* (d) release the locks on the TVars, writing updates to them in the case of a
* commit, (e) unlock the STM.
*
- * Queues of waiting threads hang off the first_watch_queue_entry field of each
- * TVar. This may only be manipulated when holding that TVar's lock. In
- * particular, when a thread is putting itself to sleep, it mustn't release
- * the TVar's lock until it has added itself to the wait queue and marked its
- * TSO as BlockedOnSTM -- this makes sure that other threads will know to wake it.
+ * Queues of waiting threads hang off the first_watch_queue_entry
+ * field of each TVar. This may only be manipulated when holding that
+ * TVar's lock. In particular, when a thread is putting itself to
+ * sleep, it mustn't release the TVar's lock until it has added itself
+ * to the wait queue and marked its TSO as BlockedOnSTM -- this makes
+ * sure that other threads will know to wake it.
*
* ---------------------------------------------------------------------------*/
#include "PosixSource.h"
#include "Rts.h"
-#include "RtsFlags.h"
+
#include "RtsUtils.h"
-#include "Storage.h"
#include "Schedule.h"
-#include "SMP.h"
#include "STM.h"
#include "Trace.h"
+#include "Threads.h"
-#include <stdlib.h>
#include <stdio.h>
#define TRUE 1
do {
do {
result = s -> current_value;
- } while (GET_INFO(result) == &stg_TREC_HEADER_info);
+ } while (GET_INFO(UNTAG_CLOSURE(result)) == &stg_TREC_HEADER_info);
} while (cas((void *)&(s -> current_value),
(StgWord)result, (StgWord)trec) != (StgWord)result);
return result;
static void unpark_waiters_on(Capability *cap, StgTVar *s) {
StgTVarWatchQueue *q;
+ StgTVarWatchQueue *trail;
TRACE("unpark_waiters_on tvar=%p", s);
- for (q = s -> first_watch_queue_entry;
- q != END_STM_WATCH_QUEUE;
+ // unblock TSOs in reverse order, to be a bit fairer (#2319)
+ for (q = s -> first_watch_queue_entry, trail = q;
+ q != END_STM_WATCH_QUEUE;
q = q -> next_queue_entry) {
+ trail = q;
+ }
+ q = trail;
+ for (;
+ q != END_STM_WATCH_QUEUE;
+ q = q -> prev_queue_entry) {
if (watcher_is_tso(q)) {
unpark_tso(cap, (StgTSO *)(q -> closure));
}
result = tvar -> current_value;
#if defined(STM_FG_LOCKS)
- while (GET_INFO(result) == &stg_TREC_HEADER_info) {
+ while (GET_INFO(UNTAG_CLOSURE(result)) == &stg_TREC_HEADER_info) {
TRACE("%p : read_current_value(%p) saw %p", trec, tvar, result);
result = tvar -> current_value;
}
StgClosure *stmReadTVar(Capability *cap,
StgTRecHeader *trec,
StgTVar *tvar) {
- StgTRecHeader *entry_in;
+ StgTRecHeader *entry_in = NULL;
StgClosure *result = NULL;
TRecEntry *entry = NULL;
TRACE("%p : stmReadTVar(%p)", trec, tvar);
StgTVar *tvar,
StgClosure *new_value) {
- StgTRecHeader *entry_in;
+ StgTRecHeader *entry_in = NULL;
TRecEntry *entry = NULL;
TRACE("%p : stmWriteTVar(%p, %p)", trec, tvar, new_value);
ASSERT (trec != NO_TREC);