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/*
* Copyright 2018 Google
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "Firestore/core/include/firebase/firestore/timestamp.h"
#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
namespace firebase {
Timestamp::Timestamp() {
}
Timestamp::Timestamp(const int64_t seconds, const int32_t nanoseconds)
: seconds_(seconds), nanoseconds_(nanoseconds) {
ValidateBounds();
}
Timestamp Timestamp::Now() {
#if !defined(_STLPORT_VERSION)
// Use the standard <chrono> library from C++11 if possible.
return FromTimePoint(std::chrono::system_clock::now());
#else
// If <chrono> is unavailable, use clock_gettime from POSIX, which supports up
// to nanosecond resolution. Note that it's a non-standard function contained
// in <time.h>.
//
// Note: it's possible to check for availability of POSIX clock_gettime using
// macros (see "Availability" at https://linux.die.net/man/3/clock_gettime).
// However, the only platform where <chrono> isn't available is Android with
// STLPort standard library, where clock_gettime is known to be available.
timespec now;
clock_gettime(CLOCK_REALTIME, &now);
return Timestamp(now.tv_sec, now.tv_nsec);
#endif // !defined(_STLPORT_VERSION)
}
Timestamp Timestamp::FromTimeT(const time_t seconds_since_unix_epoch) {
return {seconds_since_unix_epoch, 0};
}
#if !defined(_STLPORT_VERSION)
Timestamp Timestamp::FromTimePoint(
const std::chrono::time_point<std::chrono::system_clock> time_point) {
namespace chr = std::chrono;
const auto epoch_time = time_point.time_since_epoch();
auto seconds = chr::duration_cast<chr::duration<int64_t>>(epoch_time);
auto nanoseconds = chr::duration_cast<chr::nanoseconds>(epoch_time - seconds);
HARD_ASSERT(nanoseconds.count() < 1 * 1000 * 1000 * 1000);
if (nanoseconds.count() < 0) {
// Timestamp format always has a positive number of nanoseconds that is
// counting forward. For negative time, we need to transform chrono
// representation of (negative seconds s1 + negative nanoseconds ns1) to
// (negative seconds s2 + positive nanoseconds ns2). Since nanosecond part
// is always less than 1 second in our representation, instead of starting
// at s1 and going back ns1 nanoseconds, start at (s1 minus one second) and
// go *forward* ns2 = (1 second + ns1, ns1 < 0) nanoseconds.
//
// Note: if nanoseconds are negative, it must mean that seconds are
// non-positive, but the formula would still be valid, so no need to check.
seconds = seconds - chr::seconds(1);
nanoseconds = chr::seconds(1) + nanoseconds;
}
const Timestamp result{seconds.count(),
static_cast<int32_t>(nanoseconds.count())};
result.ValidateBounds();
return result;
}
#endif // !defined(_STLPORT_VERSION)
std::string Timestamp::ToString() const {
return std::string("Timestamp(seconds=") + std::to_string(seconds_) +
", nanoseconds=" + std::to_string(nanoseconds_) + ")";
}
void Timestamp::ValidateBounds() const {
HARD_ASSERT(nanoseconds_ >= 0, "Timestamp nanoseconds out of range: %s",
nanoseconds_);
HARD_ASSERT(nanoseconds_ < 1e9, "Timestamp nanoseconds out of range: %s",
nanoseconds_);
// Midnight at the beginning of 1/1/1 is the earliest timestamp Firestore
// supports.
HARD_ASSERT(seconds_ >= -62135596800L, "Timestamp seconds out of range: %s",
seconds_);
// This will break in the year 10,000.
HARD_ASSERT(seconds_ < 253402300800L, "Timestamp seconds out of range: %s",
seconds_);
}
} // namespace firebase
namespace std {
size_t hash<firebase::Timestamp>::operator()(
const firebase::Timestamp& timestamp) const {
// Note: if sizeof(size_t) == 4, this discards high-order bits of seconds.
return 37 * static_cast<size_t>(timestamp.seconds()) +
static_cast<size_t>(timestamp.nanoseconds());
}
} // namespace std
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