Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 663 insertions, 0 deletions

diff --git a/src/backend/access/transam/transsup.c b/src/backend/access/transam/transsup.c
new file mode 100644
index 00000000000..a1e5b17ec13
--- /dev/null
+++ b/src/backend/access/transam/transsup.c
@@ -0,0 +1,663 @@
+/*-------------------------------------------------------------------------
+ *
+ * transsup.c--
+ *    postgres transaction access method support code
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/access/transam/Attic/transsup.c,v 1.1.1.1 1996/07/09 06:21:13 scrappy Exp $
+ *
+ * NOTES
+ *    This file contains support functions for the high
+ *    level access method interface routines found in transam.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "machine.h"		/* in port/ directory (needed for BLCKSZ) */
+
+#include "storage/buf.h"
+#include "storage/bufmgr.h"
+
+#include "utils/rel.h"
+#include "utils/elog.h"
+#include "utils/memutils.h"
+#include "utils/nabstime.h"
+
+#include "catalog/heap.h"
+#include "access/transam.h"	/* where the declarations go */
+#include "access/xact.h"	/* where the declarations go */
+
+#include "storage/smgr.h"
+
+/* ----------------------------------------------------------------
+ *		      general support routines
+ * ----------------------------------------------------------------
+ */
+
+/* --------------------------------
+ *	AmiTransactionOverride
+ *
+ *	This function is used to manipulate the bootstrap flag.
+ * --------------------------------
+ */
+void
+AmiTransactionOverride(bool flag)
+{
+    AMI_OVERRIDE = flag;
+}
+
+/* --------------------------------
+ *	TransComputeBlockNumber
+ * --------------------------------
+ */
+void
+TransComputeBlockNumber(Relation relation, /* relation to test */
+			TransactionId transactionId, /* transaction id to test */
+			BlockNumber *blockNumberOutP)
+{
+    long	itemsPerBlock;
+    
+    /* ----------------
+     *  we calculate the block number of our transaction
+     *  by dividing the transaction id by the number of
+     *  transaction things per block.  
+     * ----------------
+     */
+    if (relation == LogRelation)
+	itemsPerBlock = TP_NumXidStatusPerBlock;
+    else if (relation == TimeRelation)
+	itemsPerBlock = TP_NumTimePerBlock;
+    else
+	elog(WARN, "TransComputeBlockNumber: unknown relation");
+    
+    /* ----------------
+     *	warning! if the transaction id's get too large
+     *  then a BlockNumber may not be large enough to hold the results
+     *  of our division.
+     *
+     *	XXX  this will all vanish soon when we implement an improved
+     *       transaction id schema -cim 3/23/90
+     *
+     *  This has vanished now that xid's are 4 bytes (no longer 5).
+     *  -mer 5/24/92
+     * ----------------
+     */
+    (*blockNumberOutP) = transactionId / itemsPerBlock;
+}
+
+
+/* ----------------------------------------------------------------
+ *		     trans block support routines
+ * ----------------------------------------------------------------
+ */
+
+/* --------------------------------
+ *	TransBlockGetLastTransactionIdStatus
+ *
+ *	This returns the status and transaction id of the last
+ *	transaction information recorded on the given TransBlock.
+ * --------------------------------
+ */
+
+XidStatus
+TransBlockGetLastTransactionIdStatus(Block tblock,
+				     TransactionId baseXid,
+				     TransactionId *returnXidP)
+{
+    Index         index;
+    Index         maxIndex;
+    bits8         bit1;
+    bits8	  bit2;
+    BitIndex      offset;
+    XidStatus     xstatus;
+    
+    /* ----------------
+     *	sanity check
+     * ----------------
+     */
+    Assert((tblock != NULL));
+    
+    /* ----------------
+     *	search downward from the top of the block data, looking
+     *  for the first Non-in progress transaction status.  Since we
+     *  are scanning backward, this will be last recorded transaction
+     *  status on the block.
+     * ----------------
+     */
+    maxIndex = TP_NumXidStatusPerBlock;
+    for (index = maxIndex-1; index>=0; index--) {
+	offset =  BitIndexOf(index);
+	bit1 =    ((bits8) BitArrayBitIsSet((BitArray) tblock, offset++)) << 1;
+	bit2 =    (bits8)  BitArrayBitIsSet((BitArray) tblock, offset);
+	
+	xstatus =  (bit1 | bit2) ;
+	
+	/* ----------------
+	 *  here we have the status of some transaction, so test
+	 *  if the status is recorded as "in progress".  If so, then
+	 *  we save the transaction id in the place specified by the caller.
+	 * ----------------
+	 */
+	if (xstatus != XID_INPROGRESS) {
+	    if (returnXidP != NULL) {
+		TransactionIdStore(baseXid, returnXidP);
+		TransactionIdAdd(returnXidP, index);
+	    }
+	    break;
+	}
+    }
+    
+    /* ----------------
+     *	if we get here and index is 0 it means we couldn't find
+     *  a non-inprogress transaction on the block.  For now we just
+     *  return this info to the user.  They can check if the return
+     *  status is "in progress" to know this condition has arisen.
+     * ----------------
+     */
+    if (index == 0) {
+	if (returnXidP != NULL)
+	    TransactionIdStore(baseXid, returnXidP);
+    }
+    
+    /* ----------------
+     *	return the status to the user
+     * ----------------
+     */
+    return xstatus;
+}
+
+/* --------------------------------
+ *	TransBlockGetXidStatus
+ *
+ *	This returns the status of the desired transaction
+ * --------------------------------
+ */
+
+XidStatus
+TransBlockGetXidStatus(Block tblock,
+		       TransactionId transactionId)
+{
+    Index       		index;
+    bits8       		bit1;
+    bits8			bit2;
+    BitIndex    		offset;
+    
+    /* ----------------
+     *	sanity check
+     * ----------------
+     */
+    if (tblock == NULL) {
+	return XID_INVALID;
+    }
+    
+    /* ----------------
+     *	calculate the index into the transaction data where
+     *  our transaction status is located
+     *
+     *  XXX this will be replaced soon when we move to the
+     *      new transaction id scheme -cim 3/23/90
+     *
+     *  The old system has now been replaced. -mer 5/24/92
+     * ----------------
+     */
+    index = transactionId % TP_NumXidStatusPerBlock;
+    
+    /* ----------------
+     *	get the data at the specified index
+     * ----------------
+     */
+    offset =    BitIndexOf(index);
+    bit1 =      ((bits8)   BitArrayBitIsSet((BitArray) tblock, offset++)) << 1;
+    bit2 =      (bits8)    BitArrayBitIsSet((BitArray) tblock, offset);
+    
+    /* ----------------
+     *	return the transaction status to the caller
+     * ----------------
+     */
+    return (XidStatus)
+	(bit1 | bit2);
+}
+
+/* --------------------------------
+ *	TransBlockSetXidStatus
+ *
+ *	This sets the status of the desired transaction
+ * --------------------------------
+ */
+void
+TransBlockSetXidStatus(Block tblock,
+		       TransactionId transactionId, 
+		       XidStatus xstatus)
+{
+    Index       		index;
+    BitIndex    		offset;
+    
+    /* ----------------
+     *	sanity check
+     * ----------------
+     */
+    if (tblock == NULL)
+	return;
+    
+    /* ----------------
+     *	calculate the index into the transaction data where
+     *  we sould store our transaction status.
+     *
+     *  XXX this will be replaced soon when we move to the
+     *      new transaction id scheme -cim 3/23/90
+     *
+     *  The new scheme is here -mer 5/24/92
+     * ----------------
+     */
+    index = transactionId % TP_NumXidStatusPerBlock;
+    
+    offset =    BitIndexOf(index);
+    
+    /* ----------------
+     *	store the transaction value at the specified offset
+     * ----------------
+     */
+    switch(xstatus) {
+    case XID_COMMIT:             /* set 10 */
+	BitArraySetBit((BitArray) tblock, offset);
+	BitArrayClearBit((BitArray) tblock, offset + 1);
+	break;
+    case XID_ABORT:             /* set 01 */
+	BitArrayClearBit((BitArray) tblock, offset);
+	BitArraySetBit((BitArray) tblock, offset + 1);
+	break;
+    case XID_INPROGRESS:        /* set 00 */
+	BitArrayClearBit((BitArray) tblock, offset);
+	BitArrayClearBit((BitArray) tblock, offset + 1);
+	break;
+    default:
+	elog(NOTICE,
+	     "TransBlockSetXidStatus: invalid status: %d (ignored)",
+	     xstatus);
+	break;
+    }
+}
+
+/* --------------------------------
+ *	TransBlockGetCommitTime
+ *
+ *	This returns the transaction commit time for the
+ *	specified transaction id in the trans block.
+ * --------------------------------
+ */
+AbsoluteTime
+TransBlockGetCommitTime(Block tblock,
+			TransactionId transactionId)
+{
+    Index			index;
+    AbsoluteTime		*timeArray;
+    
+    /* ----------------
+     *	sanity check
+     * ----------------
+     */
+    if (tblock == NULL)
+	return INVALID_ABSTIME;
+    
+    /* ----------------
+     *	calculate the index into the transaction data where
+     *  our transaction commit time is located
+     *
+     *  XXX this will be replaced soon when we move to the
+     *      new transaction id scheme -cim 3/23/90
+     *
+     *  The new scheme is here. -mer 5/24/92
+     * ----------------
+     */
+    index = transactionId % TP_NumTimePerBlock;
+    
+    /* ----------------
+     *	return the commit time to the caller
+     * ----------------
+     */
+    timeArray =  (AbsoluteTime *) tblock;
+    return (AbsoluteTime)
+	timeArray[ index ];
+}
+
+/* --------------------------------
+ *	TransBlockSetCommitTime
+ *
+ *	This sets the commit time of the specified transaction
+ * --------------------------------
+ */
+void
+TransBlockSetCommitTime(Block tblock,
+			TransactionId transactionId,
+			AbsoluteTime commitTime)
+{
+    Index		index;
+    AbsoluteTime	*timeArray;
+    
+    /* ----------------
+     *	sanity check
+     * ----------------
+     */
+    if (tblock == NULL)
+	return;
+    
+    
+    /* ----------------
+     *	calculate the index into the transaction data where
+     *  we sould store our transaction status.  
+     *
+     *  XXX this will be replaced soon when we move to the
+     *      new transaction id scheme -cim 3/23/90
+     *
+     *  The new scheme is here.  -mer 5/24/92
+     * ----------------
+     */
+    index = transactionId % TP_NumTimePerBlock;
+    
+    /* ----------------
+     *	store the transaction commit time at the specified index
+     * ----------------
+     */
+    timeArray =  (AbsoluteTime *) tblock;
+    timeArray[ index ] = commitTime;
+}
+
+/* ----------------------------------------------------------------
+ *	           transam i/o support routines
+ * ----------------------------------------------------------------
+ */
+
+/* --------------------------------
+ *	TransBlockNumberGetXidStatus
+ * --------------------------------
+ */
+XidStatus
+TransBlockNumberGetXidStatus(Relation relation,
+			     BlockNumber blockNumber,
+			     TransactionId xid,
+			     bool *failP)
+{
+    Buffer	   	buffer;		/* buffer associated with block */
+    Block		block;		/* block containing xstatus */
+    XidStatus		xstatus;	/* recorded status of xid */
+    bool		localfail;      /* bool used if failP = NULL */
+    
+    /* ----------------
+     *	SOMEDAY place a read lock on the log relation
+     *  That someday is today 5 Aug 1991 -mer
+     * ----------------
+     */
+    RelationSetLockForRead(relation);
+    
+    /* ----------------
+     *	get the page containing the transaction information
+     * ----------------
+     */
+    buffer = 	   ReadBuffer(relation, blockNumber);
+    block =   	   BufferGetBlock(buffer);
+    
+    /* ----------------
+     *	get the status from the block.  note, for now we always
+     *  return false in failP.
+     * ----------------
+     */
+    if (failP == NULL)
+	failP = &localfail;
+    (*failP) = false;
+    
+    xstatus = TransBlockGetXidStatus(block, xid);
+    
+    /* ----------------
+     *	release the buffer and return the status
+     * ----------------
+     */
+    ReleaseBuffer(buffer);
+    
+    /* ----------------
+     *	SOMEDAY release our lock on the log relation
+     * ----------------
+     */
+    RelationUnsetLockForRead(relation);
+    
+    return
+	xstatus;
+}
+
+/* --------------------------------
+ *	TransBlockNumberSetXidStatus
+ * --------------------------------
+ */
+void
+TransBlockNumberSetXidStatus(Relation relation,
+			     BlockNumber blockNumber,
+			     TransactionId xid,
+			     XidStatus xstatus,
+			     bool *failP)
+{
+    Buffer	   	buffer;		/* buffer associated with block */
+    Block		block;		/* block containing xstatus */
+    bool		localfail;      /* bool used if failP = NULL */
+    
+    /* ----------------
+     *	SOMEDAY gain exclusive access to the log relation
+     *
+     *  That someday is today 5 Aug 1991 -mer
+     * ----------------
+     */
+    RelationSetLockForWrite(relation);
+    
+    /* ----------------
+     *	get the block containing the transaction status
+     * ----------------
+     */
+    buffer = 	ReadBuffer(relation, blockNumber);
+    block =   	BufferGetBlock(buffer);
+    
+    /* ----------------
+     *	attempt to update the status of the transaction on the block.
+     *  if we are successful, write the block. otherwise release the buffer.
+     *  note, for now we always return false in failP.
+     * ----------------
+     */
+    if (failP == NULL)
+	failP = &localfail;
+    (*failP) = false;
+    
+    TransBlockSetXidStatus(block, xid, xstatus);
+    
+    if ((*failP) == false)
+	WriteBuffer(buffer);
+    else
+	ReleaseBuffer(buffer);
+    
+    /* ----------------
+     *	SOMEDAY release our lock on the log relation
+     * ----------------
+     */    
+    RelationUnsetLockForWrite(relation);
+}
+
+/* --------------------------------
+ *	TransBlockNumberGetCommitTime
+ * --------------------------------
+ */
+AbsoluteTime
+TransBlockNumberGetCommitTime(Relation relation,
+			      BlockNumber blockNumber,
+			      TransactionId xid,
+			      bool *failP)
+{
+    Buffer	   	buffer;		/* buffer associated with block */
+    Block		block;		/* block containing commit time */
+    bool		localfail;      /* bool used if failP = NULL */
+    AbsoluteTime	xtime;		/* commit time */
+    
+    /* ----------------
+     *	SOMEDAY place a read lock on the time relation
+     *
+     *  That someday is today 5 Aug. 1991 -mer
+     * ----------------
+     */
+    RelationSetLockForRead(relation);
+    
+    /* ----------------
+     *	get the block containing the transaction information
+     * ----------------
+     */
+    buffer = 		ReadBuffer(relation, blockNumber);
+    block =   		BufferGetBlock(buffer);
+    
+    /* ----------------
+     *	get the commit time from the block
+     *  note, for now we always return false in failP.
+     * ----------------
+     */
+    if (failP == NULL)
+	failP = &localfail;
+    (*failP) = false;
+    
+    xtime = TransBlockGetCommitTime(block, xid);
+    
+    /* ----------------
+     *	release the buffer and return the commit time
+     * ----------------
+     */
+    ReleaseBuffer(buffer);
+    
+    /* ----------------
+     *	SOMEDAY release our lock on the time relation
+     * ----------------
+     */
+    RelationUnsetLockForRead(relation);
+    
+    if ((*failP) == false)
+	return xtime;
+    else
+	return INVALID_ABSTIME;
+    
+}
+
+/* --------------------------------
+ *	TransBlockNumberSetCommitTime
+ * --------------------------------
+ */
+void
+TransBlockNumberSetCommitTime(Relation relation,
+			      BlockNumber blockNumber,
+			      TransactionId xid,
+			      AbsoluteTime xtime,
+			      bool *failP)
+{
+    Buffer	   	buffer;		/* buffer associated with block */
+    Block		block;		/* block containing commit time */
+    bool		localfail;      /* bool used if failP = NULL */
+    
+    /* ----------------
+     *	SOMEDAY gain exclusive access to the time relation
+     *
+     *  That someday is today 5 Aug. 1991 -mer
+     * ----------------
+     */
+    RelationSetLockForWrite(relation);
+    
+    /* ----------------
+     *	get the block containing our commit time
+     * ----------------
+     */
+    buffer = 	   ReadBuffer(relation, blockNumber);
+    block =   	   BufferGetBlock(buffer);
+    
+    /* ----------------
+     *	attempt to update the commit time of the transaction on the block.
+     *  if we are successful, write the block. otherwise release the buffer.
+     *  note, for now we always return false in failP.
+     * ----------------
+     */
+    if (failP == NULL)
+	failP = &localfail;
+    (*failP) = false;
+    
+    TransBlockSetCommitTime(block, xid, xtime);
+    
+    if ((*failP) == false)
+	WriteBuffer(buffer);
+    else
+	ReleaseBuffer(buffer);
+    
+    /* ----------------
+     *	SOMEDAY release our lock on the time relation
+     * ----------------
+     */
+    RelationUnsetLockForWrite(relation);
+    
+}
+
+/* --------------------------------
+ *	TransGetLastRecordedTransaction
+ * --------------------------------
+ */
+void
+TransGetLastRecordedTransaction(Relation relation,
+				TransactionId xid, /* return: transaction id */
+				bool *failP)
+{
+    BlockNumber	  	blockNumber;	/* block number */
+    Buffer	   	buffer;		/* buffer associated with block */
+    Block		block;		/* block containing xid status */
+    BlockNumber		n;		/* number of blocks in the relation */
+    TransactionId	baseXid;
+    
+    (*failP) = false;
+    
+    /* ----------------
+     *	SOMEDAY gain exclusive access to the log relation
+     *
+     *  That someday is today 5 Aug. 1991 -mer
+     *  It looks to me like we only need to set a read lock here, despite
+     *  the above comment about exclusive access.  The block is never 
+     *  actually written into, we only check status bits.
+     * ----------------
+     */
+    RelationSetLockForRead(relation);
+    
+    /* ----------------
+     *	we assume the last block of the log contains the last
+     *  recorded transaction.  If the relation is empty we return
+     *  failure to the user.
+     * ----------------
+     */
+    n = RelationGetNumberOfBlocks(relation);
+    if (n == 0) {
+	(*failP) = true;
+	return;
+    }
+    
+    /* ----------------
+     *	get the block containing the transaction information
+     * ----------------
+     */
+    blockNumber =  n-1;
+    buffer = 	ReadBuffer(relation, blockNumber);
+    block =   	BufferGetBlock(buffer);
+    
+    /* ----------------
+     *	get the last xid on the block
+     * ----------------
+     */
+    baseXid = blockNumber * TP_NumXidStatusPerBlock;
+
+/* XXX ???? xid won't get returned! - AY '94 */
+    (void) TransBlockGetLastTransactionIdStatus(block, baseXid, &xid);
+    
+    ReleaseBuffer(buffer);
+    
+    /* ----------------
+     *	SOMEDAY release our lock on the log relation
+     * ----------------
+     */
+    RelationUnsetLockForRead(relation);
+}