| 1 | //
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2021 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 | // locks.hfa -- PUBLIC
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| 8 | // Runtime locks that used with the runtime thread system.
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| 9 | //
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| 10 | // Author : Colby Alexander Parsons
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| 11 | // Created On : Thu Jan 21 19:46:50 2021
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| 12 | // Last Modified By :
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| 13 | // Last Modified On :
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| 14 | // Update Count :
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| 15 | //
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| 16 |
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| 17 | #pragma once
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| 18 |
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| 19 | #include <stdbool.h>
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| 20 |
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| 21 | #include "bits/weakso_locks.hfa"
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| 22 | #include "containers/queueLockFree.hfa"
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| 23 | #include "limits.hfa"
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| 24 | #include "thread.hfa"
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| 25 |
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| 26 | #include "time_t.hfa"
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| 27 | #include "time.hfa"
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| 28 |
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| 29 | //-----------------------------------------------------------------------------
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| 30 | // Semaphores
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| 31 |
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| 32 | // '0-nary' semaphore
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| 33 | // Similar to a counting semaphore except the value of one is never reached
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| 34 | // as a consequence, a V() that would bring the value to 1 *spins* until
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| 35 | // a P consumes it
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| 36 | struct Semaphore0nary {
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| 37 | __spinlock_t lock; // needed to protect
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| 38 | mpsc_queue($thread) queue;
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| 39 | };
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| 40 |
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| 41 | static inline bool P(Semaphore0nary & this, $thread * thrd) {
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| 42 | /* paranoid */ verify(!(thrd->seqable.next));
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| 43 | /* paranoid */ verify(!(thrd`next));
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| 44 |
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| 45 | push(this.queue, thrd);
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| 46 | return true;
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| 47 | }
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| 48 |
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| 49 | static inline bool P(Semaphore0nary & this) {
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| 50 | $thread * thrd = active_thread();
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| 51 | P(this, thrd);
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| 52 | park();
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| 53 | return true;
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| 54 | }
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| 55 |
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| 56 | static inline $thread * V(Semaphore0nary & this, bool doUnpark = true) {
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| 57 | $thread * next;
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| 58 | lock(this.lock __cfaabi_dbg_ctx2);
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| 59 | for (;;) {
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| 60 | next = pop(this.queue);
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| 61 | if (next) break;
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| 62 | Pause();
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| 63 | }
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| 64 | unlock(this.lock);
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| 65 |
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| 66 | if (doUnpark) unpark(next);
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| 67 | return next;
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| 68 | }
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| 69 |
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| 70 | // Wrapper used on top of any sempahore to avoid potential locking
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| 71 | struct BinaryBenaphore {
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| 72 | volatile ssize_t counter;
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| 73 | };
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| 74 |
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| 75 | static inline {
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| 76 | void ?{}(BinaryBenaphore & this) { this.counter = 0; }
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| 77 | void ?{}(BinaryBenaphore & this, zero_t) { this.counter = 0; }
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| 78 | void ?{}(BinaryBenaphore & this, one_t ) { this.counter = 1; }
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| 79 |
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| 80 | // returns true if no blocking needed
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| 81 | bool P(BinaryBenaphore & this) {
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| 82 | return __atomic_fetch_sub(&this.counter, 1, __ATOMIC_SEQ_CST) > 0;
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| 83 | }
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| 84 |
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| 85 | bool tryP(BinaryBenaphore & this) {
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| 86 | ssize_t c = this.counter;
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| 87 | /* paranoid */ verify( c > MIN );
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| 88 | return (c >= 1) && __atomic_compare_exchange_n(&this.counter, &c, c-1, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED);
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| 89 | }
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| 90 |
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| 91 | // returns true if notify needed
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| 92 | bool V(BinaryBenaphore & this) {
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| 93 | ssize_t c = 0;
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| 94 | for () {
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| 95 | /* paranoid */ verify( this.counter < MAX );
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| 96 | if (__atomic_compare_exchange_n(&this.counter, &c, c+1, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
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| 97 | if (c == 0) return true;
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| 98 | /* paranoid */ verify(c < 0);
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| 99 | return false;
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| 100 | } else {
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| 101 | if (c == 1) return true;
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| 102 | /* paranoid */ verify(c < 1);
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| 103 | Pause();
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| 104 | }
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| 105 | }
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| 106 | }
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| 107 | }
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| 108 |
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| 109 | // Binary Semaphore based on the BinaryBenaphore on top of the 0-nary Semaphore
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| 110 | struct ThreadBenaphore {
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| 111 | BinaryBenaphore ben;
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| 112 | Semaphore0nary sem;
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| 113 | };
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| 114 |
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| 115 | static inline void ?{}(ThreadBenaphore & this) {}
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| 116 | static inline void ?{}(ThreadBenaphore & this, zero_t) { (this.ben){ 0 }; }
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| 117 | static inline void ?{}(ThreadBenaphore & this, one_t ) { (this.ben){ 1 }; }
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| 118 |
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| 119 | static inline bool P(ThreadBenaphore & this) { return P(this.ben) ? false : P(this.sem); }
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| 120 | static inline bool tryP(ThreadBenaphore & this) { return tryP(this.ben); }
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| 121 | static inline bool P(ThreadBenaphore & this, bool wait) { return wait ? P(this) : tryP(this); }
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| 122 |
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| 123 | static inline $thread * V(ThreadBenaphore & this, bool doUnpark = true) {
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| 124 | if (V(this.ben)) return 0p;
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| 125 | return V(this.sem, doUnpark);
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| 126 | }
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| 127 |
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| 128 | //-----------------------------------------------------------------------------
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| 129 | // Semaphore
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| 130 | struct semaphore {
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| 131 | __spinlock_t lock;
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| 132 | int count;
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| 133 | __queue_t($thread) waiting;
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| 134 | };
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| 135 |
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| 136 | void ?{}(semaphore & this, int count = 1);
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| 137 | void ^?{}(semaphore & this);
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| 138 | bool P (semaphore & this);
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| 139 | bool V (semaphore & this);
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| 140 | bool V (semaphore & this, unsigned count);
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| 141 | $thread * V (semaphore & this, bool );
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| 142 |
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| 143 | //----------
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| 144 | struct single_acquisition_lock {
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| 145 | inline blocking_lock;
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| 146 | };
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| 147 |
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| 148 | static inline void ?{}( single_acquisition_lock & this ) {((blocking_lock &)this){ false, false };}
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| 149 | static inline void ^?{}( single_acquisition_lock & this ) {}
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| 150 | static inline void lock ( single_acquisition_lock & this ) { lock ( (blocking_lock &)this ); }
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| 151 | static inline bool try_lock ( single_acquisition_lock & this ) { return try_lock( (blocking_lock &)this ); }
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| 152 | static inline void unlock ( single_acquisition_lock & this ) { unlock ( (blocking_lock &)this ); }
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| 153 | static inline size_t on_wait ( single_acquisition_lock & this ) { return on_wait ( (blocking_lock &)this ); }
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| 154 | static inline void on_wakeup( single_acquisition_lock & this, size_t v ) { on_wakeup ( (blocking_lock &)this, v ); }
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| 155 | static inline void on_notify( single_acquisition_lock & this, struct $thread * t ) { on_notify( (blocking_lock &)this, t ); }
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| 156 |
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| 157 | //----------
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| 158 | struct owner_lock {
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| 159 | inline blocking_lock;
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| 160 | };
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| 161 |
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| 162 | static inline void ?{}( owner_lock & this ) {((blocking_lock &)this){ true, true };}
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| 163 | static inline void ^?{}( owner_lock & this ) {}
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| 164 | static inline void lock ( owner_lock & this ) { lock ( (blocking_lock &)this ); }
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| 165 | static inline bool try_lock ( owner_lock & this ) { return try_lock( (blocking_lock &)this ); }
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| 166 | static inline void unlock ( owner_lock & this ) { unlock ( (blocking_lock &)this ); }
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| 167 | static inline size_t on_wait ( owner_lock & this ) { return on_wait ( (blocking_lock &)this ); }
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| 168 | static inline void on_wakeup( owner_lock & this, size_t v ) { on_wakeup ( (blocking_lock &)this, v ); }
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| 169 | static inline void on_notify( owner_lock & this, struct $thread * t ) { on_notify( (blocking_lock &)this, t ); }
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| 170 |
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| 171 | struct fast_lock {
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| 172 | $thread * volatile owner;
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| 173 | ThreadBenaphore sem;
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| 174 | };
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| 175 |
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| 176 | static inline bool $try_lock(fast_lock & this, $thread * thrd) {
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| 177 | $thread * exp = 0p;
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| 178 | return __atomic_compare_exchange_n(&this.owner, &exp, thrd, false, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED);
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| 179 | }
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| 180 |
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| 181 | static inline void lock( fast_lock & this ) __attribute__((artificial));
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| 182 | static inline void lock( fast_lock & this ) {
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| 183 | $thread * thrd = active_thread();
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| 184 | /* paranoid */verify(thrd != this.owner);
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| 185 |
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| 186 | for (;;) {
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| 187 | if ($try_lock(this, thrd)) return;
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| 188 | P(this.sem);
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| 189 | }
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| 190 | }
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| 191 |
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| 192 | static inline bool try_lock( fast_lock & this ) __attribute__((artificial));
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| 193 | static inline bool try_lock ( fast_lock & this ) {
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| 194 | $thread * thrd = active_thread();
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| 195 | /* paranoid */ verify(thrd != this.owner);
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| 196 | return $try_lock(this, thrd);
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| 197 | }
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| 198 |
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| 199 | static inline $thread * unlock( fast_lock & this ) __attribute__((artificial));
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| 200 | static inline $thread * unlock( fast_lock & this ) {
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| 201 | /* paranoid */ verify(active_thread() == this.owner);
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| 202 |
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| 203 | // open 'owner' before unlocking anyone
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| 204 | // so new and unlocked threads don't park incorrectly.
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| 205 | // This may require additional fencing on ARM.
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| 206 | this.owner = 0p;
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| 207 |
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| 208 | return V(this.sem);
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| 209 | }
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| 210 |
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| 211 | static inline size_t on_wait( fast_lock & this ) { unlock(this); return 0; }
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| 212 | static inline void on_wakeup( fast_lock & this, size_t ) { lock(this); }
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| 213 | static inline void on_notify( fast_lock &, struct $thread * t ) { unpark(t); }
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| 214 |
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| 215 | struct mcs_node {
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| 216 | mcs_node * volatile next;
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| 217 | single_sem sem;
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| 218 | };
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| 219 |
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| 220 | static inline void ?{}(mcs_node & this) { this.next = 0p; }
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| 221 |
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| 222 | static inline mcs_node * volatile & ?`next ( mcs_node * node ) {
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| 223 | return node->next;
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| 224 | }
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| 225 |
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| 226 | struct mcs_lock {
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| 227 | mcs_queue(mcs_node) queue;
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| 228 | };
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| 229 |
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| 230 | static inline void lock(mcs_lock & l, mcs_node & n) {
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| 231 | if(push(l.queue, &n))
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| 232 | wait(n.sem);
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| 233 | }
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| 234 |
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| 235 | static inline void unlock(mcs_lock & l, mcs_node & n) {
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| 236 | mcs_node * next = advance(l.queue, &n);
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| 237 | if(next) post(next->sem);
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| 238 | }
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| 239 |
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| 240 | //-----------------------------------------------------------------------------
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| 241 | // is_blocking_lock
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| 242 | trait is_blocking_lock(L & | sized(L)) {
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| 243 | // For synchronization locks to use when acquiring
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| 244 | void on_notify( L &, struct $thread * );
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| 245 |
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| 246 | // For synchronization locks to use when releasing
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| 247 | size_t on_wait( L & );
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| 248 |
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| 249 | // to set recursion count after getting signalled;
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| 250 | void on_wakeup( L &, size_t recursion );
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| 251 | };
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| 252 |
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| 253 | //-----------------------------------------------------------------------------
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| 254 | // info_thread
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| 255 | // the info thread is a wrapper around a thread used
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| 256 | // to store extra data for use in the condition variable
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| 257 | forall(L & | is_blocking_lock(L)) {
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| 258 | struct info_thread;
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| 259 |
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| 260 | // for use by sequence
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| 261 | info_thread(L) *& Back( info_thread(L) * this );
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| 262 | info_thread(L) *& Next( info_thread(L) * this );
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| 263 | }
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| 264 |
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| 265 | //-----------------------------------------------------------------------------
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| 266 | // Synchronization Locks
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| 267 | forall(L & | is_blocking_lock(L)) {
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| 268 | struct condition_variable {
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| 269 | // Spin lock used for mutual exclusion
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| 270 | __spinlock_t lock;
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| 271 |
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| 272 | // List of blocked threads
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| 273 | Sequence( info_thread(L) ) blocked_threads;
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| 274 |
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| 275 | // Count of current blocked threads
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| 276 | int count;
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| 277 | };
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| 278 |
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| 279 | void ?{}( condition_variable(L) & this );
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| 280 | void ^?{}( condition_variable(L) & this );
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| 281 |
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| 282 | bool notify_one( condition_variable(L) & this );
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| 283 | bool notify_all( condition_variable(L) & this );
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| 284 |
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| 285 | uintptr_t front( condition_variable(L) & this );
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| 286 |
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| 287 | bool empty ( condition_variable(L) & this );
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| 288 | int counter( condition_variable(L) & this );
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| 289 |
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| 290 | void wait( condition_variable(L) & this );
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| 291 | void wait( condition_variable(L) & this, uintptr_t info );
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| 292 | bool wait( condition_variable(L) & this, Duration duration );
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| 293 | bool wait( condition_variable(L) & this, uintptr_t info, Duration duration );
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| 294 |
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| 295 | void wait( condition_variable(L) & this, L & l );
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| 296 | void wait( condition_variable(L) & this, L & l, uintptr_t info );
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| 297 | bool wait( condition_variable(L) & this, L & l, Duration duration );
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| 298 | bool wait( condition_variable(L) & this, L & l, uintptr_t info, Duration duration );
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| 299 | }
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