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4389cb06da42389bffd144cca425e5fbbfdde98c
MaxScale/server/core/dcb.c
VilhoRaatikka 8b91a5f078 Fix to bug #610, http://bugs.mariadb.com/show_bug.cgi?id=610 
Fixes to Coverity issues 72728, 72755, 72745
2014-11-05 14:41:04 +02:00

2039 lines
59 KiB
C
Raw Blame History

/*
* This file is distributed as part of the MariaDB Corporation MaxScale. It is free
* software: you can redistribute it and/or modify it under the terms of the
* GNU General Public License as published by the Free Software Foundation,
* version 2.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Copyright MariaDB Corporation Ab 2013-2014
*/
/**
* @file dcb.c - Descriptor Control Block generic functions
*
* Descriptor control blocks provide the key mechanism for the interface
* with the non-blocking socket polling routines. The descriptor control
* block is the user data that is handled by the epoll system and contains
* the state data and pointers to other components that relate to the
* use of a file descriptor.
*
* @verbatim
* Revision History
*
* Date Who Description
* 12/06/13 Mark Riddoch Initial implementation
* 21/06/13 Massimiliano Pinto free_dcb is used
* 25/06/13 Massimiliano Pinto Added checks to session and router_session
* 28/06/13 Mark Riddoch Changed the free mechanism to
* introduce a zombie state for the
* dcb
* 02/07/2013 Massimiliano Pinto Addition of delayqlock, delayq and
* authlock for handling backend
* asynchronous protocol connection
* and a generic lock for backend
* authentication
* 16/07/2013 Massimiliano Pinto Added command type for dcb
* 23/07/2013 Mark Riddoch Tidy up logging
* 02/09/2013 Massimiliano Pinto Added session refcount
* 27/09/2013 Massimiliano Pinto dcb_read returns 0 if ioctl returns no
* error and 0 bytes to read.
* This fixes a bug with many reads from
* backend
* 07/05/2014 Mark Riddoch Addition of callback mechanism
* 20/06/2014 Mark Riddoch Addition of dcb_clone
*
* @endverbatim
*/
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <dcb.h>
#include <spinlock.h>
#include <server.h>
#include <session.h>
#include <service.h>
#include <modules.h>
#include <router.h>
#include <errno.h>
#include <gw.h>
#include <poll.h>
#include <atomic.h>
#include <skygw_utils.h>
#include <log_manager.h>
#include <hashtable.h>
extern int lm_enabled_logfiles_bitmask;
static DCB *allDCBs = NULL; /* Diagnostics need a list of DCBs */
static DCB *zombies = NULL;
static SPINLOCK dcbspin = SPINLOCK_INIT;
static SPINLOCK zombiespin = SPINLOCK_INIT;
static void dcb_final_free(DCB *dcb);
static bool dcb_set_state_nomutex(
DCB* dcb,
const dcb_state_t new_state,
dcb_state_t* old_state);
static void dcb_call_callback(DCB *dcb, DCB_REASON reason);
static DCB* dcb_get_next (DCB* dcb);
static int dcb_null_write(DCB *dcb, GWBUF *buf);
static int dcb_null_close(DCB *dcb);
static int dcb_null_auth(DCB *dcb, SERVER *server, SESSION *session, GWBUF *buf);
static int dcb_isvalid_nolock(DCB *dcb);
/**
* Return the pointer to the lsit of zombie DCB's
*
* @return Zombies DCB list
*/
DCB *
dcb_get_zombies(void)
{
return zombies;
}
/**
* Allocate a new DCB.
*
* This routine performs the generic initialisation on the DCB before returning
* the newly allocated DCB.
*
* @return A newly allocated DCB or NULL if non could be allocated.
*/
DCB *
dcb_alloc(dcb_role_t role)
{
DCB *rval;
if ((rval = calloc(1, sizeof(DCB))) == NULL)
{
return NULL;
}
#if defined(SS_DEBUG)
rval->dcb_chk_top = CHK_NUM_DCB;
rval->dcb_chk_tail = CHK_NUM_DCB;
rval->dcb_errhandle_called = false;
#endif
rval->dcb_role = role;
spinlock_init(&rval->dcb_initlock);
spinlock_init(&rval->writeqlock);
spinlock_init(&rval->delayqlock);
spinlock_init(&rval->authlock);
spinlock_init(&rval->cb_lock);
spinlock_init(&rval->pollinlock);
spinlock_init(&rval->polloutlock);
rval->pollinbusy = 0;
rval->readcheck = 0;
rval->polloutbusy = 0;
rval->writecheck = 0;
rval->fd = -1;
rval->evq.next = NULL;
rval->evq.prev = NULL;
rval->evq.pending_events = 0;
rval->evq.processing = 0;
spinlock_init(&rval->evq.eventqlock);
memset(&rval->stats, 0, sizeof(DCBSTATS)); // Zero the statistics
rval->state = DCB_STATE_ALLOC;
bitmask_init(&rval->memdata.bitmask);
rval->writeqlen = 0;
rval->high_water = 0;
rval->low_water = 0;
rval->next = NULL;
rval->callbacks = NULL;
rval->remote = NULL;
rval->user = NULL;
rval->flags = 0;
spinlock_acquire(&dcbspin);
if (allDCBs == NULL)
allDCBs = rval;
else
{
DCB *ptr = allDCBs;
while (ptr->next)
ptr = ptr->next;
ptr->next = rval;
}
spinlock_release(&dcbspin);
return rval;
}
/**
* Free a DCB that has not been associated with a descriptor.
*
* @param dcb The DCB to free
*/
void
dcb_free(DCB *dcb)
{
if (dcb->fd == -1)
dcb_final_free(dcb);
else
{
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Attempt to free a DCB via dcb_fee "
"that has been associated with a descriptor.")));
}
}
/**
* Add the DCB to the end of zombies list.
*
* Adding to list occurs once per DCB. This is ensured by changing the
* state of DCB to DCB_STATE_ZOMBIE after addition. Prior insertion, DCB state
* is checked and operation proceeds only if state differs from DCB_STATE_ZOMBIE.
* @param dcb The DCB to add to the zombie list
* @return none
*/
void
dcb_add_to_zombieslist(DCB *dcb)
{
bool succp = false;
dcb_state_t prev_state = DCB_STATE_UNDEFINED;
CHK_DCB(dcb);
/*<
* Protect zombies list access.
*/
spinlock_acquire(&zombiespin);
/*<
* If dcb is already added to zombies list, return.
*/
if (dcb->state != DCB_STATE_NOPOLLING) {
ss_dassert(dcb->state != DCB_STATE_POLLING &&
dcb->state != DCB_STATE_LISTENING);
spinlock_release(&zombiespin);
return;
}
/*<
* Add closing dcb to the top of the list.
*/
dcb->memdata.next = zombies;
zombies = dcb;
/*<
* Set state which indicates that it has been added to zombies
* list.
*/
succp = dcb_set_state(dcb, DCB_STATE_ZOMBIE, &prev_state);
ss_info_dassert(succp, "Failed to set DCB_STATE_ZOMBIE");
spinlock_release(&zombiespin);
}
/*
* Clone a DCB for internal use, mostly used for specialist filters
* to create dummy clients based on real clients.
*
* @param orig The DCB to clone
* @return A DCB that can be used as a client
*/
DCB *
dcb_clone(DCB *orig)
{
DCB *clone;
if ((clone = dcb_alloc(DCB_ROLE_REQUEST_HANDLER)) == NULL)
{
return NULL;
}
clone->fd = -1;
clone->flags |= DCBF_CLONE;
clone->state = orig->state;
clone->data = orig->data;
if (orig->remote)
clone->remote = strdup(orig->remote);
if (orig->user)
clone->user = strdup(orig->user);
clone->protocol = orig->protocol;
clone->func.write = dcb_null_write;
clone->func.close = dcb_null_close;
clone->func.auth = dcb_null_auth;
return clone;
}
/**
* Free a DCB and remove it from the chain of all DCBs
*
* NB This is called with the caller holding the zombie queue
* spinlock
*
* @param dcb The DCB to free
*/
static void
dcb_final_free(DCB *dcb)
{
DCB_CALLBACK *cb;
CHK_DCB(dcb);
ss_info_dassert(dcb->state == DCB_STATE_DISCONNECTED ||
dcb->state == DCB_STATE_ALLOC,
"dcb not in DCB_STATE_DISCONNECTED not in DCB_STATE_ALLOC state.");
/*< First remove this DCB from the chain */
spinlock_acquire(&dcbspin);
if (allDCBs == dcb)
{
/*<
* Deal with the special case of removing the DCB at the head of
* the chain.
*/
allDCBs = dcb->next;
}
else
{
/*<
* We find the DCB that point to the one we are removing and then
* set the next pointer of that DCB to the next pointer of the
* DCB we are removing.
*/
DCB *ptr = allDCBs;
while (ptr && ptr->next != dcb)
ptr = ptr->next;
if (ptr)
ptr->next = dcb->next;
}
spinlock_release(&dcbspin);
if (dcb->session) {
/*<
* Terminate client session.
*/
{
SESSION *local_session = dcb->session;
CHK_SESSION(local_session);
/*<
* Remove reference from session if dcb is client.
*/
if (local_session->client == dcb) {
local_session->client = NULL;
}
dcb->session = NULL;
session_free(local_session);
}
}
if (dcb->protocol && ((dcb->flags & DCBF_CLONE) ==0))
free(dcb->protocol);
if (dcb->data && ((dcb->flags & DCBF_CLONE) ==0))
free(dcb->data);
if (dcb->remote)
free(dcb->remote);
if (dcb->user)
free(dcb->user);
/* Clear write and read buffers */
if (dcb->delayq) {
GWBUF *queue = dcb->delayq;
while ((queue = gwbuf_consume(queue, GWBUF_LENGTH(queue))) != NULL);
}
if (dcb->dcb_readqueue)
{
GWBUF* queue = dcb->dcb_readqueue;
while ((queue = gwbuf_consume(queue, GWBUF_LENGTH(queue))) != NULL);
}
spinlock_acquire(&dcb->cb_lock);
while ((cb = dcb->callbacks) != NULL)
{
dcb->callbacks = cb->next;
free(cb);
}
spinlock_release(&dcb->cb_lock);
bitmask_free(&dcb->memdata.bitmask);
free(dcb);
}
/**
* Process the DCB zombie queue
*
* This routine is called by each of the polling threads with
* the thread id of the polling thread. It must clear the bit in
* the memdata bitmask for the polling thread that calls it. If the
* operation of clearing this bit means that no bits are set in
* the memdata.bitmask then the DCB is no longer able to be
* referenced and it can be finally removed.
*
* @param threadid The thread ID of the caller
*/
DCB *
dcb_process_zombies(int threadid)
{
DCB *ptr, *lptr;
DCB* dcb_list = NULL;
DCB* dcb = NULL;
bool succp = false;
/**
* Perform a dirty read to see if there is anything in the queue.
* This avoids threads hitting the queue spinlock when the queue
* is empty. This will really help when the only entry is being
* freed, since the queue is updated before the expensive call to
* dcb_final_free.
*/
if (!zombies)
return NULL;
/*
* Process the zombie queue and create a list of DCB's that can be
* finally freed. This processing is down under a spinlock that
* will prevent new entries being added to the zombie queue. Therefore
* we do not want to do any expensive operations under this spinlock
* as it will block other threads. The expensive operations will be
* performed on the victim queue within holding the zombie queue
* spinlock.
*/
spinlock_acquire(&zombiespin);
ptr = zombies;
lptr = NULL;
while (ptr)
{
CHK_DCB(ptr);
/*
* Skip processing of DCB's that are
* in the event queue waiting to be processed.
*/
if (ptr->evq.next || ptr->evq.prev)
{
lptr = ptr;
ptr = ptr->memdata.next;
}
else
{
bitmask_clear(&ptr->memdata.bitmask, threadid);
if (bitmask_isallclear(&ptr->memdata.bitmask))
{
/**
* Remove the DCB from the zombie queue
* and call the final free routine for the
* DCB
*
* ptr is the DCB we are processing
* lptr is the previous DCB on the zombie queue
* or NULL if the DCB is at the head of the
* queue tptr is the DCB after the one we are
* processing on the zombie queue
*/
DCB *tptr = ptr->memdata.next;
if (lptr == NULL)
zombies = tptr;
else
lptr->memdata.next = tptr;
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_DEBUG,
"%lu [dcb_process_zombies] Remove dcb "
"%p fd %d " "in state %s from the "
"list of zombies.",
pthread_self(),
ptr,
ptr->fd,
STRDCBSTATE(ptr->state))));
ss_info_dassert(ptr->state == DCB_STATE_ZOMBIE,
"dcb not in DCB_STATE_ZOMBIE state.");
/*<
* Move dcb to linked list of victim dcbs.
*/
if (dcb_list == NULL) {
dcb_list = ptr;
dcb = dcb_list;
} else {
dcb->memdata.next = ptr;
dcb = dcb->memdata.next;
}
dcb->memdata.next = NULL;
ptr = tptr;
}
else
{
lptr = ptr;
ptr = ptr->memdata.next;
}
}
}
spinlock_release(&zombiespin);
/*
* Process the victim queue. These are DCBs that are not in
* use by any thread.
* The corresponding file descriptor is closed, the DCB marked
* as disconnected and the DCB itself is fianlly freed.
*/
dcb = dcb_list;
while (dcb != NULL) {
DCB* dcb_next = NULL;
int rc = 0;
/*<
* Close file descriptor and move to clean-up phase.
*/
rc = close(dcb->fd);
if (rc < 0) {
int eno = errno;
errno = 0;
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Failed to close "
"socket %d on dcb %p due error %d, %s.",
dcb->fd,
dcb,
eno,
strerror(eno))));
}
#if defined(SS_DEBUG)
else {
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_DEBUG,
"%lu [dcb_process_zombies] Closed socket "
"%d on dcb %p.",
pthread_self(),
dcb->fd,
dcb)));
conn_open[dcb->fd] = false;
ss_debug(dcb->fd = -1;)
}
#endif
succp = dcb_set_state(dcb, DCB_STATE_DISCONNECTED, NULL);
ss_dassert(succp);
dcb_next = dcb->memdata.next;
dcb_final_free(dcb);
dcb = dcb_next;
}
return zombies;
}
/**
* Connect to a server
*
* This routine will create a server connection
* If succesful the new dcb will be put in
* epoll set by dcb->func.connect
*
* @param server The server to connect to
* @param session The session this connection is being made for
* @param protocol The protocol module to use
* @return The new allocated dcb or NULL if the DCB was not connected
*/
DCB *
dcb_connect(SERVER *server, SESSION *session, const char *protocol)
{
DCB *dcb;
GWPROTOCOL *funcs;
int fd;
int rc;
if ((dcb = dcb_alloc(DCB_ROLE_REQUEST_HANDLER)) == NULL)
{
return NULL;
}
if ((funcs = (GWPROTOCOL *)load_module(protocol,
MODULE_PROTOCOL)) == NULL)
{
dcb_set_state(dcb, DCB_STATE_DISCONNECTED, NULL);
dcb_final_free(dcb);
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Failed to load protocol module for %s, free "
"dcb %p\n",
protocol,
dcb)));
return NULL;
}
memcpy(&(dcb->func), funcs, sizeof(GWPROTOCOL));
/*<
* Link dcb to session. Unlink is called in dcb_final_free
*/
if (!session_link_dcb(session, dcb))
{
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_connect] Failed to link to session, the "
"session has been removed.",
pthread_self())));
dcb_final_free(dcb);
return NULL;
}
fd = dcb->func.connect(dcb, server, session);
if (fd == -1) {
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_connect] Failed to connect to server %s:%d, "
"from backend dcb %p, client dcp %p fd %d.",
pthread_self(),
server->name,
server->port,
dcb,
session->client,
session->client->fd)));
dcb_set_state(dcb, DCB_STATE_DISCONNECTED, NULL);
dcb_final_free(dcb);
return NULL;
} else {
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_DEBUG,
"%lu [dcb_connect] Connected to server %s:%d, "
"from backend dcb %p, client dcp %p fd %d.",
pthread_self(),
server->name,
server->port,
dcb,
session->client,
session->client->fd)));
}
ss_dassert(dcb->fd == -1); /*< must be uninitialized at this point */
/*<
* Successfully connected to backend. Assign file descriptor to dcb
*/
dcb->fd = fd;
/** Copy status field to DCB */
dcb->dcb_server_status = server->status;
ss_debug(dcb->dcb_port = server->port;)
/*<
* backend_dcb is connected to backend server, and once backend_dcb
* is added to poll set, authentication takes place as part of
* EPOLLOUT event that will be received once the connection
* is established.
*/
/*<
* Add the dcb in the poll set
*/
rc = poll_add_dcb(dcb);
if (rc == -1) {
dcb_set_state(dcb, DCB_STATE_DISCONNECTED, NULL);
dcb_final_free(dcb);
return NULL;
}
/*<
* The dcb will be addded into poll set by dcb->func.connect
*/
atomic_add(&server->stats.n_connections, 1);
atomic_add(&server->stats.n_current, 1);
return dcb;
}
/**
* General purpose read routine to read data from a socket in the
* Descriptor Control Block and append it to a linked list of buffers.
* The list may be empty, in which case *head == NULL
*
* @param dcb The DCB to read from
* @param head Pointer to linked list to append data to
* @return -1 on error, otherwise the number of read bytes on the last
* iteration of while loop. 0 is returned if no data available.
*/
int dcb_read(
DCB *dcb,
GWBUF **head)
{
GWBUF *buffer = NULL;
int b;
int rc;
int n ;
int nread = 0;
int eno = 0;
CHK_DCB(dcb);
while (true)
{
int bufsize;
rc = ioctl(dcb->fd, FIONREAD, &b);
if (rc == -1)
{
eno = errno;
errno = 0;
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : ioctl FIONREAD for dcb %p in "
"state %s fd %d failed due error %d, %s.",
dcb,
STRDCBSTATE(dcb->state),
dcb->fd,
eno,
strerror(eno))));
n = -1;
goto return_n;
}
if (b == 0 && nread == 0)
{
/** Handle closed client socket */
if (dcb_isclient(dcb))
{
char c;
int l_errno = 0;
int r = -1;
/* try to read 1 byte, without consuming the socket buffer */
r = recv(dcb->fd, &c, sizeof(char), MSG_PEEK);
l_errno = errno;
if (r <= 0 &&
l_errno != EAGAIN &&
l_errno != EWOULDBLOCK)
{
n = -1;
goto return_n;
}
}
n = 0;
goto return_n;
}
else if (b == 0)
{
n = 0;
goto return_n;
}
bufsize = MIN(b, MAX_BUFFER_SIZE);
if ((buffer = gwbuf_alloc(bufsize)) == NULL)
{
/*<
* This is a fatal error which should cause shutdown.
* Todo shutdown if memory allocation fails.
*/
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Failed to allocate read buffer "
"for dcb %p fd %d, due %d, %s.",
dcb,
dcb->fd,
eno,
strerror(eno))));
n = -1;
ss_dassert(buffer != NULL);
goto return_n;
}
GW_NOINTR_CALL(n = read(dcb->fd, GWBUF_DATA(buffer), bufsize);
dcb->stats.n_reads++);
if (n <= 0)
{
int eno = errno;
errno = 0;
if (eno != 0 && eno != EAGAIN && eno != EWOULDBLOCK)
{
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Read failed, dcb %p in state "
"%s fd %d, due %d, %s.",
dcb,
STRDCBSTATE(dcb->state),
dcb->fd,
eno,
strerror(eno))));
}
gwbuf_free(buffer);
goto return_n;
}
nread += n;
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_read] Read %d bytes from dcb %p in state %s "
"fd %d.",
pthread_self(),
n,
dcb,
STRDCBSTATE(dcb->state),
dcb->fd)));
/*< Append read data to the gwbuf */
*head = gwbuf_append(*head, buffer);
} /*< while (true) */
return_n:
return n;
}
/**
* General purpose routine to write to a DCB
*
* @param dcb The DCB of the client
* @param queue Queue of buffers to write
*/
int
dcb_write(DCB *dcb, GWBUF *queue)
{
int w;
int saved_errno = 0;
int below_water;
below_water = (dcb->high_water && dcb->writeqlen < dcb->high_water) ? 1 : 0;
ss_dassert(queue != NULL);
/**
* SESSION_STATE_STOPPING means that one of the backends is closing
* the router session. Some backends may have not completed
* authentication yet and thus they have no information about router
* being closed. Session state is changed to SESSION_STATE_STOPPING
* before router's closeSession is called and that tells that DCB may
* still be writable.
*/
if (queue == NULL ||
(dcb->state != DCB_STATE_ALLOC &&
dcb->state != DCB_STATE_POLLING &&
dcb->state != DCB_STATE_LISTENING &&
dcb->state != DCB_STATE_NOPOLLING &&
dcb->session->state != SESSION_STATE_STOPPING))
{
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_write] Write aborted to dcb %p because "
"it is in state %s",
pthread_self(),
dcb->stats.n_buffered,
dcb,
STRDCBSTATE(dcb->state),
dcb->fd)));
ss_dassert(false);
return 0;
}
spinlock_acquire(&dcb->writeqlock);
if (dcb->writeq != NULL)
{
/*
* We have some queued data, so add our data to
* the write queue and return.
* The assumption is that there will be an EPOLLOUT
* event to drain what is already queued. We are protected
* by the spinlock, which will also be acquired by the
* the routine that drains the queue data, so we should
* not have a race condition on the event.
*/
if (queue)
{
int qlen;
qlen = gwbuf_length(queue);
atomic_add(&dcb->writeqlen, qlen);
dcb->writeq = gwbuf_append(dcb->writeq, queue);
dcb->stats.n_buffered++;
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_write] Append to writequeue. %d writes "
"buffered for dcb %p in state %s fd %d",
pthread_self(),
dcb->stats.n_buffered,
dcb,
STRDCBSTATE(dcb->state),
dcb->fd)));
}
}
else
{
/*
* Loop over the buffer chain that has been passed to us
* from the reading side.
* Send as much of the data in that chain as possible and
* add any balance to the write queue.
*/
while (queue != NULL)
{
int qlen;
#if defined(SS_DEBUG)
if (dcb->dcb_role == DCB_ROLE_REQUEST_HANDLER &&
dcb->session != NULL)
{
if (dcb_isclient(dcb) && fail_next_client_fd) {
dcb_fake_write_errno[dcb->fd] = 32;
dcb_fake_write_ev[dcb->fd] = 29;
fail_next_client_fd = false;
} else if (!dcb_isclient(dcb) &&
fail_next_backend_fd)
{
dcb_fake_write_errno[dcb->fd] = 32;
dcb_fake_write_ev[dcb->fd] = 29;
fail_next_backend_fd = false;
}
}
#endif /* SS_DEBUG */
qlen = GWBUF_LENGTH(queue);
GW_NOINTR_CALL(
w = gw_write(
#if defined(SS_DEBUG)
dcb,
#endif
dcb->fd, GWBUF_DATA(queue), qlen);
dcb->stats.n_writes++;
);
if (w < 0)
{
saved_errno = errno;
errno = 0;
if (LOG_IS_ENABLED(LOGFILE_DEBUG))
{
if (saved_errno == EPIPE)
{
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_write] Write to dcb "
"%p in state %s fd %d failed "
"due errno %d, %s",
pthread_self(),
dcb,
STRDCBSTATE(dcb->state),
dcb->fd,
saved_errno,
strerror(saved_errno))));
}
}
if (LOG_IS_ENABLED(LOGFILE_ERROR))
{
if (saved_errno != EPIPE &&
saved_errno != EAGAIN &&
saved_errno != EWOULDBLOCK)
{
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Write to dcb %p in "
"state %s fd %d failed due "
"errno %d, %s",
dcb,
STRDCBSTATE(dcb->state),
dcb->fd,
saved_errno,
strerror(saved_errno))));
}
}
break;
}
/*
* Pull the number of bytes we have written from
* queue with have.
*/
queue = gwbuf_consume(queue, w);
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_write] Wrote %d Bytes to dcb %p in "
"state %s fd %d",
pthread_self(),
w,
dcb,
STRDCBSTATE(dcb->state),
dcb->fd)));
} /*< while (queue != NULL) */
/*<
* What wasn't successfully written is stored to write queue
* for suspended write.
*/
dcb->writeq = queue;
if (queue)
{
int qlen;
qlen = gwbuf_length(queue);
atomic_add(&dcb->writeqlen, qlen);
dcb->stats.n_buffered++;
}
} /* if (dcb->writeq) */
if (saved_errno != 0 &&
queue != NULL &&
saved_errno != EAGAIN &&
saved_errno != EWOULDBLOCK)
{
bool dolog = true;
/**
* Do not log if writing COM_QUIT to backend failed.
*/
if (GWBUF_IS_TYPE_MYSQL(queue))
{
uint8_t* data = GWBUF_DATA(queue);
if (data[4] == 0x01)
{
dolog = false;
}
}
if (dolog)
{
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_write] Writing to %s socket failed due %d, %s.",
pthread_self(),
dcb_isclient(dcb) ? "client" : "backend server",
saved_errno,
strerror(saved_errno))));
}
spinlock_release(&dcb->writeqlock);
return 0;
}
spinlock_release(&dcb->writeqlock);
if (dcb->high_water && dcb->writeqlen > dcb->high_water && below_water)
{
atomic_add(&dcb->stats.n_high_water, 1);
dcb_call_callback(dcb, DCB_REASON_HIGH_WATER);
}
return 1;
}
/**
* Drain the write queue of a DCB. This is called as part of the EPOLLOUT handling
* of a socket and will try to send any buffered data from the write queue
* up until the point the write would block.
*
* @param dcb DCB to drain the write queue of
* @return The number of bytes written
*/
int
dcb_drain_writeq(DCB *dcb)
{
int n = 0;
int w;
int saved_errno = 0;
int above_water;
above_water = (dcb->low_water && dcb->writeqlen > dcb->low_water) ? 1 : 0;
spinlock_acquire(&dcb->writeqlock);
if (dcb->writeq)
{
int len;
/*
* Loop over the buffer chain in the pending writeq
* Send as much of the data in that chain as possible and
* leave any balance on the write queue.
*/
while (dcb->writeq != NULL)
{
len = GWBUF_LENGTH(dcb->writeq);
GW_NOINTR_CALL(w = gw_write(
#if defined(SS_DEBUG)
dcb,
#endif
dcb->fd,
GWBUF_DATA(dcb->writeq),
len););
saved_errno = errno;
errno = 0;
if (w < 0)
{
#if defined(SS_DEBUG)
if (saved_errno == EAGAIN ||
saved_errno == EWOULDBLOCK)
#else
if (saved_errno == EAGAIN ||
saved_errno == EWOULDBLOCK ||
saved_errno == EPIPE)
#endif
{
break;
}
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Write to dcb %p "
"in state %s fd %d failed due errno %d, %s",
dcb,
STRDCBSTATE(dcb->state),
dcb->fd,
saved_errno,
strerror(saved_errno))));
break;
}
/*
* Pull the number of bytes we have written from
* queue with have.
*/
dcb->writeq = gwbuf_consume(dcb->writeq, w);
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_drain_writeq] Wrote %d Bytes to dcb %p "
"in state %s fd %d",
pthread_self(),
w,
dcb,
STRDCBSTATE(dcb->state),
dcb->fd)));
n += w;
}
}
spinlock_release(&dcb->writeqlock);
atomic_add(&dcb->writeqlen, -n);
/* The write queue has drained, potentially need to call a callback function */
if (dcb->writeq == NULL)
dcb_call_callback(dcb, DCB_REASON_DRAINED);
if (above_water && dcb->writeqlen < dcb->low_water)
{
atomic_add(&dcb->stats.n_low_water, 1);
dcb_call_callback(dcb, DCB_REASON_LOW_WATER);
}
return n;
}
/**
* Removes dcb from poll set, and adds it to zombies list. As a consequense,
* dcb first moves to DCB_STATE_NOPOLLING, and then to DCB_STATE_ZOMBIE state.
* At the end of the function state may not be DCB_STATE_ZOMBIE because once
* dcb_initlock is released parallel threads may change the state.
*
* Parameters:
* @param dcb The DCB to close
*
*
*/
void
dcb_close(DCB *dcb)
{
int rc;
CHK_DCB(dcb);
/*<
* dcb_close may be called for freshly created dcb, in which case
* it only needs to be freed.
*/
if (dcb->state == DCB_STATE_ALLOC)
{
dcb_set_state(dcb, DCB_STATE_DISCONNECTED, NULL);
dcb_final_free(dcb);
return;
}
ss_dassert(dcb->state == DCB_STATE_POLLING ||
dcb->state == DCB_STATE_NOPOLLING ||
dcb->state == DCB_STATE_ZOMBIE);
/*<
* Stop dcb's listening and modify state accordingly.
*/
if (dcb->state == DCB_STATE_POLLING)
{
rc = poll_remove_dcb(dcb);
if (rc == 0) {
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_close] Removed dcb %p in state %s from "
"poll set.",
pthread_self(),
dcb,
STRDCBSTATE(dcb->state))));
} else {
LOGIF(LE, (skygw_log_write(
LOGFILE_ERROR,
"Error : Removing DCB fd == %d in state %s from "
"poll set failed.",
dcb->fd,
STRDCBSTATE(dcb->state))));
}
if (rc == 0)
{
/**
* close protocol and router session
*/
if (dcb->func.close != NULL)
{
dcb->func.close(dcb);
}
dcb_call_callback(dcb, DCB_REASON_CLOSE);
if (dcb->state == DCB_STATE_NOPOLLING)
{
dcb_add_to_zombieslist(dcb);
}
}
}
ss_dassert(dcb->state == DCB_STATE_NOPOLLING ||
dcb->state == DCB_STATE_ZOMBIE);
}
/**
* Diagnostic to print a DCB
*
* @param dcb The DCB to print
*
*/
void
printDCB(DCB *dcb)
{
printf("DCB: %p\n", (void *)dcb);
printf("\tDCB state: %s\n", gw_dcb_state2string(dcb->state));
if (dcb->remote)
printf("\tConnected to: %s\n", dcb->remote);
if (dcb->user)
printf("\tUsername to: %s\n", dcb->user);
if (dcb->writeq)
printf("\tQueued write data: %d\n",gwbuf_length(dcb->writeq));
printf("\tStatistics:\n");
printf("\t\tNo. of Reads: %d\n",
dcb->stats.n_reads);
printf("\t\tNo. of Writes: %d\n",
dcb->stats.n_writes);
printf("\t\tNo. of Buffered Writes: %d\n",
dcb->stats.n_buffered);
printf("\t\tNo. of Accepts: %d\n",
dcb->stats.n_accepts);
printf("\t\tNo. of High Water Events: %d\n",
dcb->stats.n_high_water);
printf("\t\tNo. of Low Water Events: %d\n",
dcb->stats.n_low_water);
}
/**
* Display an entry from the spinlock statistics data
*
* @param dcb The DCB to print to
* @param desc Description of the statistic
* @param value The statistic value
*/
static void
spin_reporter(void *dcb, char *desc, int value)
{
dcb_printf((DCB *)dcb, "\t\t%-40s %d\n", desc, value);
}
/**
* Diagnostic to print all DCB allocated in the system
*
*/
void printAllDCBs()
{
DCB *dcb;
spinlock_acquire(&dcbspin);
dcb = allDCBs;
while (dcb)
{
printDCB(dcb);
dcb = dcb->next;
}
spinlock_release(&dcbspin);
}
/**
* Diagnostic to print all DCB allocated in the system
*
*/
void dprintAllDCBs(DCB *pdcb)
{
DCB *dcb;
spinlock_acquire(&dcbspin);
#if SPINLOCK_PROFILE
dcb_printf(pdcb, "DCB List Spinlock Statistics:\n");
spinlock_stats(&dcbspin, spin_reporter, pdcb);
dcb_printf(pdcb, "Zombie Queue Lock Statistics:\n");
spinlock_stats(&zombiespin, spin_reporter, pdcb);
#endif
dcb = allDCBs;
while (dcb)
{
dcb_printf(pdcb, "DCB: %p\n", (void *)dcb);
dcb_printf(pdcb, "\tDCB state: %s\n",
gw_dcb_state2string(dcb->state));
if (dcb->session && dcb->session->service)
dcb_printf(pdcb, "\tService: %s\n",
dcb->session->service->name);
if (dcb->remote)
dcb_printf(pdcb, "\tConnected to: %s\n",
dcb->remote);
if (dcb->user)
dcb_printf(pdcb, "\tUsername: %s\n",
dcb->user);
if (dcb->writeq)
dcb_printf(pdcb, "\tQueued write data: %d\n",
gwbuf_length(dcb->writeq));
dcb_printf(pdcb, "\tStatistics:\n");
dcb_printf(pdcb, "\t\tNo. of Reads: %d\n", dcb->stats.n_reads);
dcb_printf(pdcb, "\t\tNo. of Writes: %d\n", dcb->stats.n_writes);
dcb_printf(pdcb, "\t\tNo. of Buffered Writes: %d\n", dcb->stats.n_buffered);
dcb_printf(pdcb, "\t\tNo. of Accepts: %d\n", dcb->stats.n_accepts);
dcb_printf(pdcb, "\t\tNo. of High Water Events: %d\n", dcb->stats.n_high_water);
dcb_printf(pdcb, "\t\tNo. of Low Water Events: %d\n", dcb->stats.n_low_water);
if (dcb->flags & DCBF_CLONE)
dcb_printf(pdcb, "\t\tDCB is a clone.\n");
dcb = dcb->next;
}
spinlock_release(&dcbspin);
}
/**
* Diagnotic routine to print DCB data in a tabular form.
*
* @param pdcb DCB to print results to
*/
void
dListDCBs(DCB *pdcb)
{
DCB *dcb;
spinlock_acquire(&dcbspin);
dcb = allDCBs;
dcb_printf(pdcb, "Descriptor Control Blocks\n");
dcb_printf(pdcb, "------------------+----------------------------+--------------------+----------\n");
dcb_printf(pdcb, " %-16s | %-26s | %-18s | %s\n",
"DCB", "State", "Service", "Remote");
dcb_printf(pdcb, "------------------+----------------------------+--------------------+----------\n");
while (dcb)
{
dcb_printf(pdcb, " %-16p | %-26s | %-18s | %s\n",
dcb, gw_dcb_state2string(dcb->state),
((dcb->session && dcb->session->service) ? dcb->session->service->name : ""),
(dcb->remote ? dcb->remote : ""));
dcb = dcb->next;
}
dcb_printf(pdcb, "------------------+----------------------------+--------------------+----------\n\n");
spinlock_release(&dcbspin);
}
/**
* Diagnotic routine to print client DCB data in a tabular form.
*
* @param pdcb DCB to print results to
*/
void
dListClients(DCB *pdcb)
{
DCB *dcb;
spinlock_acquire(&dcbspin);
dcb = allDCBs;
dcb_printf(pdcb, "Client Connections\n");
dcb_printf(pdcb, "-----------------+------------------+----------------------+------------\n");
dcb_printf(pdcb, " %-15s | %-16s | %-20s | %s\n",
"Client", "DCB", "Service", "Session");
dcb_printf(pdcb, "-----------------+------------------+----------------------+------------\n");
while (dcb)
{
if (dcb_isclient(dcb)
&& dcb->dcb_role == DCB_ROLE_REQUEST_HANDLER)
{
dcb_printf(pdcb, " %-15s | %16p | %-20s | %10p\n",
(dcb->remote ? dcb->remote : ""),
dcb, (dcb->session->service ?
dcb->session->service->name : ""),
dcb->session);
}
dcb = dcb->next;
}
dcb_printf(pdcb, "-----------------+------------------+----------------------+------------\n\n");
spinlock_release(&dcbspin);
}
/**
* Diagnostic to print a DCB to another DCB
*
* @param pdcb The DCB to which send the output
* @param dcb The DCB to print
*/
void
dprintDCB(DCB *pdcb, DCB *dcb)
{
dcb_printf(pdcb, "DCB: %p\n", (void *)dcb);
dcb_printf(pdcb, "\tDCB state: %s\n", gw_dcb_state2string(dcb->state));
if (dcb->session && dcb->session->service)
dcb_printf(pdcb, "\tService: %s\n",
dcb->session->service->name);
if (dcb->remote)
dcb_printf(pdcb, "\tConnected to: %s\n", dcb->remote);
if (dcb->user)
dcb_printf(pdcb, "\tUsername: %s\n",
dcb->user);
dcb_printf(pdcb, "\tOwning Session: %p\n", dcb->session);
if (dcb->writeq)
dcb_printf(pdcb, "\tQueued write data: %d\n", gwbuf_length(dcb->writeq));
if (dcb->delayq)
dcb_printf(pdcb, "\tDelayed write data: %d\n", gwbuf_length(dcb->delayq));
dcb_printf(pdcb, "\tStatistics:\n");
dcb_printf(pdcb, "\t\tNo. of Reads: %d\n",
dcb->stats.n_reads);
dcb_printf(pdcb, "\t\tNo. of Writes: %d\n",
dcb->stats.n_writes);
dcb_printf(pdcb, "\t\tNo. of Buffered Writes: %d\n",
dcb->stats.n_buffered);
dcb_printf(pdcb, "\t\tNo. of Accepts: %d\n",
dcb->stats.n_accepts);
dcb_printf(pdcb, "\t\tNo. of High Water Events: %d\n",
dcb->stats.n_high_water);
dcb_printf(pdcb, "\t\tNo. of Low Water Events: %d\n",
dcb->stats.n_low_water);
if (dcb->flags & DCBF_CLONE)
dcb_printf(pdcb, "\t\tDCB is a clone.\n");
#if SPINLOCK_PROFILE
dcb_printf(pdcb, "\tInitlock Statistics:\n");
spinlock_stats(&dcb->dcb_initlock, spin_reporter, pdcb);
dcb_printf(pdcb, "\tWrite Queue Lock Statistics:\n");
spinlock_stats(&dcb->writeqlock, spin_reporter, pdcb);
dcb_printf(pdcb, "\tDelay Queue Lock Statistics:\n");
spinlock_stats(&dcb->delayqlock, spin_reporter, pdcb);
dcb_printf(pdcb, "\tPollin Lock Statistics:\n");
spinlock_stats(&dcb->pollinlock, spin_reporter, pdcb);
dcb_printf(pdcb, "\tPollout Lock Statistics:\n");
spinlock_stats(&dcb->polloutlock, spin_reporter, pdcb);
dcb_printf(pdcb, "\tCallback Lock Statistics:\n");
spinlock_stats(&dcb->cb_lock, spin_reporter, pdcb);
#endif
}
/**
* Return a string representation of a DCB state.
*
* @param state The DCB state
* @return String representation of the state
*
*/
const char *
gw_dcb_state2string (int state) {
switch(state) {
case DCB_STATE_ALLOC:
return "DCB Allocated";
case DCB_STATE_POLLING:
return "DCB in the polling loop";
case DCB_STATE_LISTENING:
return "DCB for listening socket";
case DCB_STATE_DISCONNECTED:
return "DCB socket closed";
case DCB_STATE_FREED:
return "DCB memory could be freed";
case DCB_STATE_ZOMBIE:
return "DCB Zombie";
default:
return "DCB (unknown)";
}
}
/**
* A DCB based wrapper for printf. Allows formatting printing to
* a descritor control block.
*
* @param dcb Descriptor to write to
* @param fmt A printf format string
* @param ... Variable arguments for the print format
*/
void
dcb_printf(DCB *dcb, const char *fmt, ...)
{
GWBUF *buf;
va_list args;
if ((buf = gwbuf_alloc(10240)) == NULL)
return;
va_start(args, fmt);
vsnprintf(GWBUF_DATA(buf), 10240, fmt, args);
va_end(args);
buf->end = GWBUF_DATA(buf) + strlen(GWBUF_DATA(buf));
dcb->func.write(dcb, buf);
}
/**
* Determine the role that a DCB plays within a session.
*
* @param dcb
* @return Non-zero if the DCB is the client of the session
*/
int
dcb_isclient(DCB *dcb)
{
if(dcb->session) {
if (dcb->session->client) {
return (dcb->session && dcb == dcb->session->client);
}
}
return 0;
}
/**
* Print hash table statistics to a DCB
*
* @param dcb The DCB to send the information to
* @param table The hash table
*/
void dcb_hashtable_stats(
DCB* dcb,
void* table)
{
int total;
int longest;
int hashsize;
total = 0;
longest = 0;
hashtable_get_stats(table, &hashsize, &total, &longest);
dcb_printf(dcb,
"Hashtable: %p, size %d\n",
table,
hashsize);
dcb_printf(dcb, "\tNo. of entries: %d\n", total);
dcb_printf(dcb, "\tAverage chain length: %.1f\n", (float)total / hashsize);
dcb_printf(dcb, "\tLongest chain length: %d\n", longest);
}
bool dcb_set_state(
DCB* dcb,
const dcb_state_t new_state,
dcb_state_t* old_state)
{
bool succp;
dcb_state_t state ;
CHK_DCB(dcb);
spinlock_acquire(&dcb->dcb_initlock);
succp = dcb_set_state_nomutex(dcb, new_state, &state);
spinlock_release(&dcb->dcb_initlock);
if (old_state != NULL) {
*old_state = state;
}
return succp;
}
static bool dcb_set_state_nomutex(
DCB* dcb,
const dcb_state_t new_state,
dcb_state_t* old_state)
{
bool succp = false;
dcb_state_t state = DCB_STATE_UNDEFINED;
CHK_DCB(dcb);
state = dcb->state;
if (old_state != NULL) {
*old_state = state;
}
switch (state) {
case DCB_STATE_UNDEFINED:
dcb->state = new_state;
succp = true;
break;
case DCB_STATE_ALLOC:
switch (new_state) {
/** fall through, for client requests */
case DCB_STATE_POLLING:
/** fall through, for connect listeners */
case DCB_STATE_LISTENING:
/** for failed connections */
case DCB_STATE_DISCONNECTED:
dcb->state = new_state;
succp = true;
break;
default:
ss_dassert(old_state != NULL);
break;
}
break;
case DCB_STATE_POLLING:
switch(new_state) {
case DCB_STATE_NOPOLLING:
dcb->state = new_state;
succp = true;
break;
default:
ss_dassert(old_state != NULL);
break;
}
break;
case DCB_STATE_LISTENING:
switch(new_state) {
case DCB_STATE_NOPOLLING:
dcb->state = new_state;
succp = true;
break;
default:
ss_dassert(old_state != NULL);
break;
}
break;
case DCB_STATE_NOPOLLING:
switch (new_state) {
case DCB_STATE_ZOMBIE: /*< fall through */
dcb->state = new_state;
case DCB_STATE_POLLING: /*< ok to try but state can't change */
succp = true;
break;
default:
ss_dassert(old_state != NULL);
break;
}
break;
case DCB_STATE_ZOMBIE:
switch (new_state) {
case DCB_STATE_DISCONNECTED: /*< fall through */
dcb->state = new_state;
case DCB_STATE_POLLING: /*< ok to try but state can't change */
succp = true;
break;
default:
ss_dassert(old_state != NULL);
break;
}
break;
case DCB_STATE_DISCONNECTED:
switch (new_state) {
case DCB_STATE_FREED:
dcb->state = new_state;
succp = true;
break;
default:
ss_dassert(old_state != NULL);
break;
}
break;
case DCB_STATE_FREED:
ss_dassert(old_state != NULL);
break;
default:
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Unknown dcb state %s for "
"dcb %p",
STRDCBSTATE(dcb->state),
dcb)));
ss_dassert(false);
break;
} /*< switch (dcb->state) */
if (succp) {
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_DEBUG,
"%lu [dcb_set_state_nomutex] dcb %p fd %d %s -> %s",
pthread_self(),
dcb,
dcb->fd,
STRDCBSTATE(state),
STRDCBSTATE(dcb->state))));
}
else
{
LOGIF(LD, (skygw_log_write(
LOGFILE_DEBUG,
"%lu [dcb_set_state_nomutex] Failed "
"to change state of DCB %p. "
"Old state %s > new state %s.",
pthread_self(),
dcb,
(old_state == NULL ? "NULL" : STRDCBSTATE(*old_state)),
STRDCBSTATE(new_state))));
}
return succp;
}
int gw_write(
#if defined(SS_DEBUG)
DCB* dcb,
#endif
int fd,
const void* buf,
size_t nbytes)
{
int w;
#if defined(SS_DEBUG)
if (dcb_fake_write_errno[fd] != 0) {
ss_dassert(dcb_fake_write_ev[fd] != 0);
w = write(fd, buf, nbytes/2); /*< leave peer to read missing bytes */
if (w > 0) {
w = -1;
errno = dcb_fake_write_errno[fd];
}
} else {
w = write(fd, buf, nbytes);
}
#else
w = write(fd, buf, nbytes);
#endif /* SS_DEBUG && SS_TEST */
#if defined(SS_DEBUG_MYSQL)
{
size_t len;
uint8_t* packet = (uint8_t *)buf;
char* str;
/** Print only MySQL packets */
if (w > 5)
{
str = (char *)&packet[5];
len = packet[0];
len += 256*packet[1];
len += 256*256*packet[2];
if (strncmp(str, "insert", 6) == 0 ||
strncmp(str, "create", 6) == 0 ||
strncmp(str, "drop", 4) == 0)
{
ss_dassert((dcb->dcb_server_status & (SERVER_RUNNING|SERVER_MASTER|SERVER_SLAVE))==(SERVER_RUNNING|SERVER_MASTER));
}
if (strncmp(str, "set autocommit", 14) == 0 && nbytes > 17)
{
char* s = (char *)calloc(1, nbytes+1);
if (nbytes-5 > len)
{
size_t len2 = packet[4+len];
len2 += 256*packet[4+len+1];
len2 += 256*256*packet[4+len+2];
char* str2 = (char *)&packet[4+len+5];
snprintf(s, 5+len+len2, "long %s %s", (char *)str, (char *)str2);
}
else
{
snprintf(s, len, "%s", (char *)str);
}
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [gw_write] Wrote %d bytes : %s ",
pthread_self(),
w,
s)));
free(s);
}
}
}
#endif
return w;
}
/**
* Add a callback
*
* Duplicate registrations are not allowed, therefore an error will be
* returned if the specific function, reason and userdata triple
* are already registered.
* An error will also be returned if the is insufficient memeory available to
* create the registration.
*
* @param dcb The DCB to add the callback to
* @param reason The callback reason
* @param callback The callback function to call
* @param userdata User data to send in the call
* @return Non-zero (true) if the callback was added
*/
int
dcb_add_callback(DCB *dcb, DCB_REASON reason, int (*callback)(struct dcb *, DCB_REASON, void *), void *userdata)
{
DCB_CALLBACK *cb, *ptr;
int rval = 1;
if ((ptr = (DCB_CALLBACK *)malloc(sizeof(DCB_CALLBACK))) == NULL)
{
return 0;
}
ptr->reason = reason;
ptr->cb = callback;
ptr->userdata = userdata;
ptr->next = NULL;
spinlock_acquire(&dcb->cb_lock);
cb = dcb->callbacks;
if (cb == NULL)
{
dcb->callbacks = ptr;
spinlock_release(&dcb->cb_lock);
}
else
{
while (cb)
{
if (cb->reason == reason && cb->cb == callback &&
cb->userdata == userdata)
{
free(ptr);
spinlock_release(&dcb->cb_lock);
return 0;
}
if (cb->next == NULL)
{
cb->next = ptr;
break;
}
cb = cb->next;
}
spinlock_release(&dcb->cb_lock);
}
return rval;
}
/**
* Remove a callback from the callback list for the DCB
*
* Searches down the linked list to find the callback with a matching reason, function
* and userdata.
*
* @param dcb The DCB to add the callback to
* @param reason The callback reason
* @param callback The callback function to call
* @param userdata User data to send in the call
* @return Non-zero (true) if the callback was removed
*/
int
dcb_remove_callback(DCB *dcb, DCB_REASON reason, int (*callback)(struct dcb *, DCB_REASON, void *), void *userdata)
{
DCB_CALLBACK *cb, *pcb = NULL;
int rval = 0;
spinlock_acquire(&dcb->cb_lock);
cb = dcb->callbacks;
if (cb == NULL)
{
rval = 0;
}
else
{
while (cb)
{
if (cb->reason == reason && cb->cb == callback
&& cb->userdata == userdata)
{
if (pcb != NULL)
pcb->next = cb->next;
else
dcb->callbacks = cb->next;
spinlock_release(&dcb->cb_lock);
free(cb);
rval = 1;
break;
}
pcb = cb;
cb = cb->next;
}
}
if (!rval)
spinlock_release(&dcb->cb_lock);
return rval;
}
/**
* Call the set of callbacks registered for a particular reason.
*
* @param dcb The DCB to call the callbacks regarding
* @param reason The reason that has triggered the call
*/
static void
dcb_call_callback(DCB *dcb, DCB_REASON reason)
{
DCB_CALLBACK *cb, *nextcb;
spinlock_acquire(&dcb->cb_lock);
cb = dcb->callbacks;
while (cb)
{
if (cb->reason == reason)
{
nextcb = cb->next;
spinlock_release(&dcb->cb_lock);
cb->cb(dcb, reason, cb->userdata);
spinlock_acquire(&dcb->cb_lock);
cb = nextcb;
}
else
cb = cb->next;
}
spinlock_release(&dcb->cb_lock);
}
/**
* Check the passed DCB to ensure it is in the list of allDCBS
*
* @param dcb The DCB to check
* @return 1 if the DCB is in the list, otherwise 0
*/
int
dcb_isvalid(DCB *dcb)
{
int rval = 0;
if (dcb)
{
spinlock_acquire(&dcbspin);
rval = dcb_isvalid_nolock(dcb);
spinlock_release(&dcbspin);
}
return rval;
}
/**
* Check the passed DCB to ensure it is in the list of allDCBS.
* Requires that the DCB list is already locked before call.
*
* @param dcb The DCB to check
* @return 1 if the DCB is in the list, otherwise 0
*/
static int
dcb_isvalid_nolock(DCB *dcb)
{
DCB *ptr;
int rval = 0;
if (dcb)
{
ptr = allDCBs;
while (ptr && ptr != dcb)
{
ptr = ptr->next;
}
rval = (ptr == dcb);
}
return rval;
}
/**
* Get the next DCB in the list of all DCB's
*
* @param dcb The current DCB
* @return The pointer to the next DCB or NULL if this is the last
*/
static DCB *
dcb_get_next (DCB* dcb)
{
spinlock_acquire(&dcbspin);
if (dcb) {
dcb = dcb_isvalid_nolock(dcb) ? dcb->next : NULL;
}
else dcb = allDCBs;
spinlock_release(&dcbspin);
return dcb;
}
/**
* Call all the callbacks on all DCB's that match the reason given
*
* @param reason The DCB_REASON that triggers the callback
*/
void
dcb_call_foreach(DCB_REASON reason)
{
switch (reason) {
case DCB_REASON_CLOSE:
case DCB_REASON_DRAINED:
case DCB_REASON_HIGH_WATER:
case DCB_REASON_LOW_WATER:
case DCB_REASON_ERROR:
case DCB_REASON_HUP:
case DCB_REASON_NOT_RESPONDING:
{
DCB* dcb;
dcb = dcb_get_next(NULL);
while (dcb != NULL)
{
if (dcb->state == DCB_STATE_POLLING)
{
dcb_call_callback(dcb, DCB_REASON_NOT_RESPONDING);
}
dcb = dcb_get_next(dcb);
}
break;
}
default:
break;
}
return;
}
/**
* Null protocol write routine used for cloned dcb's. It merely consumes
* buffers written on the cloned DCB.
*
* @param dcb The descriptor control block
* @param buf The buffer being written
* @return Always returns a good write operation result
*/
static int
dcb_null_write(DCB *dcb, GWBUF *buf)
{
while (buf)
{
buf = gwbuf_consume(buf, GWBUF_LENGTH(buf));
}
return 1;
}
/**
* Null protocol close operation for use by cloned DCB's.
*
* @param dcb The DCB being closed.
*/
static int
dcb_null_close(DCB *dcb)
{
return 0;
}
/**
* Null protocol auth operation for use by cloned DCB's.
*
* @param dcb The DCB being closed.
* @param server The server to auth against
* @param session The user session
* @param buf The buffer with the new auth request
*/
static int
dcb_null_auth(DCB *dcb, SERVER *server, SESSION *session, GWBUF *buf)
{
return 0;
}
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