Enduro/X Core

tpsuspend() -> for prosgres we prepare tran. For Mysql we end tran.
tpresume() -> we request new XID from TMSRV.

When flag "TPTRANSUSPEND" is set for tpcall() no suspend is needed, because target invocation will be in different branch, thus no locking will be required.

For posgresql support, seems that TLOG on disk we need to open at the begining of the transaction, because there is no such thing on PG as active transaction (globally), it is either active locally or prepared (which is done on xa_end).

Thus we need to track all xids to do their abort.

We need some kind of flag to be passed to TMAPI to request new xid which shall be part of the transaction.

The XID by it self as XIDSTR we could leave as is, no need to append any bqual data there.

postgresql xid string format:

    return xid.getFormatId() + "_" 
        + Base64.encodeBytes(xid.getGlobalTransactionId(), Base64.DONT_BREAK_LINES) + "_" 
        + Base64.encodeBytes(xid.getBranchQualifier(), Base64.DONT_BREAK_LINES);

mysql:

    private static void appendXid(StringBuilder builder, Xid xid) {
        byte[] gtrid = xid.getGlobalTransactionId();
        byte[] btrid = xid.getBranchQualifier();

        if (gtrid != null) {
            StringUtils.appendAsHex(builder, gtrid);
        }

        builder.append(',');
        if (btrid != null) {
            StringUtils.appendAsHex(builder, btrid);
        }

        builder.append(',');
        StringUtils.appendAsHex(builder, xid.getFormatId());
    }

/**
 * Get connection handle for non XA resources.
 * This shall perform callback initialized by ndrx_get_xa_switch().
 * the ndrx_get_xa_switch() shall provide the function pointer by ndrx_xa_setgetconn()
 */
void * tpgetconn();

Posgresql mode C mode driver shall work in ECPG:

/* Open / close */
bool     ECPGconnect (int lineno, int c, const char *name, const char *user, const char *passwd, const char *connection_name, int autocommit) 
bool     ECPGdisconnect (int lineno, const char *connection_name)

/*
 * Returns current connection name for PG
 */
tpgetconn();

with this you may access:

- get dynamic connection:
- PGconn * ECPGget_PGconn (const char *connection_name)

- get esql connection:
- ecpg_get_connection(const char *connection_name)

and thus provide connections for both embeded env & dynamic env. Both mode shall be tested.

for postgres to avoid the commits where process have works still in progress, we shall do following protocol:

- at start of TID, the PG RM goes into Unknown state ('u').
- when process reaches end, it updates the TMSRV with XA_RM_STATUS_PREP if prepare transaction was ok
- if prepare transaction was failure (PG performs automatic rollback), TMSRV shall be updated with status XA_RM_STATUS_ABORTED.

- In case if tmsrv reaches timeout, and transaction is in state of 'u', the transaction must be assigned for abort
- The status change shall be allowed only when state is 'u' or states matches (for repeated send). If status not changed or transaction is not found, error shall be reported back to caller. In case of unmatched state/not 'u' or transaction is not found, the local process must roll back it.

when doing tpabort(), posgresql must be rolled back with out attempt of doing prepare transaction at xa_end().
The XA driver shall export the callback function for local transaction abort.