Prep for FIRTimestampValue migration to C++ (#3155)

* Clean up GeoPoint port to C++

... based on things learned porting Timestamps.

There's no good way to include conversions equivalent to toGeoPoint in
FIRTimestamp, so pull out separate conversion functions that match other
similar things.

* Extract MakeTimePoint into time_testing.h

... for reuse elsewhere

* Add TimestampInternal Hash/Truncate

* Use a method similar to NSDate to get current time on apple platforms

Author: wilhuff

Firestore/Example/Firestore.xcodeproj/project.pbxproj

@@ -107,6 +107,7 @@
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+		2D220B9ABFA36CD7AC43D0A7 /* time_testing.cc in Sources */ = {isa = PBXBuildFile; fileRef = 5497CB76229DECDE000FB92F /* time_testing.cc */; };
 		2E0BBA7E627EB240BA11B0D0 /* exponential_backoff_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = B6D1B68420E2AB1A00B35856 /* exponential_backoff_test.cc */; };
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@@ -273,6 +274,9 @@
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 		5495EB032040E90200EBA509 /* CodableGeoPointTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5495EB022040E90200EBA509 /* CodableGeoPointTests.swift */; };
+		5497CB77229DECDE000FB92F /* time_testing.cc in Sources */ = {isa = PBXBuildFile; fileRef = 5497CB76229DECDE000FB92F /* time_testing.cc */; };
+		5497CB78229DECDE000FB92F /* time_testing.cc in Sources */ = {isa = PBXBuildFile; fileRef = 5497CB76229DECDE000FB92F /* time_testing.cc */; };
+		5497CB79229DECDE000FB92F /* time_testing.cc in Sources */ = {isa = PBXBuildFile; fileRef = 5497CB76229DECDE000FB92F /* time_testing.cc */; };
 		54995F6F205B6E12004EFFA0 /* leveldb_key_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = 54995F6E205B6E12004EFFA0 /* leveldb_key_test.cc */; };
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@@ -371,6 +375,7 @@
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+		6300709ECDE8E0B5A8645F8D /* time_testing.cc in Sources */ = {isa = PBXBuildFile; fileRef = 5497CB76229DECDE000FB92F /* time_testing.cc */; };
 		63BB61B6366E7F80C348419D /* FSTLevelDBTransactionTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 132E36BB104830BD806351AC /* FSTLevelDBTransactionTests.mm */; };
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@@ -468,6 +473,7 @@
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+		A25FF76DEF542E01A2DF3B0E /* time_testing.cc in Sources */ = {isa = PBXBuildFile; fileRef = 5497CB76229DECDE000FB92F /* time_testing.cc */; };
 		A21819C437C3C80450D7EEEE /* writer_test.cc in Sources */ = {isa = PBXBuildFile; fileRef = BC3C788D290A935C353CEAA1 /* writer_test.cc */; };
 		A38F4AE525A87FDEA41DED47 /* FSTLevelDBQueryCacheTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E0982021552C00B64F25 /* FSTLevelDBQueryCacheTests.mm */; };
 		A4ECA8335000CBDF94586C94 /* FSTDatastoreTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 5492E07E202154EC00B64F25 /* FSTDatastoreTests.mm */; };
@@ -775,7 +781,8 @@
 		4425A513895DEC60325A139E /* xcgmock_test.mm */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.cpp.objcpp; path = xcgmock_test.mm; sourceTree = "<group>"; };
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-		5342CDDB137B4E93E2E85CCA /* byte_string_test.cc */ = {isa = PBXFileReference; includeInIndex = 1; name = byte_string_test.cc; path = nanopb/byte_string_test.cc; sourceTree = "<group>"; };
+		5342CDDB137B4E93E2E85CCA /* byte_string_test.cc */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.cpp.cpp; name = byte_string_test.cc; path = nanopb/byte_string_test.cc; sourceTree = "<group>"; };
+		535B1420A19BEAA7FA4D77C8 /* ordered_code_benchmark.mm */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.cpp.objcpp; path = ordered_code_benchmark.mm; sourceTree = "<group>"; };
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 		544129D121C2DDC800EFB9CC /* common.pb.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = common.pb.h; sourceTree = "<group>"; };
@@ -865,6 +872,8 @@
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+		5497CB75229DECDE000FB92F /* time_testing.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = time_testing.h; sourceTree = "<group>"; };
+		5497CB76229DECDE000FB92F /* time_testing.cc */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = time_testing.cc; sourceTree = "<group>"; };
 		54995F6E205B6E12004EFFA0 /* leveldb_key_test.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = leveldb_key_test.cc; sourceTree = "<group>"; };
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@@ -1237,6 +1246,8 @@
 				CD422AF3E4515FB8E9BE67A0 /* equals_tester.h */,
 				54A0352820A3B3BD003E0143 /* testutil.cc */,
 				54A0352920A3B3BD003E0143 /* testutil.h */,
+				5497CB76229DECDE000FB92F /* time_testing.cc */,
+				5497CB75229DECDE000FB92F /* time_testing.h */,
 				BA6E5B9D53CCF301F58A62D7 /* xcgmock.h */,
 				4425A513895DEC60325A139E /* xcgmock_test.mm */,
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@@ -3130,6 +3141,7 @@
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 				E764F0F389E7119220EB212C /* target_id_generator_test.cc in Sources */,
 				32A95242C56A1A230231DB6A /* testutil.cc in Sources */,
+				5497CB78229DECDE000FB92F /* time_testing.cc in Sources */,
 				ACC9369843F5ED3BD2284078 /* timestamp_test.cc in Sources */,
 				2AAEABFD550255271E3BAC91 /* to_string_apple_test.mm in Sources */,
 				1E2AE064CF32A604DC7BFD4D /* to_string_test.cc in Sources */,
@@ -3306,6 +3318,7 @@
 				81B23D2D4E061074958AF12F /* target.pb.cc in Sources */,
 				DA4303684707606318E1914D /* target_id_generator_test.cc in Sources */,
 				8388418F43042605FB9BFB92 /* testutil.cc in Sources */,
+				5497CB79229DECDE000FB92F /* time_testing.cc in Sources */,
 				26CB3D7C871BC56456C6021E /* timestamp_test.cc in Sources */,
 				5BE49546D57C43DDFCDB6FBD /* to_string_apple_test.mm in Sources */,
 				E500AB82DF2E7F3AFDB1AB3F /* to_string_test.cc in Sources */,
@@ -3345,6 +3358,7 @@
 				4D42E5C756229C08560DD731 /* XCTestCase+Await.mm in Sources */,
 				7B8D7BAC1A075DB773230505 /* app_testing.mm in Sources */,
 				409C0F2BFC2E1BECFFAC4D32 /* testutil.cc in Sources */,
+				6300709ECDE8E0B5A8645F8D /* time_testing.cc in Sources */,
 				1EF47EF3D03B0847007C2318 /* xcgmock_test.mm in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -3374,6 +3388,7 @@
 				736C4E82689F1CA1859C4A3F /* XCTestCase+Await.mm in Sources */,
 				8F4F40E9BC7ED588F67734D5 /* app_testing.mm in Sources */,
 				A17DBC8F24127DA8A381F865 /* testutil.cc in Sources */,
+				A25FF76DEF542E01A2DF3B0E /* time_testing.cc in Sources */,
 				A94884460990CD48CC0AD070 /* xcgmock_test.mm in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -3557,6 +3572,7 @@
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 				AB380CFB2019388600D97691 /* target_id_generator_test.cc in Sources */,
 				54A0352A20A3B3BD003E0143 /* testutil.cc in Sources */,
+				5497CB77229DECDE000FB92F /* time_testing.cc in Sources */,
 				ABF6506C201131F8005F2C74 /* timestamp_test.cc in Sources */,
 				B68B1E012213A765008977EF /* to_string_apple_test.mm in Sources */,
 				B696858E2214B53900271095 /* to_string_test.cc in Sources */,
@@ -3615,6 +3631,7 @@
 				5492E0442021457E00B64F25 /* XCTestCase+Await.mm in Sources */,
 				EBFC611B1BF195D0EC710AF4 /* app_testing.mm in Sources */,
 				CA989C0E6020C372A62B7062 /* testutil.cc in Sources */,
+				2D220B9ABFA36CD7AC43D0A7 /* time_testing.cc in Sources */,
 				4D1F46B2DD91198C8867C04C /* xcgmock_test.mm in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Firestore/core/include/firebase/firestore/timestamp.h

@@ -46,7 +46,7 @@ class Timestamp {
    * Creates a new timestamp representing the epoch (with seconds and
    * nanoseconds set to 0).
    */
-  Timestamp();
+  Timestamp() = default;
 
   /**
    * Creates a new timestamp.

Firestore/core/src/firebase/firestore/CMakeLists.txt

@@ -18,6 +18,7 @@ cc_library(
   SOURCES
     geo_point.cc
     timestamp.cc
+    timestamp_internal.cc
     timestamp_internal.h
   DEPENDS
     firebase_firestore_util

Firestore/core/src/firebase/firestore/model/field_value.cc

@@ -25,6 +25,7 @@
 #include <vector>
 
 #include "Firestore/core/src/firebase/firestore/immutable/sorted_map.h"
+#include "Firestore/core/src/firebase/firestore/timestamp_internal.h"
 #include "Firestore/core/src/firebase/firestore/util/comparison.h"
 #include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 #include "Firestore/core/src/firebase/firestore/util/hashing.h"
@@ -241,7 +242,7 @@ class TimestampValue : public BaseValue {
   }
 
   size_t Hash() const override {
-    return util::Hash(value().seconds(), value().nanoseconds());
+    return TimestampInternal::Hash(value());
   }
 
   const Timestamp& value() const {
@@ -293,9 +294,7 @@ class ServerTimestampValue : public FieldValue::BaseValue {
   }
 
   size_t Hash() const override {
-    size_t result = util::Hash(local_write_time_.seconds(),
-                               local_write_time_.nanoseconds());
-
+    size_t result = TimestampInternal::Hash(local_write_time_);
     if (previous_value_) {
       result = util::Hash(result, *previous_value_);
     }

Firestore/core/src/firebase/firestore/timestamp.cc

@@ -18,35 +18,84 @@
 
 #include <ostream>
 
+#if defined(__APPLE__)
+#import <CoreFoundation/CoreFoundation.h>
+#elif defined(_STLPORT_VERSION)
+#include <ctime>
+#endif
+
 #include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 #include "absl/strings/str_cat.h"
 
 namespace firebase {
 
-Timestamp::Timestamp() {
+namespace {
+
+// We pass it by value without std::move.
+static_assert(std::is_trivially_copyable<Timestamp>::value,
+              "Timestamp must be trivially copyable");
+
+constexpr int32_t kNanosPerSecond = 1E9;
+
+/**
+ * Creates a `Timestamp` from the given non-normalized inputs.
+ *
+ * Timestamp protos require `Timestamp` to always has a positive number of
+ * nanoseconds that is counting forward. For negative time, we need to adjust
+ * representations with negative nanoseconds. That is, make (negative seconds s1
+ * + negative nanoseconds ns1) into (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.
+ */
+Timestamp MakeNormalizedTimestamp(int64_t seconds, int64_t nanos) {
+  if (nanos < 0) {
+    // 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 - 1;
+    nanos = kNanosPerSecond + nanos;
+  }
+
+  HARD_ASSERT(nanos < kNanosPerSecond);
+
+  return {seconds, static_cast<int32_t>(nanos)};
 }
 
+}  // namespace
+
 Timestamp::Timestamp(const int64_t seconds, const int32_t nanoseconds)
     : seconds_(seconds), nanoseconds_(nanoseconds) {
   ValidateBounds();
 }
 
 Timestamp Timestamp::Now() {
-#if !defined(_STLPORT_VERSION)
+#if defined(__APPLE__)
+  // Originally, FIRTimestamp used NSDate to get current time. This method
+  // preserves the lower accuracy of that method.
+  CFAbsoluteTime now =
+      CFAbsoluteTimeGetCurrent() + kCFAbsoluteTimeIntervalSince1970;
+  double seconds_double;
+  double fraction = modf(now, &seconds_double);
+  auto seconds = static_cast<int64_t>(seconds_double);
+  auto nanos = static_cast<int32_t>(fraction * kNanosPerSecond);
+  return MakeNormalizedTimestamp(seconds, nanos);
+
+#elif !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>.
+  // 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);
+  return MakeNormalizedTimestamp(now.tv_sec, now.tv_nsec);
 #endif  // !defined(_STLPORT_VERSION)
 }
 
@@ -60,26 +109,9 @@ Timestamp Timestamp::FromTimePoint(
   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;
-  }
+  auto nanos = chr::duration_cast<chr::nanoseconds>(epoch_time - seconds);
 
-  const Timestamp result{seconds.count(),
-                         static_cast<int32_t>(nanoseconds.count())};
+  Timestamp result = MakeNormalizedTimestamp(seconds.count(), nanos.count());
   result.ValidateBounds();
   return result;
 }
@@ -98,8 +130,8 @@ std::ostream& operator<<(std::ostream& out, const Timestamp& timestamp) {
 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_);
+  HARD_ASSERT(nanoseconds_ < kNanosPerSecond,
+              "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",

Firestore/core/src/firebase/firestore/timestamp_internal.cc

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2019 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/src/firebase/firestore/timestamp_internal.h"
+
+#include "Firestore/core/src/firebase/firestore/util/hashing.h"
+
+namespace util = firebase::firestore::util;
+
+namespace firebase {
+
+size_t TimestampInternal::Hash(const Timestamp& timestamp) {
+  return util::Hash(timestamp.seconds(), timestamp.nanoseconds());
+}
+
+Timestamp TimestampInternal::Truncate(const Timestamp& timestamp) {
+  int32_t truncated_nanos = timestamp.nanoseconds() / 1000 * 1000;
+  return Timestamp(timestamp.seconds(), truncated_nanos);
+}
+
+}  // namespace firebase

Firestore/core/src/firebase/firestore/timestamp_internal.h

@@ -42,6 +42,14 @@ class TimestampInternal {
   static firebase::Timestamp Min() {
     return {-62135596800L, 0};
   }
+
+  static size_t Hash(const Timestamp& timestamp);
+
+  /**
+   * Truncates the input timestamp to microsecond precision to match backend
+   * behavior.
+   */
+  static Timestamp Truncate(const Timestamp& timestamp);
 };
 
 }  // namespace firebase

Firestore/core/test/firebase/firestore/CMakeLists.txt

@@ -18,5 +18,6 @@ cc_test(
     geo_point_test.cc
     timestamp_test.cc
   DEPENDS
+    absl_time
     firebase_firestore_types
 )