bool Throttle::requestPermission(int numActions,
const bsls::TimeInterval& now)
{
#if defined(BSLS_ASSERT_IS_ACTIVE)
BSLS_ASSERT(0 < numActions);
BSLS_ASSERT(now.seconds() <= k_MAX_SECONDS);
BSLS_ASSERT(now.seconds() >= k_MIN_SECONDS);
const Int64 sns = k_BILLION * now.seconds(); // Seconds in NanoSeconds
if (0 <= sns) {
BSLS_ASSERT(LLONG_MAX - sns > now.nanoseconds());
}
else {
BSLS_ASSERT(LLONG_MIN - sns < now.nanoseconds());
}
#endif
if (d_maxSimultaneousActions < numActions) {
BSLS_ASSERT(0 == d_maxSimultaneousActions);
// It is best to deal with the 'allow none' case here. We have to do
// the above two conditions just for asserts on our way into the
// method, and if we don't handle the
// 'd_maxSimultaneousActions < numActions' case here we risk undefined
// behavior due to signed arithmetic overflow later on.
return false; // RETURN
}
// Testing for 'k_ALLOW_ALL' here prevents undefined behavior later in the
// function due to overflowing signed arithmetic.
if (k_ALLOW_ALL == d_nanosecondsPerAction) {
return true; // RETURN
}
const Int64 currentTime = now.totalNanoseconds();
const Int64 requiredTime = numActions * d_nanosecondsPerAction;
const Int64 lagTime = d_nanosecondsPerTotalReset - requiredTime;
Int64 prevLeakTime = AtomicOps::getInt64Acquire(&d_prevLeakTime);
while (true) {
const Int64 timeDiff = currentTime - prevLeakTime;
if (timeDiff < requiredTime) {
return false; // RETURN
}
const Int64 nextLeakTime = d_nanosecondsPerTotalReset <= timeDiff
? currentTime - lagTime
: prevLeakTime + requiredTime;
const Int64 swappedLeakTime = AtomicOps::testAndSwapInt64AcqRel(
&d_prevLeakTime,
prevLeakTime,
nextLeakTime);
if (swappedLeakTime == prevLeakTime) {
return true; // RETURN
}
prevLeakTime = swappedLeakTime;
}
}
bool Throttle::requestPermission(const bsls::TimeInterval& now)
{
#if defined(BSLS_ASSERT_IS_ACTIVE)
BSLS_ASSERT(now.seconds() <= k_MAX_SECONDS);
BSLS_ASSERT(now.seconds() >= k_MIN_SECONDS);
const Int64 sns = k_BILLION * now.seconds(); // Seconds in NanoSeconds
if (0 <= sns) {
BSLS_ASSERT(LLONG_MAX - sns > now.nanoseconds());
}
else {
BSLS_ASSERT(LLONG_MIN - sns < now.nanoseconds());
}
#endif
// Special casing 'allow all' here prevents undefined behavior later in
// the function due to overflowing signed arithmetic.
if (k_ALLOW_ALL == d_nanosecondsPerAction) {
return true; // RETURN
}
const Int64 currentTime = now.totalNanoseconds();
Int64 prevLeakTime = AtomicOps::getInt64Acquire(&d_prevLeakTime);
while (true) {
const Int64 timeDiff = currentTime - prevLeakTime;
if (timeDiff < d_nanosecondsPerAction) {
return false; // RETURN
}
const Int64 nextLeakTime =
d_nanosecondsPerTotalReset <= timeDiff
? currentTime - d_nanosecondsPerTotalReset + d_nanosecondsPerAction
: prevLeakTime + d_nanosecondsPerAction;
const Int64 swappedLeakTime = AtomicOps::testAndSwapInt64AcqRel(
&d_prevLeakTime,
prevLeakTime,
nextLeakTime);
if (swappedLeakTime == prevLeakTime) {
return true; // RETURN
}
prevLeakTime = swappedLeakTime;
}
}
int Throttle::requestPermissionIfValid(bool *result,
int numActions,
const bsls::TimeInterval& now)
{
if (numActions <= 0 || (d_maxSimultaneousActions < numActions &&
0 != d_maxSimultaneousActions)) {
return -1; // RETURN
}
if (k_MAX_SECONDS < now.seconds() || now.seconds() < k_MIN_SECONDS) {
return -1; // RETURN
}
const Int64 sns = k_BILLION * now.seconds(); // Seconds in NanoSeconds
if (0 <= sns ? LLONG_MAX - sns < now.nanoseconds()
: LLONG_MIN - sns > now.nanoseconds()) {
return -1; // RETURN
}
*result = this->requestPermission(numActions, now);
return 0;
}