ADTast-experimentalpthread-emulation
Last change
on this file since 9f99799 was
a18373a,
checked in by Thierry Delisle <tdelisle@…>, 2 years ago
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Added a hook for the barrier's last block.
Added testing to go with it.
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-
Property mode set to
100644
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File size:
1.6 KB
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[93b8cf4] | 1 | // |
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2022 University of Waterloo |
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| 3 | // |
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| 4 | // The contents of this file are covered under the licence agreement in the |
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| 5 | // file "LICENCE" distributed with Cforall. |
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| 6 | // |
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| 7 | // barrier.hfa -- simple barrier implemented from monitors |
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| 8 | // |
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| 9 | // Author : Thierry Delisle |
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| 10 | // Created On : Thu Mar 31 16:51:35 2022 |
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| 11 | // Last Modified By : |
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| 12 | // Last Modified On : |
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| 13 | // Update Count : |
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| 14 | // |
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| 15 | |
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| 16 | #pragma once |
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| 17 | |
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| 18 | #include <monitor.hfa> |
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| 19 | |
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[31ef267] | 20 | // Simple barrier based on a monitor |
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[93b8cf4] | 21 | monitor barrier { |
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[31ef267] | 22 | // Number of threads blocking needed to unblock the barrier |
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| 23 | // Unsigned should be enough, I don't expect use cases with 2^32 thread barriers. |
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| 24 | unsigned width; |
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[93b8cf4] | 25 | |
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[31ef267] | 26 | // Current count (counting backwards) |
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| 27 | unsigned count; |
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| 28 | |
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| 29 | // Barrier uses internal scheduling |
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[93b8cf4] | 30 | condition c; |
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| 31 | }; |
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| 32 | |
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[31ef267] | 33 | // Constructor |
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| 34 | void ?{}( barrier & this, unsigned width ) { |
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| 35 | this.width = width; |
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| 36 | this.count = width; // Count backwards so initialize at width |
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[93b8cf4] | 37 | } |
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| 38 | |
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[31ef267] | 39 | // block until the number of threads needed have blocked |
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| 40 | // returns an value indicating the reverse order the threads arrived in |
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| 41 | // i.e. last thread will return 0 (and not block) |
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| 42 | // second last thread returns 1 |
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| 43 | // etc. |
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[a18373a] | 44 | // last is an optional hook that will be called by the last thread |
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| 45 | // before unblocking the others |
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| 46 | static inline unsigned block(barrier & mutex this, fptr_t last = (fptr_t)0 ) { |
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[31ef267] | 47 | this.count -= 1; // prefix decrement so we the last is 0 and not 1 |
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| 48 | unsigned arrival = this.count; // Note arrival order |
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| 49 | if(arrival == 0) { |
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[a18373a] | 50 | if(last) last(); |
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[31ef267] | 51 | // If arrived last unblock everyone and reset |
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[93b8cf4] | 52 | signal_all(this.c); |
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[31ef267] | 53 | this.count = this.width; |
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| 54 | } else { |
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| 55 | // Otherwise block |
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| 56 | wait(this.c); |
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[93b8cf4] | 57 | } |
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[31ef267] | 58 | return arrival; // return arrival order |
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[93b8cf4] | 59 | } |
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