sourcemod-central: extensions/sqlite/sqlite-source/vdbefifo.c@6dd851ba15fd (annotated)

ds@1952	1	/*
ds@1952	2	** 2005 June 16
ds@1952	3	**
ds@1952	4	** The author disclaims copyright to this source code. In place of
ds@1952	5	** a legal notice, here is a blessing:
ds@1952	6	**
ds@1952	7	** May you do good and not evil.
ds@1952	8	** May you find forgiveness for yourself and forgive others.
ds@1952	9	** May you share freely, never taking more than you give.
ds@1952	10	**
ds@1952	11	*************************************************************************
ds@1952	12	** This file implements a FIFO queue of rowids used for processing
ds@1952	13	** UPDATE and DELETE statements.
ds@1952	14	*/
ds@1952	15	#include "sqliteInt.h"
ds@1952	16	#include "vdbeInt.h"
ds@1952	17
ds@1952	18	/*
ds@1952	19	** Allocate a new FifoPage and return a pointer to it. Return NULL if
ds@1952	20	** we run out of memory. Leave space on the page for nEntry entries.
ds@1952	21	*/
ds@1952	22	static FifoPage *allocateFifoPage(int nEntry){
ds@1952	23	FifoPage *pPage;
ds@1952	24	if( nEntry>32767 ){
ds@1952	25	nEntry = 32767;
ds@1952	26	}
ds@1952	27	pPage = sqlite3_malloc( sizeof(FifoPage) + sizeof(i64)*(nEntry-1) );
ds@1952	28	if( pPage ){
ds@1952	29	pPage->nSlot = nEntry;
ds@1952	30	pPage->iWrite = 0;
ds@1952	31	pPage->iRead = 0;
ds@1952	32	pPage->pNext = 0;
ds@1952	33	}
ds@1952	34	return pPage;
ds@1952	35	}
ds@1952	36
ds@1952	37	/*
ds@1952	38	** Initialize a Fifo structure.
ds@1952	39	*/
ds@1952	40	void sqlite3VdbeFifoInit(Fifo *pFifo){
ds@1952	41	memset(pFifo, 0, sizeof(*pFifo));
ds@1952	42	}
ds@1952	43
ds@1952	44	/*
ds@1952	45	** Push a single 64-bit integer value into the Fifo. Return SQLITE_OK
ds@1952	46	** normally. SQLITE_NOMEM is returned if we are unable to allocate
ds@1952	47	** memory.
ds@1952	48	*/
ds@1952	49	int sqlite3VdbeFifoPush(Fifo *pFifo, i64 val){
ds@1952	50	FifoPage *pPage;
ds@1952	51	pPage = pFifo->pLast;
ds@1952	52	if( pPage==0 ){
ds@1952	53	pPage = pFifo->pLast = pFifo->pFirst = allocateFifoPage(20);
ds@1952	54	if( pPage==0 ){
ds@1952	55	return SQLITE_NOMEM;
ds@1952	56	}
ds@1952	57	}else if( pPage->iWrite>=pPage->nSlot ){
ds@1952	58	pPage->pNext = allocateFifoPage(pFifo->nEntry);
ds@1952	59	if( pPage->pNext==0 ){
ds@1952	60	return SQLITE_NOMEM;
ds@1952	61	}
ds@1952	62	pPage = pFifo->pLast = pPage->pNext;
ds@1952	63	}
ds@1952	64	pPage->aSlot[pPage->iWrite++] = val;
ds@1952	65	pFifo->nEntry++;
ds@1952	66	return SQLITE_OK;
ds@1952	67	}
ds@1952	68
ds@1952	69	/*
ds@1952	70	** Extract a single 64-bit integer value from the Fifo. The integer
ds@1952	71	** extracted is the one least recently inserted. If the Fifo is empty
ds@1952	72	** return SQLITE_DONE.
ds@1952	73	*/
ds@1952	74	int sqlite3VdbeFifoPop(Fifo pFifo, i64 pVal){
ds@1952	75	FifoPage *pPage;
ds@1952	76	if( pFifo->nEntry==0 ){
ds@1952	77	return SQLITE_DONE;
ds@1952	78	}
ds@1952	79	assert( pFifo->nEntry>0 );
ds@1952	80	pPage = pFifo->pFirst;
ds@1952	81	assert( pPage!=0 );
ds@1952	82	assert( pPage->iWrite>pPage->iRead );
ds@1952	83	assert( pPage->iWrite<=pPage->nSlot );
ds@1952	84	assert( pPage->iRead<pPage->nSlot );
ds@1952	85	assert( pPage->iRead>=0 );
ds@1952	86	*pVal = pPage->aSlot[pPage->iRead++];
ds@1952	87	pFifo->nEntry--;
ds@1952	88	if( pPage->iRead>=pPage->iWrite ){
ds@1952	89	pFifo->pFirst = pPage->pNext;
ds@1952	90	sqlite3_free(pPage);
ds@1952	91	if( pFifo->nEntry==0 ){
ds@1952	92	assert( pFifo->pLast==pPage );
ds@1952	93	pFifo->pLast = 0;
ds@1952	94	}else{
ds@1952	95	assert( pFifo->pFirst!=0 );
ds@1952	96	}
ds@1952	97	}else{
ds@1952	98	assert( pFifo->nEntry>0 );
ds@1952	99	}
ds@1952	100	return SQLITE_OK;
ds@1952	101	}
ds@1952	102
ds@1952	103	/*
ds@1952	104	** Delete all information from a Fifo object. Free all memory held
ds@1952	105	** by the Fifo.
ds@1952	106	*/
ds@1952	107	void sqlite3VdbeFifoClear(Fifo *pFifo){
ds@1952	108	FifoPage pPage, pNextPage;
ds@1952	109	for(pPage=pFifo->pFirst; pPage; pPage=pNextPage){
ds@1952	110	pNextPage = pPage->pNext;
ds@1952	111	sqlite3_free(pPage);
ds@1952	112	}
ds@1952	113	sqlite3VdbeFifoInit(pFifo);
ds@1952	114	}

author	David Anderson <dvander@alliedmods.net>
	Sun Aug 30 01:54:45 2009 -0700 (2009-08-30)
changeset 2790	6dd851ba15fd
parent 1952	b7aa2b626807
permissions	-rw-r--r--