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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 -- SYSTEM.TASK_PRIMITIVES.OPERATIONS.MONOTONIC --
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6 -- --
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7 -- B o d y --
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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 the Monotonic version of this package for Posix and Linux targets.
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33
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34 separate (System.Task_Primitives.Operations)
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35 package body Monotonic is
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36
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37 -----------------------
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38 -- Local Subprograms --
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39 -----------------------
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40
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41 procedure Compute_Deadline
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42 (Time : Duration;
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43 Mode : ST.Delay_Modes;
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44 Check_Time : out Duration;
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131
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45 Abs_Time : out Duration);
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111
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46 -- Helper for Timed_Sleep and Timed_Delay: given a deadline specified by
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47 -- Time and Mode, compute the current clock reading (Check_Time), and the
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131
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48 -- target absolute and relative clock readings (Abs_Time). The
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49 -- epoch for Time depends on Mode; the epoch for Check_Time and Abs_Time
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50 -- is always that of CLOCK_RT_Ada.
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51
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52 ---------------------
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53 -- Monotonic_Clock --
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54 ---------------------
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55
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56 function Monotonic_Clock return Duration is
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57 TS : aliased timespec;
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58 Result : Interfaces.C.int;
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59 begin
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60 Result := clock_gettime
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61 (clock_id => OSC.CLOCK_RT_Ada, tp => TS'Unchecked_Access);
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62 pragma Assert (Result = 0);
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63
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64 return To_Duration (TS);
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65 end Monotonic_Clock;
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66
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67 -------------------
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68 -- RT_Resolution --
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69 -------------------
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70
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71 function RT_Resolution return Duration is
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72 TS : aliased timespec;
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73 Result : Interfaces.C.int;
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74
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75 begin
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76 Result := clock_getres (OSC.CLOCK_REALTIME, TS'Unchecked_Access);
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77 pragma Assert (Result = 0);
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78
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79 return To_Duration (TS);
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80 end RT_Resolution;
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81
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82 ----------------------
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83 -- Compute_Deadline --
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84 ----------------------
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85
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86 procedure Compute_Deadline
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87 (Time : Duration;
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88 Mode : ST.Delay_Modes;
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89 Check_Time : out Duration;
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90 Abs_Time : out Duration)
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91 is
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92 begin
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93 Check_Time := Monotonic_Clock;
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94
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95 -- Relative deadline
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96
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97 if Mode = Relative then
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98 Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
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99
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100 pragma Warnings (Off);
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101 -- Comparison "OSC.CLOCK_RT_Ada = OSC.CLOCK_REALTIME" is compile
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102 -- time known.
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103
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104 -- Absolute deadline specified using the tasking clock (CLOCK_RT_Ada)
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105
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106 elsif Mode = Absolute_RT
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107 or else OSC.CLOCK_RT_Ada = OSC.CLOCK_REALTIME
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108 then
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109 pragma Warnings (On);
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110 Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
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111
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112 -- Absolute deadline specified using the calendar clock, in the
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113 -- case where it is not the same as the tasking clock: compensate for
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114 -- difference between clock epochs (Base_Time - Base_Cal_Time).
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115
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116 else
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117 declare
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118 Cal_Check_Time : constant Duration := OS_Primitives.Clock;
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119 RT_Time : constant Duration :=
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120 Time + Check_Time - Cal_Check_Time;
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121
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122 begin
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123 Abs_Time :=
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124 Duration'Min (Check_Time + Max_Sensible_Delay, RT_Time);
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125
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126 end;
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127 end if;
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128 end Compute_Deadline;
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129
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130 -----------------
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131 -- Timed_Sleep --
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132 -----------------
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133
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134 -- This is for use within the run-time system, so abort is
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135 -- assumed to be already deferred, and the caller should be
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136 -- holding its own ATCB lock.
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137
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138 procedure Timed_Sleep
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139 (Self_ID : ST.Task_Id;
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140 Time : Duration;
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141 Mode : ST.Delay_Modes;
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142 Reason : System.Tasking.Task_States;
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143 Timedout : out Boolean;
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144 Yielded : out Boolean)
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145 is
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146 pragma Unreferenced (Reason);
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147
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148 Base_Time : Duration;
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149 Check_Time : Duration;
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150 Abs_Time : Duration;
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151 P_Abs_Time : Duration;
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152
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153 Request : aliased timespec;
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154 Result : Interfaces.C.int;
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155 Exit_Outer : Boolean := False;
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156
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157 begin
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158 Timedout := True;
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159 Yielded := False;
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160
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161 Compute_Deadline
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162 (Time => Time,
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163 Mode => Mode,
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164 Check_Time => Check_Time,
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165 Abs_Time => Abs_Time);
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166 Base_Time := Check_Time;
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167
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131
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168 -- To keep a sensible Max_Sensible_Delay on a target whose system
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169 -- maximum is less than sensible, we split the delay into manageable
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170 -- chunks of time less than or equal to the Max_System_Delay.
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171
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172 if Abs_Time > Check_Time then
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173
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174 Outer : loop
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175
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131
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176 pragma Warnings (Off, "condition is always *");
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177 if Max_System_Delay < Max_Sensible_Delay and then
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178 Abs_Time > Check_Time + Max_System_Delay
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179 then
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180 P_Abs_Time := Check_Time + Max_System_Delay;
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181 else
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182 P_Abs_Time := Abs_Time;
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183 Exit_Outer := True;
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184 end if;
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185 pragma Warnings (On);
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186
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187 Request := To_Timespec (P_Abs_Time);
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188
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189 Inner : loop
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190 exit Outer
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191 when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
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192
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193 Result :=
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194 pthread_cond_timedwait
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195 (cond => Self_ID.Common.LL.CV'Access,
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196 mutex => (if Single_Lock
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197 then Single_RTS_Lock'Access
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198 else Self_ID.Common.LL.L'Access),
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199 abstime => Request'Access);
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200
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131
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201 case Result is
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202 when 0 | EINTR =>
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203 -- Somebody may have called Wakeup for us
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204 Timedout := False;
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205 exit Outer;
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206
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207 when ETIMEDOUT =>
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208 exit Outer when Exit_Outer;
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209 Check_Time := Monotonic_Clock;
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210 exit Inner;
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211
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212 when others =>
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213 pragma Assert (False);
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214
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215 end case;
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216
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217 exit Outer
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218 when Abs_Time <= Check_Time or else Check_Time < Base_Time;
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219
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220 end loop Inner;
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221 end loop Outer;
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222 end if;
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223 end Timed_Sleep;
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224
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225 -----------------
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226 -- Timed_Delay --
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227 -----------------
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228
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229 -- This is for use in implementing delay statements, so we assume the
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230 -- caller is abort-deferred but is holding no locks.
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231
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232 procedure Timed_Delay
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233 (Self_ID : ST.Task_Id;
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234 Time : Duration;
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235 Mode : ST.Delay_Modes)
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236 is
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237 Base_Time : Duration;
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238 Check_Time : Duration;
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239 Abs_Time : Duration;
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240 P_Abs_Time : Duration;
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241 Request : aliased timespec;
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242
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243 Result : Interfaces.C.int;
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244 Exit_Outer : Boolean := False;
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111
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245
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246 begin
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247 if Single_Lock then
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248 Lock_RTS;
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249 end if;
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250
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251 Write_Lock (Self_ID);
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252
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253 Compute_Deadline
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254 (Time => Time,
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255 Mode => Mode,
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256 Check_Time => Check_Time,
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257 Abs_Time => Abs_Time);
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258 Base_Time := Check_Time;
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259
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131
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260 -- To keep a sensible Max_Sensible_Delay on a target whose system
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261 -- maximum is less than sensible, we split the delay into manageable
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262 -- chunks of time less than or equal to the Max_System_Delay.
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263
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264 if Abs_Time > Check_Time then
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265 Self_ID.Common.State := Delay_Sleep;
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266
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131
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267 Outer : loop
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268
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269 pragma Warnings (Off, "condition is always *");
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270 if Max_System_Delay < Max_Sensible_Delay and then
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271 Abs_Time > Check_Time + Max_System_Delay
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272 then
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273 P_Abs_Time := Check_Time + Max_System_Delay;
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274 else
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275 P_Abs_Time := Abs_Time;
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276 Exit_Outer := True;
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277 end if;
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278 pragma Warnings (On);
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279
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280 Request := To_Timespec (P_Abs_Time);
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281
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282 Inner : loop
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283 exit Outer
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284 when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
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285
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131
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286 Result :=
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287 pthread_cond_timedwait
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288 (cond => Self_ID.Common.LL.CV'Access,
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289 mutex => (if Single_Lock
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290 then Single_RTS_Lock'Access
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291 else Self_ID.Common.LL.L'Access),
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292 abstime => Request'Access);
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293
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131
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294 case Result is
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295 when ETIMEDOUT =>
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296 exit Outer when Exit_Outer;
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297 Check_Time := Monotonic_Clock;
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298 exit Inner;
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299
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300 when 0 | EINTR => null;
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111
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301
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131
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302 when others =>
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303 pragma Assert (False);
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304
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305 end case;
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306
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307 exit Outer
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308 when Abs_Time <= Check_Time or else Check_Time < Base_Time;
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309
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310 end loop Inner;
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311 end loop Outer;
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111
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312
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313 Self_ID.Common.State := Runnable;
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314 end if;
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315
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316 Unlock (Self_ID);
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317
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318 if Single_Lock then
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319 Unlock_RTS;
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320 end if;
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321
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131
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322 pragma Unreferenced (Result);
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111
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323 Result := sched_yield;
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324 end Timed_Delay;
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325
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326 end Monotonic;
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