aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/core/lib/support
diff options
context:
space:
mode:
Diffstat (limited to 'src/core/lib/support')
-rw-r--r--src/core/lib/support/mpscq.c83
-rw-r--r--src/core/lib/support/mpscq.h65
2 files changed, 148 insertions, 0 deletions
diff --git a/src/core/lib/support/mpscq.c b/src/core/lib/support/mpscq.c
new file mode 100644
index 0000000000..5b9323275a
--- /dev/null
+++ b/src/core/lib/support/mpscq.c
@@ -0,0 +1,83 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ * * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/support/mpscq.h"
+
+#include <grpc/support/log.h>
+
+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, (gpr_atm)NULL);
+}
+
+void gpr_mpscq_destroy(gpr_mpscq *q) {
+ GPR_ASSERT(gpr_atm_no_barrier_load(&q->head) == (gpr_atm)&q->stub);
+ GPR_ASSERT(q->tail == &q->stub);
+}
+
+void gpr_mpscq_push(gpr_mpscq *q, gpr_mpscq_node *n) {
+ 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_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;
+ next = (gpr_mpscq_node *)gpr_atm_acq_load(&tail->next);
+ }
+ if (next != NULL) {
+ q->tail = next;
+ return tail;
+ }
+ gpr_mpscq_node *head = (gpr_mpscq_node *)gpr_atm_acq_load(&q->head);
+ if (tail != head) {
+ // 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);
+ if (next != NULL) {
+ 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
new file mode 100644
index 0000000000..977a117952
--- /dev/null
+++ b/src/core/lib/support/mpscq.h
@@ -0,0 +1,65 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ * * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SUPPORT_MPSCQ_H
+#define GRPC_CORE_LIB_SUPPORT_MPSCQ_H
+
+#include <grpc/support/atm.h>
+#include <stddef.h>
+
+// Multiple-producer single-consumer lock free queue, based upon the
+// 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 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
+typedef struct gpr_mpscq {
+ gpr_atm head;
+ // make sure head & tail don't share a cacheline
+ char padding[GPR_CACHELINE_SIZE];
+ gpr_mpscq_node *tail;
+ gpr_mpscq_node stub;
+} gpr_mpscq;
+
+void gpr_mpscq_init(gpr_mpscq *q);
+void gpr_mpscq_destroy(gpr_mpscq *q);
+// Push a node
+void gpr_mpscq_push(gpr_mpscq *q, gpr_mpscq_node *n);
+// Pop a node (returns NULL if no node is ready - which doesn't indicate that
+// the queue is empty!!)
+gpr_mpscq_node *gpr_mpscq_pop(gpr_mpscq *q);
+
+#endif /* GRPC_CORE_LIB_SUPPORT_MPSCQ_H */