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Remove all linked list handling from remote client event loop

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Directly messing around with the linked list is potentially
dangerous. Introduce some helper APIs to deal with list
manipulating the list

* src/rpc/virnetclient.c: Create linked list handlers
This commit is contained in:
Daniel P. Berrange 2011-11-11 15:26:16 +00:00
parent d776170012
commit 2501d27e18
1 changed files with 144 additions and 63 deletions
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207
src/rpc/virnetclient.c
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@ -110,6 +110,97 @@ static void virNetClientIncomingEvent(virNetSocketPtr sock,
int events,
void *opaque);
/* Append a call to the end of the list */
static void virNetClientCallQueue(virNetClientCallPtr *head,
virNetClientCallPtr call)
{
virNetClientCallPtr tmp = *head;
while (tmp && tmp->next) {
tmp = tmp->next;
}
if (tmp)
tmp->next = call;
else
*head = call;
call->next = NULL;
}
#if 0
/* Obtain a call from the head of the list */
static virNetClientCallPtr virNetClientCallServe(virNetClientCallPtr *head)
{
virNetClientCallPtr tmp = *head;
if (tmp)
*head = tmp->next;
else
*head = NULL;
tmp->next = NULL;
return tmp;
}
#endif
/* Remove a call from anywhere in the list */
static void virNetClientCallRemove(virNetClientCallPtr *head,
virNetClientCallPtr call)
{
virNetClientCallPtr tmp = *head;
virNetClientCallPtr prev = NULL;
while (tmp) {
if (tmp == call) {
if (prev)
prev->next = tmp->next;
else
*head = tmp->next;
tmp->next = NULL;
return;
}
prev = tmp;
tmp = tmp->next;
}
}
/* Predicate returns true if matches */
typedef bool (*virNetClientCallPredicate)(virNetClientCallPtr call, void *opaque);
/* Remove a list of calls from the list based on a predicate */
static void virNetClientCallRemovePredicate(virNetClientCallPtr *head,
virNetClientCallPredicate pred,
void *opaque)
{
virNetClientCallPtr tmp = *head;
virNetClientCallPtr prev = NULL;
while (tmp) {
virNetClientCallPtr next = tmp->next;
tmp->next = NULL; /* Temp unlink */
if (pred(tmp, opaque)) {
if (prev)
prev->next = next;
else
*head = next;
} else {
tmp->next = next; /* Reverse temp unlink */
prev = tmp;
}
tmp = next;
}
}
/* Returns true if the predicate matches at least one call in the list */
static bool virNetClientCallMatchPredicate(virNetClientCallPtr head,
virNetClientCallPredicate pred,
void *opaque)
{
virNetClientCallPtr tmp = head;
while (tmp) {
if (pred(tmp, opaque)) {
return true;
}
tmp = tmp->next;
}
return false;
}
static void virNetClientEventFree(void *opaque)
{
virNetClientPtr client = opaque;
@ -896,6 +987,42 @@ virNetClientIOHandleInput(virNetClientPtr client)
}
static bool virNetClientIOEventLoopPollEvents(virNetClientCallPtr call,
void *opaque)
{
struct pollfd *fd = opaque;
if (call->mode == VIR_NET_CLIENT_MODE_WAIT_RX)
fd->events |= POLLIN;
if (call->mode == VIR_NET_CLIENT_MODE_WAIT_TX)
fd->events |= POLLOUT;
return false;
}
static bool virNetClientIOEventLoopRemoveDone(virNetClientCallPtr call,
void *opaque)
{
virNetClientCallPtr thiscall = opaque;
if (call == thiscall)
return false;
if (call->mode != VIR_NET_CLIENT_MODE_COMPLETE)
return false;
/*
* ...they won't actually wakeup until
* we release our mutex a short while
* later...
*/
VIR_DEBUG("Waking up sleeping call %p", call);
virCondSignal(&call->cond);
return true;
}
/*
* Process all calls pending dispatch/receive until we
* get a reply to our own call. Then quit and pass the buck
@ -911,8 +1038,6 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
fds[1].fd = client->wakeupReadFD;
for (;;) {
virNetClientCallPtr tmp = client->waitDispatch;
virNetClientCallPtr prev;
char ignore;
sigset_t oldmask, blockedsigs;
int timeout = -1;
@ -928,14 +1053,11 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
fds[1].events = fds[1].revents = 0;
fds[1].events = POLLIN;
while (tmp) {
if (tmp->mode == VIR_NET_CLIENT_MODE_WAIT_RX)
fds[0].events |= POLLIN;
if (tmp->mode == VIR_NET_CLIENT_MODE_WAIT_TX)
fds[0].events |= POLLOUT;
tmp = tmp->next;
}
/* Calculate poll events for calls */
virNetClientCallMatchPredicate(client->waitDispatch,
virNetClientIOEventLoopPollEvents,
&fds[0]);
/* We have to be prepared to receive stream data
* regardless of whether any of the calls waiting
@ -1008,37 +1130,16 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
/* Iterate through waiting threads and if
* any are complete then tell 'em to wakeup
*/
tmp = client->waitDispatch;
prev = NULL;
while (tmp) {
if (tmp != thiscall &&
tmp->mode == VIR_NET_CLIENT_MODE_COMPLETE) {
/* Take them out of the list */
if (prev)
prev->next = tmp->next;
else
client->waitDispatch = tmp->next;
/* And wake them up....
* ...they won't actually wakeup until
* we release our mutex a short while
* later...
*/
VIR_DEBUG("Waking up sleep %p %p", tmp, client->waitDispatch);
virCondSignal(&tmp->cond);
} else {
prev = tmp;
}
tmp = tmp->next;
}
virNetClientCallRemovePredicate(&client->waitDispatch,
virNetClientIOEventLoopRemoveDone,
thiscall);
/* Now see if *we* are done */
if (thiscall->mode == VIR_NET_CLIENT_MODE_COMPLETE) {
/* We're at head of the list already, so
* remove us
*/
client->waitDispatch = thiscall->next;
virNetClientCallRemove(&client->waitDispatch, thiscall);
VIR_DEBUG("Giving up the buck %p %p", thiscall, client->waitDispatch);
/* See if someone else is still waiting
* and if so, then pass the buck ! */
if (client->waitDispatch) {
@ -1058,7 +1159,7 @@ static int virNetClientIOEventLoop(virNetClientPtr client,
error:
client->waitDispatch = thiscall->next;
virNetClientCallRemove(&client->waitDispatch, thiscall);
VIR_DEBUG("Giving up the buck due to I/O error %p %p", thiscall, client->waitDispatch);
/* See if someone else is still waiting
* and if so, then pass the buck ! */
@ -1119,22 +1220,13 @@ static int virNetClientIO(virNetClientPtr client,
/* Check to see if another thread is dispatching */
if (client->waitDispatch) {
/* Stick ourselves on the end of the wait queue */
virNetClientCallPtr tmp = client->waitDispatch;
char ignore = 1;
while (tmp && tmp->next)
tmp = tmp->next;
if (tmp)
tmp->next = thiscall;
else
client->waitDispatch = thiscall;
/* Stick ourselves on the end of the wait queue */
virNetClientCallQueue(&client->waitDispatch, thiscall);
/* Force other thread to wakeup from poll */
if (safewrite(client->wakeupSendFD, &ignore, sizeof(ignore)) != sizeof(ignore)) {
if (tmp)
tmp->next = NULL;
else
client->waitDispatch = NULL;
virNetClientCallRemove(&client->waitDispatch, thiscall);
virReportSystemError(errno, "%s",
_("failed to wake up polling thread"));
return -1;
@ -1143,17 +1235,7 @@ static int virNetClientIO(virNetClientPtr client,
VIR_DEBUG("Going to sleep %p %p", client->waitDispatch, thiscall);
/* Go to sleep while other thread is working... */
if (virCondWait(&thiscall->cond, &client->lock) < 0) {
if (client->waitDispatch == thiscall) {
client->waitDispatch = thiscall->next;
} else {
tmp = client->waitDispatch;
while (tmp && tmp->next &&
tmp->next != thiscall) {
tmp = tmp->next;
}
if (tmp && tmp->next == thiscall)
tmp->next = thiscall->next;
}
virNetClientCallRemove(&client->waitDispatch, thiscall);
virNetError(VIR_ERR_INTERNAL_ERROR, "%s",
_("failed to wait on condition"));
return -1;
@ -1177,10 +1259,9 @@ static int virNetClientIO(virNetClientPtr client,
}
/* Grr, someone passed the buck onto us ... */
} else {
/* We're first to catch the buck */
client->waitDispatch = thiscall;
/* We're the first to arrive */
virNetClientCallQueue(&client->waitDispatch, thiscall);
}
VIR_DEBUG("We have the buck %p %p", client->waitDispatch, thiscall);