| 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 -- LIBCFATHREAD
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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 | #define __cforall_thread__
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| 18 | #define _GNU_SOURCE
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| 19 |
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| 20 | #include "locks.hfa"
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| 21 | #include "kernel/private.hfa"
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| 22 |
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| 23 | #include <kernel.hfa>
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| 24 | #include <stdlib.hfa>
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| 25 |
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| 26 | #pragma GCC visibility push(default)
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| 27 |
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| 28 | //-----------------------------------------------------------------------------
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| 29 | // info_thread
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| 30 | forall(L & | is_blocking_lock(L)) {
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| 31 | struct info_thread {
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| 32 | // used to put info_thread on a dl queue
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| 33 | inline dlink(info_thread(L));
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| 34 |
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| 35 | // waiting thread
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| 36 | struct thread$ * t;
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| 37 |
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| 38 | // shadow field
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| 39 | uintptr_t info;
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| 40 |
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| 41 | // lock that is passed to wait() (if one is passed)
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| 42 | L * lock;
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| 43 |
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| 44 | // true when signalled and false when timeout wakes thread
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| 45 | bool signalled;
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| 46 | };
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| 47 | P9_EMBEDDED( info_thread(L), dlink(info_thread(L)) )
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| 48 |
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| 49 | void ?{}( info_thread(L) & this, thread$ * t, uintptr_t info, L * l ) {
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| 50 | this.t = t;
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| 51 | this.info = info;
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| 52 | this.lock = l;
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| 53 | }
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| 54 |
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| 55 | void ^?{}( info_thread(L) & this ) {}
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| 56 | }
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| 57 |
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| 58 | //-----------------------------------------------------------------------------
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| 59 | // Blocking Locks
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| 60 | void ?{}( blocking_lock & this, bool multi_acquisition, bool strict_owner ) {
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| 61 | this.lock{};
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| 62 | this.blocked_threads{};
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| 63 | this.wait_count = 0;
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| 64 | this.multi_acquisition = multi_acquisition;
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| 65 | this.strict_owner = strict_owner;
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| 66 | this.owner = 0p;
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| 67 | this.recursion_count = 0;
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| 68 | }
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| 69 |
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| 70 | void ^?{}( blocking_lock & this ) {}
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| 71 |
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| 72 |
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| 73 | void lock( blocking_lock & this ) with( this ) {
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| 74 | lock( lock __cfaabi_dbg_ctx2 );
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| 75 | thread$ * thrd = active_thread();
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| 76 |
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| 77 | // single acquisition lock is held by current thread
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| 78 | /* paranoid */ verifyf( owner != thrd || multi_acquisition, "Single acquisition lock holder (%p) attempted to reacquire the lock %p resulting in a deadlock.", owner, &this );
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| 79 |
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| 80 | // lock is held by some other thread
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| 81 | if ( owner != 0p && owner != thrd ) {
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| 82 | insert_last( blocked_threads, *thrd );
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| 83 | wait_count++;
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| 84 | unlock( lock );
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| 85 | park( );
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| 86 | }
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| 87 | // multi acquisition lock is held by current thread
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| 88 | else if ( owner == thrd && multi_acquisition ) {
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| 89 | recursion_count++;
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| 90 | unlock( lock );
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| 91 | }
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| 92 | // lock isn't held
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| 93 | else {
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| 94 | owner = thrd;
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| 95 | recursion_count = 1;
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| 96 | unlock( lock );
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| 97 | }
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| 98 | }
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| 99 |
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| 100 | bool try_lock( blocking_lock & this ) with( this ) {
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| 101 | bool ret = false;
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| 102 | lock( lock __cfaabi_dbg_ctx2 );
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| 103 |
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| 104 | // lock isn't held
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| 105 | if ( owner == 0p ) {
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| 106 | owner = active_thread();
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| 107 | recursion_count = 1;
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| 108 | ret = true;
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| 109 | }
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| 110 | // multi acquisition lock is held by current thread
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| 111 | else if ( owner == active_thread() && multi_acquisition ) {
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| 112 | recursion_count++;
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| 113 | ret = true;
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| 114 | }
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| 115 |
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| 116 | unlock( lock );
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| 117 | return ret;
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| 118 | }
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| 119 |
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| 120 | static void pop_and_set_new_owner( blocking_lock & this ) with( this ) {
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| 121 | thread$ * t = &try_pop_front( blocked_threads );
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| 122 | owner = t;
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| 123 | recursion_count = ( t ? 1 : 0 );
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| 124 | if ( t ) wait_count--;
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| 125 | unpark( t );
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| 126 | }
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| 127 |
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| 128 | void unlock( blocking_lock & this ) with( this ) {
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| 129 | lock( lock __cfaabi_dbg_ctx2 );
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| 130 | /* paranoid */ verifyf( owner != 0p, "Attempt to release lock %p that isn't held", &this );
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| 131 | /* paranoid */ verifyf( owner == active_thread() || !strict_owner , "Thread %p other than the owner %p attempted to release owner lock %p", owner, active_thread(), &this );
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| 132 | /* paranoid */ verifyf( recursion_count == 1 || multi_acquisition, "Thread %p attempted to release owner lock %p which is not recursive but has a recursive count of %zu", active_thread(), &this, recursion_count );
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| 133 |
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| 134 | // if recursion count is zero release lock and set new owner if one is waiting
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| 135 | recursion_count--;
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| 136 | if ( recursion_count == 0 ) {
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| 137 | pop_and_set_new_owner( this );
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| 138 | }
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| 139 | unlock( lock );
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| 140 | }
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| 141 |
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| 142 | size_t wait_count( blocking_lock & this ) with( this ) {
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| 143 | return wait_count;
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| 144 | }
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| 145 |
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| 146 | void on_notify( blocking_lock & this, thread$ * t ) with( this ) {
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| 147 | lock( lock __cfaabi_dbg_ctx2 );
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| 148 | // lock held
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| 149 | if ( owner != 0p ) {
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| 150 | insert_last( blocked_threads, *t );
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| 151 | wait_count++;
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| 152 | unlock( lock );
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| 153 | }
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| 154 | // lock not held
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| 155 | else {
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| 156 | owner = t;
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| 157 | recursion_count = 1;
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| 158 | unpark( t );
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| 159 | unlock( lock );
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| 160 | }
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| 161 | }
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| 162 |
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| 163 | size_t on_wait( blocking_lock & this ) with( this ) {
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| 164 | lock( lock __cfaabi_dbg_ctx2 );
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| 165 | /* paranoid */ verifyf( owner != 0p, "Attempt to release lock %p that isn't held", &this );
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| 166 | /* paranoid */ verifyf( owner == active_thread() || !strict_owner, "Thread %p other than the owner %p attempted to release owner lock %p", owner, active_thread(), &this );
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| 167 |
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| 168 | size_t ret = recursion_count;
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| 169 |
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| 170 | pop_and_set_new_owner( this );
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| 171 | unlock( lock );
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| 172 | return ret;
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| 173 | }
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| 174 |
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| 175 | void on_wakeup( blocking_lock & this, size_t recursion ) with( this ) {
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| 176 | recursion_count = recursion;
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| 177 | }
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| 178 |
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| 179 | //-----------------------------------------------------------------------------
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| 180 | // alarm node wrapper
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| 181 | forall(L & | is_blocking_lock(L)) {
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| 182 | struct alarm_node_wrap {
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| 183 | alarm_node_t alarm_node;
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| 184 | condition_variable(L) * cond;
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| 185 | info_thread(L) * info_thd;
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| 186 | };
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| 187 |
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| 188 | void ?{}( alarm_node_wrap(L) & this, Duration alarm, Duration period, Alarm_Callback callback, condition_variable(L) * c, info_thread(L) * i ) {
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| 189 | this.alarm_node{ callback, alarm, period };
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| 190 | this.cond = c;
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| 191 | this.info_thd = i;
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| 192 | }
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| 193 |
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| 194 | void ^?{}( alarm_node_wrap(L) & this ) { }
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| 195 |
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| 196 | static void timeout_handler ( alarm_node_wrap(L) & this ) with( this ) {
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| 197 | // This condition_variable member is called from the kernel, and therefore, cannot block, but it can spin.
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| 198 | lock( cond->lock __cfaabi_dbg_ctx2 );
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| 199 |
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| 200 | // this check is necessary to avoid a race condition since this timeout handler
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| 201 | // may still be called after a thread has been removed from the queue but
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| 202 | // before the alarm is unregistered
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| 203 | if ( (*info_thd)`isListed ) { // is thread on queue
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| 204 | info_thd->signalled = false;
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| 205 | // remove this thread O(1)
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| 206 | remove( *info_thd );
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| 207 | cond->count--;
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| 208 | if( info_thd->lock ) {
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| 209 | // call lock's on_notify if a lock was passed
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| 210 | on_notify(*info_thd->lock, info_thd->t);
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| 211 | } else {
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| 212 | // otherwise wake thread
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| 213 | unpark( info_thd->t );
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| 214 | }
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| 215 | }
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| 216 | unlock( cond->lock );
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| 217 | }
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| 218 |
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| 219 | // this casts the alarm node to our wrapped type since we used type erasure
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| 220 | static void alarm_node_wrap_cast( alarm_node_t & a ) { timeout_handler( (alarm_node_wrap(L) &)a ); }
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| 221 | }
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| 222 |
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| 223 | //-----------------------------------------------------------------------------
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| 224 | // Synchronization Locks
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| 225 | forall(L & | is_blocking_lock(L)) {
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| 226 |
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| 227 | //-----------------------------------------------------------------------------
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| 228 | // condition variable
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| 229 | void ?{}( condition_variable(L) & this ){
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| 230 | this.lock{};
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| 231 | this.blocked_threads{};
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| 232 | this.count = 0;
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| 233 | }
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| 234 |
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| 235 | void ^?{}( condition_variable(L) & this ){ }
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| 236 |
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| 237 | static void process_popped( condition_variable(L) & this, info_thread(L) & popped ) with( this ) {
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| 238 | if(&popped != 0p) {
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| 239 | popped.signalled = true;
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| 240 | count--;
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| 241 | if (popped.lock) {
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| 242 | // if lock passed call on_notify
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| 243 | on_notify(*popped.lock, popped.t);
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| 244 | } else {
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| 245 | // otherwise wake thread
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| 246 | unpark(popped.t);
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| 247 | }
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| 248 | }
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| 249 | }
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| 250 |
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| 251 | bool notify_one( condition_variable(L) & this ) with( this ) {
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| 252 | lock( lock __cfaabi_dbg_ctx2 );
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| 253 | bool ret = ! blocked_threads`isEmpty;
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| 254 | process_popped(this, try_pop_front( blocked_threads ));
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| 255 | unlock( lock );
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| 256 | return ret;
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| 257 | }
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| 258 |
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| 259 | bool notify_all( condition_variable(L) & this ) with(this) {
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| 260 | lock( lock __cfaabi_dbg_ctx2 );
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| 261 | bool ret = ! blocked_threads`isEmpty;
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| 262 | while( ! blocked_threads`isEmpty ) {
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| 263 | process_popped(this, try_pop_front( blocked_threads ));
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| 264 | }
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| 265 | unlock( lock );
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| 266 | return ret;
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| 267 | }
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| 268 |
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| 269 | uintptr_t front( condition_variable(L) & this ) with(this) {
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| 270 | return blocked_threads`isEmpty ? NULL : blocked_threads`first.info;
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| 271 | }
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| 272 |
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| 273 | bool empty( condition_variable(L) & this ) with(this) {
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| 274 | lock( lock __cfaabi_dbg_ctx2 );
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| 275 | bool ret = blocked_threads`isEmpty;
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| 276 | unlock( lock );
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| 277 | return ret;
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| 278 | }
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| 279 |
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| 280 | int counter( condition_variable(L) & this ) with(this) { return count; }
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| 281 |
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| 282 | static size_t queue_and_get_recursion( condition_variable(L) & this, info_thread(L) * i ) with(this) {
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| 283 | // add info_thread to waiting queue
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| 284 | insert_last( blocked_threads, *i );
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| 285 | count++;
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| 286 | size_t recursion_count = 0;
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| 287 | if (i->lock) {
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| 288 | // if lock was passed get recursion count to reset to after waking thread
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| 289 | recursion_count = on_wait( *i->lock );
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| 290 | }
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| 291 | return recursion_count;
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| 292 | }
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| 293 |
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| 294 | // helper for wait()'s' with no timeout
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| 295 | static void queue_info_thread( condition_variable(L) & this, info_thread(L) & i ) with(this) {
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| 296 | lock( lock __cfaabi_dbg_ctx2 );
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| 297 | size_t recursion_count = queue_and_get_recursion(this, &i);
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| 298 | unlock( lock );
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| 299 |
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| 300 | // blocks here
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| 301 | park( );
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| 302 |
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| 303 | // resets recursion count here after waking
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| 304 | if (i.lock) on_wakeup(*i.lock, recursion_count);
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| 305 | }
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| 306 |
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| 307 | #define WAIT( u, l ) \
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| 308 | info_thread( L ) i = { active_thread(), u, l }; \
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| 309 | queue_info_thread( this, i );
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| 310 |
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| 311 | // helper for wait()'s' with a timeout
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| 312 | static void queue_info_thread_timeout( condition_variable(L) & this, info_thread(L) & info, Duration t, Alarm_Callback callback ) with(this) {
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| 313 | lock( lock __cfaabi_dbg_ctx2 );
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| 314 | size_t recursion_count = queue_and_get_recursion(this, &info);
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| 315 | alarm_node_wrap(L) node_wrap = { t, 0`s, callback, &this, &info };
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| 316 | register_self( &node_wrap.alarm_node );
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| 317 | unlock( lock );
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| 318 |
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| 319 | // blocks here
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| 320 | park();
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| 321 |
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| 322 | // unregisters alarm so it doesn't go off if this happens first
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| 323 | unregister_self( &node_wrap.alarm_node );
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| 324 |
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| 325 | // resets recursion count here after waking
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| 326 | if (info.lock) on_wakeup(*info.lock, recursion_count);
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| 327 | }
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| 328 |
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| 329 | #define WAIT_TIME( u, l, t ) \
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| 330 | info_thread( L ) i = { active_thread(), u, l }; \
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| 331 | queue_info_thread_timeout(this, i, t, alarm_node_wrap_cast ); \
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| 332 | return i.signalled;
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| 333 |
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| 334 | void wait( condition_variable(L) & this ) with(this) { WAIT( 0, 0p ) }
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| 335 | void wait( condition_variable(L) & this, uintptr_t info ) with(this) { WAIT( info, 0p ) }
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| 336 | void wait( condition_variable(L) & this, L & l ) with(this) { WAIT( 0, &l ) }
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| 337 | void wait( condition_variable(L) & this, L & l, uintptr_t info ) with(this) { WAIT( info, &l ) }
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| 338 |
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| 339 | bool wait( condition_variable(L) & this, Duration duration ) with(this) { WAIT_TIME( 0 , 0p , duration ) }
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| 340 | bool wait( condition_variable(L) & this, uintptr_t info, Duration duration ) with(this) { WAIT_TIME( info, 0p , duration ) }
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| 341 | bool wait( condition_variable(L) & this, L & l, Duration duration ) with(this) { WAIT_TIME( 0 , &l , duration ) }
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| 342 | bool wait( condition_variable(L) & this, L & l, uintptr_t info, Duration duration ) with(this) { WAIT_TIME( info, &l , duration ) }
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| 343 |
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| 344 | //-----------------------------------------------------------------------------
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| 345 | // fast_cond_var
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| 346 | void ?{}( fast_cond_var(L) & this ){
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| 347 | this.blocked_threads{};
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| 348 | #ifdef __CFA_DEBUG__
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| 349 | this.lock_used = 0p;
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| 350 | #endif
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| 351 | }
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| 352 | void ^?{}( fast_cond_var(L) & this ){ }
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| 353 |
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| 354 | bool notify_one( fast_cond_var(L) & this ) with(this) {
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| 355 | bool ret = ! blocked_threads`isEmpty;
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| 356 | if ( ret ) {
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| 357 | info_thread(L) & popped = try_pop_front( blocked_threads );
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| 358 | on_notify(*popped.lock, popped.t);
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| 359 | }
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| 360 | return ret;
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| 361 | }
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| 362 | bool notify_all( fast_cond_var(L) & this ) with(this) {
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| 363 | bool ret = ! blocked_threads`isEmpty;
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| 364 | while( ! blocked_threads`isEmpty ) {
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| 365 | info_thread(L) & popped = try_pop_front( blocked_threads );
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| 366 | on_notify(*popped.lock, popped.t);
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| 367 | }
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| 368 | return ret;
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| 369 | }
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| 370 |
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| 371 | uintptr_t front( fast_cond_var(L) & this ) with(this) { return blocked_threads`isEmpty ? NULL : blocked_threads`first.info; }
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| 372 | bool empty ( fast_cond_var(L) & this ) with(this) { return blocked_threads`isEmpty; }
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| 373 |
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| 374 | void wait( fast_cond_var(L) & this, L & l ) {
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| 375 | wait( this, l, 0 );
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| 376 | }
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| 377 |
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| 378 | void wait( fast_cond_var(L) & this, L & l, uintptr_t info ) with(this) {
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| 379 | // brand cond lock with lock
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| 380 | #ifdef __CFA_DEBUG__
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| 381 | if ( lock_used == 0p ) lock_used = &l;
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| 382 | else { assert(lock_used == &l); }
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| 383 | #endif
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| 384 | info_thread( L ) i = { active_thread(), info, &l };
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| 385 | insert_last( blocked_threads, i );
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| 386 | size_t recursion_count = on_wait( *i.lock );
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| 387 | park( );
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| 388 | on_wakeup(*i.lock, recursion_count);
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| 389 | }
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| 390 | }
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| 391 |
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| 392 | //-----------------------------------------------------------------------------
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| 393 | // Semaphore
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| 394 | void ?{}( semaphore & this, int count = 1 ) {
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| 395 | (this.lock){};
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| 396 | this.count = count;
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| 397 | (this.waiting){};
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| 398 | }
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| 399 | void ^?{}(semaphore & this) {}
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| 400 |
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| 401 | bool P(semaphore & this) with( this ){
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| 402 | lock( lock __cfaabi_dbg_ctx2 );
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| 403 | count -= 1;
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| 404 | if ( count < 0 ) {
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| 405 | // queue current task
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| 406 | append( waiting, active_thread() );
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| 407 |
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| 408 | // atomically release spin lock and block
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| 409 | unlock( lock );
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| 410 | park();
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| 411 | return true;
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| 412 | }
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| 413 | else {
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| 414 | unlock( lock );
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| 415 | return false;
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| 416 | }
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| 417 | }
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| 418 |
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| 419 | thread$ * V (semaphore & this, const bool doUnpark ) with( this ) {
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| 420 | thread$ * thrd = 0p;
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| 421 | lock( lock __cfaabi_dbg_ctx2 );
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| 422 | count += 1;
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| 423 | if ( count <= 0 ) {
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| 424 | // remove task at head of waiting list
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| 425 | thrd = pop_head( waiting );
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| 426 | }
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| 427 |
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| 428 | unlock( lock );
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| 429 |
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| 430 | // make new owner
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| 431 | if( doUnpark ) unpark( thrd );
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| 432 |
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| 433 | return thrd;
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| 434 | }
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| 435 |
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| 436 | bool V(semaphore & this) with( this ) {
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| 437 | thread$ * thrd = V(this, true);
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| 438 | return thrd != 0p;
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| 439 | }
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| 440 |
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| 441 | bool V(semaphore & this, unsigned diff) with( this ) {
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| 442 | thread$ * thrd = 0p;
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| 443 | lock( lock __cfaabi_dbg_ctx2 );
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| 444 | int release = max(-count, (int)diff);
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| 445 | count += diff;
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| 446 | for(release) {
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| 447 | unpark( pop_head( waiting ) );
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| 448 | }
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| 449 |
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| 450 | unlock( lock );
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| 451 |
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| 452 | return thrd != 0p;
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| 453 | }
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