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Diffstat (limited to 'docs')
| -rw-r--r-- | docs/tcp_replication.rst | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/docs/tcp_replication.rst b/docs/tcp_replication.rst index 62225ba6f4..73436cea62 100644 --- a/docs/tcp_replication.rst +++ b/docs/tcp_replication.rst @@ -137,7 +137,6 @@ for each stream so that on reconneciton it can start streaming from the correct place. Note: not all RDATA have valid tokens due to batching. See ``RdataCommand`` for more details. - Example ~~~~~~~ @@ -221,3 +220,28 @@ SYNC (S, C) See ``synapse/replication/tcp/commands.py`` for a detailed description and the format of each command. + + +Cache Invalidation Stream +~~~~~~~~~~~~~~~~~~~~~~~~~ + +The cache invalidation stream is used to inform workers when they need to +invalidate any of their caches in the data store. This is done by streaming all +cache invalidations done on master down to the workers, assuming that any caches +on the workers also exist on the master. + +Each individual cache invalidation results in a row being sent down replication, +which includes the cache name (the name of the function) and they key to +invalidate. For example:: + + > RDATA caches 550953771 ["get_user_by_id", ["@bob:example.com"], 1550574873251] + +However, there are times when a number of caches need to be invalidated at the +same time with the same key. To reduce traffic we batch those invalidations into +a single poke by defining a special cache name that workers understand to mean +to expand to invalidate the correct caches. + +Currently the special cache names are declared in ``synapse/storage/_base.py`` +and are: + +1. ``cs_cache_fake`` ─ invalidates caches that depend on the current state |