/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 2011 Oracle and/or its affiliates.  All rights reserved.
 *
 * $Id$
 */

#include "db_config.h"

#include "db_int.h"
#include "dbinc/log.h"
#include "dbinc/mp.h"
#include "dbinc/txn.h"

/*
 * __memp_dirty --
 *	Upgrade a page from a read-only to a writeable pointer.
 *
 * PUBLIC: int __memp_dirty __P((DB_MPOOLFILE *, void *,
 * PUBLIC:     DB_THREAD_INFO *, DB_TXN *, DB_CACHE_PRIORITY, u_int32_t));
 */
int
__memp_dirty(dbmfp, addrp, ip, txn, priority, flags)
	DB_MPOOLFILE *dbmfp;
	void *addrp;
	DB_THREAD_INFO *ip;
	DB_TXN *txn;
	DB_CACHE_PRIORITY priority;
	u_int32_t flags;
{
	BH *bhp;
	DB_MPOOL *dbmp;
	DB_MPOOL_HASH *hp;
	DB_TXN *ancestor;
	ENV *env;
	MPOOL *c_mp;
#ifdef DIAG_MVCC
	MPOOLFILE *mfp;
#endif
	REGINFO *infop;
	int mvcc, ret;
	db_pgno_t pgno;
	void *pgaddr;

	env = dbmfp->env;
	dbmp = env->mp_handle;
	mvcc = atomic_read(&dbmfp->mfp->multiversion);

	/* Convert the page address to a buffer header. */
	pgaddr = *(void **)addrp;
	bhp = (BH *)((u_int8_t *)pgaddr - SSZA(BH, buf));
	pgno = bhp->pgno;

	/* If we have it exclusively then its already dirty. */
	if (F_ISSET(bhp, BH_EXCLUSIVE)) {
		DB_ASSERT(env, F_ISSET(bhp, BH_DIRTY));
		return (0);
	}

	if (flags == 0)
		flags = DB_MPOOL_DIRTY;
	DB_ASSERT(env, flags == DB_MPOOL_DIRTY || flags == DB_MPOOL_EDIT);

	if (F_ISSET(dbmfp, MP_READONLY)) {
		__db_errx(env, "%s: dirty flag set for readonly file page",
		    __memp_fn(dbmfp));
		return (EACCES);
	}

	for (ancestor = txn;
	    ancestor != NULL && ancestor->parent != NULL;
	    ancestor = ancestor->parent)
		;

	if (mvcc && txn != NULL && flags == DB_MPOOL_DIRTY &&
	    (!BH_OWNED_BY(env, bhp, ancestor) || SH_CHAIN_HASNEXT(bhp, vc))) {
		atomic_inc(env, &bhp->ref);
		*(void **)addrp = NULL;
		if ((ret = __memp_fput(dbmfp, ip, pgaddr, priority)) != 0) {
			__db_errx(env,
			    "%s: error releasing a read-only page",
			    __memp_fn(dbmfp));
			atomic_dec(env, &bhp->ref);
			return (ret);
		}
		if ((ret = __memp_fget(dbmfp,
		    &pgno, ip, txn, flags, addrp)) != 0) {
			if (ret != DB_LOCK_DEADLOCK)
				__db_errx(env,
				    "%s: error getting a page for writing",
				    __memp_fn(dbmfp));
			atomic_dec(env, &bhp->ref);
			return (ret);
		}
		atomic_dec(env, &bhp->ref);

		/*
		 * If the MVCC handle count hasn't changed, we should get a
		 * different version of the page.
		 */
		DB_ASSERT(env, *(void **)addrp != pgaddr ||
		    mvcc != atomic_read(&dbmfp->mfp->multiversion));

		pgaddr = *(void **)addrp;
		bhp = (BH *)((u_int8_t *)pgaddr - SSZA(BH, buf));
		DB_ASSERT(env, pgno == bhp->pgno);
		return (0);
	}

	infop = &dbmp->reginfo[bhp->region];
	c_mp = infop->primary;
	hp = R_ADDR(infop, c_mp->htab);
	hp = &hp[bhp->bucket];

	/* Drop the shared latch and get an exclusive. We have the buf ref'ed.*/
	MUTEX_UNLOCK(env, bhp->mtx_buf);
	MUTEX_LOCK(env, bhp->mtx_buf);
	DB_ASSERT(env, !F_ISSET(bhp, BH_EXCLUSIVE));
	F_SET(bhp, BH_EXCLUSIVE);

	/* Set/clear the page bits. */
	if (!F_ISSET(bhp, BH_DIRTY)) {
#ifdef DIAGNOSTIC
		MUTEX_LOCK(env, hp->mtx_hash);
#endif
		atomic_inc(env, &hp->hash_page_dirty);
		F_SET(bhp, BH_DIRTY);
#ifdef DIAGNOSTIC
		MUTEX_UNLOCK(env, hp->mtx_hash);
#endif
	}

#ifdef DIAG_MVCC
	mfp = R_ADDR(env->mp_handle->reginfo, bhp->mf_offset);
	MVCC_MPROTECT(bhp->buf, mfp->pagesize, PROT_READ | PROT_WRITE);
#endif
	DB_ASSERT(env, !F_ISSET(bhp, BH_DIRTY) ||
	    atomic_read(&hp->hash_page_dirty) != 0);
	return (0);
}

/*
 * __memp_shared --
 *	Downgrade a page from exlusively held to shared.
 *
 * PUBLIC: int __memp_shared __P((DB_MPOOLFILE *, void *));
 */
int
__memp_shared(dbmfp, pgaddr)
	DB_MPOOLFILE *dbmfp;
	void *pgaddr;
{
	BH *bhp;
	ENV *env;

	env = dbmfp->env;
	/* Convert the page address to a buffer header. */
	bhp = (BH *)((u_int8_t *)pgaddr - SSZA(BH, buf));

	if (F_ISSET(bhp, BH_DIRTY))
		dbmfp->mfp->file_written = 1;
	DB_ASSERT(env, F_ISSET(bhp, BH_EXCLUSIVE));
	F_CLR(bhp, BH_EXCLUSIVE);
	MUTEX_UNLOCK(env, bhp->mtx_buf);
	MUTEX_READLOCK(env, bhp->mtx_buf);

	return (0);
}
