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/*-
* Copyright (c) 2014-2015 MongoDB, Inc.
* Copyright (c) 2008-2014 WiredTiger, Inc.
* All rights reserved.
*
* See the file LICENSE for redistribution information.
*/
#include "wt_internal.h"
/*
* __sweep --
* Close unused dhandles on the connection dhandle list.
*/
static int
__sweep(WT_SESSION_IMPL *session)
{
WT_CONNECTION_IMPL *conn;
WT_DATA_HANDLE *dhandle, *dhandle_next;
WT_DECL_RET;
time_t now;
int locked;
conn = S2C(session);
/* Don't discard handles that have been open recently. */
WT_RET(__wt_seconds(session, &now));
WT_STAT_FAST_CONN_INCR(session, dh_conn_sweeps);
dhandle = SLIST_FIRST(&conn->dhlh);
for (; dhandle != NULL; dhandle = dhandle_next) {
dhandle_next = SLIST_NEXT(dhandle, l);
if (WT_IS_METADATA(dhandle))
continue;
if (dhandle->session_inuse != 0 ||
now <= dhandle->timeofdeath + WT_DHANDLE_SWEEP_WAIT)
continue;
if (dhandle->timeofdeath == 0) {
dhandle->timeofdeath = now;
WT_STAT_FAST_CONN_INCR(session, dh_conn_tod);
continue;
}
/*
* We have a candidate for closing; if it's open, acquire an
* exclusive lock on the handle and close it. We might be
* blocking opens for a long time (over disk I/O), but the
* handle was quiescent for awhile.
*
* The close can fail if an update cannot be written (updates
* in a no-longer-referenced file might not yet be globally
* visible if sessions have disjoint sets of files open). If
* the handle is busy, skip it, we'll retry the close the next
* time, after the transaction state has progressed.
*
* We don't set WT_DHANDLE_EXCLUSIVE deliberately, we want
* opens to block on us rather than returning an EBUSY error to
* the application.
*/
if ((ret =
__wt_try_writelock(session, dhandle->rwlock)) == EBUSY)
continue;
WT_RET(ret);
locked = 1;
/* If the handle is open, try to close it. */
if (F_ISSET(dhandle, WT_DHANDLE_OPEN)) {
WT_WITH_DHANDLE(session, dhandle,
ret = __wt_conn_btree_sync_and_close(session, 0));
if (ret != 0)
goto unlock;
/* We closed the btree handle, bump the statistic. */
WT_STAT_FAST_CONN_INCR(session, dh_conn_handles);
}
/*
* If there are no longer any references to the handle in any
* sessions, attempt to discard it. The called function
* re-checks that the handle is not in use, which is why we
* don't do any special handling of EBUSY returns above.
*/
if (dhandle->session_inuse == 0 && dhandle->session_ref == 0) {
WT_WITH_DHANDLE(session, dhandle,
ret = __wt_conn_dhandle_discard_single(session, 0));
if (ret != 0)
goto unlock;
/* If the handle was discarded, it isn't locked. */
locked = 0;
} else
WT_STAT_FAST_CONN_INCR(session, dh_conn_ref);
unlock: if (locked)
WT_TRET(__wt_writeunlock(session, dhandle->rwlock));
WT_RET_BUSY_OK(ret);
}
return (0);
}
/*
* __sweep_server --
* The handle sweep server thread.
*/
static void *
__sweep_server(void *arg)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_SESSION_IMPL *session;
session = arg;
conn = S2C(session);
/*
* Sweep for dead handles.
*/
while (F_ISSET(conn, WT_CONN_SERVER_RUN) &&
F_ISSET(conn, WT_CONN_SERVER_SWEEP)) {
/* Wait until the next event. */
WT_ERR(__wt_cond_wait(session,
conn->sweep_cond, WT_DHANDLE_SWEEP_PERIOD * WT_MILLION));
/* Sweep the handles. */
WT_ERR(__sweep(session));
}
if (0) {
err: WT_PANIC_MSG(session, ret, "handle sweep server error");
}
return (NULL);
}
/*
* __wt_sweep_create --
* Start the handle sweep thread.
*/
int
__wt_sweep_create(WT_SESSION_IMPL *session)
{
WT_CONNECTION_IMPL *conn;
conn = S2C(session);
/* Set first, the thread might run before we finish up. */
F_SET(conn, WT_CONN_SERVER_SWEEP);
WT_RET(__wt_open_internal_session(
conn, "sweep-server", 1, 1, &conn->sweep_session));
session = conn->sweep_session;
/*
* Handle sweep does enough I/O it may be called upon to perform slow
* operations for the block manager.
*/
F_SET(session, WT_SESSION_CAN_WAIT);
WT_RET(__wt_cond_alloc(
session, "handle sweep server", 0, &conn->sweep_cond));
WT_RET(__wt_thread_create(
session, &conn->sweep_tid, __sweep_server, session));
conn->sweep_tid_set = 1;
return (0);
}
/*
* __wt_sweep_destroy --
* Destroy the handle-sweep thread.
*/
int
__wt_sweep_destroy(WT_SESSION_IMPL *session)
{
WT_CONNECTION_IMPL *conn;
WT_DECL_RET;
WT_SESSION *wt_session;
conn = S2C(session);
F_CLR(conn, WT_CONN_SERVER_SWEEP);
if (conn->sweep_tid_set) {
WT_TRET(__wt_cond_signal(session, conn->sweep_cond));
WT_TRET(__wt_thread_join(session, conn->sweep_tid));
conn->sweep_tid_set = 0;
}
WT_TRET(__wt_cond_destroy(session, &conn->sweep_cond));
if (conn->sweep_session != NULL) {
wt_session = &conn->sweep_session->iface;
WT_TRET(wt_session->close(wt_session, NULL));
conn->sweep_session = NULL;
}
return (ret);
}
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