--- a/engine/sqlite/src/mem4.cpp Wed May 26 10:44:32 2010 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,398 +0,0 @@
-/*
-** 2007 August 14
-**
-** The author disclaims copyright to this source code. In place of
-** a legal notice, here is a blessing:
-**
-** May you do good and not evil.
-** May you find forgiveness for yourself and forgive others.
-** May you share freely, never taking more than you give.
-**
-*************************************************************************
-** This file contains the C functions that implement a memory
-** allocation subsystem for use by SQLite.
-**
-** $Id: mem4.cpp 1282 2008-11-13 09:31:33Z LarsPson $
-*/
-
-/*
-** This version of the memory allocator attempts to obtain memory
-** from mmap() if the size of the allocation is close to the size
-** of a virtual memory page. If the size of the allocation is different
-** from the virtual memory page size, then ordinary malloc() is used.
-** Ordinary malloc is also used if space allocated to mmap() is
-** exhausted.
-**
-** Enable this memory allocation by compiling with -DSQLITE_MMAP_HEAP_SIZE=nnn
-** where nnn is the maximum number of bytes of mmap-ed memory you want
-** to support. This module may choose to use less memory than requested.
-**
-*/
-#if defined(SQLITE_MMAP_HEAP_SIZE)
-
-#if defined(SQLITE_MEMDEBUG) || defined(SQLITE_MEMORY_SIZE)
-# error cannot use SQLITE_MMAP_HEAP_SIZE with either SQLITE_MEMDEBUG \
- or SQLITE_MEMORY_SIZE
-#endif
-
-/*
-** This is a test version of the memory allocator that attempts to
-** use mmap() and madvise() for allocations and frees of approximately
-** the virtual memory page size.
-*/
-#include <sys/types.h>
-#include <sys/mman.h>
-#include <errno.h>
-#include "sqliteInt.h"
-#include <unistd.h>
-
-
-/*
-** All of the static variables used by this module are collected
-** into a single structure named "mem". This is to keep the
-** static variables organized and to reduce namespace pollution
-** when this module is combined with other in the amalgamation.
-*/
-static struct {
- /*
- ** The alarm callback and its arguments. The mem.mutex lock will
- ** be held while the callback is running. Recursive calls into
- ** the memory subsystem are allowed, but no new callbacks will be
- ** issued. The alarmBusy variable is set to prevent recursive
- ** callbacks.
- */
- sqlite3_int64 alarmThreshold;
- void (*alarmCallback)(void*, sqlite3_int64,int);
- void *alarmArg;
- int alarmBusy;
-
- /*
- ** Mutex to control access to the memory allocation subsystem.
- */
- sqlite3_mutex *mutex;
-
- /*
- ** Current allocation and high-water mark.
- */
- sqlite3_int64 nowUsed;
- sqlite3_int64 mxUsed;
-
- /*
- ** Current allocation and high-water marks for mmap allocated memory.
- */
- sqlite3_int64 nowUsedMMap;
- sqlite3_int64 mxUsedMMap;
-
- /*
- ** Size of a single mmap page. Obtained from sysconf().
- */
- int szPage;
- int mnPage;
-
- /*
- ** The number of available mmap pages.
- */
- int nPage;
-
- /*
- ** Index of the first free page. 0 means no pages have been freed.
- */
- int firstFree;
-
- /* First unused page on the top of the heap.
- */
- int firstUnused;
-
- /*
- ** Bulk memory obtained from from mmap().
- */
- char *mmapHeap; /* first byte of the heap */
-
-} mem;
-
-
-/*
-** Enter the mutex mem.mutex. Allocate it if it is not already allocated.
-** The mmap() region is initialized the first time this routine is called.
-*/
-static void memsys4Enter(void){
- if( mem.mutex==0 ){
- mem.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM);
- }
- sqlite3_mutex_enter(mem.mutex);
-}
-
-/*
-** Attempt to free memory to the mmap heap. This only works if
-** the pointer p is within the range of memory addresses that
-** comprise the mmap heap. Return 1 if the memory was freed
-** successfully. Return 0 if the pointer is out of range.
-*/
-static int mmapFree(void *p){
- char *z;
- int idx, *a;
- if( mem.mmapHeap==MAP_FAILED || mem.nPage==0 ){
- return 0;
- }
- z = (char*)p;
- idx = (z - mem.mmapHeap)/mem.szPage;
- if( idx<1 || idx>=mem.nPage ){
- return 0;
- }
- a = (int*)mem.mmapHeap;
- a[idx] = a[mem.firstFree];
- mem.firstFree = idx;
- mem.nowUsedMMap -= mem.szPage;
- madvise(p, mem.szPage, MADV_DONTNEED);
- return 1;
-}
-
-/*
-** Attempt to allocate nBytes from the mmap heap. Return a pointer
-** to the allocated page. Or, return NULL if the allocation fails.
-**
-** The allocation will fail if nBytes is not the right size.
-** Or, the allocation will fail if the mmap heap has been exhausted.
-*/
-static void *mmapAlloc(int nBytes){
- int idx = 0;
- if( nBytes>mem.szPage || nBytes<mem.mnPage ){
- return 0;
- }
- if( mem.nPage==0 ){
- mem.szPage = sysconf(_SC_PAGE_SIZE);
- mem.mnPage = mem.szPage - mem.szPage/10;
- mem.nPage = SQLITE_MMAP_HEAP_SIZE/mem.szPage;
- if( mem.nPage * sizeof(int) > mem.szPage ){
- mem.nPage = mem.szPage/sizeof(int);
- }
- mem.mmapHeap = mmap(0, mem.szPage*mem.nPage, PROT_WRITE|PROT_READ,
- MAP_ANONYMOUS|MAP_SHARED, -1, 0);
- if( mem.mmapHeap==MAP_FAILED ){
- mem.firstUnused = errno;
- }else{
- mem.firstUnused = 1;
- mem.nowUsedMMap = mem.szPage;
- }
- }
- if( mem.mmapHeap==MAP_FAILED ){
- return 0;
- }
- if( mem.firstFree ){
- int idx = mem.firstFree;
- int *a = (int*)mem.mmapHeap;
- mem.firstFree = a[idx];
- }else if( mem.firstUnused<mem.nPage ){
- idx = mem.firstUnused++;
- }
- if( idx ){
- mem.nowUsedMMap += mem.szPage;
- if( mem.nowUsedMMap>mem.mxUsedMMap ){
- mem.mxUsedMMap = mem.nowUsedMMap;
- }
- return (void*)&mem.mmapHeap[idx*mem.szPage];
- }else{
- return 0;
- }
-}
-
-/*
-** Release the mmap-ed memory region if it is currently allocated and
-** is not in use.
-*/
-static void mmapUnmap(void){
- if( mem.mmapHeap==MAP_FAILED ) return;
- if( mem.nPage==0 ) return;
- if( mem.nowUsedMMap>mem.szPage ) return;
- munmap(mem.mmapHeap, mem.nPage*mem.szPage);
- mem.nowUsedMMap = 0;
- mem.nPage = 0;
-}
-
-
-/*
-** Return the amount of memory currently checked out.
-*/
-sqlite3_int64 sqlite3_memory_used(void){
- sqlite3_int64 n;
- memsys4Enter();
- n = mem.nowUsed + mem.nowUsedMMap;
- sqlite3_mutex_leave(mem.mutex);
- return n;
-}
-
-/*
-** Return the maximum amount of memory that has ever been
-** checked out since either the beginning of this process
-** or since the most recent reset.
-*/
-sqlite3_int64 sqlite3_memory_highwater(int resetFlag){
- sqlite3_int64 n;
- memsys4Enter();
- n = mem.mxUsed + mem.mxUsedMMap;
- if( resetFlag ){
- mem.mxUsed = mem.nowUsed;
- mem.mxUsedMMap = mem.nowUsedMMap;
- }
- sqlite3_mutex_leave(mem.mutex);
- return n;
-}
-
-/*
-** Change the alarm callback
-*/
-int sqlite3_memory_alarm(
- void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
- void *pArg,
- sqlite3_int64 iThreshold
-){
- memsys4Enter();
- mem.alarmCallback = xCallback;
- mem.alarmArg = pArg;
- mem.alarmThreshold = iThreshold;
- sqlite3_mutex_leave(mem.mutex);
- return SQLITE_OK;
-}
-
-/*
-** Trigger the alarm
-*/
-static void sqlite3MemsysAlarm(int nByte){
- void (*xCallback)(void*,sqlite3_int64,int);
- sqlite3_int64 nowUsed;
- void *pArg;
- if( mem.alarmCallback==0 || mem.alarmBusy ) return;
- mem.alarmBusy = 1;
- xCallback = mem.alarmCallback;
- nowUsed = mem.nowUsed;
- pArg = mem.alarmArg;
- sqlite3_mutex_leave(mem.mutex);
- xCallback(pArg, nowUsed, nByte);
- sqlite3_mutex_enter(mem.mutex);
- mem.alarmBusy = 0;
-}
-
-/*
-** Allocate nBytes of memory
-*/
-static void *memsys4Malloc(int nBytes){
- sqlite3_int64 *p = 0;
- if( mem.alarmCallback!=0
- && mem.nowUsed+mem.nowUsedMMap+nBytes>=mem.alarmThreshold ){
- sqlite3MemsysAlarm(nBytes);
- }
- if( (p = mmapAlloc(nBytes))==0 ){
- p = malloc(nBytes+8);
- if( p==0 ){
- sqlite3MemsysAlarm(nBytes);
- p = malloc(nBytes+8);
- }
- if( p ){
- p[0] = nBytes;
- p++;
- mem.nowUsed += nBytes;
- if( mem.nowUsed>mem.mxUsed ){
- mem.mxUsed = mem.nowUsed;
- }
- }
- }
- return (void*)p;
-}
-
-/*
-** Return the size of a memory allocation
-*/
-static int memsys4Size(void *pPrior){
- char *z = (char*)pPrior;
- int idx = mem.nPage ? (z - mem.mmapHeap)/mem.szPage : 0;
- int nByte;
- if( idx>=1 && idx<mem.nPage ){
- nByte = mem.szPage;
- }else{
- sqlite3_int64 *p = pPrior;
- p--;
- nByte = (int)*p;
- }
- return nByte;
-}
-
-/*
-** Free memory.
-*/
-static void memsys4Free(void *pPrior){
- sqlite3_int64 *p;
- int nByte;
- if( mmapFree(pPrior)==0 ){
- p = pPrior;
- p--;
- nByte = (int)*p;
- mem.nowUsed -= nByte;
- free(p);
- if( mem.nowUsed==0 ){
- mmapUnmap();
- }
- }
-}
-
-/*
-** Allocate nBytes of memory
-*/
-void *sqlite3_malloc(int nBytes){
- sqlite3_int64 *p = 0;
- if( nBytes>0 ){
- memsys4Enter();
- p = memsys4Malloc(nBytes);
- sqlite3_mutex_leave(mem.mutex);
- }
- return (void*)p;
-}
-
-/*
-** Free memory.
-*/
-void sqlite3_free(void *pPrior){
- if( pPrior==0 ){
- return;
- }
- assert( mem.mutex!=0 );
- sqlite3_mutex_enter(mem.mutex);
- memsys4Free(pPrior);
- sqlite3_mutex_leave(mem.mutex);
-}
-
-
-
-/*
-** Change the size of an existing memory allocation
-*/
-void *sqlite3_realloc(void *pPrior, int nBytes){
- int nOld;
- sqlite3_int64 *p;
- if( pPrior==0 ){
- return sqlite3_malloc(nBytes);
- }
- if( nBytes<=0 ){
- sqlite3_free(pPrior);
- return 0;
- }
- nOld = memsys4Size(pPrior);
- if( nBytes<=nOld && nBytes>=nOld-128 ){
- return pPrior;
- }
- assert( mem.mutex!=0 );
- sqlite3_mutex_enter(mem.mutex);
- p = memsys4Malloc(nBytes);
- if( p ){
- if( nOld<nBytes ){
- memcpy(p, pPrior, nOld);
- }else{
- memcpy(p, pPrior, nBytes);
- }
- memsys4Free(pPrior);
- }
- assert( mem.mutex!=0 );
- sqlite3_mutex_leave(mem.mutex);
- return (void*)p;
-}
-
-#endif /* !SQLITE_MEMDEBUG && !SQLITE_OMIT_MEMORY_ALLOCATION */