diff options
author | 2016-09-02 09:30:26 -0700 | |
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committer | 2016-09-02 09:30:26 -0700 | |
commit | 57ceb42df03058806a377dbe07f5951ee511da0f (patch) | |
tree | 89d4e3d920311c89e48cba9721f42953e6c0e9ba /src/core/lib/support | |
parent | 39b9914d850e856ae5a3e22ab2972b746229ce2a (diff) | |
parent | 56f21aa79c794cad614bec30702e6c5ff3922518 (diff) |
Merge branch 'who-combines-the-combiners' into direct-calls
Diffstat (limited to 'src/core/lib/support')
-rw-r--r-- | src/core/lib/support/mpscq.c | 11 | ||||
-rw-r--r-- | src/core/lib/support/mpscq.h | 4 |
2 files changed, 9 insertions, 6 deletions
diff --git a/src/core/lib/support/mpscq.c b/src/core/lib/support/mpscq.c index 25b055b172..cdd6335f82 100644 --- a/src/core/lib/support/mpscq.c +++ b/src/core/lib/support/mpscq.c @@ -38,7 +38,7 @@ void gpr_mpscq_init(gpr_mpscq *q) { gpr_atm_no_barrier_store(&q->head, (gpr_atm)&q->stub); q->tail = &q->stub; - gpr_atm_no_barrier_store(&q->stub.next, 0); + gpr_atm_no_barrier_store(&q->stub.next, (gpr_atm)NULL); } void gpr_mpscq_destroy(gpr_mpscq *q) { @@ -47,16 +47,17 @@ void gpr_mpscq_destroy(gpr_mpscq *q) { } void gpr_mpscq_push(gpr_mpscq *q, gpr_mpscq_node *n) { - gpr_atm_no_barrier_store(&n->next, 0); + gpr_atm_no_barrier_store(&n->next, (gpr_atm)NULL); gpr_mpscq_node *prev = (gpr_mpscq_node *)gpr_atm_full_xchg(&q->head, (gpr_atm)n); - gpr_atm_rel_store(&prev->next, (gpr_atm)n); + gpr_atm_no_barrier_store(&prev->next, (gpr_atm)n); } gpr_mpscq_node *gpr_mpscq_pop(gpr_mpscq *q) { gpr_mpscq_node *tail = q->tail; gpr_mpscq_node *next = (gpr_mpscq_node *)gpr_atm_acq_load(&tail->next); if (tail == &q->stub) { + // indicates the list is actually (ephemerally) empty if (next == NULL) return NULL; q->tail = next; tail = next; @@ -68,7 +69,8 @@ gpr_mpscq_node *gpr_mpscq_pop(gpr_mpscq *q) { } gpr_mpscq_node *head = (gpr_mpscq_node *)gpr_atm_acq_load(&q->head); if (tail != head) { - return 0; + // indicates a retry is in order: we're still adding + return NULL; } gpr_mpscq_push(q, &q->stub); next = (gpr_mpscq_node *)gpr_atm_acq_load(&tail->next); @@ -76,5 +78,6 @@ gpr_mpscq_node *gpr_mpscq_pop(gpr_mpscq *q) { q->tail = next; return tail; } + // indicates a retry is in order: we're still adding return NULL; } diff --git a/src/core/lib/support/mpscq.h b/src/core/lib/support/mpscq.h index 1201edceb1..977a117952 100644 --- a/src/core/lib/support/mpscq.h +++ b/src/core/lib/support/mpscq.h @@ -41,8 +41,8 @@ // implementation from Dmitry Vyukov here: // http://www.1024cores.net/home/lock-free-algorithms/queues/intrusive-mpsc-node-based-queue -// List node (include this in a data structure and dangle the rest of the -// interesting bits off the end) +// List node (include this in a data structure at the top, and add application +// fields after it - to simulate inheritance) typedef struct gpr_mpscq_node { gpr_atm next; } gpr_mpscq_node; // Actual queue type |