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Add support for nested timeouts.
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We "fake" these by stopping the outer timeout and, if necessary,
restarting it after the inner one completes. There are annoyingly many
cases.
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@stevelinton @markuspf
stevelinton authored and markuspf committed Mar 7, 2016
1 parent 2bf271e commit ce694b2
Showing 1 changed file with 134 additions and 60 deletions.
194 changes: 134 additions & 60 deletions src/gap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1340,67 +1340,141 @@ Obj FuncSetUserHasQuit( Obj Self, Obj value)
}

Obj FuncCALL_WITH_TIMEOUT( Obj self, Obj seconds, Obj microseconds, Obj func, Obj args )
{
Obj res;
Obj currLVars;
Obj result;
Int recursionDepth;
Stat currStat;
{
Obj res;
Obj currLVars;
Obj result;
Int recursionDepth;
Stat currStat;
UInt newJumpBuf = 1;
UInt mayNeedToRestore = 0;
Int iseconds, imicroseconds;
Int curr_seconds, curr_microseconds, curr_nanoseconds;
Int restore_seconds = 0, restore_microseconds = 0;
if (!SyHaveAlarms)
ErrorMayQuit("CALL_WITH_TIMEOUT: timeouts not supported on this system", 0L, 0L);
if (!IS_INTOBJ(seconds) || 0 > INT_INTOBJ(seconds))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>, <args>):"
" <seconds> must be a non-negative small integer",0,0);
if (!IS_INTOBJ(microseconds) || 0 > INT_INTOBJ(microseconds) || 999999 < INT_INTOBJ(microseconds))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>, <args>):"
" <microseconds> must be a non-negative small integer less than 10^9",0,0);
iseconds = INT_INTOBJ(seconds);
imicroseconds = INT_INTOBJ(microseconds);
if (!IS_FUNC(func))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>, <args>): <func> must be a function",0,0);
if (!IS_LIST(args))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>, <args>): <args> must be a list",0,0);
if (SyAlarmRunning) {
/* ErrorMayQuit("CALL_WITH_TIMEOUT cannot currently be nested except via break loops."
" There is already a timeout running", 0, 0); */
SyStopAlarm((UInt *)&curr_seconds, (UInt *)&curr_nanoseconds);
curr_microseconds = curr_nanoseconds/1000;
if (iseconds > curr_seconds || (iseconds == curr_seconds && imicroseconds > curr_microseconds)) {
/* The existing timeout will go off before we would so don't bother to set a timeout
just reset the existing one and call the function */
iseconds = curr_seconds;
imicroseconds = curr_microseconds;
newJumpBuf = 0;
} else {
/* We would time out before the other function, so we need to
set our timeout, but remember to reset things later */
mayNeedToRestore = 1;
newJumpBuf = 1;
}
}
if (newJumpBuf) {
if (NumAlarmJumpBuffers >= MAX_TIMEOUT_NESTING_DEPTH-1)
ErrorMayQuit("Nesting depth of timeouts limited to %i", MAX_TIMEOUT_NESTING_DEPTH, 0L);
currLVars = TLS(CurrLVars);
currStat = TLS(CurrStat);
recursionDepth = TLS(RecursionDepth);
if (sySetjmp(AlarmJumpBuffers[NumAlarmJumpBuffers++])) {
/* Timeout happened */
TLS(CurrLVars) = currLVars;
TLS(PtrLVars) = PTR_BAG(TLS(CurrLVars));
TLS(PtrBody) = (Stat*)PTR_BAG(BODY_FUNC(CURR_FUNC));
TLS(CurrStat) = currStat;
TLS(RecursionDepth) = recursionDepth;
if (mayNeedToRestore) {
/* In this case we used our ration of CPU time,
so we know how much we need to restore
The jump buffer stack is already taken care of by the time we
get here */
restore_seconds = curr_seconds - iseconds;
restore_microseconds = curr_microseconds - imicroseconds;
if (restore_microseconds < 0) {
restore_microseconds += 1000000;
restore_seconds -= 1;
}
SyInstallAlarm(restore_seconds, 1000*restore_microseconds);
}
res = NEW_PLIST(T_PLIST_DENSE+IMMUTABLE,1);
SET_ELM_PLIST(res,1,False);
SET_LEN_PLIST(res,1);
return res;
}
}

/* Here we actually call the function */
SyInstallAlarm( iseconds, 1000*imicroseconds);
result = CallFuncList(func, args);

/* if newJumpBuf is false then we didn't set up our own alarm,
just reset the outer one,
and the outer one hasn't gone off yet, so we just return */
if (newJumpBuf) {
/* Here we did set our own alarm, but it hasn't gone off */
Int unused_seconds, unused_microseconds, unused_nanoseconds;
SyStopAlarm( (UInt *)&unused_seconds, (UInt *)&unused_nanoseconds);
unused_microseconds = unused_nanoseconds/1000;
/* Now the alarm might have gone off since we executed the last statement
of func. So */
if (SyAlarmHasGoneOff) {
SyAlarmHasGoneOff = 0;
UnInterruptExecStat();
}
assert(NumAlarmJumpBuffers);
NumAlarmJumpBuffers--;

if (!SyHaveAlarms)
ErrorMayQuit("CALL_WITH_TIMEOUT: timeouts not supported on this system", 0L, 0L);
if (!IS_INTOBJ(seconds) || 0 > INT_INTOBJ(seconds))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>, <args>):"
" <seconds> must be a non-negative small integer",0,0);
if (!IS_INTOBJ(microseconds) || 0 > INT_INTOBJ(microseconds) || 999999999 < INT_INTOBJ(microseconds))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>, <args>):"
" <microseconds> must be a non-negative small integer less than 10^9",0,0);
if (!IS_FUNC(func))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>,<args>): <func> must be a function",0,0);
if (!IS_LIST(args))
ErrorMayQuit("CALL_WITH_TIMEOUT(<seconds>, <microseconds>, <func>,<args>): <args> must be a list",0,0);
if (SyAlarmRunning) {
ErrorMayQuit("CALL_WITH_TIMEOUT cannot currently be nested except via break loops."
" There is already a timeout running", 0, 0);
}
if (NumAlarmJumpBuffers >= MAX_TIMEOUT_NESTING_DEPTH-1)
ErrorMayQuit("Nesting depth of timeouts via break loops limited to %i", MAX_TIMEOUT_NESTING_DEPTH, 0L);
currLVars = TLS(CurrLVars);
currStat = TLS(CurrStat);
recursionDepth = TLS(RecursionDepth);
res = NEW_PLIST( T_PLIST_DENSE+IMMUTABLE, 2 );
SET_LEN_PLIST(res, 1);
if (sySetjmp(AlarmJumpBuffers[NumAlarmJumpBuffers++])) {
/* Timeout happened */
TLS(CurrLVars) = currLVars;
TLS(PtrLVars) = PTR_BAG(TLS(CurrLVars));
TLS(PtrBody) = (Stat*)PTR_BAG(BODY_FUNC(CURR_FUNC));
TLS(CurrStat) = currStat;
TLS(RecursionDepth) = recursionDepth;
SET_ELM_PLIST(res, 1, False);
} else {
SyInstallAlarm( INT_INTOBJ(seconds), 1000*INT_INTOBJ(microseconds));
result = CallFuncList(func, args);
/* make sure the alarm is not still running */
SyStopAlarm( NULL, NULL);
/* Now the alarm might have gone off since we executed the last statement
of func. So */
if (SyAlarmHasGoneOff) {
SyAlarmHasGoneOff = 0;
UnInterruptExecStat();
}
assert(NumAlarmJumpBuffers);
NumAlarmJumpBuffers--;
SET_ELM_PLIST(res,1,True);
if (result)
{
SET_LEN_PLIST(res,2);
SET_ELM_PLIST(res,2,result);
}
}
CHANGED_BAG(res);
return res;
}
/* If there is an outer timer, we need to reset it */
if (mayNeedToRestore) {
restore_seconds = curr_seconds - (iseconds - unused_seconds);
restore_microseconds = curr_microseconds - (imicroseconds - unused_microseconds);
while (restore_microseconds < 0) {
restore_microseconds += 1000000;
restore_seconds -= 1;
}
while (restore_microseconds > 999999) {
restore_microseconds -= 1000000;
restore_seconds += 1;
}

/* nasty hack -- if the outer timer was right on the edge of going off
and we try to restore it to zero we will actually stop it */
if (!restore_seconds && !restore_microseconds)
restore_microseconds = 1;

SyInstallAlarm(restore_seconds, 1000*restore_microseconds);
}

}

/* assemble and return the result */
res = NEW_PLIST(T_PLIST_DENSE+IMMUTABLE, 2);
SET_ELM_PLIST(res,1,True);
if (result)
{
SET_LEN_PLIST(res,2);
SET_ELM_PLIST(res,2,result);
CHANGED_BAG(res);
}
else {
SET_LEN_PLIST(res,1);
}
return res;
}

Obj FuncSTOP_TIMEOUT( Obj self ) {
UInt seconds, nanoseconds;
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