source: libcfa/src/bits/locks.hfa @ aec68b6

arm-ehjacob/cs343-translationnew-ast-unique-expr
Last change on this file since aec68b6 was a3821fa, checked in by Thierry Delisle <tdelisle@…>, 7 months ago

Changed enable interrupts:

  • no longer save the caller for debugging
  • now polls based on parameter passed in
  • Property mode set to 100644
File size: 2.6 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// bits/locks.hfa -- Basic spinlocks that are reused in the system.
8// Used for locks that aren't specific to cforall threads and can be used anywhere
9//
10//  *** Must not contain code specific to libcfathread ***
11//
12// Author           : Thierry Delisle
13// Created On       : Tue Oct 31 15:14:38 2017
14// Last Modified By : Peter A. Buhr
15// Last Modified On : Wed Aug 12 14:18:07 2020
16// Update Count     : 13
17//
18
19#pragma once
20
21#include "bits/debug.hfa"
22#include "bits/defs.hfa"
23#include <assert.h>
24
25struct __spinlock_t {
26        // Wrap in struct to prevent false sharing with debug info
27        volatile bool lock;
28        #ifdef __CFA_DEBUG__
29                // previous function to acquire the lock
30                const char * prev_name;
31                // previous thread to acquire the lock
32                void* prev_thrd;
33        #endif
34};
35
36#ifdef __cforall
37        extern "C" {
38                extern void disable_interrupts() OPTIONAL_THREAD;
39                extern void enable_interrupts( bool poll = true ) OPTIONAL_THREAD;
40
41                #ifdef __CFA_DEBUG__
42                        void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]);
43                #else
44                        #define __cfaabi_dbg_record_lock(x, y)
45                #endif
46        }
47
48        static inline void ?{}( __spinlock_t & this ) {
49                this.lock = 0;
50        }
51
52        // Lock the spinlock, return false if already acquired
53        static inline bool try_lock  ( __spinlock_t & this __cfaabi_dbg_ctx_param2 ) {
54                disable_interrupts();
55                bool result = (this.lock == 0) && (__atomic_test_and_set( &this.lock, __ATOMIC_ACQUIRE ) == 0);
56                if( result ) {
57                        __cfaabi_dbg_record_lock( this, caller );
58                } else {
59                        enable_interrupts( false );
60                }
61                return result;
62        }
63
64        // Lock the spinlock, spin if already acquired
65        static inline void lock( __spinlock_t & this __cfaabi_dbg_ctx_param2 ) {
66                #ifndef NOEXPBACK
67                        enum { SPIN_START = 4, SPIN_END = 64 * 1024, };
68                        unsigned int spin = SPIN_START;
69                #endif
70
71                disable_interrupts();
72                for ( unsigned int i = 1;; i += 1 ) {
73                        if ( (this.lock == 0) && (__atomic_test_and_set( &this.lock, __ATOMIC_ACQUIRE ) == 0) ) break;
74                        #ifndef NOEXPBACK
75                                // exponential spin
76                                for ( volatile unsigned int s = 0; s < spin; s += 1 ) Pause();
77
78                                // slowly increase by powers of 2
79                                if ( i % 64 == 0 ) spin += spin;
80
81                                // prevent overflow
82                                if ( spin > SPIN_END ) spin = SPIN_START;
83                        #else
84                                Pause();
85                        #endif
86                }
87                __cfaabi_dbg_record_lock( this, caller );
88        }
89
90        static inline void unlock( __spinlock_t & this ) {
91                __atomic_clear( &this.lock, __ATOMIC_RELEASE );
92                enable_interrupts( false );
93        }
94#endif
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