mp_fopen.c

这是国外的resip协议栈

		if ((ret = __memp_alloc(dbmp, dbmp->reginfo,
		    NULL, strlen(path) + 1, &mfp->path_off, &p)) != 0)
			goto err;
		memcpy(p, path, strlen(path) + 1);

		/* Copy the file identification string into shared memory. */
		if ((ret = __memp_alloc(dbmp, dbmp->reginfo,
		    NULL, DB_FILE_ID_LEN, &mfp->fileid_off, &p)) != 0)
			goto err;
		memcpy(p, dbmfp->fileid, DB_FILE_ID_LEN);
	}

	/* Copy the page cookie into shared memory. */
	if (dbmfp->pgcookie == NULL || dbmfp->pgcookie->size == 0) {
		mfp->pgcookie_len = 0;
		mfp->pgcookie_off = 0;
	} else {
		if ((ret = __memp_alloc(dbmp, dbmp->reginfo,
		    NULL, dbmfp->pgcookie->size, &mfp->pgcookie_off, &p)) != 0)
			goto err;
		memcpy(p, dbmfp->pgcookie->data, dbmfp->pgcookie->size);
		mfp->pgcookie_len = dbmfp->pgcookie->size;
	}

	/*
	 * Prepend the MPOOLFILE to the list of MPOOLFILE's.
	 */
	R_LOCK(dbenv, dbmp->reginfo);
	ret = __db_mutex_setup(dbenv, dbmp->reginfo, &mfp->mutex,
	    MUTEX_NO_RLOCK);
	if (ret == 0)
		SH_TAILQ_INSERT_HEAD(&mp->mpfq, mfp, q, __mpoolfile);
	R_UNLOCK(dbenv, dbmp->reginfo);
	if (ret != 0)
		goto err;

have_mfp:
	/*
	 * We need to verify that all handles open a file either durable or not
	 * durable.  This needs to be cross process and cross sub-databases, so
	 * mpool is the place to do it.
	 */
	if (!LF_ISSET(DB_DURABLE_UNKNOWN | DB_RDONLY)) {
		if (F_ISSET(mfp, MP_DURABLE_UNKNOWN)) {
			if (LF_ISSET(MP_NOT_DURABLE))
				F_SET(mfp, MP_NOT_DURABLE);
			F_CLR(mfp, MP_DURABLE_UNKNOWN);
		} else if (!LF_ISSET(DB_TXN_NOT_DURABLE) !=
		    !F_ISSET(mfp, MP_NOT_DURABLE)) {
			__db_err(dbenv,
	     "Cannot open DURABLE and NOT DURABLE handles in the same file");
			ret = EINVAL;
			goto err;
		}
	}
	/*
	 * All paths to here have initialized the mfp variable to reference
	 * the selected (or allocated) MPOOLFILE.
	 */
	dbmfp->mfp = mfp;

	/*
	 * Check to see if we can mmap the file.  If a file:
	 *	+ isn't temporary
	 *	+ is read-only
	 *	+ doesn't require any pgin/pgout support
	 *	+ the DB_NOMMAP flag wasn't set (in either the file open or
	 *	  the environment in which it was opened)
	 *	+ and is less than mp_mmapsize bytes in size
	 *
	 * we can mmap it instead of reading/writing buffers.  Don't do error
	 * checking based on the mmap call failure.  We want to do normal I/O
	 * on the file if the reason we failed was because the file was on an
	 * NFS mounted partition, and we can fail in buffer I/O just as easily
	 * as here.
	 *
	 * We'd like to test to see if the file is too big to mmap.  Since we
	 * don't know what size or type off_t's or size_t's are, or the largest
	 * unsigned integral type is, or what random insanity the local C
	 * compiler will perpetrate, doing the comparison in a portable way is
	 * flatly impossible.  Hope that mmap fails if the file is too large.
	 */
#define	DB_MAXMMAPSIZE	(10 * 1024 * 1024)	/* 10 MB. */
	if (F_ISSET(mfp, MP_CAN_MMAP)) {
		if (path == NULL)
			F_CLR(mfp, MP_CAN_MMAP);
		else if (!F_ISSET(dbmfp, MP_READONLY))
			F_CLR(mfp, MP_CAN_MMAP);
		else if (dbmfp->ftype != 0)
			F_CLR(mfp, MP_CAN_MMAP);
		else if (LF_ISSET(DB_NOMMAP) || F_ISSET(dbenv, DB_ENV_NOMMAP))
			F_CLR(mfp, MP_CAN_MMAP);
		else {
			R_LOCK(dbenv, dbmp->reginfo);
			maxmap = mp->mp_mmapsize == 0 ?
			    DB_MAXMMAPSIZE : mp->mp_mmapsize;
			R_UNLOCK(dbenv, dbmp->reginfo);
			if (mbytes > maxmap / MEGABYTE ||
			    (mbytes == maxmap / MEGABYTE &&
			    bytes >= maxmap % MEGABYTE))
				F_CLR(mfp, MP_CAN_MMAP);
		}

		dbmfp->addr = NULL;
		if (F_ISSET(mfp, MP_CAN_MMAP)) {
			dbmfp->len = (size_t)mbytes * MEGABYTE + bytes;
			if (__os_mapfile(dbenv, rpath,
			    dbmfp->fhp, dbmfp->len, 1, &dbmfp->addr) != 0) {
				dbmfp->addr = NULL;
				F_CLR(mfp, MP_CAN_MMAP);
			}
		}
	}

	F_SET(dbmfp, MP_OPEN_CALLED);

	/*
	 * Share the underlying file descriptor if that's possible.
	 *
	 * Add the file to the process' list of DB_MPOOLFILEs.
	 */
	MUTEX_THREAD_LOCK(dbenv, dbmp->mutexp);

	for (tmp_dbmfp = TAILQ_FIRST(&dbmp->dbmfq);
	    tmp_dbmfp != NULL; tmp_dbmfp = TAILQ_NEXT(tmp_dbmfp, q))
		if (dbmfp->mfp == tmp_dbmfp->mfp &&
		    (F_ISSET(dbmfp, MP_READONLY) ||
		    !F_ISSET(tmp_dbmfp, MP_READONLY))) {
			if (dbmfp->fhp->mutexp != NULL)
				__db_mutex_free(
				    dbenv, dbmp->reginfo, dbmfp->fhp->mutexp);
			(void)__os_closehandle(dbenv, dbmfp->fhp);

			++tmp_dbmfp->fhp->ref;
			dbmfp->fhp = tmp_dbmfp->fhp;
			break;
		}

	TAILQ_INSERT_TAIL(&dbmp->dbmfq, dbmfp, q);

	MUTEX_THREAD_UNLOCK(dbenv, dbmp->mutexp);

	if (0) {
err:		if (refinc) {
			/*
			 * If mpf_cnt goes to zero here and unlink_on_close is
			 * set, then we missed the last close, but there was an
			 * error trying to open the file, so we probably cannot
			 * unlink it anyway.
			 */
			MUTEX_LOCK(dbenv, &mfp->mutex);
			--mfp->mpf_cnt;
			MUTEX_UNLOCK(dbenv, &mfp->mutex);
		}

	}
	if (rpath != NULL)
		__os_free(dbenv, rpath);
	return (ret);
}

/*
 * memp_fclose_pp --
 *	DB_MPOOLFILE->close pre/post processing.
 *
 * PUBLIC: int __memp_fclose_pp __P((DB_MPOOLFILE *, u_int32_t));
 */
int
__memp_fclose_pp(dbmfp, flags)
	DB_MPOOLFILE *dbmfp;
	u_int32_t flags;
{
	DB_ENV *dbenv;
	int rep_check, ret, t_ret;

	dbenv = dbmfp->dbenv;

	/*
	 * Validate arguments, but as a handle destructor, we can't fail.
	 *
	 * !!!
	 * DB_MPOOL_DISCARD: Undocumented flag: DB private.
	 */
	ret = __db_fchk(dbenv, "DB_MPOOLFILE->close", flags, DB_MPOOL_DISCARD);

	rep_check = IS_ENV_REPLICATED(dbenv) ? 1 : 0;
	if (rep_check)
		__env_rep_enter(dbenv);
	if ((t_ret = __memp_fclose(dbmfp, flags)) != 0 && ret == 0)
		ret = t_ret;
	if (rep_check)
		__env_db_rep_exit(dbenv);
	return (ret);
}

/*
 * __memp_fclose --
 *	DB_MPOOLFILE->close.
 *
 * PUBLIC: int __memp_fclose __P((DB_MPOOLFILE *, u_int32_t));
 */
int
__memp_fclose(dbmfp, flags)
	DB_MPOOLFILE *dbmfp;
	u_int32_t flags;
{
	DB_ENV *dbenv;
	DB_MPOOL *dbmp;
	MPOOLFILE *mfp;
	char *rpath;
	u_int32_t ref;
	int deleted, ret, t_ret;

	dbenv = dbmfp->dbenv;
	dbmp = dbenv->mp_handle;
	ret = 0;

	/*
	 * Remove the DB_MPOOLFILE from the process' list.
	 *
	 * It's possible the underlying mpool cache may never have been created.
	 * In that case, all we have is a structure, discard it.
	 *
	 * It's possible the DB_MPOOLFILE was never added to the DB_MPOOLFILE
	 * file list, check the MP_OPEN_CALLED flag to be sure.
	 */
	if (dbmp == NULL)
		goto done;

	MUTEX_THREAD_LOCK(dbenv, dbmp->mutexp);

	DB_ASSERT(dbmfp->ref >= 1);
	if ((ref = --dbmfp->ref) == 0 && F_ISSET(dbmfp, MP_OPEN_CALLED))
		TAILQ_REMOVE(&dbmp->dbmfq, dbmfp, q);

	/*
	 * Decrement the file descriptor's ref count -- if we're the last ref,
	 * we'll discard the file descriptor.
	 */
	if (ref == 0 && dbmfp->fhp != NULL && --dbmfp->fhp->ref > 0)
		dbmfp->fhp = NULL;
	MUTEX_THREAD_UNLOCK(dbenv, dbmp->mutexp);
	if (ref != 0)
		return (0);

	/* Complain if pinned blocks never returned. */
	if (dbmfp->pinref != 0) {
		__db_err(dbenv, "%s: close: %lu blocks left pinned",
		    __memp_fn(dbmfp), (u_long)dbmfp->pinref);
		ret = __db_panic(dbenv, DB_RUNRECOVERY);
	}

	/* Discard any mmap information. */
	if (dbmfp->addr != NULL &&
	    (ret = __os_unmapfile(dbenv, dbmfp->addr, dbmfp->len)) != 0)
		__db_err(dbenv, "%s: %s", __memp_fn(dbmfp), db_strerror(ret));

	/*
	 * Close the file and discard the descriptor structure; temporary
	 * files may not yet have been created.
	 */
	if (dbmfp->fhp != NULL) {
		if (dbmfp->fhp->mutexp != NULL) {
			__db_mutex_free(
			    dbenv, dbmp->reginfo, dbmfp->fhp->mutexp);
			dbmfp->fhp->mutexp = NULL;
		}
		if ((t_ret = __os_closehandle(dbenv, dbmfp->fhp)) != 0) {
			__db_err(dbenv, "%s: %s",
			    __memp_fn(dbmfp), db_strerror(t_ret));
			if (ret == 0)
				ret = t_ret;
		}
		dbmfp->fhp = NULL;
	}

	/*
	 * Discard our reference on the underlying MPOOLFILE, and close it
	 * if it's no longer useful to anyone.  It possible the open of the
	 * file never happened or wasn't successful, in which case, mpf will
	 * be NULL and MP_OPEN_CALLED will not be set.
	 */
	mfp = dbmfp->mfp;
	DB_ASSERT((F_ISSET(dbmfp, MP_OPEN_CALLED) && mfp != NULL) ||
	    (!F_ISSET(dbmfp, MP_OPEN_CALLED) && mfp == NULL));
	if (!F_ISSET(dbmfp, MP_OPEN_CALLED))
		goto done;

	/*
	 * If it's a temp file, all outstanding references belong to unflushed
	 * buffers.  (A temp file can only be referenced by one DB_MPOOLFILE).
	 * We don't care about preserving any of those buffers, so mark the
	 * MPOOLFILE as dead so that even the dirty ones just get discarded
	 * when we try to flush them.
	 */
	deleted = 0;
	MUTEX_LOCK(dbenv, &mfp->mutex);
	if (--mfp->mpf_cnt == 0 || LF_ISSET(DB_MPOOL_DISCARD)) {
		if (LF_ISSET(DB_MPOOL_DISCARD) ||
		    F_ISSET(mfp, MP_TEMP) || mfp->unlink_on_close)
			mfp->deadfile = 1;
		if (mfp->unlink_on_close) {
			if ((t_ret = __db_appname(dbmp->dbenv,
			    DB_APP_DATA, R_ADDR(dbmp->reginfo,
			    mfp->path_off), 0, NULL, &rpath)) != 0 && ret == 0)
				ret = t_ret;
			if (t_ret == 0) {
				if ((t_ret = __os_unlink(
				    dbmp->dbenv, rpath)) != 0 && ret == 0)
					ret = t_ret;
				__os_free(dbenv, rpath);
			}
		}
		if (mfp->block_cnt == 0) {
			if ((t_ret =
			    __memp_mf_discard(dbmp, mfp)) != 0 && ret == 0)
				ret = t_ret;
			deleted = 1;
		}
	}
	if (deleted == 0)
		MUTEX_UNLOCK(dbenv, &mfp->mutex);

done:	/* Discard the DB_MPOOLFILE structure. */
	if (dbmfp->pgcookie != NULL) {
		__os_free(dbenv, dbmfp->pgcookie->data);
		__os_free(dbenv, dbmfp->pgcookie);
	}
	__os_free(dbenv, dbmfp);

	return (ret);
}

/*
 * __memp_mf_discard --
 *	Discard an MPOOLFILE.
 *
 * PUBLIC: int __memp_mf_discard __P((DB_MPOOL *, MPOOLFILE *));
 */
int
__memp_mf_discard(dbmp, mfp)
	DB_MPOOL *dbmp;
	MPOOLFILE *mfp;
{
	DB_ENV *dbenv;
	DB_MPOOL_STAT *sp;
	MPOOL *mp;
	int need_sync, ret;

	dbenv = dbmp->dbenv;
	mp = dbmp->reginfo[0].primary;

	/*
	 * Expects caller to be holding the MPOOLFILE mutex.
	 *
	 * When discarding a file, we have to flush writes from it to disk.
	 * The scenario is that dirty buffers from this file need to be
	 * flushed to satisfy a future checkpoint, but when the checkpoint
	 * calls mpool sync, the sync code won't know anything about them.
	 * Ignore files not written, discarded, or only temporary.
	 */
	need_sync =
	   mfp->file_written && !mfp->deadfile && !F_ISSET(mfp, MP_TEMP);

	/*
	 * We have to release the MPOOLFILE mutex before acquiring the region
	 * mutex so we don't deadlock.  Make sure nobody ever looks at this
	 * structure again.
	 */
	mfp->deadfile = 1;

	/* Discard the mutex we're holding. */
	MUTEX_UNLOCK(dbenv, &mfp->mutex);

	/* Lock the region and delete from the list of MPOOLFILEs. */
	R_LOCK(dbenv, dbmp->reginfo);
	SH_TAILQ_REMOVE(&mp->mpfq, mfp, q, __mpoolfile);

	ret = need_sync ? __memp_mf_sync(dbmp, mfp) : 0;

	/* Copy the statistics into the region. */
	sp = &mp->stat;
	sp->st_cache_hit += mfp->stat.st_cache_hit;
	sp->st_cache_miss += mfp->stat.st_cache_miss;
	sp->st_map += mfp->stat.st_map;
	sp->st_page_create += mfp->stat.st_page_create;
	sp->st_page_in += mfp->stat.st_page_in;
	sp->st_page_out += mfp->stat.st_page_out;

	/* Clear the mutex this MPOOLFILE recorded. */
	__db_shlocks_clear(&mfp->mutex, dbmp->reginfo,
	    R_ADDR(dbmp->reginfo, mp->maint_off));

	/* Free the space. */
	if (mfp->path_off != 0)
		__db_shalloc_free(&dbmp->reginfo[0],
		    R_ADDR(dbmp->reginfo, mfp->path_off));
	if (mfp->fileid_off != 0)
		__db_shalloc_free(&dbmp->reginfo[0],
		    R_ADDR(dbmp->reginfo, mfp->fileid_off));
	if (mfp->pgcookie_off != 0)
		__db_shalloc_free(&dbmp->reginfo[0],
		    R_ADDR(dbmp->reginfo, mfp->pgcookie_off));
	__db_shalloc_free(&dbmp->reginfo[0], mfp);

	R_UNLOCK(dbenv, dbmp->reginfo);

	return (ret);
}