fis-gtm/sr_port/tp_unwind.c

/****************************************************************
 *								*
 *	Copyright 2001, 2012 Fidelity Information Services, Inc	*
 *								*
 *	This source code contains the intellectual property	*
 *	of its copyright holder(s), and is made available	*
 *	under a license.  If you do not know the terms of	*
 *	the license, please stop and do not read further.	*
 *								*
 ****************************************************************/

#include "mdef.h"

#include <signal.h>             /* for VSIG_ATOMIC_T type */
#include "gtm_stdio.h"
#include "gtm_string.h"

#include <rtnhdr.h>
#include "mv_stent.h"
#include "stack_frame.h"
#include "tp_frame.h"
#include "mlkdef.h"
#include "hashtab_int4.h"	/* needed for tp.h */
#include "lv_val.h"
#include "op.h"
#include "tp_unwind.h"
#include "mlk_pvtblk_delete.h"	/* for prototype */
#include "mlk_unlock.h"		/* for prototype */
#include "gdsroot.h"
#include "gtm_facility.h"
#include "fileinfo.h"
#include "gdsbt.h"
#include "gdsfhead.h"
#include "alias.h"
#include "filestruct.h"
#include "gdscc.h"
#include "have_crit.h"
#include "gdskill.h"
#include "buddy_list.h"		/* needed for tp.h */
#include "jnl.h"
#include "tp.h"
#include "tp_restart.h"
#ifdef UNIX
#include "deferred_signal_handler.h"
#endif
#ifdef GTM_TRIGGER
#include "gv_trigger.h"
#include "gtm_trigger.h"
#endif

GBLREF	stack_frame	*frame_pointer;
GBLREF	unsigned char	*msp, *stackbase, *stacktop;
GBLREF	mv_stent	*mv_chain;
GBLREF	tp_frame	*tp_pointer;
GBLREF	unsigned char	*tp_sp, *tpstackbase, *tpstacktop;
GBLREF	mlk_pvtblk	*mlk_pvt_root;
GBLREF	uint4		dollar_tlevel;
GBLREF	symval		*curr_symval;
#ifdef GTM_TRIGGER
GBLREF	int		tprestart_state;	/* When triggers restart, multiple states possible. See tp_restart.h */
#endif

error_def(ERR_STACKUNDERFLO);
error_def(ERR_TPRETRY);

void	tp_unwind(uint4 newlevel, enum tp_unwind_invocation invocation_type, int *tprestart_rc)
{
	mlk_pvtblk	**prior, *mlkp;
	mlk_tp		*oldlock, *nextlock;
	int		tl;
	lv_val		*save_lv, *curr_lv, *lv;
	tp_var		*restore_ent;
	mv_stent	*mvc;
	boolean_t	restore_lv, rollback_locks;
	lvscan_blk	*lvscan, *lvscan_next, first_lvscan;
	int		elemindx, rc;
	lvTree		*lvt_child;

	/* We are about to clean up structures. Defer MUPIP STOP/signal handling until function end. */
	DEFER_INTERRUPTS(INTRPT_IN_TP_UNWIND);

	DBGRFCT((stderr, "\ntp_unwind: Beginning TP unwind process\n"));
	restore_lv = (invocation_type == RESTART_INVOCATION);
	lvscan = &first_lvscan;
	lvscan->next = NULL;
	lvscan->elemcnt = 0;
	assert(tp_sp <= tpstackbase  &&  tp_sp > tpstacktop);
	assert(tp_pointer <= (tp_frame *)tpstackbase  &&  tp_pointer > (tp_frame *)tpstacktop);
	for (tl = dollar_tlevel;  tl > newlevel;  --tl)
	{
		DBGRFCT((stderr, "\ntp_unwind: Unwinding level %d -- tp_pointer: 0x"lvaddr"\n", tl, tp_pointer));
		assert(NULL != tp_pointer);
		for (restore_ent = tp_pointer->vars;  NULL != restore_ent;  restore_ent = tp_pointer->vars)
		{
			/*********************************************************************************/
			/* TP_VAR_CLONE sets the var_cloned flag, showing that the tree has been cloned  */
			/* If var_cloned is not set, it shows that curr_lv and save_lv are still sharing */
			/* the tree, so it should not be killed.                                         */
			/*********************************************************************************/
			curr_lv = restore_ent->current_value;
			save_lv = restore_ent->save_value;
			assert(curr_lv);
			assert(save_lv);
			assert(LV_IS_BASE_VAR(curr_lv));
			assert(LV_IS_BASE_VAR(save_lv));
			assert(0 < curr_lv->stats.trefcnt);
			assert(curr_lv->tp_var);
			assert(curr_lv->tp_var == restore_ent);
			/* In order to restart sub-transactions, this would have to maintain
			 * the chain that currently is not built by op_tstart()
			 */
			if (restore_lv)
			{
				rc = tp_unwind_restlv(curr_lv, save_lv, restore_ent, NULL, tprestart_rc);
#				ifdef GTM_TRIGGER
				if (0 != rc)
				{
					ENABLE_INTERRUPTS(INTRPT_IN_TP_UNWIND); /* drive any MUPIP STOP/signals deferred
										 * while in this function */
					dollar_tlevel = tl;		/* Record fact if we unwound some tp_frames */
					INVOKE_RESTART;
				}
#				endif
			} else if (restore_ent->var_cloned)
			{	/* curr_lv has been cloned.
				 * Note: LV_CHILD(save_lv) can be non-NULL only if restore_ent->var_cloned is TRUE
				 */
				DBGRFCT((stderr, "\ntp_unwind: Not restoring curr_lv and is cloned\n"));
				lvt_child = LV_GET_CHILD(save_lv);
				if (NULL != lvt_child)
				{	/* If subtree exists, we have to blow away the cloned tree */
					DBGRFCT((stderr, "\ntp_unwind: save_lv has children\n"));
					assert(save_lv->tp_var);
					DBGRFCT((stderr,"\ntp_unwind: For lv_val 0x"lvaddr": Deleting saved lv_val 0x"lvaddr"\n",
						 curr_lv, save_lv));
					assert(LVT_PARENT(lvt_child) == (lvTreeNode *)save_lv);
					lv_kill(save_lv, DOTPSAVE_FALSE, DO_SUBTREE_TRUE);
				}
				restore_ent->var_cloned = FALSE;
			} else
			{	/* If not cloned, we still have to reduce the reference counts of any
				 * container vars in the untouched tree that were added to keep anything
				 * they referenced from disappearing.
				 */
				DBGRFCT((stderr, "\ntp_unwind: Not restoring curr_lv and is NOT cloned\n"));
				lvt_child = LV_GET_CHILD(curr_lv);
				if (NULL != lvt_child)
				{
					DBGRFCT((stderr, "\ntp_unwind: curr_lv has children and so reducing ref counts\n"));
					TPUNWND_CNTNRS_IN_TREE(curr_lv);
				}
			}
			LV_FREESLOT(save_lv);
			/* Not easy to predict what the trefcnt will be except that it should be greater than zero. In
			 * most cases, it will have its own hash table ref plus the extras we added but it is also
			 * possible that the entry has been kill *'d in which case the ONLY ref that will be left is
			 * our own increment but there is no [quick] way to distinguish this case so we just
			 * test for > 0.
			 */
			assert(0 < curr_lv->stats.trefcnt);
			assert(0 < curr_lv->stats.crefcnt);
			DECR_CREFCNT(curr_lv);	/* Remove the copy refcnt we added in in op_tstart() or lv_newname() */
			DECR_BASE_REF_NOSYM(curr_lv, FALSE);
			curr_lv->tp_var = NULL;
			tp_pointer->vars = restore_ent->next;
			free(restore_ent);
		}
		if (tp_pointer->fp == frame_pointer && mv_chain->mv_st_type == MVST_TPHOLD && msp == (unsigned char *)mv_chain)
			POP_MV_STENT();
		if (NULL == tp_pointer->old_tp_frame)
			tp_sp = tpstackbase;
		else
			tp_sp = (unsigned char *)tp_pointer->old_tp_frame;
		if (tp_sp > tpstackbase)
			rts_error(VARLSTCNT(1) ERR_STACKUNDERFLO);
		if (tp_pointer->tp_save_all_flg)
			--tp_pointer->sym->tp_save_all;
		if ((NULL != (tp_pointer = tp_pointer->old_tp_frame))	/* Note assignment */
			&& ((tp_pointer < (tp_frame *)tp_sp) || (tp_pointer > (tp_frame *)tpstackbase)
			|| (tp_pointer < (tp_frame *)tpstacktop)))
				rts_error(VARLSTCNT(1) ERR_STACKUNDERFLO);
	}
	if ((0 != newlevel) && restore_lv)
	{	/* Restore current context (without releasing) */
		DBGRFCT((stderr, "\n\n** tp_unwind: Newlevel (%d) != 0 loop processing\n", newlevel));
		for (restore_ent = tp_pointer->vars;  NULL != restore_ent;  restore_ent = restore_ent->next)
		{
			curr_lv = restore_ent->current_value;
			save_lv = restore_ent->save_value;
			assert(curr_lv);
			assert(save_lv);
			assert(LV_IS_BASE_VAR(curr_lv));
			assert(LV_IS_BASE_VAR(save_lv));
			assert(curr_lv->tp_var);
			assert(curr_lv->tp_var == restore_ent);
			assert(0 < curr_lv->stats.trefcnt);
			rc = tp_unwind_restlv(curr_lv, save_lv, restore_ent, &lvscan, tprestart_rc);
#			ifdef GTM_TRIGGER
			if (0 != rc)
			{
				ENABLE_INTERRUPTS(INTRPT_IN_TP_UNWIND);	/* drive any MUPIP STOP/signals deferred while
									 * in this function */
				dollar_tlevel = tl;		/* Record fact if we unwound some levels */
				INVOKE_RESTART;
			}
#			endif
			assert(0 < curr_lv->stats.trefcnt);	/* Should have its own hash table ref plus the extras we added */
			assert(0 < curr_lv->stats.crefcnt);
		}
		/* If we have any lv_vals queued up to be scanned for container vars, do that now */
		DBGRFCT((stderr, "\ntp_unwind: Starting deferred rescan of lv trees needing refcnt processing\n"));
		while (0 < lvscan->elemcnt)
		{
			assert(ARY_SCNCNTNR_DIM >= lvscan->elemcnt);
			for (elemindx = 0; lvscan->elemcnt > elemindx; ++elemindx)
			{
				lv = lvscan->ary_scncntnr[elemindx];
				DBGRFCT((stderr, "\n**tp_unwind_process_lvscan_array: Deferred processing lv 0x"lvaddr"\n", lv));
				assert(LV_IS_BASE_VAR(lv));
				/* This is the final level being restored so redo the counters on these vars */
				TPREST_CNTNRS_IN_TREE(lv);
			}
			/* If we allocated any secondary blocks, we are done with them now so release them. Only the
			 * very last block on the chain is the original block that was automatically allocated which
			 * should not be freed in this fashion.
			 */
			lvscan_next = lvscan->next;
			if (NULL != lvscan_next)
			{	/* There is another block on the chain so this one can be freed */
				free(lvscan);
				DBGRFCT((stderr, "\ntp_unwind_process_lvscan_array: Freeing lvscan array\n"));
				lvscan = lvscan_next;
			} else
			{	/* Since this is the original block allocated on the C stack which we may reuse,
				 * zero the element count.
				 */
				lvscan->elemcnt = 0;
				DBGRFCT((stderr, "\ntp_unwind_process_lvscan_array: Setting elemcnt to 0 in original "
					 "lvscan block\n"));
				assert(lvscan == &first_lvscan);
			}
		}
	}
	assert(0 == lvscan->elemcnt);	/* verify no elements queued that were not scanned */
	rollback_locks = (invocation_type != COMMIT_INVOCATION);
	for (prior = &mlk_pvt_root, mlkp = *prior;  NULL != mlkp;  mlkp = *prior)
	{
		if (mlkp->granted)
		{	/* This was a pre-existing lock */
			for (oldlock = mlkp->tp;  (NULL != oldlock) && ((int)oldlock->tplevel > newlevel);  oldlock = nextlock)
			{	/* Remove references to the lock from levels being unwound */
				nextlock = oldlock->next;
				free(oldlock);
			}
			if (rollback_locks)
			{
				if (NULL == oldlock)
				{	/* Lock did not exist at the tp level being unwound to */
					mlk_unlock(mlkp);
					mlk_pvtblk_delete(prior);
					continue;
				} else
				{	/* Lock still exists but restore lock state as it was when the transaction started. */
					mlkp->level = oldlock->level;
					mlkp->zalloc = oldlock->zalloc;
				}
			}
			if (NULL != oldlock && oldlock->tplevel == newlevel)
			{	/* Remove lock reference from level being unwound to,
				 * now that any {level,zalloc} state information has been restored.
				 */
				assert(NULL == oldlock->next || oldlock->next->tplevel < newlevel);
				mlkp->tp = oldlock->next;	/* update root reference pointer */
				free(oldlock);
			} else
				mlkp->tp = oldlock;	/* update root reference pointer */
			prior = &mlkp->next;
		} else
			mlk_pvtblk_delete(prior);
	}
	DBGRFCT((stderr, "tp_unwind: Processing complete\n"));
	dollar_tlevel = newlevel;
	ENABLE_INTERRUPTS(INTRPT_IN_TP_UNWIND);	/* check if any MUPIP STOP/signals were deferred while in this function */
}


/* Restore given local variable from supplied TP restore entry into given symval. Note lvscan_anchor will only be non-NULL
 * for the final level we are restoring (but not unwinding). We don't need to restore counters for any vars except the
 * very last level.
 *
 * The return code is only used when unrolling the M stack runs into a trigger base frame which must be unrolled
 * by gtm_trigger. A non-zero return code signals to tp_unwind() that it needs to rethrow the tprestart error.
 */
int tp_unwind_restlv(lv_val *curr_lv, lv_val *save_lv, tp_var *restore_ent, lvscan_blk **lvscan_anchor, int *tprestart_rc)
{
	ht_ent_mname	*tabent;
	lv_val		*inuse_lv;
	int		elemindx;
	mv_stent	*mvc;
	lvscan_blk	*lvscan, *newlvscan;
	lvTree		*lvt_child;
	boolean_t	var_cloned;

	assert(curr_lv);
	assert(LV_IS_BASE_VAR(curr_lv));
	assert(curr_lv->tp_var);
	DBGRFCT((stderr, "\ntp_unwind_restlv: Entered for varname: '%.*s' curr_lv: 0x"lvaddr"  save_lv: 0x"lvaddr"\n",
		 restore_ent->key.var_name.len, restore_ent->key.var_name.addr, curr_lv, save_lv));
	DBGRFCT((stderr, "tp_unwind_restlv: tp_pointer/current: fp: 0x"lvaddr"/0x"lvaddr" mvc: 0x"lvaddr"/0x"lvaddr
		 " symval: 0x"lvaddr"/0x"lvaddr"\n",
		 tp_pointer->fp, frame_pointer, tp_pointer->mvc, mv_chain, tp_pointer->sym, curr_symval));

	/* First get the stack in the position where we can actually process this entry. Need to make sure we are processing
	 * the symbol table we need to be processing so unwind enough stuff to get there.
	 */
	if (curr_symval != tp_pointer->sym)
	{	/* Unwind as many stackframes as are necessary up to the max */
		while(curr_symval != tp_pointer->sym && frame_pointer < tp_pointer->fp)
		{
#			ifdef GTM_TRIGGER
			if (SFT_TRIGR & frame_pointer->type)
			{	/* We have encountered a trigger base frame. We cannot unroll it because there are C frames
				 * associated with it so we must interrupt this tp_restart and return to gtm_trigger() so
				 * it can unroll the base frame and rethrow the error to properly unroll the C stack.
				 */
				*tprestart_rc = ERR_TPRETRY;
				tprestart_state = TPRESTART_STATE_TPUNW;
				DBGTRIGR((stderr, "tp_unwind: Encountered trigger base frame during M-stack unwind - "
					  "rethrowing\n"));
				return -1;
			}
#			endif
			op_unwind();
		}
		if (curr_symval != tp_pointer->sym)
		{	/* Unwind as many mv_stents as are necessary up to the max */
			mvc = mv_chain;
			while(curr_symval != tp_pointer->sym && mvc < tp_pointer->mvc)
			{
				unw_mv_ent(mvc);
				mvc = (mv_stent *)(mvc->mv_st_next + (char *)mvc);
			}
			mv_chain = mvc;
			/* Final check */
			if (curr_symval != tp_pointer->sym)
				GTMASSERT;
		}
	}
	var_cloned = curr_lv->tp_var->var_cloned;
	if (var_cloned)
	{	/* Var/tree has been copied (and modified) -- see about restoring it */
		DBGRFCT((stderr, "\ntp_unwind_restlv: curr_lv was modified and cloned -- needs restoration\n"));
		if (NULL != restore_ent->key.var_name.addr)
		{	/* Restore data into a named variable (hash table entry)
			 * Step 1 -- find its hash table address to see what lv_val is there now.
			 */
			tabent = lookup_hashtab_mname(&((tp_pointer->sym)->h_symtab), &restore_ent->key);
			assert(tabent);
			/* Step 2 -- If lv_val is NOT the same as it was, then we must replace the lv_val
			 * currently in use. Decrement its use count (which will delete it and the tree if
			 * it is no longer used) and replace with desired previous lv_val whose use count
			 * was incremented when it was saved.
			 */
			if (curr_lv != (inuse_lv = (lv_val *)tabent->value))
			{
				if (inuse_lv)
					DECR_BASE_REF_RQ(tabent, inuse_lv, FALSE);
				DBGRFCT((stderr, "tp_unwind: hte 0x"lvaddr" being reset from 0x"lvaddr" to 0x"lvaddr"\n",
					 tabent, tabent->value, curr_lv));
				tabent->value = (void *)curr_lv;
				INCR_TREFCNT(curr_lv);			/* Back in the hash table, bump its reference */
			}
		} /* Else, if restoring orphaned data, just prune the old var and copy in the saved tree (if one existed) */
		/* Step 3 -- We have the correct lv_val in the hash table now but it has the wrong value.
		 * Get rid of its current tree if any.
		 */
		if (lvt_child = LV_GET_CHILD(curr_lv))	/* Note assignment */
		{
			DBGRFCT((stderr, "\ntp_unwind_restlv: Killing children of curr_lv 0x"lvaddr"\n", curr_lv));
			assert((lvTreeNode *)curr_lv == LVT_PARENT(lvt_child));
			LV_CHILD(curr_lv) = NULL;	/* prevent recursion due to alias containers */
			lv_killarray(lvt_child, FALSE);
		}
		/* Step 4:  Copy in the needed fields from the saved flavor lv_val back to curr_lv.
		 * Preserve the ref counts of the current var since the copy's ref counts have not been kept up to date.
		 */
		DBGRFCT((stderr, "\ntp_unwind_restlv: Restoring value of lv 0x"lvaddr" back into lv 0x"lvaddr"\n",
			save_lv, curr_lv));
		/* The following is optimized to do the initialization of just the needed structure members. For that it assumes a
		 * particular "lv_val" structure layout. The assumed layout is asserted so any changes to the layout will
		 * automatically show an issue here and cause the below initialization to be accordingly reworked.
		 */
		assert(0 == OFFSETOF(lv_val, v));
		assert(OFFSETOF(lv_val, v) + SIZEOF(curr_lv->v) == OFFSETOF(lv_val, ptrs));
		assert(OFFSETOF(lv_val, ptrs) + SIZEOF(curr_lv->ptrs) == OFFSETOF(lv_val, stats));
		assert(OFFSETOF(lv_val, stats) + SIZEOF(curr_lv->stats) == OFFSETOF(lv_val, has_aliascont));
		assert(OFFSETOF(lv_val, has_aliascont) + SIZEOF(curr_lv->has_aliascont) == OFFSETOF(lv_val, lvmon_mark));
		assert(OFFSETOF(lv_val, lvmon_mark) + SIZEOF(curr_lv->lvmon_mark) == OFFSETOF(lv_val, tp_var));
		assert(OFFSETOF(lv_val, tp_var) + SIZEOF(curr_lv->tp_var) == SIZEOF(lv_val));
		/* save_lv -> curr_lv Copy begin */
		curr_lv->v = save_lv->v;
		curr_lv->ptrs = save_lv->ptrs;
		assert(0 < curr_lv->stats.trefcnt);	/* No need to copy "stats" as curr_lv is more uptodate */
		assert(0 < curr_lv->stats.crefcnt);
		assert(8 == (OFFSETOF(lv_val, tp_var) - OFFSETOF(lv_val, has_aliascont)));
		curr_lv->has_aliascont = save_lv->has_aliascont;
		DBGALS_ONLY(curr_lv->lvmon_mark = save_lv->has_aliascont);
		assert(save_lv->tp_var == curr_lv->tp_var);	/* no need to copy this field */
		/* save_lv -> curr_lv Copy done */
		/* Some fixup may need to be done if the variable was cloned (and thus moved around) */
		curr_lv->tp_var->var_cloned = FALSE;
		if (lvt_child = LV_GET_CHILD(curr_lv))
		{	/* Some pointer fix up needs to be done since the owner of the restored tree changed */
			assert(LVT_PARENT(lvt_child) == ((lvTreeNode *)curr_lv->tp_var->save_value));
			LV_CHILD(save_lv) = NULL;	/* now that curr_lv->tp_var->var_cloned has been reset */
			LVT_PARENT(lvt_child) = (lvTreeNode *)curr_lv;
			if (curr_lv->has_aliascont && NULL != lvscan_anchor)
			{	/* Some ref counts need to be restored for arrays this tree points to -- but only if the
				 * array contains pointers (alias containers).
				 */
				DBGRFCT((stderr, "\ntp_unwind_restlv: Putting lv 0x:"lvaddr" on the lvscan list\n", curr_lv));
				/* This array needs to have container pointer target reference counts reestablished. Record
				 * the lv so this can happen after all vars are restored.
				 */
				lvscan = *lvscan_anchor;
				elemindx = lvscan->elemcnt++;	/* Note post increment so elemindx has minus-one value */
				if (ARY_SCNCNTNR_MAX < elemindx)
				{	/* Present block is full so allocate a new one and chain it on */
					lvscan->elemcnt--;		/* New element ended up not being in that block.. */
					newlvscan = (lvscan_blk *)malloc(SIZEOF(lvscan_blk));
					newlvscan->next = lvscan;
					newlvscan->elemcnt = 1;		/* Going to use first one *now* */
					elemindx = 0;
					*lvscan_anchor = newlvscan;
					lvscan = newlvscan;
				}
				assert(ARY_SCNCNTNR_MAX >= elemindx && 0 <= elemindx);
				lvscan->ary_scncntnr[elemindx] = curr_lv;
			}
		}
	} else
	{
		DBGRFCT((stderr, "\ntp_unwind_restlv: curr_lv was NOT modified or cloned\n"));
		assert(NULL == LV_CHILD(save_lv));
		assert(!save_lv->tp_var->var_cloned);
		/* We know that the subscript array underneath curr_lv did not change since saving it into save_lv. But the
		 * unsubscripted lv could have changed (have no way of checking if that is the case) so restore it unconditionally.
		 */
		curr_lv->v = save_lv->v;
		/* No need to copy "save_lv->ptrs" as "ptrs" contains 2 fields both of which are already correct in "curr_lv" */
		assert(save_lv->ptrs.val_ent.parent.sym == curr_lv->ptrs.val_ent.parent.sym);
		assert(NULL == save_lv->ptrs.val_ent.children);
		/* No need to copy "save_lv->stats" as "curr_lv->stats" is more uptodate */
		assert(save_lv->has_aliascont == curr_lv->has_aliascont);	/* no need to copy this field */
		assert(save_lv->lvmon_mark == curr_lv->lvmon_mark);	/* no need to copy this field */
		assert(save_lv->tp_var == curr_lv->tp_var);	/* no need to copy this field */
	}
	if (NULL == lvscan_anchor)
		/* Means this is completely unwinding a nested level so we need to reset the tstartcycle in this
		 * lvval so it gets handled correctly when this lv is encountered again after the restart completes.
		 */
		curr_lv->stats.tstartcycle = 0;
	return 0;
}