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Ethan
535c775f2a
Closes CODAGT-736 Concurrent chat model config writes on a deployment with no default all elect themselves default: at READ COMMITTED neither transaction sees the other's uncommitted default, so both self-promote and `idx_chat_model_configs_single_default` rejects the loser as a spurious 409. The coderd Terraform provider hits this routinely, since a single `terraform apply` creates or deletes many configs in parallel by design. The fix serializes the election with a transaction-scoped advisory lock: the create, update, and delete handlers run their default election inside a transaction that first takes `pg_advisory_xact_lock` on a dedicated `LockIDChatModelConfigDefault`, so elections run one at a time and the index is never contended. The partial unique index stays in place as the schema-level invariant, and the existing 409 mapping remains as a backstop for any writer that bypasses the lock. We considered a singleton pointer table (one row holding a `model_config_id` FK, making a second default unrepresentable), which would remove the race outright, but it needs a migration, new queries, dbauthz rules, and handler/read-path rework. Not proportionate for an experimental endpoint.
29 lines
855 B
Go
29 lines
855 B
Go
package database
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import "hash/fnv"
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// Well-known lock IDs for lock functions in the database. These should not
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// change. If locks are deprecated, they should be kept in this list to avoid
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// reusing the same ID.
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const (
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LockIDDeploymentSetup = iota + 1
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LockIDEnterpriseDeploymentSetup
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LockIDDBRollup
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LockIDDBPurge
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LockIDNotificationsReportGenerator
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LockIDCryptoKeyRotation
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LockIDReconcilePrebuilds
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LockIDReconcileSystemRoles
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LockIDBoundaryUsageStats
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LockIDAIProvidersEnvSeed
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LockIDChatModelConfigWrites
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)
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// GenLockID generates a unique and consistent lock ID from a given string.
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func GenLockID(name string) int64 {
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hash := fnv.New64()
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_, _ = hash.Write([]byte(name))
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// #nosec G115 - Safe conversion as FNV hash should be treated as random value and both uint64/int64 have the same range of unique values
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return int64(hash.Sum64())
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}
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