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PG remote backend: use a unique creation lock for each database schema #35069

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PG remote backend: use a unique creation lock for each database schema #35069

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5299736
PG remote backend: use a unique creation lock for each database schema
jnielsendotnet Apr 23, 2024
d4ca838
Fix missed fmt.Sprintf, whitespace agreement
jnielsendotnet Apr 24, 2024
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15 changes: 8 additions & 7 deletions internal/backend/remote-state/pg/client.go
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Expand Up @@ -88,15 +88,16 @@ func (c *RemoteClient) Lock(info *statemgr.LockInfo) (string, error) {
return nil
}

// Try to acquire locks for the existing row `id` and the creation lock `-1`.
query := `SELECT %s.id, pg_try_advisory_lock(%s.id), pg_try_advisory_lock(-1) FROM %s.%s WHERE %s.name = $1`
row := c.Client.QueryRow(fmt.Sprintf(query, statesTableName, statesTableName, c.SchemaName, statesTableName, statesTableName), c.Name)
// Try to acquire locks for the existing row `id` and the creation lock.
creation_lock := fmt.Sprintf("%s_create", c.SchemaName)
query := `SELECT %s.id, pg_try_advisory_lock(%s.id), pg_try_advisory_lock(%s) FROM %s.%s WHERE %s.name = $1`
row := c.Client.QueryRow(fmt.Sprintf(query, statesTableName, statesTableName, creation_lock, c.SchemaName, statesTableName, statesTableName), c.Name)
var pgLockId, didLock, didLockForCreate []byte
err = row.Scan(&pgLockId, &didLock, &didLockForCreate)
switch {
case err == sql.ErrNoRows:
// No rows means we're creating the workspace. Take the creation lock.
innerRow := c.Client.QueryRow(`SELECT pg_try_advisory_lock(-1)`)
innerRow := c.Client.QueryRow(fmt.Sprintf(`SELECT pg_try_advisory_lock(%s)`, creation_lock))
var innerDidLock []byte
err := innerRow.Scan(&innerDidLock)
if err != nil {
Expand All @@ -105,20 +106,20 @@ func (c *RemoteClient) Lock(info *statemgr.LockInfo) (string, error) {
if string(innerDidLock) == "false" {
return "", &statemgr.LockError{Info: info, Err: fmt.Errorf("Already locked for workspace creation: %s", c.Name)}
}
info.Path = "-1"
info.Path = creation_lock
case err != nil:
return "", &statemgr.LockError{Info: info, Err: err}
case string(didLock) == "false":
// Existing workspace is already locked. Release the attempted creation lock.
lockUnlock("-1")
lockUnlock(creation_lock)
return "", &statemgr.LockError{Info: info, Err: fmt.Errorf("Workspace is already locked: %s", c.Name)}
case string(didLockForCreate) == "false":
// Someone has the creation lock already. Release the existing workspace because it might not be safe to touch.
lockUnlock(string(pgLockId))
return "", &statemgr.LockError{Info: info, Err: fmt.Errorf("Cannot lock workspace; already locked for workspace creation: %s", c.Name)}
default:
// Existing workspace is now locked. Release the attempted creation lock.
lockUnlock("-1")
lockUnlock(creation_lock)
info.Path = string(pgLockId)
}
c.info = info
Expand Down