66Q9cHc=
-golang.org/x/crypto v0.14.0/go.mod h1:MVFd36DqK4CsrnJYDkBA3VC4m2GkXAM0PvzMCn4JQf4=
+golang.org/x/crypto v0.16.0 h1:mMMrFzRSCF0GvB7Ne27XVtVAaXLrPmgPC7/v0tkwHaY=
+golang.org/x/crypto v0.16.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq4=
 golang.org/x/exp v0.0.0-20180321215751-8460e604b9de/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20180807140117-3d87b88a115f/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190125153040-c74c464bbbf2/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -422,24 +422,24 @@ golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
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 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
-golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=
+golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
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-golang.org/x/term v0.13.0 h1:bb+I9cTfFazGW51MZqBVmZy7+JEJMouUHTUSKVQLBek=
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