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Clean up more code

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The *NSYNC linked list API is good enough that it deserves to be part of
the C libray, so this change writes an improved version of it which uses
that offsetof() trick from the Linux Kernel. We vendor all of the *NSYNC
tests in third_party which helped confirm the needed refactoring is safe

This change also deletes more old code that didn't pan out. My goal here
is to work towards a vision where the Cosmopolitan core libraries become
less experimental and more focused on curation. This better reflects the
current level of quality we've managed to achieve.
This commit is contained in:
Justine Tunney 2023-07-06 06:57:28 -07:00
parent 88612a2cd7
commit 0a24b4fc3c
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GPG key ID: BE714B4575D6E328
268 changed files with 632 additions and 8688 deletions
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89
third_party/nsync/mem/nsync_cv.c vendored
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@ -16,12 +16,12 @@
│ limitations under the License. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/cp.internal.h"
#include "libc/intrin/dll.h"
#include "libc/str/str.h"
#include "libc/thread/thread.h"
#include "third_party/nsync/atomic.internal.h"
#include "third_party/nsync/common.internal.h"
#include "third_party/nsync/cv.h"
#include "third_party/nsync/dll.h"
#include "third_party/nsync/races.internal.h"
#include "third_party/nsync/wait_s.internal.h"
#include "third_party/nsync/waiter.h"
@ -38,7 +38,7 @@ https://github.com/google/nsync\"");
/* Initialize *cv. */
void nsync_cv_init (nsync_cv *cv) {
memset ((void *) cv, 0, sizeof (*cv));
bzero ((void *) cv, sizeof (*cv));
}
/* Wake the cv waiters in the circular list pointed to by
@ -46,10 +46,10 @@ void nsync_cv_init (nsync_cv *cv) {
nsync_mu, the "wakeup" may consist of transferring the waiters to the nsync_mu's
queue. Requires that every waiter is associated with the same mutex.
all_readers indicates whether all the waiters on the list are readers. */
static void wake_waiters (nsync_dll_list_ to_wake_list, int all_readers) {
nsync_dll_element_ *p = NULL;
nsync_dll_element_ *next = NULL;
nsync_dll_element_ *first_waiter = nsync_dll_first_ (to_wake_list);
static void wake_waiters (struct Dll *to_wake_list, int all_readers) {
struct Dll *p = NULL;
struct Dll *next = NULL;
struct Dll *first_waiter = dll_first (to_wake_list);
struct nsync_waiter_s *first_nw = DLL_NSYNC_WAITER (first_waiter);
waiter *first_w = NULL;
nsync_mu *pmu = NULL;
@ -71,7 +71,7 @@ static void wake_waiters (nsync_dll_list_ to_wake_list, int all_readers) {
*/
uint32_t old_mu_word = ATM_LOAD (&pmu->word);
int first_cant_acquire = ((old_mu_word & first_w->l_type->zero_to_acquire) != 0);
next = nsync_dll_next_ (to_wake_list, first_waiter);
next = dll_next (to_wake_list, first_waiter);
if ((old_mu_word&MU_ANY_LOCK) != 0 &&
(old_mu_word&MU_SPINLOCK) == 0 &&
(first_cant_acquire || (next != NULL && !all_readers)) &&
@ -88,8 +88,8 @@ static void wake_waiters (nsync_dll_list_ to_wake_list, int all_readers) {
int woke_areader = 0;
/* Transfer the first waiter iff it can't acquire *pmu. */
if (first_cant_acquire) {
to_wake_list = nsync_dll_remove_ (to_wake_list, first_waiter);
pmu->waiters = nsync_dll_make_last_in_list_ (pmu->waiters, first_waiter);
dll_remove (&to_wake_list, first_waiter);
dll_make_last (&pmu->waiters, first_waiter);
/* tell nsync_cv_wait_with_deadline() that we
moved the waiter to *pmu's queue. */
first_w->cv_mu = NULL;
@ -107,7 +107,7 @@ static void wake_waiters (nsync_dll_list_ to_wake_list, int all_readers) {
if ((p_nw->flags & NSYNC_WAITER_FLAG_MUCV) != 0) {
p_w = DLL_WAITER (p);
}
next = nsync_dll_next_ (to_wake_list, p);
next = dll_next (to_wake_list, p);
p_is_writer = (p_w != NULL &&
DLL_WAITER (p)->l_type == nsync_writer_type_);
/* We transfer this element if any of:
@ -117,8 +117,8 @@ static void wake_waiters (nsync_dll_list_ to_wake_list, int all_readers) {
if (p_w == NULL) {
/* wake non-native waiter */
} else if (first_cant_acquire || first_is_writer || p_is_writer) {
to_wake_list = nsync_dll_remove_ (to_wake_list, p);
pmu->waiters = nsync_dll_make_last_in_list_ (pmu->waiters, p);
dll_remove (&to_wake_list, p);
dll_make_last (&pmu->waiters, p);
/* tell nsync_cv_wait_with_deadline()
that we moved the waiter to *pmu's
queue. */
@ -147,10 +147,10 @@ static void wake_waiters (nsync_dll_list_ to_wake_list, int all_readers) {
}
/* Wake any waiters we didn't manage to enqueue on the mu. */
for (p = nsync_dll_first_ (to_wake_list); p != NULL; p = next) {
for (p = dll_first (to_wake_list); p != NULL; p = next) {
struct nsync_waiter_s *p_nw = DLL_NSYNC_WAITER (p);
next = nsync_dll_next_ (to_wake_list, p);
to_wake_list = nsync_dll_remove_ (to_wake_list, p);
next = dll_next (to_wake_list, p);
dll_remove (&to_wake_list, p);
/* Wake the waiter. */
ATM_STORE_REL (&p_nw->waiting, 0); /* release store */
nsync_mu_semaphore_v (p_nw->sem);
@ -239,7 +239,7 @@ int nsync_cv_wait_with_deadline_generic (nsync_cv *pcv, void *pmu,
/* acquire spinlock, set non-empty */
old_word = nsync_spin_test_and_set_ (&pcv->word, CV_SPINLOCK, CV_SPINLOCK|CV_NON_EMPTY, 0);
pcv->waiters = nsync_dll_make_last_in_list_ (pcv->waiters, &w->nw.q);
dll_make_last (&pcv->waiters, &w->nw.q);
remove_count = ATM_LOAD (&w->remove_count);
/* Release the spin lock. */
ATM_STORE_REL (&pcv->word, old_word|CV_NON_EMPTY); /* release store */
@ -277,12 +277,11 @@ int nsync_cv_wait_with_deadline_generic (nsync_cv *pcv, void *pmu,
queue, and declare a
timeout/cancellation. */
outcome = sem_outcome;
pcv->waiters = nsync_dll_remove_ (pcv->waiters,
&w->nw.q);
dll_remove (&pcv->waiters, &w->nw.q);
do {
old_value = ATM_LOAD (&w->remove_count);
} while (!ATM_CAS (&w->remove_count, old_value, old_value+1));
if (nsync_dll_is_empty_ (pcv->waiters)) {
if (dll_is_empty (pcv->waiters)) {
old_word &= ~(CV_NON_EMPTY);
}
ATM_STORE_REL (&w->nw.waiting, 0); /* release store */
@ -328,27 +327,26 @@ int nsync_cv_wait_with_deadline_generic (nsync_cv *pcv, void *pmu,
void nsync_cv_signal (nsync_cv *pcv) {
IGNORE_RACES_START ();
if ((ATM_LOAD_ACQ (&pcv->word) & CV_NON_EMPTY) != 0) { /* acquire load */
nsync_dll_list_ to_wake_list = NULL; /* waiters that we will wake */
struct Dll *to_wake_list = NULL; /* waiters that we will wake */
int all_readers = 0;
/* acquire spinlock */
uint32_t old_word = nsync_spin_test_and_set_ (&pcv->word, CV_SPINLOCK,
CV_SPINLOCK, 0);
if (!nsync_dll_is_empty_ (pcv->waiters)) {
if (!dll_is_empty (pcv->waiters)) {
/* Point to first waiter that enqueued itself, and
detach it from all others. */
struct nsync_waiter_s *first_nw;
nsync_dll_element_ *first = nsync_dll_first_ (pcv->waiters);
pcv->waiters = nsync_dll_remove_ (pcv->waiters, first);
struct Dll *first = dll_first (pcv->waiters);
dll_remove (&pcv->waiters, first);
first_nw = DLL_NSYNC_WAITER (first);
if ((first_nw->flags & NSYNC_WAITER_FLAG_MUCV) != 0) {
uint32_t old_value;
do {
old_value =
ATM_LOAD (&DLL_WAITER (first)->remove_count);
old_value = ATM_LOAD (&DLL_WAITER (first)->remove_count);
} while (!ATM_CAS (&DLL_WAITER (first)->remove_count,
old_value, old_value+1));
}
to_wake_list = nsync_dll_make_last_in_list_ (to_wake_list, first);
dll_make_last (&to_wake_list, first);
if ((first_nw->flags & NSYNC_WAITER_FLAG_MUCV) != 0 &&
DLL_WAITER (first)->l_type == nsync_reader_type_) {
int woke_writer;
@ -363,14 +361,14 @@ void nsync_cv_signal (nsync_cv *pcv) {
the condition; the client is expecting only one writer to be
able make use of the wakeup, or he would have called
nsync_cv_broadcast(). */
nsync_dll_element_ *p = NULL;
nsync_dll_element_ *next = NULL;
struct Dll *p = NULL;
struct Dll *next = NULL;
all_readers = 1;
woke_writer = 0;
for (p = nsync_dll_first_ (pcv->waiters); p != NULL; p = next) {
for (p = dll_first (pcv->waiters); p != NULL; p = next) {
struct nsync_waiter_s *p_nw = DLL_NSYNC_WAITER (p);
int should_wake;
next = nsync_dll_next_ (pcv->waiters, p);
next = dll_next (pcv->waiters, p);
should_wake = 0;
if ((p_nw->flags & NSYNC_WAITER_FLAG_MUCV) != 0 &&
DLL_WAITER (p)->l_type == nsync_reader_type_) {
@ -381,7 +379,7 @@ void nsync_cv_signal (nsync_cv *pcv) {
should_wake = 1;
}
if (should_wake) {
pcv->waiters = nsync_dll_remove_ (pcv->waiters, p);
dll_remove (&pcv->waiters, p);
if ((p_nw->flags & NSYNC_WAITER_FLAG_MUCV) != 0) {
uint32_t old_value;
do {
@ -390,18 +388,17 @@ void nsync_cv_signal (nsync_cv *pcv) {
} while (!ATM_CAS (&DLL_WAITER (p)->remove_count,
old_value, old_value+1));
}
to_wake_list = nsync_dll_make_last_in_list_ (
to_wake_list, p);
dll_make_last (&to_wake_list, p);
}
}
}
if (nsync_dll_is_empty_ (pcv->waiters)) {
if (dll_is_empty (pcv->waiters)) {
old_word &= ~(CV_NON_EMPTY);
}
}
/* Release spinlock. */
ATM_STORE_REL (&pcv->word, old_word); /* release store */
if (!nsync_dll_is_empty_ (to_wake_list)) {
if (!dll_is_empty (to_wake_list)) {
wake_waiters (to_wake_list, all_readers);
}
}
@ -412,22 +409,22 @@ void nsync_cv_signal (nsync_cv *pcv) {
void nsync_cv_broadcast (nsync_cv *pcv) {
IGNORE_RACES_START ();
if ((ATM_LOAD_ACQ (&pcv->word) & CV_NON_EMPTY) != 0) { /* acquire load */
nsync_dll_element_ *p;
nsync_dll_element_ *next;
struct Dll *p;
struct Dll *next;
int all_readers;
nsync_dll_list_ to_wake_list = NULL; /* waiters that we will wake */
struct Dll *to_wake_list = NULL; /* waiters that we will wake */
/* acquire spinlock */
nsync_spin_test_and_set_ (&pcv->word, CV_SPINLOCK, CV_SPINLOCK, 0);
p = NULL;
next = NULL;
all_readers = 1;
/* Wake entire waiter list, which we leave empty. */
for (p = nsync_dll_first_ (pcv->waiters); p != NULL; p = next) {
for (p = dll_first (pcv->waiters); p != NULL; p = next) {
struct nsync_waiter_s *p_nw = DLL_NSYNC_WAITER (p);
next = nsync_dll_next_ (pcv->waiters, p);
next = dll_next (pcv->waiters, p);
all_readers = all_readers && (p_nw->flags & NSYNC_WAITER_FLAG_MUCV) != 0 &&
(DLL_WAITER (p)->l_type == nsync_reader_type_);
pcv->waiters = nsync_dll_remove_ (pcv->waiters, p);
dll_remove (&pcv->waiters, p);
if ((p_nw->flags & NSYNC_WAITER_FLAG_MUCV) != 0) {
uint32_t old_value;
do {
@ -435,11 +432,11 @@ void nsync_cv_broadcast (nsync_cv *pcv) {
} while (!ATM_CAS (&DLL_WAITER (p)->remove_count,
old_value, old_value+1));
}
to_wake_list = nsync_dll_make_last_in_list_ (to_wake_list, p);
dll_make_last (&to_wake_list, p);
}
/* Release spinlock and mark queue empty. */
ATM_STORE_REL (&pcv->word, 0); /* release store */
if (!nsync_dll_is_empty_ (to_wake_list)) { /* Wake them. */
if (!dll_is_empty (to_wake_list)) { /* Wake them. */
wake_waiters (to_wake_list, all_readers);
}
}
@ -477,7 +474,7 @@ static int cv_enqueue (void *v, struct nsync_waiter_s *nw) {
nsync_cv *pcv = (nsync_cv *) v;
/* acquire spinlock */
uint32_t old_word = nsync_spin_test_and_set_ (&pcv->word, CV_SPINLOCK, CV_SPINLOCK, 0);
pcv->waiters = nsync_dll_make_last_in_list_ (pcv->waiters, &nw->q);
dll_make_last (&pcv->waiters, &nw->q);
ATM_STORE (&nw->waiting, 1);
/* Release spinlock. */
ATM_STORE_REL (&pcv->word, old_word | CV_NON_EMPTY); /* release store */
@ -490,11 +487,11 @@ static int cv_dequeue (void *v, struct nsync_waiter_s *nw) {
/* acquire spinlock */
uint32_t old_word = nsync_spin_test_and_set_ (&pcv->word, CV_SPINLOCK, CV_SPINLOCK, 0);
if (ATM_LOAD_ACQ (&nw->waiting) != 0) {
pcv->waiters = nsync_dll_remove_ (pcv->waiters, &nw->q);
dll_remove (&pcv->waiters, &nw->q);
ATM_STORE (&nw->waiting, 0);
was_queued = 1;
}
if (nsync_dll_is_empty_ (pcv->waiters)) {
if (dll_is_empty (pcv->waiters)) {
old_word &= ~(CV_NON_EMPTY);
}
/* Release spinlock. */