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/*-
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
/*
* WT_DATA_HANDLE_CACHE --
* Per-session cache of handles to avoid synchronization when opening
* cursors.
*/
struct __wt_data_handle_cache {
WT_DATA_HANDLE *dhandle;
SLIST_ENTRY(__wt_data_handle_cache) l;
};
/*
* 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
};
/* Get the connection implementation for a session */
#define S2C(session) ((WT_CONNECTION_IMPL *)(session)->iface.connection)
#define S2C_SAFE(session) ((session) == NULL ? NULL : S2C(session))
/* Get the btree for a session */
#define S2BT(session) ((WT_BTREE *)(session)->dhandle->handle)
#define S2BT_SAFE(session) ((session)->dhandle == NULL ? NULL : S2BT(session))
/*
* WT_SESSION_IMPL --
* Implementation of WT_SESSION.
*/
struct __wt_session_impl {
WT_SESSION iface;
void *lang_private; /* Language specific private storage */
u_int active; /* Non-zero if the session is in-use */
const char *name; /* Name */
uint32_t id; /* UID, offset in session array */
WT_CONDVAR *cond; /* Condition variable */
uint32_t rnd[2]; /* Random number generation state */
WT_EVENT_HANDLER *event_handler;/* Application's event handlers */
WT_DATA_HANDLE *dhandle; /* Current data handle */
/* Session handle reference list */
SLIST_HEAD(__dhandles, __wt_data_handle_cache) dhandles;
#define WT_DHANDLE_SWEEP_WAIT 60 /* Wait before discarding */
#define WT_DHANDLE_SWEEP_PERIOD 20 /* Only sweep every 20 seconds */
time_t last_sweep; /* Last sweep for dead handles */
WT_CURSOR *cursor; /* Current cursor */
/* Cursors closed with the session */
TAILQ_HEAD(__cursors, __wt_cursor) cursors;
WT_CURSOR_BACKUP *bkp_cursor; /* Hot backup cursor */
WT_COMPACT *compact; /* Compact state */
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 **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. */
WT_REF **excl; /* Eviction exclusive list */
u_int excl_next; /* Next empty slot */
size_t excl_allocated; /* Bytes allocated */
void *block_manager; /* Block-manager support */
int (*block_manager_cleanup)(WT_SESSION_IMPL *);
WT_DATA_HANDLE **ckpt_handle; /* Checkpoint support */
u_int ckpt_handle_next; /* Next empty slot */
size_t ckpt_handle_allocated; /* Bytes allocated */
void *reconcile; /* Reconciliation support */
int (*reconcile_cleanup)(WT_SESSION_IMPL *);
int compaction; /* Compaction did some work */
/*
* The split stash memory and hazard information persist past session
* close, because they are accessed by threads of control other than
* the thread owning the session. They live at the end of the
* structure so it's somewhat easier to clear everything but the fields
* that persist.
*/
#define WT_SESSION_CLEAR_SIZE(s) \
(WT_PTRDIFF(&(s)->flags, s) + sizeof((s)->flags))
uint32_t flags;
/*
* Splits can "free" memory that may still be in use, and we use a
* split generation number to track it, that is, the session stores a
* reference to the memory and allocates a split generation; when no
* session is reading from that split generation, the memory can be
* freed for real.
*/
struct __wt_split_stash {
uint64_t split_gen; /* Split generation */
void *p; /* Memory, length */
size_t len;
} *split_stash; /* Split stash array */
size_t split_stash_cnt; /* Array entries */
size_t split_stash_alloc; /* Allocated bytes */
uint64_t split_gen; /* Reading split generation */
/*
* Hazard pointers.
* The number of hazard pointers that can be in use grows dynamically.
*/
#define WT_HAZARD_INCR 10
uint32_t hazard_size; /* Allocated slots in hazard array. */
uint32_t nhazard; /* Count of active hazard pointers */
WT_HAZARD *hazard; /* Hazard pointer array */
} WT_GCC_ATTRIBUTE((aligned(WT_CACHE_LINE_ALIGNMENT)));
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