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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2008-2011 WiredTiger, Inc.
* All rights reserved.
*/
/*
* WT_EVICT_LIST --
* Encapsulation of an eviction candidate.
*/
struct __wt_evict_list {
WT_PAGE *page; /* Page */
WT_BTREE *btree; /* Underlying file object */
};
/*
* WT_EVICT_REQ --
* Encapsulation of a eviction request.
*/
struct __wt_evict_req {
WT_SESSION_IMPL *session; /* Requesting thread */
WT_BTREE *btree; /* Btree */
WT_PAGE **retry; /* Pages to retry */
uint32_t retry_next; /* Next retry slot */
uint32_t retry_entries; /* Total retry slots */
size_t retry_allocated; /* Bytes allocated */
int retry_cnt; /* We only try a few times. */
int close_method; /* Discard pages */
};
/*
* WT_READ_REQ --
* Encapsulation of a read request.
*/
struct __wt_read_req {
WT_SESSION_IMPL *session; /* Requesting thread */
WT_PAGE *parent; /* Parent */
WT_REF *ref; /* Reference/Address */
int dsk_verify; /* Verify the disk image */
};
/*
* WiredTiger cache structure.
*/
struct __wt_cache {
WT_MTX *mtx_evict; /* Cache eviction server mutex */
/*
* File sync can temporarily fail when a tree is active, that is, we may
* not be able to immediately reconcile all of the file's pages. If the
* pending_retry value is non-zero, it means there are pending requests
* we need to handle.
*/
int pending_retry; /* Eviction request needs completion */
WT_EVICT_LIST *evict; /* Pages being tracked for eviction */
size_t evict_allocated; /* Bytes allocated */
uint32_t evict_entries; /* Total evict slots */
WT_EVICT_REQ evict_request[20]; /* Eviction requests:
slot available if session is NULL */
WT_MTX *mtx_read; /* Cache read server mutex */
u_int volatile read_lockout; /* No reading until memory drains */
WT_READ_REQ read_request[40]; /* Read requests:
slot available if session is NULL */
uint32_t read_gen; /* Page read generation (LRU) */
/*
* Different threads read/write pages to/from the cache and create pages
* in the cache, so we cannot know precisely how much memory is in use
* at any specific time. However, even though the values don't have to
* be exact, they can't be garbage, we track what comes in and what goes
* out and calculate the difference as needed.
*/
uint64_t bytes_read; /* Bytes/pages read by read server */
uint64_t pages_read;
uint64_t bytes_workq; /* Bytes/pages created by workQ */
uint64_t bytes_evict; /* Bytes/pages discarded by eviction */
uint64_t pages_evict;
};
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