From 0d489da11220c272765fcc64d390be6bb50ff87f Mon Sep 17 00:00:00 2001
From: sje <sje@4f64403b-2f21-0410-a795-97e2b3489a10>
Date: Fri, 27 Jul 2007 15:27:25 +0000
Subject: based on mmap

git-svn-id: https://server.scottellis.com.au/svn/mim_plugs@302 4f64403b-2f21-0410-a795-97e2b3489a10
---
 db3x_autobackups/dbcache.c | 248 ++++++++++++++++++++-------------------------
 1 file changed, 110 insertions(+), 138 deletions(-)

(limited to 'db3x_autobackups/dbcache.c')

diff --git a/db3x_autobackups/dbcache.c b/db3x_autobackups/dbcache.c
index dd3bc5a..601670d 100644
--- a/db3x_autobackups/dbcache.c
+++ b/db3x_autobackups/dbcache.c
@@ -2,8 +2,8 @@
 
 Miranda IM: the free IM client for Microsoft* Windows*
 
-Copyright 2000-2003 Miranda ICQ/IM project, 
-all portions of this codebase are copyrighted to the people 
+Copyright 2000-2003 Miranda ICQ/IM project,
+all portions of this codebase are copyrighted to the people
 listed in contributors.txt.
 
 This program is free software; you can redistribute it and/or
@@ -22,165 +22,124 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
 
 #include "commonheaders.h"
-#include "database.h"
 
+BOOL safetyMode = TRUE;
+static int flushBuffersTimerId;
 
-#define CACHESECTIONSIZE   4096
-#define CACHESECTIONCOUNT  32
-
-extern HANDLE hDbFile;
-extern CRITICAL_SECTION csDbAccess;
+static PBYTE pNull = 0;
+static PBYTE pDbCache = NULL;
+static HANDLE hMap = NULL;
+static DWORD dwFileSize = 0;
+static DWORD ChunkSize = 65536;
 
-static BOOL safetyMode=TRUE;
-static PBYTE pDbCache;
-static DWORD lastUseCounter;
-struct DBCacheSectionInfo {
-	DWORD ofsBase;
-	DWORD lastUsed;
-} static cacheSectionInfo[CACHESECTIONCOUNT];
 
-static __inline int FindSectionForOffset(const DWORD ofs)
+void Map()
 {
-	int i;
-	for(i=0;i<CACHESECTIONCOUNT;i++)
-		if(ofs>=cacheSectionInfo[i].ofsBase && ofs<cacheSectionInfo[i].ofsBase+CACHESECTIONSIZE)
-			return i;
-	return -1;
-}
+	hMap = CreateFileMapping(hDbFile, NULL, PAGE_READWRITE, 0, dwFileSize, NULL);
 
-static __inline int FindLRUSection(void)
-{
-	int i,lru=0;
-	DWORD lowestLastUse=cacheSectionInfo[0].lastUsed;
-	for(i=1;i<CACHESECTIONCOUNT;i++) if(cacheSectionInfo[i].lastUsed<lowestLastUse) {lru=i; lowestLastUse=cacheSectionInfo[i].lastUsed;}
-	return lru;
+	if (hMap)
+		pDbCache = MapViewOfFile(hMap, FILE_MAP_ALL_ACCESS/*FILE_MAP_WRITE*/, 0, 0 ,0);
+	else
+		DatabaseCorruption("%s (CreateFileMapping failed. Code: %d)");
+
+	if (!pDbCache)
+		DatabaseCorruption("%s (MapViewOfFile failed. Code: %d)");
 }
 
-static __inline void LoadSection(const int i,DWORD ofs)
+void UnMap() 
 {
-	cacheSectionInfo[i].ofsBase=ofs-ofs%CACHESECTIONSIZE;
-	log1("readsect %08x",ofs);
-	SetFilePointer(hDbFile,cacheSectionInfo[i].ofsBase,NULL,FILE_BEGIN);
-	ReadFile(hDbFile,pDbCache+i*CACHESECTIONSIZE,CACHESECTIONSIZE,&ofs,NULL);
+	KillTimer(NULL,flushBuffersTimerId);
+//	FlushViewOfFile(pDbCache, 0);
+	UnmapViewOfFile(pDbCache);
+	pDbCache = NULL;
+	CloseHandle(hMap);
 }
 
-static __inline void MoveSection(int *sectId,int dest)
+void ReMap(DWORD needed)
 {
-	CopyMemory(pDbCache+dest*CACHESECTIONSIZE,pDbCache+(*sectId)*CACHESECTIONSIZE,CACHESECTIONSIZE);
-	cacheSectionInfo[dest].ofsBase=cacheSectionInfo[*sectId].ofsBase;
-	*sectId=dest;
+	KillTimer(NULL,flushBuffersTimerId);
+
+	log3("remapping %d + %d (file end: %d)",dwFileSize,needed,dbHeader.ofsFileEnd);
+
+	if (needed > ChunkSize)
+	{
+		if ((needed + dwFileSize) - dbHeader.ofsFileEnd > ChunkSize)
+			DatabaseCorruption("%s (Too large increment)");
+		else
+		{
+			DWORD x = dbHeader.ofsFileEnd/ChunkSize;
+			dwFileSize = (x+1)*ChunkSize;
+		}
+	}
+	else
+		dwFileSize += ChunkSize;
+
+//	FlushViewOfFile(pDbCache, 0);
+	UnmapViewOfFile(pDbCache);
+	pDbCache = NULL;
+	CloseHandle(hMap);
+
+	Map();
 }
 
+void DBMoveChunk(DWORD ofsDest,DWORD ofsSource,int bytes)
+{
+    int x = 0;
+	log3("move %d %08x->%08x",bytes,ofsSource,ofsDest);
+	if (ofsDest+bytes>dwFileSize) ReMap(ofsDest+bytes-dwFileSize);
+	if (ofsSource+bytes>dwFileSize) {
+		x = ofsSource+bytes-dwFileSize;
+		log0("buggy move!");
+		_ASSERT(0);
+	}
+	if (x > 0)
+		ZeroMemory(pDbCache+ofsDest+bytes-x, x);
+	if (ofsSource < dwFileSize)
+		MoveMemory(pDbCache+ofsDest,pDbCache+ofsSource, bytes-x);
 
+	logg();
+}
 
 //we are assumed to be in a mutex here
 PBYTE DBRead(DWORD ofs,int bytesRequired,int *bytesAvail)
 {
-
-	int part1sect;
-	int part2sect;
-
-
-	part1sect = FindSectionForOffset(ofs);
-	if (ofs%CACHESECTIONSIZE+bytesRequired<CACHESECTIONSIZE) {
-		//only one section required
-		if(part1sect==-1) {
-			part1sect=FindLRUSection();
-			LoadSection(part1sect,ofs);
-		}
-		cacheSectionInfo[part1sect].lastUsed=++lastUseCounter;
-		if(bytesAvail!=NULL) *bytesAvail=cacheSectionInfo[part1sect].ofsBase+CACHESECTIONSIZE-ofs;
-		return pDbCache+part1sect*CACHESECTIONSIZE+(ofs-cacheSectionInfo[part1sect].ofsBase);
-	}
-	//two sections are required
-	part2sect=FindSectionForOffset(ofs+CACHESECTIONSIZE);
-	if(part1sect!=-1) {
-		if(part2sect==-1) {  //first part in cache, but not second part
-			if(part1sect==CACHESECTIONCOUNT-1) MoveSection(&part1sect,0);
-			LoadSection(part1sect+1,ofs+CACHESECTIONSIZE);
-		}
-		else if(part2sect!=part1sect+1) {   //both parts are in cache, but not already consecutive
-			if(part1sect==CACHESECTIONCOUNT-1) {
-				//first part is at end, move to before second part
-				if(part2sect==0) //second part is at start: need to move both
-					MoveSection(&part2sect,1);
-				MoveSection(&part1sect,part2sect-1);
-			}
-			else  //move second part to after first part
-				MoveSection(&part2sect,part1sect+1);
-		}
-	}
-	else {
-		if(part2sect==-1) {  //neither section is in cache
-			part1sect=0; part2sect=1;
-			LoadSection(part1sect,ofs); LoadSection(part2sect,ofs+CACHESECTIONSIZE);
-		}
-		else {    //part 2 is in cache, but not part 1
-			if(part2sect==0) MoveSection(&part2sect,1);
-			part1sect=part2sect-1;
-			LoadSection(part1sect,ofs);
-		}
+	// buggy read
+	if (ofs>=dwFileSize) {
+		log2("read from outside %d@%08x",bytesRequired,ofs);
+		if (bytesAvail!=NULL) *bytesAvail = ChunkSize;
+		return pNull;
 	}
-	//both sections are now consecutive, starting at part1sect
-	cacheSectionInfo[part1sect].lastUsed=++lastUseCounter;
-	cacheSectionInfo[part1sect+1].lastUsed=++lastUseCounter;
-	if(bytesAvail!=NULL) *bytesAvail=cacheSectionInfo[part1sect+1].ofsBase+CACHESECTIONSIZE-ofs;
-	return pDbCache+part1sect*CACHESECTIONSIZE+(ofs-cacheSectionInfo[part1sect].ofsBase);
+	log3((ofs+bytesRequired>dwFileSize)?"read %d@%08x, only %d avaliable":"read %d@%08x",bytesRequired,ofs,dwFileSize-ofs);
+	if (bytesAvail!=NULL) *bytesAvail = dwFileSize - ofs;
+	return pDbCache+ofs;
 }
 
-
-
 //we are assumed to be in a mutex here
 void DBWrite(DWORD ofs,PVOID pData,int bytes)
 {
-	//write direct, and rely on Windows' write caching
-	DWORD bytesWritten;
-	int i;
-
 	log2("write %d@%08x",bytes,ofs);
-	SetFilePointer(hDbFile,ofs,NULL,FILE_BEGIN);
-	if (WriteFile(hDbFile,pData,bytes,&bytesWritten,NULL)==0)
-	{
-		DatabaseCorruption();
-	}
+	if (ofs+bytes>dwFileSize) ReMap(ofs+bytes-dwFileSize);
+	MoveMemory(pDbCache+ofs,pData,bytes);
 	logg();
-	//check if any of the cache sections contain this bit
-	for(i=0;i<CACHESECTIONCOUNT;i++) {
-		if(ofs+bytes>=cacheSectionInfo[i].ofsBase && ofs<cacheSectionInfo[i].ofsBase+CACHESECTIONSIZE) {
-			if(ofs<cacheSectionInfo[i].ofsBase) {  //don't start at beginning
-				if(ofs+bytes>=cacheSectionInfo[i].ofsBase+CACHESECTIONSIZE)   //don't finish at end
-					CopyMemory(pDbCache+i*CACHESECTIONSIZE,(PBYTE)pData+cacheSectionInfo[i].ofsBase-ofs,CACHESECTIONSIZE);
-				else CopyMemory(pDbCache+i*CACHESECTIONSIZE,(PBYTE)pData+cacheSectionInfo[i].ofsBase-ofs,bytes-(cacheSectionInfo[i].ofsBase-ofs));
-			}
-			else {	  //start at beginning
-				if(ofs+bytes>=cacheSectionInfo[i].ofsBase+CACHESECTIONSIZE)   //don't finish at end
-					CopyMemory(pDbCache+i*CACHESECTIONSIZE+ofs-cacheSectionInfo[i].ofsBase,pData,cacheSectionInfo[i].ofsBase+CACHESECTIONSIZE-ofs);
-				else CopyMemory(pDbCache+i*CACHESECTIONSIZE+ofs-cacheSectionInfo[i].ofsBase,pData,bytes);
-			}
-		}
-	}
 }
 
-void DBMoveChunk(DWORD ofsDest,DWORD ofsSource,int bytes)
+//we are assumed to be in a mutex here
+void DBFill(DWORD ofs,int bytes)
 {
-	DWORD bytesRead;
-	PBYTE buf;
-
-	log3("move %d %08x->%08x",bytes,ofsSource,ofsDest);
-	buf=(PBYTE)mir_alloc(bytes);
-	SetFilePointer(hDbFile,ofsSource,NULL,FILE_BEGIN);
-	ReadFile(hDbFile,buf,bytes,&bytesRead,NULL);
-	DBWrite(ofsDest,buf,bytes);
-	mir_free(buf);
+	log2("zerofill %d@%08x",bytes,ofs);
+	if (ofs+bytes<=dwFileSize)
+		ZeroMemory(pDbCache+ofs,bytes);
 	logg();
 }
 
-static int flushBuffersTimerId;
 static VOID CALLBACK DoBufferFlushTimerProc(HWND hwnd,UINT message,UINT idEvent,DWORD dwTime)
 {
+    if (!pDbCache) return;
+
 	KillTimer(NULL,flushBuffersTimerId);
 	log0("tflush1");
-	FlushFileBuffers(hDbFile);
+	if (FlushViewOfFile(pDbCache, 0) == 0)
+		DatabaseCorruption(NULL);
 	log0("tflush2");
 }
 
@@ -188,7 +147,10 @@ void DBFlush(int setting)
 {
 	if(!setting) {
 		log0("nflush1");
-		if(safetyMode) FlushFileBuffers(hDbFile);
+		if(safetyMode && pDbCache) {
+			if (FlushViewOfFile(pDbCache, 0) == 0)
+				DatabaseCorruption(NULL);
+		}
 		log0("nflush2");
 		return;
 	}
@@ -201,29 +163,39 @@ static int CacheSetSafetyMode(WPARAM wParam,LPARAM lParam)
 	EnterCriticalSection(&csDbAccess);
 	safetyMode=wParam;
 	LeaveCriticalSection(&csDbAccess);
-	if(safetyMode) FlushFileBuffers(hDbFile);
+	DBFlush(1);
 	return 0;
 }
 
 int InitCache(void)
 {
-	int i;
-	DWORD bytesRead;
-	
+	DWORD x;
+	SYSTEM_INFO sinf;
+
+	GetSystemInfo(&sinf);
+	ChunkSize = sinf.dwAllocationGranularity;
+
+	dwFileSize = GetFileSize(hDbFile,  NULL);
+
+	// Align to chunk
+	x = dwFileSize % ChunkSize;
+	if (x) dwFileSize += ChunkSize - x;
+
+	Map();
+
+	// zero region for reads outside the file
+	pNull = calloc(ChunkSize,1);
+
 	CreateServiceFunction(MS_DB_SETSAFETYMODE,CacheSetSafetyMode);
-	pDbCache=(PBYTE)mir_alloc(CACHESECTIONSIZE*CACHESECTIONCOUNT);
-	lastUseCounter=CACHESECTIONCOUNT;
-	for(i=0;i<CACHESECTIONCOUNT;i++) {
-		cacheSectionInfo[i].ofsBase=0;
-		cacheSectionInfo[i].lastUsed=i;
-		SetFilePointer(hDbFile,cacheSectionInfo[i].ofsBase,NULL,FILE_BEGIN);
-		ReadFile(hDbFile,pDbCache+i*CACHESECTIONSIZE,CACHESECTIONSIZE,&bytesRead,NULL);
-	}
+
 	return 0;
 }
 
 void UninitCache(void)
 {
-	mir_free(pDbCache);
 	KillTimer(NULL,flushBuffersTimerId);
+	FlushViewOfFile(pDbCache, 0);
+	UnmapViewOfFile(pDbCache);
+	CloseHandle(hMap);
+	if (pNull) free(pNull);
 }
-- 
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