DIRECTORYCamelot,PBasics,YggEnvironment,YggLog,YggLogBasic,YggLogInline,YggLogBasicInternal,YggLogRep,VM;YggLogBasicWriteImpl: CEDAR MONITORIMPORTSPBasics, YggLog, YggLogBasic, YggLogBasicInternal, YggLogInlineEXPORTSYggLogBasic =BEGINPageNumber: TYPE = YggEnvironment.PageNumber;RecordID: TYPE = YggLog.RecordID;CallerProgrammingError: ERROR = CODE;curPageRecordID: YggLog.RecordID;curPageWordsUsed: CARD;  -- in machine dependent wordscurPagePtr: LONG POINTER _ NIL;pagesLeft: INT;curVersion: YggLogRep.PageVersion;nPagesWritten: INT _ 0;nPartFullPagesWritten: INT _ 0;OpenForPut: PUBLIC ENTRY PROC [nextPage: PageNumber, version: YggLogRep.PageVersion, nextRecord: RecordID] = {IF YggLogInline.WordInPageFromRecordID[nextRecord, VM.wordsPerPage] # 0 THENERROR CallerProgrammingError;curPageRecordID _ nextRecord;curPageWordsUsed _ 0;curVersion _ version;TRUSTED {[pagesLeft, curPagePtr] _ YggLogBasicInternal.OpenBasicForPut[nextPage, version, nextRecord];LOOPHOLE[curPagePtr, LONG POINTER TO CARD32]^ _ 0;};};CloseForPut: PUBLIC ENTRY PROC [] = {YggLogBasicInternal.CloseBasicForPut[];curPagePtr _ NIL;};Put: PUBLIC PROC [ from: YggLog.Block, optr: Camelot.optrT, force: BOOL, writeID: BOOL]RETURNS [thisRecord, followingRecord: RecordID, thisWordNumber: YggEnvironment.WordNumber] = TRUSTED {totalLen: INT _ 0;  -- in 32 bit wordsFOR b: YggLog.BlockPtr _ @from, b.rest UNTIL b = NIL DOlen: CARD = b.length;IF len > 0 THEN {IF b.base # NIL THEN {offset: CARD _ 0;UNTIL offset >= len*WordsINWORDS DOtouch: CARDINAL _ LOOPHOLE[b.base + offset*SIZE[INT32], LONG POINTER TO CARDINAL]^;IF offset = len - 1 THEN EXIT;offset _ offset + VM.wordsPerPage/WORDS[CARD32];IF offset >= len THEN offset _ len - 1;ENDLOOP;};totalLen _ totalLen + len;};ENDLOOP;IF totalLen NOT IN [YggLogBasic.minBlockLen .. YggLogBasic.maxBlockLen] THENERROR CallerProgrammingError;[thisRecord, followingRecord, thisWordNumber] _ PutEntry[totalLen, from, force, writeID];IF force THEN YggLogBasicInternal.ForceTo[followingRecord: followingRecord];};WordsINWORDS: CARD = WORDS[CARD32];PutEntry: ENTRY PROC [totalLen: CARDINAL, from: YggLog.Block, force: BOOL, writeID: BOOL]RETURNS [thisRecord, followingRecord: RecordID, thisWordNumber: YggEnvironment.WordNumber] = {isContinuation: BOOL _ FALSE;thisRecord _ CurrentRecordID[];thisWordNumber _ YggLogBasic.WordNumberFromRecordID[thisRecord];IF writeID THEN TRUSTED {LOOPHOLE[from.base,LONG POINTER TO YggLogRep.CheckpointCompleteRecord].thisRecordID _ thisRecord;};DOwordsThisBlock: CARD _MIN[(YggLog.wordsPerPage-WORDS[YggLogRep.Header])-curPageWordsUsed, totalLen*WordsINWORDS];  -- in machine dependent wordswordsThisCopy: CARD;totalLen _ totalLen-wordsThisBlock/WordsINWORDS; -- 32 bit words remaining to be logged when this block finishedTRUSTED {pageNumber: INT;pageNumber _ ConstArith.ToInt[ConstArith.Div[curPageRecordID, ConstArith.FromCard[YggLog.wordsPerPage]]];Header[curPagePtr+(curPageWordsUsed*UNITS[WORD])]^ _ [valid: FALSE, version: curVersion,hasContinuation: (totalLen # 0), isContinuation: isContinuation,nWords: wordsThisBlock+SIZE[YggLogRep.Header],unused1: pageNumber];};curPageWordsUsed _ curPageWordsUsed+WORDS[YggLogRep.Header];DOwordsThisCopy _ MIN[from.length*WordsINWORDS, wordsThisBlock];TRUSTED {PBasics.Copy[to: curPagePtr+(curPageWordsUsed*UNITS[WORD]), from: from.base, nwords: wordsThisCopy/WordsINWORDS];  };curPageWordsUsed _ curPageWordsUsed+wordsThisCopy;IF wordsThisCopy = wordsThisBlock THEN EXIT;wordsThisBlock _ wordsThisBlock-wordsThisCopy;TRUSTED {from _ from.rest^;};ENDLOOP;IF totalLen # 0 THEN { -- YggLog record not all written.AdvancePage[];from.base _ from.base+wordsThisCopy;from.length _ from.length-wordsThisCopy/WordsINWORDS;isContinuation _ TRUE;}ELSE { -- YggLog record all written.wpp: CARD = YggLog.wordsPerPage;IF force OR (curPageWordsUsed >= wpp-WORDS[YggLogRep.Header]) THENAdvancePage[];RETURN [thisRecord, CurrentRecordID[], thisWordNumber];}ENDLOOP;};Force: PUBLIC PROC [followingRecord: RecordID] = {AdvanceTo: ENTRY PROC [followingRecord: RecordID] = {TRUSTED {IF ConstArith.Compare[followingRecord, curPageRecordID] # greaterTHEN RETURN; };TRUSTED {IF ConstArith.Compare[followingRecord, CurrentRecordID[]] = greater THENRETURN WITH ERROR CallerProgrammingError; };AdvancePage[];};AdvanceTo[followingRecord];YggLogBasicInternal.ForceTo[followingRecord];};Header: PROC [p: LONG POINTER] RETURNS [LONG POINTER TO YggLogRep.Header] = INLINE {RETURN [LOOPHOLE[p]] };RecordIDOfNextPut: PUBLIC ENTRY PROC [] RETURNS [RecordID] = {RETURN [CurrentRecordID[]]};CurrentRecordID: INTERNAL PROC [] RETURNS [RecordID] = INLINE {RETURN [YggLogInline.AddC[curPageRecordID, curPageWordsUsed]] };AdvancePage: INTERNAL PROC [] = {IF curPageWordsUsed # YggLog.wordsPerPage THEN TRUSTED {nPartFullPagesWritten _ nPartFullPagesWritten + 1;LOOPHOLE[curPagePtr+(curPageWordsUsed*UNITS[WORD]), LONG POINTER TO CARD32]^ _ 0 };nPagesWritten _ nPagesWritten + 1;TRUSTED {Header[curPagePtr].valid _ TRUE;};pagesLeft _ pagesLeft - 1;IF pagesLeft = 0 THEN[curVersion, pagesLeft, curPagePtr] _ YggLogBasicInternal.AdvanceChunk[]ELSEcurPagePtr _ curPagePtr + YggLog.wordsPerPage * UNITS[WORD];TRUSTED {Header[curPagePtr].valid _ FALSE;};curPageRecordID _ YggLogInline.AddC[curPageRecordID, YggLog.wordsPerPage];curPageWordsUsed _ 0;};END.  ¾  YggLogBasicWriteImpl.mesaCopyright Ó 1985, 1987, 1989 by Xerox Corporation.  All rights reserved.Implements log writing.  Separate from YggLogBasicImpl to have its own monitor.  Derived from Alpine.Last edited byBob Hagmann June 16, 1989 3:47:25 pm PDTNonspecific error that clients are not expected to catch.Monitored state:Points to first word of current page buffer.Number of pages in buffer represented by curPagePtr.Version bit for page now being written.for curiosity onlyStarting and stopping logging nextRecord must be page-aligned.ensure that first store into page clears valid bit.Public writing 	Compute the total length of the block to be written, and touch all pages in it.	Total record length must be in correct range.	Append to log, then force to disk if necessary.	Note: tail monitor is not held during force.! YggLog.WriteFailed (with monitor locked; this is a server-crashing error).	On entry, there is always room in the current page for a header plus 1 word (i.e. curPageWordsUsed < wordsPerPage-SIZE[YggLogRep.Header]), so this record starts on the current page.Write one log block.	Write a header for the log block.	The first store to a page should be the one that sets valid _ FALSE.Copy a run of words to the log block.Assert wordsThisBlock > wordsThisCopy = from.length, from.rest # NIL.YggLog block is now full.  Is log record all written?Assert curPageWordsUsed = wordsPerPage.Advance page and loop.Assert from.rest = NIL.Advance page if log force or if not enough room on page for a header plus one word.YggLogBasic.Force.If the word before followingRecord is on the current page, skip the rest ofthe current page.followingRecord must not be later than record about to be written.Note: tail monitor is not held during force.Internal procedures and utilities If page is only partly full then terminate it with 0 word.Mark current page "valid".may raise WriteFailed because log is fullMark new page "invalid" Ê—  ˜ šœ™IcodešœH™H—Jšœe™ešœ™K™(—˜ šÏk	˜	Jšœ˜Jšœ˜Jšœ˜Jšœ˜Jšœ˜Jšœ˜Jšœ˜Jšœ
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