Port [] alarm management to GRPC.
This change implements a platform independent alarm manager in alarm.c.
It's integrated with iomgr, and some tests are cleaned up.
The alarm implementation itself is a fairly direct port of LazyAlarmList from eventmanager.
SpinLock has been replaced for now with gpr_mu, and other atomic operations have been dropped (again, for now).
A majority of tests have been ported.
Change on 2014/12/19 by ctiller <ctiller@google.com>
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=82551363
diff --git a/src/core/iomgr/alarm_heap.c b/src/core/iomgr/alarm_heap.c
new file mode 100644
index 0000000..693d26d
--- /dev/null
+++ b/src/core/iomgr/alarm_heap.c
@@ -0,0 +1,148 @@
+/*
+ *
+ * Copyright 2014, 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/iomgr/alarm_heap.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/useful.h>
+
+/* Adjusts a heap so as to move a hole at position i closer to the root,
+ until a suitable position is found for element t. Then, copies t into that
+ position. This functor is called each time immediately after modifying a
+ value in the underlying container, with the offset of the modified element as
+ its argument. */
+static void adjust_upwards(grpc_alarm **first, int i, grpc_alarm *t) {
+ while (i > 0) {
+ int parent = (i - 1) / 2;
+ if (gpr_time_cmp(first[parent]->deadline, t->deadline) >= 0) break;
+ first[i] = first[parent];
+ first[i]->heap_index = i;
+ i = parent;
+ }
+ first[i] = t;
+ t->heap_index = i;
+}
+
+/* Adjusts a heap so as to move a hole at position i farther away from the root,
+ until a suitable position is found for element t. Then, copies t into that
+ position. */
+static void adjust_downwards(grpc_alarm **first, int i, int length,
+ grpc_alarm *t) {
+ for (;;) {
+ int left_child = 1 + 2 * i;
+ int right_child;
+ int next_i;
+ if (left_child >= length) break;
+ right_child = left_child + 1;
+ next_i = right_child < length &&
+ gpr_time_cmp(first[left_child]->deadline,
+ first[right_child]->deadline) < 0
+ ? right_child
+ : left_child;
+ if (gpr_time_cmp(t->deadline, first[next_i]->deadline) >= 0) break;
+ first[i] = first[next_i];
+ first[i]->heap_index = i;
+ i = next_i;
+ }
+ first[i] = t;
+ t->heap_index = i;
+}
+
+#define SHRINK_MIN_ELEMS 8
+#define SHRINK_FULLNESS_FACTOR 2
+
+static void maybe_shrink(grpc_alarm_heap *heap) {
+ if (heap->alarm_count >= 8 &&
+ heap->alarm_count <= heap->alarm_capacity / SHRINK_FULLNESS_FACTOR / 2) {
+ heap->alarm_capacity = heap->alarm_count * SHRINK_FULLNESS_FACTOR;
+ heap->alarms =
+ gpr_realloc(heap->alarms, heap->alarm_capacity * sizeof(grpc_alarm *));
+ }
+}
+
+static void note_changed_priority(grpc_alarm_heap *heap, grpc_alarm *alarm) {
+ int i = alarm->heap_index;
+ int parent = (i - 1) / 2;
+ if (gpr_time_cmp(heap->alarms[parent]->deadline, alarm->deadline) < 0) {
+ adjust_upwards(heap->alarms, i, alarm);
+ } else {
+ adjust_downwards(heap->alarms, i, heap->alarm_count, alarm);
+ }
+}
+
+void grpc_alarm_heap_init(grpc_alarm_heap *heap) {
+ memset(heap, 0, sizeof(*heap));
+}
+
+void grpc_alarm_heap_destroy(grpc_alarm_heap *heap) { gpr_free(heap->alarms); }
+
+int grpc_alarm_heap_add(grpc_alarm_heap *heap, grpc_alarm *alarm) {
+ if (heap->alarm_count == heap->alarm_capacity) {
+ heap->alarm_capacity =
+ GPR_MAX(heap->alarm_capacity + 1, heap->alarm_capacity * 3 / 2);
+ heap->alarms =
+ gpr_realloc(heap->alarms, heap->alarm_capacity * sizeof(grpc_alarm *));
+ }
+ alarm->heap_index = heap->alarm_count;
+ adjust_upwards(heap->alarms, heap->alarm_count, alarm);
+ heap->alarm_count++;
+ return alarm->heap_index == 0;
+}
+
+void grpc_alarm_heap_remove(grpc_alarm_heap *heap, grpc_alarm *alarm) {
+ int i = alarm->heap_index;
+ if (i == heap->alarm_count - 1) {
+ heap->alarm_count--;
+ maybe_shrink(heap);
+ return;
+ }
+ heap->alarms[i] = heap->alarms[heap->alarm_count - 1];
+ heap->alarms[i]->heap_index = i;
+ heap->alarm_count--;
+ maybe_shrink(heap);
+ note_changed_priority(heap, heap->alarms[i]);
+}
+
+int grpc_alarm_heap_is_empty(grpc_alarm_heap *heap) {
+ return heap->alarm_count == 0;
+}
+
+grpc_alarm *grpc_alarm_heap_top(grpc_alarm_heap *heap) {
+ return heap->alarms[0];
+}
+
+void grpc_alarm_heap_pop(grpc_alarm_heap *heap) {
+ grpc_alarm_heap_remove(heap, grpc_alarm_heap_top(heap));
+}