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dcb.h

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-------
Removed DCB states DCB_STATE_IDLE, and DCB_STATE_PROCESSING.
Added DCB_STATE_UNDEFINED for initial content for state variable which doesn't have any specific value set, and DCB_STATE_NOPOLLING to indicate that dcb has been removed from poll set.

Added following dcb roles: DCB_ROLE_SERVICE_LISTENER for listeners of services, and DCB_ROLE_REQUEST_HANDLER for client/backend dcbs. Listeners may have state DCB_STATE_LISTENING, but not DCB_STATE_POLLING. Request handlers may have DCB_STATE_POLLING but not DCB_STATE_LISTENING. Role is passed as an argument to dcb.c:dcb_alloc.

From now on, struct check numbers of DCB are included and checked in DEBUG build only.

Added dcb_role_t dcb_role-member to DCB as well as SPINLOCK dcb_initlock, which protects state changes.

Removed extern keyword from function declarations because functions are by default externally visible if they are declared in header.

dcb.b
------
Function dcb_set_state, and dcb_set_state_nomutex provide functions for changing dcb states. Latter implements a state machine for dcb.
Function dcb_add_to_zombieslist replaces dcb_free. It adds in atomic step dcb to zombieslist and changes state to DCB_STATE_ZOMBIE.
Function dcb_final_free removes dcb from allDCBs list, terminates router and client sessions, and frees dcb and related memory.
Function dcb_process_zombies removes executing thread from dcb's bitmask, and it there are no further thread bits, moves dcb to a victim list, and finally, for each dcb on victim list, closes fd and sets state to DCB_STATE_DISCONNECTED.
Function dcb_close sets dcb state to DCB_STATE_NOPOLLIN, removes dcb from poll set and sets bit to bitmask for each server thread in an atomic step.  

poll.c
------
Function poll_add_dcb sets either DCB_STATE_LISTENING or DCB_STATE_POLLING state for newly created dcb, depending whether the role of dcb is DCB_ROLE_SERVICE_LISTENER, or DCB_ROLE_REQUEST_HANDLER, respectively. Then dcb is set to poll set.

poll_waitevents : commented out code which skipped event if dcb was added to zombieslist or if fd was closed. Added state checks.

service.c : Minor changes.
httpd.c : Removed dcb state changes. They are done in core.
mysql_backend.c : Added checks, removed dcb state changes.
mysql_client.c : Removed dcb state changes. Added checks.
mysql_common.c : Minor changes
telnetd.c : Removed state changes. Replaced some typecasts and pointer references with local variable reads.
skygw_debug.h : Removed two states, and added two to state printing macro.
This commit is contained in:
vraatikka
2013-09-05 22:00:02 +03:00
parent 17ec98fa3d
commit 66e9be814b
10 changed files with 576 additions and 384 deletions
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52
server/core/poll.c
View File

@ -90,12 +90,28 @@ poll_init()
int
poll_add_dcb(DCB *dcb)
{
int rc;
dcb_state_t old_state = DCB_STATE_UNDEFINED;
struct epoll_event ev;
ev.events = EPOLLIN | EPOLLOUT | EPOLLET;
ev.data.ptr = dcb;
return epoll_ctl(epoll_fd, EPOLL_CTL_ADD, dcb->fd, &ev);
/**
* Service listeners have different state than
* DCBs serving client requests.
*/
if (dcb->dcb_role == DCB_ROLE_SERVICE_LISTENER) {
dcb_set_state(dcb, DCB_STATE_LISTENING, &old_state);
} else if (dcb->dcb_role == DCB_ROLE_REQUEST_HANDLER) {
dcb_set_state(dcb, DCB_STATE_POLLING, &old_state);
}
rc = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, dcb->fd, &ev);
if (rc != 0) {
dcb_set_state(dcb, old_state, NULL);
}
return rc;
}
@ -203,15 +219,19 @@ poll_waitevents(void *arg)
__uint32_t ev = events[i].events;
CHK_DCB(dcb);
ss_dassert(dcb->state != DCB_STATE_IDLE &&
dcb->state != DCB_STATE_ALLOC);
ss_debug(spinlock_acquire(&dcb->dcb_initlock);)
ss_dassert(dcb->state != DCB_STATE_ALLOC);
ss_dassert(dcb->state != DCB_STATE_DISCONNECTED);
ss_dassert(dcb->state != DCB_STATE_FREED);
ss_debug(spinlock_release(&dcb->dcb_initlock);)
skygw_log_write(
LOGFILE_TRACE,
"%lu [poll_waitevents] event %d",
pthread_self(),
ev);
#if 0
if (DCB_ISZOMBIE(dcb))
{
skygw_log_write(
@ -233,7 +253,7 @@ poll_waitevents(void *arg)
STRDCBSTATE(dcb->state));
continue;
}
#endif
if (ev & EPOLLERR)
{
@ -255,23 +275,21 @@ poll_waitevents(void *arg)
}
if (ev & EPOLLOUT)
{
simple_mutex_lock(&dcb->dcb_write_lock, true);
simple_mutex_lock(&dcb->dcb_write_lock,
true);
ss_info_dassert(!dcb->dcb_write_active,
"Write already active");
dcb->dcb_write_active = TRUE;
skygw_log_write(LOGFILE_TRACE,
"%lu [poll_waitevents] "
"Write in fd %d",
pthread_self(),
dcb->fd);
skygw_log_write(
LOGFILE_TRACE,
"%lu [poll_waitevents] "
"Write in fd %d",
pthread_self(),
dcb->fd);
atomic_add(&pollStats.n_write, 1);
dcb->func.write_ready(dcb);
dcb->dcb_write_active = FALSE;
simple_mutex_unlock(
&dcb->dcb_write_lock);
simple_mutex_unlock(&dcb->dcb_write_lock);
}
if (ev & EPOLLIN)
{