OMCompiler/Compiler/Util/MutableWeak.mo
| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * This file is part of OpenModelica. | ||
| 3 | * | ||
| 4 | * Copyright (c) 1998-2026, Open Source Modelica Consortium (OSMC), | ||
| 5 | * c/o Linköpings universitet, Department of Computer and Information Science, | ||
| 6 | * SE-58183 Linköping, Sweden. | ||
| 7 | * | ||
| 8 | * All rights reserved. | ||
| 9 | * | ||
| 10 | * THIS PROGRAM IS PROVIDED UNDER THE TERMS OF AGPL VERSION 3 LICENSE OR | ||
| 11 | * THIS OSMC PUBLIC LICENSE (OSMC-PL) VERSION 1.8. | ||
| 12 | * ANY USE, REPRODUCTION OR DISTRIBUTION OF THIS PROGRAM CONSTITUTES | ||
| 13 | * RECIPIENT'S ACCEPTANCE OF THE OSMC PUBLIC LICENSE OR THE GNU AGPL | ||
| 14 | * VERSION 3, ACCORDING TO RECIPIENTS CHOICE. | ||
| 15 | * | ||
| 16 | * The OpenModelica software and the OSMC (Open Source Modelica Consortium) | ||
| 17 | * Public License (OSMC-PL) are obtained from OSMC, either from the above | ||
| 18 | * address, from the URLs: | ||
| 19 | * http://www.openmodelica.org or | ||
| 20 | * https://github.com/OpenModelica/ or | ||
| 21 | * http://www.ida.liu.se/projects/OpenModelica, | ||
| 22 | * and in the OpenModelica distribution. | ||
| 23 | * | ||
| 24 | * GNU AGPL version 3 is obtained from: | ||
| 25 | * https://www.gnu.org/licenses/licenses.html#GPL | ||
| 26 | * | ||
| 27 | * This program is distributed WITHOUT ANY WARRANTY; without | ||
| 28 | * even the implied warranty of MERCHANTABILITY or FITNESS | ||
| 29 | * FOR A PARTICULAR PURPOSE, EXCEPT AS EXPRESSLY SET FORTH | ||
| 30 | * IN THE BY RECIPIENT SELECTED SUBSIDIARY LICENSE CONDITIONS OF OSMC-PL. | ||
| 31 | * | ||
| 32 | * See the full OSMC Public License conditions for more details. | ||
| 33 | * | ||
| 34 | */ | ||
| 35 | |||
| 36 | encapsulated uniontype MutableWeak<T> | ||
| 37 | "A non-owning reference to a Mutable cell. | ||
| 38 | |||
| 39 | Breaks an ownership cycle so plain reference counting can reclaim it: a | ||
| 40 | child holds its parent weakly, the parent owns its children, and the whole | ||
| 41 | structure hangs off one strong root. Nothing here is reclaimed by a | ||
| 42 | collector — the point is that no collector is needed. | ||
| 43 | |||
| 44 | In the bootstrapped C compiler a weak reference *is* the strong one (Boehm | ||
| 45 | reclaims cycles by tracing, so there is nothing to break) and `upgrade` can | ||
| 46 | never fail. The Rust port gives it real weak semantics, and `upgrade` fails | ||
| 47 | if the referent is already gone. Only code that can hold a weak reference | ||
| 48 | past its owner's lifetime can observe the difference." | ||
| 49 | |||
| 50 | import Mutable; | ||
| 51 | |||
| 52 | 15439893 | impure function downgrade | |
| 53 | "A reference that does not keep the cell alive. Never fails." | ||
| 54 | input Mutable<T> mutable; | ||
| 55 | output MutableWeak<T> weak; | ||
| 56 | external "C" weak=mutableWeakDowngrade(mutable) annotation(Include=" | ||
| 57 | static inline void* mutableWeakDowngrade(void *mutable) | ||
| 58 | { | ||
| 59 | return mutable; | ||
| 60 | } | ||
| 61 | "); | ||
| 62 | end downgrade; | ||
| 63 | |||
| 64 | 18578340 | impure function upgrade | |
| 65 | "An owning cell again. Fails if the referent is already gone — which means | ||
| 66 | a weak reference outlived the structure that owned it, so the ownership | ||
| 67 | split is wrong somewhere. Dereferencing a cell never fails; only this | ||
| 68 | conversion does." | ||
| 69 | input MutableWeak<T> weak; | ||
| 70 | output Mutable<T> mutable; | ||
| 71 | external "C" mutable=mutableWeakUpgrade(weak) annotation(Include=" | ||
| 72 | static inline void* mutableWeakUpgrade(void *weak) | ||
| 73 | { | ||
| 74 | return weak; | ||
| 75 | } | ||
| 76 | "); | ||
| 77 | end upgrade; | ||
| 78 | |||
| 79 | 3138447 | impure function upgradeOwning | |
| 80 | "As `upgrade`, for a read that takes ownership of the cell (`InstNode. | ||
| 81 | fromCell`, which then rebuilds the record to set its owner) rather than | ||
| 82 | merely looking at it (`InstNode.borrow`). Identical at run time; split out | ||
| 83 | so `OPENMODELICA_CELL_STATS` can tell the two apart, since only the owning | ||
| 84 | one pays for a record copy." | ||
| 85 | input MutableWeak<T> weak; | ||
| 86 | output Mutable<T> mutable; | ||
| 87 | external "C" mutable=mutableWeakUpgrade(weak) annotation(Include=" | ||
| 88 | static inline void* mutableWeakUpgrade(void *weak) | ||
| 89 | { | ||
| 90 | return weak; | ||
| 91 | } | ||
| 92 | "); | ||
| 93 | end upgradeOwning; | ||
| 94 | |||
| 95 | ✗ | impure function ofValue | |
| 96 | "A handle that *is* the value. In the C compiler no cell is needed at all -- | ||
| 97 | a weak reference there is the strong one -- so the node is stored directly | ||
| 98 | and `value` reads it straight back, which is what the frontend did before | ||
| 99 | any of this. Never reached where `GCExt.cellsNeedOwners` is true." | ||
| 100 | input T val; | ||
| 101 | output MutableWeak<T> weak; | ||
| 102 | external "C" weak=mutableWeakOfValue(val) annotation(Include=" | ||
| 103 | static inline void* mutableWeakOfValue(void *val) | ||
| 104 | { | ||
| 105 | return val; | ||
| 106 | } | ||
| 107 | "); | ||
| 108 | end ofValue; | ||
| 109 | |||
| 110 | ✗ | impure function value | |
| 111 | "The value a handle made by `ofValue` holds." | ||
| 112 | input MutableWeak<T> weak; | ||
| 113 | output T val; | ||
| 114 | external "C" val=mutableWeakValue(weak) annotation(Include=" | ||
| 115 | static inline void* mutableWeakValue(void *weak) | ||
| 116 | { | ||
| 117 | return weak; | ||
| 118 | } | ||
| 119 | "); | ||
| 120 | end value; | ||
| 121 | |||
| 122 | uniontype Roots | ||
| 123 | "The cells one structure keeps alive. Whatever owns that structure holds this | ||
| 124 | too, so the cells outlive every weak reference into it and die with it. | ||
| 125 | Empty in the C compiler, where a weak reference is the strong one." | ||
| 126 | record ROOTS end ROOTS; | ||
| 127 | end Roots; | ||
| 128 | |||
| 129 | function newRoots | ||
| 130 | "A fresh set, and the one `root` adds to from here on. The caller stores it | ||
| 131 | in whatever owns the cells about to be made." | ||
| 132 | output Roots roots = ROOTS(); | ||
| 133 | end newRoots; | ||
| 134 | |||
| 135 | function useRoots | ||
| 136 | "Adds to `roots` again, for re-entering a structure built by an earlier run. | ||
| 137 | Inlined to nothing in the C compiler." | ||
| 138 | input Roots roots; | ||
| 139 | algorithm | ||
| 140 | annotation(__OpenModelica_EarlyInline = true); | ||
| 141 | end useRoots; | ||
| 142 | |||
| 143 | function root | ||
| 144 | "Adds a cell to the current set. Inlined to nothing in the C compiler, so the | ||
| 145 | call does not survive code generation." | ||
| 146 | input Mutable<T> mutable; | ||
| 147 | algorithm | ||
| 148 | annotation(__OpenModelica_EarlyInline = true); | ||
| 149 | end root; | ||
| 150 | |||
| 151 | function clearRoots | ||
| 152 | "Empties the current set. Its cells die with it, and a reference into them | ||
| 153 | outlives the tree by design, so only a caller that knows it is done with | ||
| 154 | them may do this. Inlined to nothing in the C compiler." | ||
| 155 | algorithm | ||
| 156 | annotation(__OpenModelica_EarlyInline = true); | ||
| 157 | end clearRoots; | ||
| 158 | |||
| 159 | annotation(__OpenModelica_Interface="util_datatypes_basic"); | ||
| 160 | end MutableWeak; | ||
| 161 |