/*-
 * Copyright (c) 2008-2013 WiredTiger, Inc.
 *	All rights reserved.
 *
 * See the file LICENSE for redistribution information.
 */

/*
 * WT_BTREE_SESSION --
 *	Per-session cache of btree handles to avoid synchronization when
 * opening cursors.
 */
struct __wt_btree_session {
	WT_BTREE *btree;

	TAILQ_ENTRY(__wt_btree_session) q;
};

/*
 * WT_HAZARD --
 *	A hazard pointer.
 */
struct __wt_hazard {
	WT_PAGE *page;			/* Page address */
#ifdef HAVE_DIAGNOSTIC
	const char *file;		/* File/line where hazard acquired */
	int	    line;
#endif
};

typedef	enum {
	WT_SERIAL_NONE=0,		/* No request */
	WT_SERIAL_FUNC=1,		/* Function, then return */
	WT_SERIAL_EVICT=2,		/* Function, then schedule evict */
} wq_state_t;

/* Get the connection implementation for a session */
#define	S2C(session) ((WT_CONNECTION_IMPL *)(session)->iface.connection)

/*
 * WT_SESSION_IMPL --
 *	Implementation of WT_SESSION.
 */
struct __wt_session_impl {
	WT_SESSION iface;

	u_int active;			/* Non-zero if the session is in-use */

	WT_CONDVAR *cond;		/* Condition variable */

	const char *name;		/* Name */

	WT_EVENT_HANDLER *event_handler;/* Application's event handlers */

	WT_BTREE *btree;		/* Current file */
	TAILQ_HEAD(__btrees, __wt_btree_session) btrees;

	WT_CURSOR *cursor;		/* Current cursor */
					/* Cursors closed with the session */
	TAILQ_HEAD(__cursors, __wt_cursor) cursors;

	WT_BTREE *metafile;		/* Metadata file */
	void	*meta_track;		/* Metadata operation tracking */
	void	*meta_track_next;	/* Current position */
	void	*meta_track_sub;	/* Child transaction / save point */
	size_t	 meta_track_alloc;	/* Currently allocated */
	int	 meta_track_nest;	/* Nesting level of meta transaction */
#define	WT_META_TRACKING(session)	(session->meta_track_next != NULL)

	TAILQ_HEAD(__tables, __wt_table) tables;

	WT_ITEM	logrec_buf;		/* Buffer for log records */
	WT_ITEM	logprint_buf;		/* Buffer for debug log records */

	WT_ITEM	**scratch;		/* Temporary memory for any function */
	u_int	scratch_alloc;		/* Currently allocated */
#ifdef HAVE_DIAGNOSTIC
	/*
	 * It's hard to figure out from where a buffer was allocated after it's
	 * leaked, so in diagnostic mode we track them; DIAGNOSTIC can't simply
	 * add additional fields to WT_ITEM structures because they are visible
	 * to applications, create a parallel structure instead.
	 */
	struct __wt_scratch_track {
		const char *file;	/* Allocating file, line */
		int line;
	} *scratch_track;
#endif

	WT_TXN_ISOLATION isolation;
	WT_TXN	txn;			/* Transaction state */
	u_int	ncursors;		/* Count of active file cursors. */

	void	*reconcile;		/* Reconciliation information */

	WT_REF **excl;			/* Eviction exclusive list */
	u_int	 excl_next;		/* Next empty slot */
	size_t	 excl_allocated;	/* Bytes allocated */

	int syncop;			/* File operation */
	int syncop_ret;			/* Return value */

	uint32_t id;			/* Offset in conn->session_array */

	uint32_t flags;

	/*
	 * The hazard pointer must be placed at the end of the structure: the
	 * structure is cleared when closed, all except the hazard pointer.
	 * Putting the hazard pointer at the end of the structure allows us to
	 * easily call a function to clear memory up to, but not including, the
	 * hazard pointer.
	 */
	uint32_t   hazard_size;		/* Allocated slots in hazard array. */
	uint32_t   nhazard;		/* Count of active hazard pointers */

#define	WT_SESSION_CLEAR(s)	memset(s, 0, WT_PTRDIFF(&(s)->hazard, s))
	WT_HAZARD *hazard;		/* Hazard pointer array */
};