| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #include "src/core/lib/iomgr/port.h" |
| |
| #ifdef GRPC_TIMER_USE_GENERIC |
| |
| #include "src/core/lib/iomgr/timer_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_timer **first, uint32_t i, grpc_timer *t) { |
| while (i > 0) { |
| uint32_t parent = (uint32_t)(((int)i - 1) / 2); |
| if (first[parent]->deadline <= t->deadline) 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_timer **first, uint32_t i, uint32_t length, |
| grpc_timer *t) { |
| for (;;) { |
| uint32_t left_child = 1u + 2u * i; |
| if (left_child >= length) break; |
| uint32_t right_child = left_child + 1; |
| uint32_t next_i = |
| right_child < length && |
| first[left_child]->deadline > first[right_child]->deadline |
| ? right_child |
| : left_child; |
| if (t->deadline <= first[next_i]->deadline) 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_timer_heap *heap) { |
| if (heap->timer_count >= 8 && |
| heap->timer_count <= heap->timer_capacity / SHRINK_FULLNESS_FACTOR / 2) { |
| heap->timer_capacity = heap->timer_count * SHRINK_FULLNESS_FACTOR; |
| heap->timers = (grpc_timer **)gpr_realloc( |
| heap->timers, heap->timer_capacity * sizeof(grpc_timer *)); |
| } |
| } |
| |
| static void note_changed_priority(grpc_timer_heap *heap, grpc_timer *timer) { |
| uint32_t i = timer->heap_index; |
| uint32_t parent = (uint32_t)(((int)i - 1) / 2); |
| if (heap->timers[parent]->deadline > timer->deadline) { |
| adjust_upwards(heap->timers, i, timer); |
| } else { |
| adjust_downwards(heap->timers, i, heap->timer_count, timer); |
| } |
| } |
| |
| void grpc_timer_heap_init(grpc_timer_heap *heap) { |
| memset(heap, 0, sizeof(*heap)); |
| } |
| |
| void grpc_timer_heap_destroy(grpc_timer_heap *heap) { gpr_free(heap->timers); } |
| |
| int grpc_timer_heap_add(grpc_timer_heap *heap, grpc_timer *timer) { |
| if (heap->timer_count == heap->timer_capacity) { |
| heap->timer_capacity = |
| GPR_MAX(heap->timer_capacity + 1, heap->timer_capacity * 3 / 2); |
| heap->timers = (grpc_timer **)gpr_realloc( |
| heap->timers, heap->timer_capacity * sizeof(grpc_timer *)); |
| } |
| timer->heap_index = heap->timer_count; |
| adjust_upwards(heap->timers, heap->timer_count, timer); |
| heap->timer_count++; |
| return timer->heap_index == 0; |
| } |
| |
| void grpc_timer_heap_remove(grpc_timer_heap *heap, grpc_timer *timer) { |
| uint32_t i = timer->heap_index; |
| if (i == heap->timer_count - 1) { |
| heap->timer_count--; |
| maybe_shrink(heap); |
| return; |
| } |
| heap->timers[i] = heap->timers[heap->timer_count - 1]; |
| heap->timers[i]->heap_index = i; |
| heap->timer_count--; |
| maybe_shrink(heap); |
| note_changed_priority(heap, heap->timers[i]); |
| } |
| |
| int grpc_timer_heap_is_empty(grpc_timer_heap *heap) { |
| return heap->timer_count == 0; |
| } |
| |
| grpc_timer *grpc_timer_heap_top(grpc_timer_heap *heap) { |
| return heap->timers[0]; |
| } |
| |
| void grpc_timer_heap_pop(grpc_timer_heap *heap) { |
| grpc_timer_heap_remove(heap, grpc_timer_heap_top(heap)); |
| } |
| |
| #endif /* GRPC_TIMER_USE_GENERIC */ |