chore: refactor Watch API flags

[miparnisari]

Description

Avoid having to store each individual configuration for Watch API inside every datastore implementation.

Important files to review:

• pkg/datastore/datastore.go - new structs and interface method
• pkg/cmd/server/server.go - wiring flags down to WatchServer
• internal/services/v1/watch.go - passing WatchServer configs to the datastore
• pkg/cmd/datastore/datastore.go removal of custom datastore settings

Testing

1. Added this to the first line of ds.Watch(): fmt.Printf("%+v\n", options)
2. docker-compose up --build
3. zed context set example localhost:50051 foobar --insecure
4. zed import development/schema.yaml
5. zed watch

CRDB

spicedb-1         | {Content:7 EmissionStrategy:0 CheckpointInterval:1s WatchBufferLength:128 WatchBufferWriteTimeout:1s WatchConnectTimeout:1s MaximumBufferedChangesByteSize:41800995}

On main:

spicedb-1         | watchBufferLength 1024
spicedb-1         | watchConnectTimeout 1s
spicedb-1         | CheckpointInterval 1s
spicedb-1         | watchBufferWriteTimeout 1s
spicedb-1         | watchBufferSize 43163130

Memory

{Content:7 EmissionStrategy:0 CheckpointInterval:1s WatchBufferLength:128 WatchBufferWriteTimeout:100ms WatchConnectTimeout:1s MaximumBufferedChangesByteSize:650564805}

On main:

watch buffer length: 1024 (the flag's default)
watch buffer write timeout: 100ms (the datastore's default)

Spanner

{Content:7 EmissionStrategy:0 CheckpointInterval:1s WatchBufferLength:128 WatchBufferWriteTimeout:1s WatchConnectTimeout:1s MaximumBufferedChangesByteSize:66296670}

On main:

spicedb-1         | watchBufferLength 1024
spicedb-1         | heartbeatInterval 1s
spicedb-1         | watchBufferWriteTimeout 1s
spicedb-1         | watchBufferSize 593989155
spicedb-1         | heartbeat interval: 1s

References

Closes #2861

[codecov]

Codecov Report

❌ Patch coverage is 83.39768% with 43 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.84%. Comparing base (fa1d7f4) to head (f7722a5).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/datastore/datastore.go	64.39%	24 Missing and 2 partials ⚠️
...nal/datastore/proxy/schemacaching/watchingcache.go	64.71%	5 Missing and 1 partial ⚠️
internal/datastore/spanner/watch.go	83.34%	2 Missing and 1 partial ⚠️
internal/services/v1/watch.go	82.36%	2 Missing and 1 partial ⚠️
internal/datastore/proxy/counting.go	0.00%	2 Missing ⚠️
internal/datastore/proxy/singleflight.go	0.00%	2 Missing ⚠️
pkg/cmd/testserver/testserver.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2867      +/-   ##
==========================================
+ Coverage   74.83%   74.84%   +0.02%     
==========================================
  Files         484      484              
  Lines       57789    57909     +120     
==========================================
+ Hits        43242    43339      +97     
- Misses      11532    11541       +9     
- Partials     3015     3029      +14     

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[miparnisari]

FYI all this code got moved to avoid circular imports

[miparnisari]

This is important