Based on the time a given task should next be woken up, finds the correct time wheel for it and returns a list of other tasks occurring at that point.
| 162 | // correct time wheel for it and returns a list of other tasks |
| 163 | // occurring at that point. |
| 164 | task_list *timewheel::task2list(task *task) |
| 165 | { |
| 166 | unsigned int wake = task->wake(); |
| 167 | |
| 168 | if (wake == 0) { |
| 169 | return &forever_list; |
| 170 | } |
| 171 | |
| 172 | assert(wake >= wheel_base); |
| 173 | if (wheel_base > clock_tick) { |
| 174 | ERROR("wheel_base is %lu, clock_tick is %lu - expected wheel_base to be less than or equal to clock_tick", wheel_base, clock_tick); |
| 175 | assert(wheel_base <= clock_tick); |
| 176 | } |
| 177 | |
| 178 | unsigned int slot_in_first_wheel = wake % LEVEL_ONE_SLOTS; |
| 179 | unsigned int slot_in_second_wheel = (wake / LEVEL_ONE_SLOTS) % LEVEL_TWO_SLOTS; |
| 180 | unsigned int slot_in_third_wheel = (wake / (LEVEL_ONE_SLOTS * LEVEL_TWO_SLOTS)); |
| 181 | |
| 182 | bool fits_in_first_wheel = ((wake / LEVEL_ONE_SLOTS) == (wheel_base / LEVEL_ONE_SLOTS)); |
| 183 | bool fits_in_second_wheel = ((wake / (LEVEL_ONE_SLOTS * LEVEL_TWO_SLOTS)) == |
| 184 | (wheel_base / (LEVEL_ONE_SLOTS * LEVEL_TWO_SLOTS))); |
| 185 | bool fits_in_third_wheel = (slot_in_third_wheel < LEVEL_THREE_SLOTS); |
| 186 | |
| 187 | if (fits_in_first_wheel) { |
| 188 | return &wheel_one[slot_in_first_wheel]; |
| 189 | } else if (fits_in_second_wheel) { |
| 190 | return &wheel_two[slot_in_second_wheel]; |
| 191 | } else if (fits_in_third_wheel) { |
| 192 | return &wheel_three[slot_in_third_wheel]; |
| 193 | } else{ |
| 194 | ERROR("Attempted to schedule a task too far in the future"); |
| 195 | return nullptr; |
| 196 | } |
| 197 | } |
| 198 | |
| 199 | /* Iterate through our sorted set of paused tasks, removing those that |
| 200 | * should no longer be paused, and adding them to the run queue. */ |