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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
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4 -- --
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5 -- S Y S T E M . T A S K I N G . R E S T R I C T E D . S T A G E S --
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6 -- --
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7 -- S p e c --
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8 -- --
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131
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9 -- Copyright (C) 1992-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNARL is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNARL was developed by the GNARL team at Florida State University. --
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28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- This is a simplified version of the System.Tasking.Stages package,
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33 -- intended to be used in a restricted run time.
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34
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35 -- This package represents the high level tasking interface used by the
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36 -- compiler to expand Ada 95 tasking constructs into simpler run time calls
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37 -- (aka GNARLI, GNU Ada Run-time Library Interface)
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38
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39 -- Note: the compiler generates direct calls to this interface, via Rtsfind.
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40 -- Any changes to this interface may require corresponding compiler changes
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41 -- in exp_ch9.adb and possibly exp_ch7.adb
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42
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43 -- The restricted GNARLI is also composed of System.Protected_Objects and
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44 -- System.Protected_Objects.Single_Entry
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45
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46 with System.Parameters;
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47 with System.Secondary_Stack;
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48 with System.Task_Info;
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49
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50 package System.Tasking.Restricted.Stages is
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51 pragma Elaborate_Body;
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52
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53 ---------------------------------
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54 -- Compiler Interface (GNARLI) --
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55 ---------------------------------
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56
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57 -- The compiler will expand in the GNAT tree the following construct:
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58
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59 -- task type T (Discr : Integer);
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60
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61 -- task body T is
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62 -- ...declarations, possibly some controlled...
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63 -- begin
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64 -- ...B...;
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65 -- end T;
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66
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67 -- T1 : T (1);
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68
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69 -- as follows:
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70
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71 -- task type t (discr : integer);
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72 -- tE : aliased boolean := false;
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73 -- tZ : size_type := unspecified_size;
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74
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75 -- type tV (discr : integer) is limited record
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76 -- _task_id : task_id;
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77 -- _atcb : aliased system__tasking__ada_task_control_block (0);
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78 -- end record;
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79
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80 -- procedure tB (_task : access tV);
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81 -- freeze tV [
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82 -- procedure tVIP (_init : in out tV; _master : master_id;
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83 -- _chain : in out activation_chain; _task_name : in string;
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84 -- discr : integer) is
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85 -- begin
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86 -- _init.discr := discr;
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87 -- _init._task_id := null;
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88 -- system__tasking__ada_task_control_blockIP (_init._atcb, 0);
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89 -- _init._task_id := _init._atcb'unchecked_access;
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90 -- create_restricted_task (unspecified_priority, tZ,
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91 -- unspecified_task_info, unspecified_cpu,
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92 -- task_procedure_access!(tB'address), _init'address,
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93 -- tE'unchecked_access, _task_name, _init._task_id);
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94 -- return;
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95 -- end tVIP;
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96
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97 -- _chain : aliased activation_chain;
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98 -- activation_chainIP (_chain);
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99
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100 -- procedure tB (_task : access tV) is
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101 -- discr : integer renames _task.discr;
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102
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103 -- procedure _clean is
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104 -- begin
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105 -- complete_restricted_task;
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106 -- finalize_list (F14b);
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107 -- return;
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108 -- end _clean;
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109
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110 -- begin
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111 -- ...declarations...
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112 -- complete_restricted_activation;
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113 -- ...B...;
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114 -- return;
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115 -- at end
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116 -- _clean;
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117 -- end tB;
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118
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119 -- tE := true;
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120 -- t1 : t (1);
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121 -- t1S : constant String := "t1";
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122 -- tIP (t1, 3, _chain, t1S, 1);
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123
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124 Partition_Elaboration_Policy : Character := 'C';
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125 pragma Export (C, Partition_Elaboration_Policy,
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126 "__gnat_partition_elaboration_policy");
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127 -- Partition elaboration policy. Value can be either 'C' for concurrent,
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128 -- which is the default or 'S' for sequential. This value can be modified
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129 -- by the binder generated code, before calling elaboration code.
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130
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131 procedure Create_Restricted_Task
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132 (Priority : Integer;
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133 Stack_Address : System.Address;
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134 Stack_Size : System.Parameters.Size_Type;
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135 Sec_Stack_Address : System.Secondary_Stack.SS_Stack_Ptr;
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136 Sec_Stack_Size : System.Parameters.Size_Type;
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137 Task_Info : System.Task_Info.Task_Info_Type;
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138 CPU : Integer;
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139 State : Task_Procedure_Access;
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140 Discriminants : System.Address;
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141 Elaborated : Access_Boolean;
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142 Chain : in out Activation_Chain;
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143 Task_Image : String;
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144 Created_Task : Task_Id);
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145 -- Compiler interface only. Do not call from within the RTS.
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146 -- This must be called to create a new task, when the partition
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147 -- elaboration policy is not specified (or is concurrent).
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148 --
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149 -- Priority is the task's priority (assumed to be in the
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150 -- System.Any_Priority'Range).
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151 --
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152 -- Stack_Address is the start address of the stack associated to the task,
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153 -- in case it has been preallocated by the compiler; it is equal to
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154 -- Null_Address when the stack needs to be allocated by the underlying
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155 -- operating system.
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156 --
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157 -- Stack_Size is the stack size of the task to create.
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158 --
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159 -- Sec_Stack_Address is the pointer to the secondary stack created by the
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160 -- compiler. If null, the secondary stack is either allocated by the binder
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161 -- or the run-time.
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162 --
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163 -- Secondary_Stack_Size is the secondary stack size of the task to create.
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164 --
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165 -- Task_Info is the task info associated with the created task, or
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166 -- Unspecified_Task_Info if none.
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167 --
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168 -- CPU is the task affinity. We pass it as an Integer to avoid an explicit
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169 -- dependency from System.Multiprocessors when not needed. Static range
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170 -- checks are performed when analyzing the pragma, and dynamic ones are
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171 -- performed before setting the affinity at run time.
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172 --
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173 -- State is the compiler generated task's procedure body.
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174 --
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175 -- Discriminants is a pointer to a limited record whose discriminants are
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176 -- those of the task to create. This parameter should be passed as the
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177 -- single argument to State.
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178 --
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179 -- Elaborated is a pointer to a Boolean that must be set to true on exit
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180 -- if the task could be successfully elaborated.
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181 --
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182 -- Chain is a linked list of task that needs to be created. On exit,
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183 -- Created_Task.Activation_Link will be Chain.T_ID, and Chain.T_ID will be
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184 -- Created_Task (the created task will be linked at the front of Chain).
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185 --
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186 -- Task_Image is a string created by the compiler that the run time can
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187 -- store to ease the debugging and the Ada.Task_Identification facility.
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188 --
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189 -- Created_Task is the resulting task.
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190 --
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191 -- This procedure can raise Storage_Error if the task creation fails.
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192
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193 procedure Create_Restricted_Task_Sequential
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194 (Priority : Integer;
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195 Stack_Address : System.Address;
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196 Stack_Size : System.Parameters.Size_Type;
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197 Sec_Stack_Address : System.Secondary_Stack.SS_Stack_Ptr;
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198 Sec_Stack_Size : System.Parameters.Size_Type;
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199 Task_Info : System.Task_Info.Task_Info_Type;
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200 CPU : Integer;
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201 State : Task_Procedure_Access;
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202 Discriminants : System.Address;
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203 Elaborated : Access_Boolean;
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204 Task_Image : String;
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205 Created_Task : Task_Id);
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206 -- Compiler interface only. Do not call from within the RTS.
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207 -- This must be called to create a new task, when the sequential partition
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208 -- elaboration policy is used.
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209 --
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210 -- The parameters are the same as Create_Restricted_Task except there is
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211 -- no Chain parameter (for the activation chain), as there is only one
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212 -- global activation chain, which is declared in the body of this package.
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213
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214 procedure Activate_Restricted_Tasks
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215 (Chain_Access : Activation_Chain_Access);
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216 -- Compiler interface only. Do not call from within the RTS.
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217 -- This must be called by the creator of a chain of one or more new tasks,
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218 -- to activate them. The chain is a linked list that up to this point is
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219 -- only known to the task that created them, though the individual tasks
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220 -- are already in the All_Tasks_List.
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221 --
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222 -- The compiler builds the chain in LIFO order (as a stack). Another
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223 -- version of this procedure had code to reverse the chain, so as to
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224 -- activate the tasks in the order of declaration. This might be nice, but
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225 -- it is not needed if priority-based scheduling is supported, since all
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226 -- the activated tasks synchronize on the activators lock before they start
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227 -- activating and so they should start activating in priority order.
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228 --
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229 -- When the partition elaboration policy is sequential, this procedure
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230 -- does nothing, tasks will be activated at end of elaboration.
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231
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232 procedure Activate_All_Tasks_Sequential;
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233 pragma Export (C, Activate_All_Tasks_Sequential,
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234 "__gnat_activate_all_tasks");
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235 -- Binder interface only. Do not call from within the RTS. This must be
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236 -- called an the end of the elaboration to activate all tasks, in order
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237 -- to implement the sequential elaboration policy.
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238
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239 procedure Complete_Restricted_Activation;
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240 -- Compiler interface only. Do not call from within the RTS. This should be
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241 -- called from the task body at the end of the elaboration code for its
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242 -- declarative part. Decrement the count of tasks to be activated by the
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243 -- activator and wake it up so it can check to see if all tasks have been
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244 -- activated. Except for the environment task, which should never call this
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245 -- procedure, T.Activator should only be null iff T has completed
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246 -- activation.
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247
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248 procedure Complete_Restricted_Task;
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249 -- Compiler interface only. Do not call from within the RTS. This should be
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250 -- called from an implicit at-end handler associated with the task body,
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251 -- when it completes. From this point, the current task will become not
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252 -- callable. If the current task have not completed activation, this should
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253 -- be done now in order to wake up the activator (the environment task).
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254
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255 function Restricted_Terminated (T : Task_Id) return Boolean;
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256 -- Compiler interface only. Do not call from within the RTS. This is called
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257 -- by the compiler to implement the 'Terminated attribute.
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258 --
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259 -- source code:
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260 -- T1'Terminated
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261 --
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262 -- code expansion:
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263 -- restricted_terminated (t1._task_id)
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264
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265 procedure Finalize_Global_Tasks;
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266 -- This is needed to support the compiler interface. It will only be called
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267 -- by the Environment task in the binder generated file (by adafinal).
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268 -- Instead, it will cause the Environment to block forever, since none of
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269 -- the dependent tasks are expected to terminate
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270
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271 end System.Tasking.Restricted.Stages;
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