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Restructure wait_for_thread_etc() to make it easier to follow.

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* Avoid needless adding of the death entry if the sem is gone already.
* Delete objects as soon as they aren't needed anymore and return
  early where possible.
* Contain the thread == NULL case in its block and return from there as
  well instead of non-obviously figuring out what happened later.
* Pull out the return code asignment.
* Minor cleanup.
This commit is contained in:
Michael Lotz 2011-12-06 02:30:17 +01:00
parent da329fc012
commit 62bb375688
1 changed files with 17 additions and 29 deletions
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46
src/system/kernel/thread.cpp
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@ -2465,10 +2465,7 @@ status_t
wait_for_thread_etc(thread_id id, uint32 flags, bigtime_t timeout,
status_t *_returnCode)
{
job_control_entry* freeDeath = NULL;
status_t status = B_OK;
if (id < B_OK)
if (id < 0)
return B_BAD_THREAD_ID;
// get the thread, queue our death entry, and fetch the semaphore we have to
@ -2480,16 +2477,14 @@ wait_for_thread_etc(thread_id id, uint32 flags, bigtime_t timeout,
if (thread != NULL) {
// remember the semaphore we have to wait on and place our death entry
exitSem = thread->exit.sem;
list_add_link_to_head(&thread->exit.waiters, &death);
if (exitSem >= 0)
list_add_link_to_head(&thread->exit.waiters, &death);
thread->UnlockAndReleaseReference();
// Note: We mustn't dereference the pointer afterwards, only check
// it.
}
thread_death_entry* threadDeathEntry = NULL;
if (thread == NULL) {
if (exitSem < 0)
return B_BAD_THREAD_ID;
} else {
// we couldn't find this thread -- maybe it's already gone, and we'll
// find its death entry in our team
Team* team = thread_get_current_thread()->team;
@ -2498,47 +2493,43 @@ wait_for_thread_etc(thread_id id, uint32 flags, bigtime_t timeout,
// check the child death entries first (i.e. main threads of child
// teams)
bool deleteEntry;
freeDeath = team_get_death_entry(team, id, &deleteEntry);
job_control_entry* freeDeath
= team_get_death_entry(team, id, &deleteEntry);
if (freeDeath != NULL) {
death.status = freeDeath->status;
if (!deleteEntry)
freeDeath = NULL;
if (deleteEntry)
delete freeDeath;
} else {
// check the thread death entries of the team (non-main threads)
thread_death_entry* threadDeathEntry = NULL;
while ((threadDeathEntry = (thread_death_entry*)list_get_next_item(
&team->dead_threads, threadDeathEntry)) != NULL) {
if (threadDeathEntry->thread == id) {
list_remove_item(&team->dead_threads, threadDeathEntry);
team->dead_threads_count--;
death.status = threadDeathEntry->status;
free(threadDeathEntry);
break;
}
}
if (threadDeathEntry == NULL)
status = B_BAD_THREAD_ID;
return B_BAD_THREAD_ID;
}
}
if (thread == NULL && status == B_OK) {
// we found the thread's death entry in our team
if (_returnCode)
*_returnCode = death.status;
delete freeDeath;
free(threadDeathEntry);
return B_OK;
}
// we need to wait for the death of the thread
if (exitSem < 0)
return B_BAD_THREAD_ID;
resume_thread(id);
// make sure we don't wait forever on a suspended thread
status = acquire_sem_etc(exitSem, 1, flags, timeout);
status_t status = acquire_sem_etc(exitSem, 1, flags, timeout);
if (status == B_OK) {
// this should never happen as the thread deletes the semaphore on exit
@ -2546,9 +2537,6 @@ wait_for_thread_etc(thread_id id, uint32 flags, bigtime_t timeout,
} else if (status == B_BAD_SEM_ID) {
// this is the way the thread normally exits
status = B_OK;
if (_returnCode)
*_returnCode = death.status;
} else {
// We were probably interrupted or the timeout occurred; we need to
// remove our death entry now.
@ -2563,12 +2551,12 @@ wait_for_thread_etc(thread_id id, uint32 flags, bigtime_t timeout,
// middle of the cleanup.
acquire_sem(exitSem);
status = B_OK;
if (_returnCode != NULL)
*_returnCode = death.status;
}
}
if (status == B_OK && _returnCode != NULL)
*_returnCode = death.status;
return status;
}