Duplicate `ContractChanges` on transaction retry in `flushBatchBufferWithRetry`

[aristidesstaffieri]

What version are you using?

latest

Problem

File: internal/services/ingest_backfill.go lines 418-486

Buggy code:

for attempt := 0; attempt < maxIngestProcessedDataRetries; attempt++ {
    err := db.RunInTransaction(ctx, m.models.DB, func(dbTx pgx.Tx) error {
        // This in-memory append is NOT rolled back when the transaction fails
        batchChanges.ContractChanges = append(batchChanges.ContractChanges, buffer.GetContractChanges()...)
        // ... DB operations that may fail ...
    })
    // On failure, retries the loop — appending ContractChanges AGAIN
}

Description: The batchChanges.ContractChanges slice append happens inside the transaction closure but is an in-memory operation not rolled back on DB transaction failure. On retry, the same contract changes are appended again, creating duplicates that propagate to ProcessTokenChanges. The map-based merges (mergeTrustlineChanges, mergeAccountChanges, etc.) are idempotent, but the slice append is not.

Suggested fix: Move the batchChanges collection after the successful transaction commit, or reset batchChanges.ContractChanges at the start of each retry.