142 lines
6.4 KiB
C
142 lines
6.4 KiB
C
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/****************************************************************
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* *
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* Copyright 2012 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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#include "mdef.h"
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#include <errno.h> /* for ENOSPC */
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#include "anticipatory_freeze.h"
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#include "wait_for_disk_space.h"
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#include "gtmio.h"
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#include "tp_grab_crit.h"
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#include "have_crit.h"
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#include "filestruct.h"
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#include "jnl.h"
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#include "error.h"
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#include "gtmmsg.h"
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GBLREF jnlpool_addrs jnlpool;
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GBLREF volatile int4 exit_state;
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GBLREF int4 exi_condition;
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GBLREF int4 forced_exit_err;
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error_def(ERR_DSKNOSPCAVAIL);
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error_def(ERR_DSKNOSPCBLOCKED);
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error_def(ERR_DSKSPCAVAILABLE);
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error_def(ERR_ENOSPCQIODEFER);
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/* In case of ENOSPC, if anticipatory freeze scheme is in effect and this process has attached to the
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* journal pool, trigger an instance freeze in this case and wait for the disk space to be available
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* at which point unfreeze the instance.
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*/
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void wait_for_disk_space(sgmnt_addrs *csa, char *fn, int fd, off_t offset, char *buf, size_t count, int *save_errno)
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{
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boolean_t was_crit;
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gd_region *reg;
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int fn_len, tmp_errno;
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boolean_t freeze_cleared;
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char wait_comment[MAX_FREEZE_COMMENT_LEN];
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DCL_THREADGBL_ACCESS; /* needed by ANTICIPATORY_FREEZE_AVAILABLE macro */
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SETUP_THREADGBL_ACCESS; /* needed by ANTICIPATORY_FREEZE_AVAILABLE macro */
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/* If anticipatory freeze scheme is not in effect OR if this database does not care about it, return right away */
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if (!ANTICIPATORY_FREEZE_ENABLED(csa))
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return;
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fn_len = STRLEN(fn);
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was_crit = csa->now_crit;
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reg = csa->region;
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/* Let us take the case this process has opened the database but does not hold crit on it. If we come in to this
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* function while trying to flush either to the db or jnl, setting the instance freeze would require a "grab_lock"
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* which could hang due to another process holding that and in turn waiting for the exact same db or jnl write
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* to succeed. This has the potential of creating a deadlock so we avoid that by returning right away. Since we
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* dont hold crit, this call to do the jnl or db write is not critical in the sense no process will be affected
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* because this write did not happen. Therefore it is okay to return right away. On the other hand if this
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* process holds crit, then it is not possible that the other process holds the jnlpool lock
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* and is waiting for the db or jnl qio (since that flow usually happens in t_end and tp_tend
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* where db crit is first obtained before jnlpool lock is). Therefore it is safe to do a grab_lock
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* in that case without worrying about potential deadlocks.
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* Update *save_errno to indicate this is not a ENOSPC condition (since we have chosen to defer
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* the ENOSPC condition to some other process that encounters it while holding crit).
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*
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* There is a possibility that if the caller is jnl_wait we will retry this logic indefinitely without ever
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* setting instance freeze because we dont hold crit. To avoid that, do tp_grab_crit to see if it is available.
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* If so, go ahead with freezing the instance. If not issue QIODEFER message and return. It is still possible
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* the same process issues multiple QIODEFER messages before the instance gets frozen. But it should be rare.
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*/
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if (!was_crit)
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tp_grab_crit(reg);
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if (!csa->now_crit)
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{
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send_msg(VARLSTCNT(4) ERR_ENOSPCQIODEFER, 2, fn_len, fn);
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*save_errno = ERR_ENOSPCQIODEFER;
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return;
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}
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/* We either came into this function holding crit or "tp_grab_crit" succeeded */
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assert(NULL != jnlpool.jnlpool_ctl);
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assert(NULL != fn); /* if "csa" is non-NULL, fn better be non-NULL as well */
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/* The "send_msg" of DSKNOSPCAVAIL done below will set instance freeze (if configuration files includes it). After that, we
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* will keep retrying the IO waiting for disk space to become available. If yes, we will clear the freeze. Until that is
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* done, we should not allow ourselves to be interrupted as otherwise interrupt code can try to write to the db/jnl (as
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* part of DB_LSEEKWRITE) and the first step there would be to wait for the freeze to be lifted off. Since we were the ones
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* who set the freeze in the first place, the auto-clearing of freeze (on disk space freeup) will no longer work in that
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* case. Hence the reason not to allow interrupts.
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*/
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DEFER_INTERRUPTS(INTRPT_IN_WAIT_FOR_DISK_SPACE);
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send_msg(VARLSTCNT(4) ERR_DSKNOSPCAVAIL, 2, fn_len, fn); /* this should set the instance freeze */
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/* Hang waiting for the disk space situation to be cleared */
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if (IS_REPL_INST_FROZEN)
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{
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GENERATE_INST_FROZEN_COMMENT(wait_comment, MAX_FREEZE_COMMENT_LEN, ERR_DSKNOSPCAVAIL);
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tmp_errno = *save_errno;
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assert(ENOSPC == tmp_errno);
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for ( ; ENOSPC == tmp_errno; )
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{
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if (!IS_REPL_INST_FROZEN)
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{ /* Some other process cleared the instance freeze. But we still dont have our disk
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* space issue resolved so set the freeze flag again until space is available for us.
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*/
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send_msg(VARLSTCNT(4) ERR_DSKNOSPCAVAIL, 2, fn_len, fn);
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} else if (exit_state != 0)
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{
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send_msg(VARLSTCNT(1) forced_exit_err);
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gtm_putmsg(VARLSTCNT(1) forced_exit_err);
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exit(-exi_condition);
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}
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/* Sleep for a while before retrying the write. Do not use "hiber_start" as that
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* uses timers and if we are already in a timer handler now, nested timers wont work.
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*/
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SHORT_SLEEP(SLEEP_IORETRYWAIT);
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/* If some other process froze the instance and changed the comment, a retry of the
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* LSEEKWRITE may not be appropriate, so just loop waiting for the freeze to be lifted.
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*/
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if (IS_REPL_INST_FROZEN && (STRCMP(wait_comment, jnlpool.jnlpool_ctl->freeze_comment) != 0))
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{
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send_msg(VARLSTCNT(4) ERR_DSKNOSPCBLOCKED, 2, fn_len, fn);
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WAIT_FOR_REPL_INST_UNFREEZE(csa)
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}
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LSEEKWRITE(fd, offset, buf, count, tmp_errno);
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}
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if (STRCMP(wait_comment, jnlpool.jnlpool_ctl->freeze_comment) == 0)
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{
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send_msg(VARLSTCNT(4) ERR_DSKSPCAVAILABLE, 2, fn_len, fn);
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CLEAR_ANTICIPATORY_FREEZE(freeze_cleared);
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REPORT_INSTANCE_UNFROZEN(freeze_cleared);
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}
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*save_errno = tmp_errno;
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} /* else ERR_DSKNOSPCAVAIL is not present in the configuration file. So, no freeze is triggered and the caller will handle
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* it accordingly
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*/
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ENABLE_INTERRUPTS(INTRPT_IN_WAIT_FOR_DISK_SPACE);
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if (!was_crit)
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rel_crit(reg);
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return;
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}
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