delerror.c

#include "lmdb.h"
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdint.h>

# define DBG(X, ...)  fprintf(stderr,X "\r\n",##__VA_ARGS__) ;

#define u8 unsigned char
#define u64 uint64_t
#define i64 int64_t
#define u32 unsigned int

typedef struct lmdb
{
	MDB_env *menv;
	MDB_txn *txn;
	MDB_dbi pagesdb;
	MDB_cursor *cursorPages;
}lmdb;

static int pagesdb_cmp(const MDB_val *a, const MDB_val *b)
{
	u64 aActor;
	u64 bActor;
	u32 aPgno;
	u32 bPgno;
	int diff;

	memcpy(&aActor,a->mv_data,sizeof(u64));
	memcpy(&bActor,b->mv_data,sizeof(u64));
	diff = aActor - bActor;
	if (diff == 0)
	{
		memcpy(&aPgno,(u8*)a->mv_data + sizeof(u64),sizeof(u32));
		memcpy(&bPgno,(u8*)b->mv_data + sizeof(u64),sizeof(u32));
		return aPgno - bPgno;
	}
	return diff;
}

static int pagesdb_val_cmp(const MDB_val *a, const MDB_val *b)
{
	u64 aEvterm,aEvnum;
	u64 bEvterm,bEvnum;
	u8 aCounter, bCounter;
	int diff;

	memcpy(&aEvterm, a->mv_data, sizeof(u64));
	memcpy(&bEvterm, b->mv_data, sizeof(u64));
	diff = aEvterm - bEvterm;
	if (diff == 0)
	{
		memcpy(&aEvnum, (u8*)a->mv_data+sizeof(u64), sizeof(u64));
		memcpy(&bEvnum, (u8*)b->mv_data+sizeof(u64), sizeof(u64));
		diff = aEvnum - bEvnum;
		if (diff == 0)
		{
			aCounter = ((u8*)a->mv_data)[sizeof(u64)*2];
			bCounter = ((u8*)b->mv_data)[sizeof(u64)*2];
			return aCounter - bCounter;
		}
		return diff;
	}
	return diff;
}


static int open_env(lmdb *lm, const char *pth, int flags)
{
	if (mdb_env_create(&lm->menv) != MDB_SUCCESS)
		return -1;
	if (mdb_env_set_maxdbs(lm->menv,5) != MDB_SUCCESS)
		return -1;
	if (mdb_env_open(lm->menv, pth, MDB_NOSUBDIR | flags, 0664) != MDB_SUCCESS)
		return -1;
	if (mdb_txn_begin(lm->menv, NULL, flags, &lm->txn) != MDB_SUCCESS)
		return -1;
	if (mdb_dbi_open(lm->txn, "pages", MDB_DUPSORT, &lm->pagesdb) != MDB_SUCCESS)
		return -1;
	if (mdb_set_compare(lm->txn, lm->pagesdb, pagesdb_cmp) != MDB_SUCCESS)
		return -1;
	if (mdb_set_dupsort(lm->txn, lm->pagesdb, pagesdb_val_cmp) != MDB_SUCCESS)
		return -1;
	if (mdb_cursor_open(lm->txn, lm->pagesdb, &lm->cursorPages) != MDB_SUCCESS)
		return -1;

	return 0;
}

int main()
{
	lmdb rd;
	u8 pagesKeyBuf[sizeof(u64)+sizeof(u32)];
	MDB_val pgKey = {0,NULL}, pgVal = {0,NULL};
	u64 evnum,evterm,aindex = 126;
	u32 pgno = 65;
	int mrc;

	memcpy(pagesKeyBuf,               &aindex,sizeof(u64));
	memcpy(pagesKeyBuf + sizeof(u64), &pgno,  sizeof(u32));
	pgKey.mv_data = pagesKeyBuf;
	pgKey.mv_size = sizeof(pagesKeyBuf);

	if (open_env(&rd, "lmdb", 0) == -1)
	{
		DBG("Unable to open source environment");
		return 0;
	}

	if (mdb_cursor_get(rd.cursorPages,&pgKey,&pgVal,MDB_SET) != MDB_SUCCESS)
	{
		return 0;
	}
	if (mdb_cursor_get(rd.cursorPages,&pgKey,&pgVal,MDB_FIRST_DUP) != MDB_SUCCESS)
		return 0;

	do{
		MDB_val pgDelKey = {0,NULL}, pgDelVal = {0,NULL};

		mdb_cursor_get(rd.cursorPages,&pgDelKey,&pgDelVal,MDB_GET_CURRENT);
		memcpy(&evterm, pgDelVal.mv_data,                 sizeof(u64));
		memcpy(&evnum,  (u8*)pgDelVal.mv_data+sizeof(u64),sizeof(u64));
		DBG("Evnum=%llu",evnum);
		// if (evnum > 5538)
		if (evnum == 5538)
		{
			mrc = mdb_cursor_del(rd.cursorPages,0);
			if (mrc != MDB_SUCCESS)
			{
				DBG("Unable to delete page on cursor! err=%d, evnum=%llu",mrc,evnum);
				return 1;
			}
			DBG("Deleted");
		}
	}while (mdb_cursor_get(rd.cursorPages,&pgKey,&pgVal,MDB_NEXT_DUP) == MDB_SUCCESS);
	mdb_txn_commit(rd.txn);

	return 0;
}