301 lines
9.7 KiB
C
301 lines
9.7 KiB
C
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/****************************************************************
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* *
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* Copyright 2001, 2007 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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/* ------------------------------------------------------------------
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* Routines & data for managing TP timeouts
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* ----------------------------------------
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*
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* These functions implement TP timeout state transitions. The states
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* below are defined by three flag variables:
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*
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* | Flag:
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* State | timed expired set-xfer
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* -------- | ------- ------- --------
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* Clear | FALSE FALSE FALSE
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* Set-timer | TRUE FALSE FALSE
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* Expired | TRUE TRUE FALSE
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* Clearing-no-set-xfer | FALSE TRUE FALSE
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* Expired-set-xfer | TRUE TRUE TRUE
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* Clearing1-set-xfer | FALSE TRUE TRUE
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* Clearing2-set-xfer | FALSE FALSE TRUE
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*
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* Only the following transitions are allowed:
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*
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* Transition
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* ----------
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* Clear -> Set
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* Set -> Clear
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* Set -> Expired
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* Expired -> Clearing-no-set-xfer
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* Expired -> Expired-set-xfer
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* Clearing-no-set-xfer -> Clear
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* Clearing1-set-xfer -> Clearing2-set-xfer
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* Clearing2-set-xfer -> Clear
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*
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* NOTE:
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* - Each "state" represents multiple program states.
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* - Transitions are designed to be monotonic, so that
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* variable values always correctly represent the current state
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* (even when interrupted between individual operations).
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* - Memory pipelining effects will require barriers in a fully
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* reentrant environment (e.g. VMS 7.x + kernel threads).
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* ------------------------------------------------------------------
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*/
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#include "mdef.h"
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#if defined (VMS)
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#include "efn.h"
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#include <ssdef.h>
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#endif
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#include "outofband.h"
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#include "gt_timer.h"
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#include "xfer_enum.h"
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#include "tp_timeout.h"
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#include "deferred_events.h"
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#include "op.h"
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#include "fix_xfer_entry.h"
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/* ------------------------------------------------------------------
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* Macro for timer ID
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* ------------------------------------------------------------------
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*/
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#define TP_TIMER_ID (TID) &tp_start_timer
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/* =============================================================================
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* EXTERNAL VARIABLES
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* =============================================================================
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*/
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GBLREF xfer_entry_t xfer_table[];
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GBLREF volatile int4 outofband;
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void tptimeout_set(int4 dummy_param);
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/* =============================================================================
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* FILE-SCOPE VARIABLES
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* =============================================================================
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*/
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/* ------------------------------------------------------------
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* Shared between timer handler and main process
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* ------------------------------------------------------------
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*/
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/* "Are we currently in a timed transaction?" It does not change asynchronously */
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static boolean_t in_timed_tn = FALSE;
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/* "Did timeout succeed in setting xfer_table?"
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* (vs. lose to another event)
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*/
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GBLDEF volatile boolean_t tp_timeout_set_xfer = FALSE;
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/* =============================================================================
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* FILE-SCOPE FUNCTIONS
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* =============================================================================
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*/
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/* ------------------------------------------------------------------
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* Timer handler (Set -> Expired)
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*
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* - Sets flag to indicate timeout has occurred.
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* - Should only happen if a timeout has been started (and not cancelled),
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* and has not yet expired.
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* - Static because it's for internal use only.
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* ------------------------------------------------------------------
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*/
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static void tp_expire_now() /* Param list is empty, not void,
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* to avoid mixing K&R with ANSI */
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{
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assert(in_timed_tn);
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/* Consider logging operator message here.
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* (ditto for network errors, etc -- log when arrive, handle later).
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*/
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tp_timeout_set_xfer = xfer_set_handlers(outofband_event, &tptimeout_set, 0);
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}
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/* ------------------------------------------------------------------
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* Set transfer table for synchronous handling of TP timeout.
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* Should be called only from set_xfer_handlers.
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*
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* Notes:
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* - Dummy parameter is for calling compatibility.
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* - Prototype goes in deferred events header file, not in
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* tp_timeout header file, because it's not for general use.
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* ------------------------------------------------------------------
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*/
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void tptimeout_set(int4 dummy_param)
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{
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#if defined (VMS)
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int4 status;
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#endif
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if (tptimeout != outofband)
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{
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FIX_XFER_ENTRY(xf_linefetch, op_fetchintrrpt);
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FIX_XFER_ENTRY(xf_linestart, op_startintrrpt);
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FIX_XFER_ENTRY(xf_zbfetch, op_fetchintrrpt);
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FIX_XFER_ENTRY(xf_zbstart, op_startintrrpt);
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FIX_XFER_ENTRY(xf_forchk1, op_startintrrpt);
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FIX_XFER_ENTRY(xf_forloop, op_forintrrpt);
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outofband = tptimeout;
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VMS_ONLY(
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status = sys$setef(efn_outofband);
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assert(SS$_WASCLR == status);
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if (status != SS$_WASCLR && status != SS$_WASSET)
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GTMASSERT;
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sys$wake(0,0);
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)
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}
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}
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/* =============================================================================
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* EXPORTED FUNCTIONS
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* =============================================================================
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*/
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/* ------------------------------------------------------------------
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* Start timer (Clear -> Set-timer)
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*
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* Change state before starting timer so
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* pops will always happen in the Set state.
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*
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* Note: timer handler data length and pointer are specified as
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* 0 and null, respectively. Handler parameter list
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* should therefore probably be (int4, char*), due to
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* how it's called from timer_handler(), but no one else does that.
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* ------------------------------------------------------------------
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*/
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void tp_start_timer(int4 timeout_seconds)
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{
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assert(!in_timed_tn);
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in_timed_tn = TRUE;
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start_timer(TP_TIMER_ID, 1000*timeout_seconds, &tp_expire_now, 0, NULL);
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}
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/* ------------------------------------------------------------------
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* Transaction done, clear pending timeout:
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* (Set-timer -> Clear)
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* (Expired -> Clearing-no-set-xfer
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* -> Clear)
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* (Expired-set-xfer -> Clearing1-set-xfer
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* -> Clearing2-set-xfer
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* -> Clear)
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*
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* - Ok to call even if no timeout was set.
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* - Reset transfer table if expired and timeout was the reason.
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* - Resets expired flag AFTER cancelling the timer,
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* in case the alarm expires just before it's cancelled.
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*
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* Notes:
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* - Test for tp_timeout_set_xfer may obsolete use of conditional
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* xfer_table reset function. If so, should change this routine
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* to simply return value of tp_timeout_set_xfer when entered.
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* ------------------------------------------------------------------
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*/
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void tp_clear_timeout(void)
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{
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boolean_t tp_timeout_check = FALSE;
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#ifdef DEBUG_DEFERRED
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#include "gtm_stdio.h"
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FPRINTF(stderr,"\nTPCT: \n");
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#endif
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if (in_timed_tn)
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{
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/* ------------------------------------------------
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* Works whether or not timer already expired.
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*
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* Would be faster to only cancel if expired, but
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* could miss a last-minute timer pop that way.
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*
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* Can save time by making timers more efficient, or
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* by setting a "cancelling" flag to ensure no
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* missed pops, and then only cancel if expired.
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* ------------------------------------------------
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*/
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cancel_timer(TP_TIMER_ID);
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/* --------------------------------------------
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* For unambiguous states, clear this flag
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* after cancelling timer and before clearing
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* expired flag.
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* --------------------------------------------
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*/
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in_timed_tn = FALSE;
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/* -----------------------------------------------------
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* Should clear xfer settings only if set them.
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* -----------------------------------------------------
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*/
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if (tp_timeout_set_xfer)
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{
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/* ------------------------------------------------
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* Get here only if set xfer_table due to timer pop.
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* - If timeout is aborting transaction, or
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* - If committing and timer popped too late to
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* stop it => want to undo xfer_table change
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* before it invokes ZTRAP via async_action.
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* - Assert should never trigger due to test of
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* tp_timeout_set_xfer.
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* --------------------------------------------
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*/
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tp_timeout_check = xfer_reset_if_setter(outofband_event);
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#ifdef DEBUG_DEFERRED
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FPRINTF(stderr,"\nTPCT: passed reset of xfer table\n");
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#endif
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assert(tp_timeout_check);
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tp_timeout_set_xfer = FALSE;
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} else
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{
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/* ----------------------------------------------------
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* Get here only if clearing TP timer when a
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* TP timeout did not set xfer_table.
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* Examples:
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* -- Before timer popped, via op_tcommit, if
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* successfully committing a timed transaction.
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* NOTE: other events could be pending, if they
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* occurred late in transaction.
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* -- After timer popped, also via op_tcommit,
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* if successfully committing
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* a timed transaction and another event
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* occurred first (but too late in transaction to
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* abort it).
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* Before or after timer popped:
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* -- If another event (e.g. ^C) happened first,
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* and now that event is clearing TP timer to
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* prevent timer pop in M handler (before it can
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* do TROLLBACK).
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* -- Via op_trollback(), whether in user code
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* or otherwise (e.g. at exit).
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* ----------------------------------------------------
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*/
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; /* (There's nothing to do) */
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}
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}
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}
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/*
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* Used in transfer table for signaling exception
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*/
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void tp_timeout_action(void)
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{
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error_def(ERR_TPTIMEOUT);
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rts_error(VARLSTCNT(1) ERR_TPTIMEOUT);
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}
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