1 | // -*- Mode: CFA -*- |
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2 | // |
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3 | // Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo |
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4 | // |
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5 | // The contents of this file are covered under the licence agreement in the |
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6 | // file "LICENCE" distributed with Cforall. |
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7 | // |
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8 | // monitor_desc.c -- |
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9 | // |
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10 | // Author : Thierry Delisle |
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11 | // Created On : Thd Feb 23 12:27:26 2017 |
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12 | // Last Modified By : Thierry Delisle |
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13 | // Last Modified On : -- |
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14 | // Update Count : 0 |
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15 | // |
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16 | |
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17 | #include "monitor" |
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18 | |
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19 | #include "kernel_private.h" |
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20 | |
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21 | void enter(monitor_desc * this) { |
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22 | lock( &this->lock ); |
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23 | thread_desc * thrd = this_thread(); |
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24 | |
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25 | if( !this->owner ) { |
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26 | //No one has the monitor, just take it |
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27 | this->owner = thrd; |
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28 | this->recursion = 1; |
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29 | } |
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30 | else if( this->owner == thrd) { |
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31 | //We already have the monitor, just not how many times we took it |
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32 | assert( this->recursion > 0 ); |
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33 | this->recursion += 1; |
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34 | } |
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35 | else { |
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36 | //Some one else has the monitor, wait in line for it |
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37 | append( &this->entry_queue, thrd ); |
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38 | ScheduleInternal( &this->lock ); |
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39 | |
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40 | //ScheduleInternal will unlock spinlock, no need to unlock ourselves |
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41 | return; |
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42 | } |
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43 | |
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44 | unlock( &this->lock ); |
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45 | } |
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46 | |
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47 | void leave(monitor_desc * this) { |
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48 | lock( &this->lock ); |
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49 | |
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50 | thread_desc * thrd = this_thread(); |
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51 | assert( thrd == this->owner ); |
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52 | |
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53 | //Leaving a recursion level, decrement the counter |
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54 | this->recursion -= 1; |
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55 | |
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56 | //If we left the last level of recursion it means we are changing who owns the monitor |
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57 | thread_desc * new_owner = 0; |
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58 | if( this->recursion == 0) { |
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59 | //Get the next thread in the list |
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60 | new_owner = this->owner = pop_head( &this->entry_queue ); |
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61 | |
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62 | //We are passing the monitor to someone else, which means recursion level is not 0 |
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63 | this->recursion = new_owner ? 1 : 0; |
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64 | } |
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65 | |
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66 | unlock( &this->lock ); |
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67 | |
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68 | //If we have a new owner, we need to wake-up the thread |
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69 | if( new_owner ) { |
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70 | ScheduleThread( new_owner ); |
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71 | } |
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72 | } |
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73 | |
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74 | void enter(monitor_desc ** monitors, int count) { |
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75 | for(int i = 0; i < count; i++) { |
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76 | enter( monitors[i] ); |
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77 | } |
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78 | } |
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79 | |
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80 | void leave(monitor_desc ** monitors, int count) { |
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81 | for(int i = count - 1; i >= 0; i--) { |
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82 | leave( monitors[i] ); |
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83 | } |
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84 | } |
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